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• Java: immutability, overuse of stack -- better data structure?

  - by HH

  I overused hashSets but it was slow, then changed to Stacks, speed boost-up. Poly's reply uses Collections.emptyList() as immutable list, cutting out excess null-checkers. No Collections.emptyStack(). Combining the words stack and immutability, from the last experiences, gets "immutable stack" (probably not related to functional prog). Java Api 5 for list interface shows that Stack is an implementing class for list and arraylist, here. The java.coccurrent pkg does not have any immutable Stack data structure. The first hinted of misusing stack. The lack of immutabily in the last and poly's book recommendation leads way to list. Something very primitive, fast, no extra layers, with methods like emptyThing(). Overuse of stack and where I use it DataFile.java: public Stack<DataFile> files; FileObject.java: public Stack<String> printViews = new Stack<String>(); FileObject.java:// private static Stack<Object> getFormat(File f){return (new Format(f)).getFormat();} Format.java: private Stack<Object> getLine(File[] fs,String s){return wF;} Format.java: private Stack<Object> getFormat(){return format;} Positions.java: public static Stack<Integer[]> getPrintPoss(String s,File f,Integer maxViewPerF) Positions.java: Stack<File> possPrint = new Stack<File>(); Positions.java: Stack<Integer> positions=new Stack<Integer>(); Record.java: private String getFormatLine(Stack<Object> st) Record.java: Stack<String> lines=new Stack<String>(); SearchToUser.java: public static final Stack<File> allFiles = findf.getFs(); SearchToUser.java: public static final Stack<File> allDirs = findf.getDs(); SearchToUser.java: private Stack<Integer[]> positionsPrint=new Stack<Integer[]>(); SearchToUser.java: public Stack<String> getSearchResults(String s, Integer countPerFile, Integer resCount) SearchToUser.java: Stack<File> filesToS=Fs2Word.getFs2W(s,50); SearchToUser.java: Stack<String> rs=new Stack<String>(); View.java: public Stack<Integer[]> poss = new Stack<Integer[4]>(); View.java: public static Stack<String> getPrintViewsFileWise(String s,Object[] df,Integer maxViewsPerF) View.java: Stack<String> substrings = new Stack<String>(); View.java: private Stack<String> printViews=new Stack<String>(); View.java: MatchView(Stack<Integer> pss,File f,Integer maxViews) View.java: Stack<String> formatFile; View.java: private Stack<Search> files; View.java: private Stack<File> matchingFiles; View.java: private Stack<String> matchViews; View.java: private Stack<String> searchMatches; View.java: private Stack<String> getSearchResults(Integer numbResults) Easier with List: AllDirs and AllFs, now looping with push, but list has more pow. methods such as addAll [OLD] From Stack to some immutable data structure How to get immutable Stack data structure? Can I box it with list? Should I switch my current implementatios from stacks to Lists to get immutable? Which immutable data structure is Very fast with about similar exec time as Stack? No immutability to Stack with Final import java.io.*; import java.util.*; public class TestStack{ public static void main(String[] args) { final Stack<Integer> test = new Stack<Integer>(); Stack<Integer> test2 = new Stack<Integer>(); test.push(37707); test2.push(80437707); //WHY is there not an error to remove an elment // from FINAL stack? System.out.println(test.pop()); System.out.println(test2.pop()); } }

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• Elusive race condition in Java

  - by nasufara

  I am creating a graphing calculator. In an attempt to squeeze some more performance out of it, I added some multithreaded to the line calculator. Essentially what my current implementation does is construct a thread-safe Queue of X values, then start however many threads it needs, each one calculating a point on the line using the queue to get its values, and then ordering the points using a HashMap when the calculations are done. This implementation works great, and that's not where my race condition is (merely some background info). In examining the performance results from this, I found that the HashMap is a performance bottleneck, since I do that synchronously on one thread. So I figured that ordering each point as its calculated would work best. I tried a PriorityQueue, but that was slower than the HashMap. I ended up creating an algorithm that essentially works like this: I construct a list of X values to calculate, like in my current algorithm. I then copy that list of values into another class, unimaginatively and temporarily named BlockingList, which is responsible for ordering the points as they are calculated. BlockingList contains a put() method, which takes in two BigDecimals as parameters, the first the X value, the second the calculated Y value. put() will only accept a value if the X value is the next one on the list to be accepted in the list of X values, and will block until another thread gives it the next excepted value. For example, since that can be confusing, say I have two threads, Thread-1 and Thread-2. Thread-2 gets the X value 10.0 from the values queue, and Thread-1 gets 9.0. However, Thread-1 completes its calculations first, and calls put() before Thread-2 does. Because BlockingList is expecting to get 10.0 first, and not 9.0, it will block on Thread-1 until Thread-2 finishes and calls put(). Once Thread-2 gives BlockingList 10.0, it notify()s all waiting threads, and expects 9.0 next. This continues until BlockingList gets all of its expected values. (I apologise if that was hard to follow, if you need more clarification, just ask.) As expected by the question title, there is a race condition in here. If I run it without any System.out.printlns, it will sometimes lock because of conflicting wait() and notifyAll()s, but if I put a println in, it will run great. A small implementation of this is included below, and exhibits the same behavior: import java.math.BigDecimal; import java.util.concurrent.ConcurrentLinkedQueue; public class Example { public static void main(String[] args) throws InterruptedException { // Various scaling values, determined based on the graph size // in the real implementation BigDecimal xMax = new BigDecimal(10); BigDecimal xStep = new BigDecimal(0.05); // Construct the values list, from -10 to 10 final ConcurrentLinkedQueue<BigDecimal> values = new ConcurrentLinkedQueue<BigDecimal>(); for (BigDecimal i = new BigDecimal(-10); i.compareTo(xMax) <= 0; i = i.add(xStep)) { values.add(i); } // Contains the calculated values final BlockingList list = new BlockingList(values); for (int i = 0; i < 4; i++) { new Thread() { public void run() { BigDecimal x; // Keep looping until there are no more values while ((x = values.poll()) != null) { PointPair pair = new PointPair(); pair.realX = x; try { list.put(pair); } catch (Exception ex) { ex.printStackTrace(); } } } }.start(); } } private static class PointPair { public BigDecimal realX; } private static class BlockingList { private final ConcurrentLinkedQueue<BigDecimal> _values; private final ConcurrentLinkedQueue<PointPair> _list = new ConcurrentLinkedQueue<PointPair>(); public BlockingList(ConcurrentLinkedQueue<BigDecimal> expectedValues) throws InterruptedException { // Copy the values into a new queue BigDecimal[] arr = expectedValues.toArray(new BigDecimal[0]); _values = new ConcurrentLinkedQueue<BigDecimal>(); for (BigDecimal dec : arr) { _values.add(dec); } } public void put(PointPair item) throws InterruptedException { while (item.realX.compareTo(_values.peek()) != 0) { synchronized (this) { // Block until someone enters the next desired value wait(); } } _list.add(item); _values.poll(); synchronized (this) { notifyAll(); } } } } My question is can anybody help me find the threading error? Thanks!

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• jQuery Templates - {Supported Tags}

  - by hajan

  I have started with Introduction to jQuery Templates, then jQuery Templates - tmpl(), template() and tmplItem() functions. In this blog we will see what supported tags are available in the jQuery Templates plugin.Template tags can be used inside template together in combination with HTML tags and plain text, which helps to iterate over JSON data. Up to now, there are several supported tags in jQuery Templates plugin: ${expr} or {{= expr}} {{each itemArray}} … {{/each}} {{if condition}} … {{else}} … {{/if}} {{html …}} {{tmpl …}} {{wrap …}} … {{/wrap}}   - ${expr} or {{= expr}} Is used for insertion of data values in the rendered template. It can evaluate fields, functions or expression. Example: <script id="attendeesTemplate" type="text/html">     <li> ${Name} {{= Surname}} </li>         </script> Either ${Name} or {{= Surname}} (with blank space between =<blankspace>Field) will work.   - {{each itemArray}} … {{/each}} each is everywhere the same "(for)each", used to loop over array or collection Example: <script id="attendeesTemplate" type="text/html">     <li>         ${Name} ${Surname}         {{if speaker}}             (<font color="red">speaks</font>)         {{else}}             (attendee)         {{/if}}                 {{each phones}}                             <br />             ${$index}: <em>${$value}</em>         {{/each}}             </li> </script> So, you see we can use ${$index} and ${$value} to get the current index and value while iterating over the item collection. Alternatively, you can add index,value on the following way: {{each(i,v) phones}}     <br />     ${i}: <em>${v}</em> {{/each}} Result would be: Here is complete working example that you can run and see the result: <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">     <title>Nesting and Looping Example :: jQuery Templates</title>     <script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.4.min.js" type="text/javascript"></script>     <script src="http://ajax.aspnetcdn.com/ajax/jquery.templates/beta1/jquery.tmpl.js" type="text/javascript"></script>     <script language="javascript" type="text/javascript">         $(function () {             var attendees = [                 { Name: "Hajan", Surname: "Selmani", speaker: true, phones:[070555555, 071888999, 071222333] },                 { Name: "Someone", Surname: "Surname", phones: [070555555, 071222333] },                 { Name: "Third", Surname: "Thirdsurname", phones: [070555555, 071888999, 071222333] },             ];             $("#attendeesTemplate").tmpl(attendees).appendTo("#attendeesList");         });     </script>     <script id="attendeesTemplate" type="text/html">         <li>             ${Name} ${Surname}             {{if speaker}}                 (<font color="red">speaks</font>)             {{else}}                 (attendee)             {{/if}}                     {{each(i,v) phones}}                 <br />                 ${i}: <em>${v}</em>             {{/each}}                 </li>     </script> </head> <body>     <ol id="attendeesList"></ol>     </body> </html>   - {{if condition}} … {{else}} … {{/if}} Standard if/else statement. Of course, you can use it without the {{else}} if you have such condition to check, however closing the {{/if}} tag is required. Example: {{if speaker}}     (<font color="red">speaks</font>) {{else}}     (attendee) {{/if}} You have this same code block in the above complete example showing the 'each' cycle ;).   - {{html …}} Is used for insertion of HTML markup strings in the rendered template. Evaluates the specified field on the current data item, or the specified JavaScript function or expression. Example: - without {{html …}} <script language="javascript" type="text/javascript">   $(function () {   var attendees = [             { Name: "Hajan", Surname: "Selmani", Info: "He <font color='red'>is the speaker of today's</font> session", speaker: true },         ];   $("#myTemplate").tmpl(attendees).appendTo("#speakers"); }); </script> <script id="myTemplate" type="text/html">     ${Name} ${Surname} <br />     ${Info} </script> Result: - with {{html …}} <script language="javascript" type="text/javascript">   $(function () {   var attendees = [             { Name: "Hajan", Surname: "Selmani", Info: "He <font color='red'>is the speaker of today's</font> session", speaker: true },         ];   $("#myTemplate").tmpl(attendees).appendTo("#speakers"); }); </script> <script id="myTemplate" type="text/html">     ${Name} ${Surname} <br />     {{html Info}} </script> Result:   - {{wrap …}} It’s used for composition and incorporation of wrapped HTML. It’s similar to {{tmpl}} Example: <script id="myTmpl" type="text/html">     <div id="personInfo">     <br />     ${Name} ${Surname}     {{wrap "#myWrapper"}}         <h2>${Info}</h2>         <div>             {{if speaker}}                 (speaker)             {{else}}                 (attendee)             {{/if}}         </div>     {{/wrap}}     </div> </script> <script id="myWrapper" type="text/html">     <table><tbody>         <tr>             {{each $item.html("div")}}                 <td>                     {{html $value}}                 </td>             {{/each}}         </tr>     </tbody></table> </script> All the HTMl content inside the {{wrap}} … {{/wrap}} is available to the $item.html(filter, textOnly) method. In our example, we have defined some standard template and created wrapper which calls the other template with id myWrapper. Then using $item.html(“div”) we find the div tag and render the html value (together with the div tag) inside the <td> … </td>. So, here inside td the <div> <speaker or attendee depending of the condition> </div>  will be rendered. The HTML output from this is:   - {{tmpl …}} Used for composition as template items Example: <script id="myTemplate" type="text/html">     <div id="bookItem">         <div id="bookCover">             {{tmpl "#bookCoverTemplate"}}         </div>         <div id="bookDetails">             <div id="book">                             ${title} - ${author}             </div>             <div id="price">$${price}</div>             <div id="Details">${pages} pgs. - ${year} year</div>         </div>     </div> </script> <script id="bookCoverTemplate" type="text/html">     <img src="${image}" alt="${title} Image" /> </script> In this example, using {{tmpl “#bookCoverTemplate”}} I’m calling another template inside the first template. In the other template I’ve created template for a book cover. The rendered HTML of this is: and   So we have seen example for each of the tags that are right now available in the jQuery Templates (beta) plugin which is created by Microsoft as a contribution to the open source jQuery Project. I hope this was useful blog post for you. Regards, HajanNEXT - jQuery Templates with ASP.NET MVC

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• CodePlex Daily Summary for Tuesday, October 25, 2011

  CodePlex Daily Summary for Tuesday, October 25, 2011Popular ReleasesScrum Task Board Card Creator: TaskCardCreator 2.5.0.0: What's New: UX improvement: Loading of work items is done in a worker thread Use memory, not the file system, when creating reports for better performance UI improvement: Better parent/child relation between the TeamProjectPicker and MainWindow Microsoft Visual Studio Scrum 1.0: Dedicated Impediment card added Supported Templates: Microsoft Visual Studio Scrum 1.0 Product Backlog Item, Task, Impediment, and Bug MSF for Agile Software Development v5.0 User Story, Task, and BugSubtitleTools: SubtitleTools 1.9: - Improved: Some DVD players need a mandatory UTF8-BOM (http://en.wikipedia.org/wiki/Byteordermark) at the beginning of the file to show RTL subtitles correctly.THE NVL Maker: The NVL Maker Ver 3.06: 3.06 ??? ??3.04，???CG MODE?? ??3.05—— ??????????????????????????????? ?????????config.tjs????????（??????????????????????????） ????config.tjs???，????????????，????????????Config.tjs。（???????，?????????，???KAGConfig??） ???????“????”??，??????????????????（Data） ??????????????????? ???????????，????????，??????????? ?fadeoutbgm?????????，???????????????，?????????? ????????，???“??????”??。（??????????macro_edu.ks??） ????????，????????A??????，???“??????”。 ?????????????，???????B??????，???“...Xomega Framework: Xomega.Framework 1.2: Release 1.2 of Xomega Framework refactors projects to allow generating assemblies for different target frameworks and profiles and allows deploying it as a NuGet package. It also includes some small fixes to the service and presentation layer classes.People's Note: People's Note 0.31: Added note tag editing. Changed note edit conflict resolution to keep the latest version. To install: copy the appropriate CAB file onto your WM device and run it.Windows Azure Toolkit for Windows Phone: Windows Azure Toolkit for Windows Phone v1.3.1: Upgraded Windows Azure projects to Windows Azure Tools for Microsoft Visual Studio 2010 1.5 – September 2011 Upgraded the tools tools to support the Windows Phone Developer Tools RTW Update SQL Azure only scenarios to use ASP.NET Universal Providers (through the System.Web.Providers v1.0.1 NuGet package) Changed Shared Access Signature service interface to support more operations Refactored Blobs API to have a similar interface and usage to that provided by the Windows Azure SDK Stor...xUnit.net Contrib: xunitcontrib-resharper 0.4.4 (dotCover): xunitcontrib release 0.4.4 (ReSharper runner) This release provides a test runner plugin for Resharper 6.0 RTM, targetting all versions of xUnit.net. (See the xUnit.net project to download xUnit.net itself.) This release addresses the following issues:Support for dotCover code coverage 4132 Note that this build work against ALL VERSIONS of xunit. The files are compiled against xunit.dll 1.8 - DO NOT REPLACE THIS FILE. Thanks to xunit's version independent runner system, this package can r...BookShop: BookShop: BookShop WP7 clientRibbon Editor for Microsoft Dynamics CRM 2011: Ribbon Editor (0.1.2122.266): Added CodePlex and PayPal links New icon Bug fix: can't connect to an IFD deployment when the discovery service url has been customizedDotNet.Framework.Common: DotNet.Framework.Common 4.0: ??????????，????????????XML Explorer: XML Explorer 4.0.5: Changes in 4.0.5: Added 'Copy Attribute XPath to Address Bar' feature. Added methods for decoding node text and value from Base64 encoded strings, and copying them to the clipboard. Added 'ChildNodeDefinitions' to the options, which allows for easier navigation of parent-child and ID-IDREF relationships. Discovery happens on-demand, as nodes are expanded and child nodes are added. Nodes can now have 'virtual' child nodes, defined by an xpath to select an identifier (usually relative to ...Media Companion: MC 3.419b Weekly: A couple of minor bug fixes, but the important fix in this release is to tackle the extremely long load times for users with large TV collections (issue #130). A note has been provided by developer Playos: "One final note, you will have to suffer one final long load and then it should be fixed... alternatively you can delete the TvCache.xml and rebuild your library... The fix was to include the file extension so it doesn't have to look for the video file (checking to see if a file exists is a...CODE Framework: 4.0.11021.0: This build adds a lot of our WPF components, including our MVVC and MVC components as well as a "Metro" and "Battleship" style.GridLibre para Visual FoxPro: GridLibre para Visual FoxPro v3.5: GridLibre Para Visual FoxPro: esta herramienta ayudara a los usuarios y programadores en los manejos de los datos, como Filtrar, multiseleccion y el autoformato a las columnas como la asignacion del controlsource.WiX Toolset: WiX v3.6 Beta: First beta release of WiX v3.6. The primary focus is on Burn but there are also many small bug fixes to the core toolset. For more information see: http://robmensching.com/blog/posts/2011/10/24/WiX-v3.6-Beta-releasedUmbraco CMS: Umbraco 5.0 CMS Alpha 3: Umbraco 5 Alpha 3Umbraco 5 (aka Jupiter) will be the next version of everyone's favourite, friendly ASP.NET CMS that already powers over 100,000 websites worldwide. Try out the Alpha of v5 today! If you're new to Umbraco and would like to get a low-down on our popular and easy-to-learn approach to content management, check out our intro video. What's Alpha 3?This is our third Alpha release. It's intended for developers looking to become familiar with the codebase & architecture, or for thos...Vkontakte WP: Vkontakte: source codeWay2Sms Applications for Android, Desktop/Laptop & Java enabled phones: Way2SMS Desktop App v2.0: 1. Fixed issue with sending messages due to changes to Way2Sms site 2. Updated the character limit to 160 from 140GART - Geo Augmented Reality Toolkit: 1.0.1: About Release 1.0.1 Release 1.0.1 is a service release that addresses several issues and improves performance. As always, check the Documentation tab for instructions on how to get started. If you don't have the Windows Phone SDK yet, grab it here. Breaking Change Please note: There is a breaking change in this release. As noted below, the WorldCalculationMode property of ARItem has been replaced by a user-definable function. ARItem is now automatically wired up with a function that perform...Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.32: Fix for issue #16710 - string literals in "constant literal operations" which contain ASP.NET substitutions should not be considered "constant." Move the JS1284 error (Misplaced Function Declaration) so it only fires when in strict mode. I got a couple complaints that people didn't like that error popping up in their existing code when they could verify that the location of that function, although not strict JS, still functions as expected cross-browser.New ProjectsApiDiff.Net: API Difference/Reporting project written in C# using the wonderful Cecil engine (http://www.mono-project.com/Cecil) to show differences between versions of a public API. Something like the unsupported MS tool "libcheck"Aspect Oriented Programming with .Net: Demo project using PostSharp for AOP in .Net.CCBBAA: CCBBAACdf.Iris.MiniProjetCalculateur: Application Client / Serveur calculateur en langage CCmjSiverlight: a silverlight libraryCSharpKaartSpel: Super Kaart Spel.Developer Team Article System Management: Developer Team Article System Management Makes it easier for Authors to publish their articles . It developed in VB.NET .DirectoryMonitor: DirectoryMonitorDNN Administrador de Tareas: Un Proyecto de codigo abierto Domek: Taki sobie domekEDXGraphics: This is Edward(Shiqiu) Liu's personal code repository. Projects here are primarily about Graphics, AI and Algorithms. For more introduction, please visit [url:www.edxgraphics.com] Enterprise SSIS Framework: The Enterprise SSIS Framework is a project intended to simplify the management of an organization’s administration and ETL assets by abstracting the coordination and control flow into metadata. This project consists of the four parts: - Core SSIS Packages: A set of packages that are responsible for workflow within the framework - SQL Server 2008 DB: Holds all the metadata necessary to drive the application - Administration App: A web-based front end to facilitate managing assets running ...FIM Task Sequencer "RunJob": Runjob is a simple batch controller for FIM (MIIS and ILM) for starting and monitoring the execution of FIM Run Profiles that allows for complex (looping and branching) sequences to be put together with a simple XML 'task' file. Key features include: * Works with MIIS / ILM / FIM * Optionally Connects to the SQL database to verify that run profiles exist * Can execute arbitrary tasks via a command line. * Based on the results of command line or previous run history can loop and jump ...Ham Bone Soup amateur radio software and electronic log: Ham Bone Soup is a open source software written for satisfying the needs of Amateur Radio operators. The central feature is an especially flexible logging system for acommodating contests and general purpose logs, but will grow to include many other vital Amateur radio features. It doesn't do anything yet, we are just geting started.H? th?ng qu?n lý chi tiêu - windows phone: H? th?ng qu?n lý chi tiêu - windows phoneJavascript Editor for SharePoint: Javascript Editor for SharePoint is a lightweight, in-browser editor that lets you quickly prototype and test custom javascript code in SharePointLegoWeb: Open source Web CMS base on ASP.NET Webparts + MARCXML metadata: LegoWeb is an open source web content management solution developed base on combination of ASP.NET 2.0 Webparts and MARCXML Metadata. It is very simple and very flexible. LuaXna: An simple engine that allow to devolop in LUA for XNA. It have logging feature and cycles.Manager Game: Student project for game developement course. Using XNA 4.0 for Windows platform.Metroed: A Metro version of the PhoneyTools (a WP7 toolkit) for use with C#/VB WinRT applications.My Masters Sample Project for Sharepoint 2010: The feature stabling example project which is provide to deploy custom master page to personel sites on Sharepoint 2010 The solution is anwering fallowing questions : * How to deploy a custom master page ? * How to customize a masterpage ? * How to attach custom master page to personal sites using stabling feature ? NDepend TFS 2010 integration: NDepend TFS 2010 integration provides build activities, a build report customization addin, and extends the TFS Warehouse in order to leverage NDepend quality statistics for your projects. Open Source Renderer: Open Source RendererPearTunes: Peartunes is a university project.Plugin Framework Web: Lighweight plugin framework for web applicationsQTP TFS Generic Test Integration: In Microsoft Visual Studio 2010 there is a Generic Test type that allows you to integrate with automation tools like QTP. I have created a pretty simple solution that allows you to use your existing QTP automation scripts within the Microsoft Visual Studio testing framework and here's a sample below. The key part of this solution is transforming HP's QTP format to Microsoft’s Generic Test format so that you can publish the results to TFS. The added benefit of this integration is that you c...RequiemDream: the project for manage workflow records reexecute to helping developers for debugging.Rift Addon Studio 2010: Rift AddOn Studio (AOS) is an open source development environment designed to bring a Visual Studio-like experience to building Rift AddOns. For more information on exactly what AOS does, check out the list of features below. Small Database Tools: This is a project for me to create small tools I created for database related functions.SQL Azure Membership, Profile, Role provider starter kit for MVC3 project: When you use out of box MVC 3 site template the Membership, Profile and Role provider DB is created as attached MDF file by the name AspNetDB.mdf. This project has needed steps to easily migrate this DB into SQL Azure. This is a complete MVC3 Starter site project and could be used for your next 'Big Thing' as soon as properly setup. Enjoy :)SQL Server BareMetal Hands-on-Labs: The SQL Server BareMetal Hands-on-Labs project allows you to build a SQL Server Hands-on-Lab Enviroment from scratch, using Windows Server 2008 R2 SP1 Hyper-V. State Theater Website: Building a website designed to provide information about live theater throughout a state. Basically, it a port of NJTheater.com from classic ASP to Asp.Net making it customizable to any state along the way.Static web generator: Zoltar let you generate your website (blog, personl website,etc) from a set of md files. Ukulele Chord Finder: Ukulele Chord FinderUser Profile Cleaner: This application allows you to manage via GUI or command line user profiles, removed the profiles no longer used by a number of days. The application allows you to set a list of profiles that can be excluded from deletion. Virtual Visit: This project have made the virtual visite for your siteWP7 Open source project collection by eLite: ??Windows Phone????????zebrawebservice: ??AWB，??OPS??

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• python list mysteriously getting set to something within my django/piston handler

  - by Anverc

  To start, I'm very new to python, let alone Django and Piston. Anyway, I've created a new BaseHandler class "class BaseApiHandler(BaseHandler)" so that I can extend some of the stff that BaseHandler does. This has been working fine until I added a new filter that could limit results to the first or last result. Now I can refresh the api page over and over and sometimes it will limit the result even if I don't include /limit/whatever in my URL... I've added some debug info into my return value to see what is happening, and that's when it gets more weird. this return value will make more sense after you see the code, but here they are for reference: When the results are correct: "statusmsg": "2 hours_detail found with query: {'empid':'22','datestamp':'2009-03-02',}", when the results are incorrect (once you read the code you'll notice two things wrong. First, it doesn't have 'limit':'None', secondly it shouldn't even get this far to begin with. "statusmsg": "1 hours_detail found with query: {'empid':'22','datestamp':'2009-03-02',with limit[0,1](limit,None),}", It may be important to note that I'm the only person with access to the server running this right now, so even if it was a cache issue, it doesn't make sense that I can just refresh and get different results by hitting F5 while viewing: http://localhost/api/hours_detail/datestamp/2009-03-02/empid/22 Here's the code broken into urls.py and handlers.py so that you can see what i'm doing: URLS.PY urlpatterns = patterns('', #hours_detail/id/{id}/empid/{empid}/projid/{projid}/datestamp/{datestamp}/daterange/{fromdate}to{todate}/limit/{first|last}/exact #empid is required # id, empid, projid, datestamp, daterange can be in any order url(r'^api/hours_detail/(?:' + \ r'(?:[/]?id/(?P<id>\d+))?' + \ r'(?:[/]?empid/(?P<empid>\d+))?' + \ r'(?:[/]?projid/(?P<projid>\d+))?' + \ r'(?:[/]?datestamp/(?P<datestamp>\d{4,}[-/\.]\d{2,}[-/\.]\d{2,}))?' + \ r'(?:[/]?daterange/(?P<daterange>(?:\d{4,}[-/\.]\d{2,}[-/\.]\d{2,})(?:to|/-)(?:\d{4,}[-/\.]\d{2,}[-/\.]\d{2,})))?' + \ r')+' + \ r'(?:/limit/(?P<limit>(?:first|last)))?' + \ r'(?:/(?P<exact>exact))?$', hours_detail_resource), HANDLERS.PY # inherit from BaseHandler to add the extra functionality i need to process the possibly null URL params class BaseApiHandler(BaseHandler): # keep track of the handler so the data is represented back to me correctly post_name = 'base' # THIS IS THE LIST IN QUESTION - SOMETIMES IT IS GETTING SET TO [0,1] MYSTERIOUSLY # this gets set to a list when the results are to be limited limit = None def has_limit(self): return (isinstance(self.limit, list) and len(self.limit) == 2) def process_kwarg_read(self, key, value, d_post, b_exact): """ this should be overridden in the derived classes to process kwargs """ pass # override 'read' so we can better handle our api's searching capabilities def read(self, request, *args, **kwargs): d_post = {'status':0,'statusmsg':'Nothing Happened'} try: # setup the named response object # select all employees then filter - querysets are lazy in django # the actual query is only done once data is needed, so this may # seem like some memory hog slow beast, but it's actually not. d_post[self.post_name] = self.queryset(request) # this is a string that holds debug information... it's the string I mentioned before pasting this code s_query = '' b_exact = False if 'exact' in kwargs and kwargs['exact'] <> None: b_exact = True s_query = '\'exact\':True,' for key,value in kwargs.iteritems(): # the regex url possibilities will push None into the kwargs dictionary # if not specified, so just continue looping through if that's the case if value == None or key == 'exact': continue # write to the s_query string so we have a nice error message s_query = '%s\'%s\':\'%s\',' % (s_query, key, value) # now process this key/value kwarg self.process_kwarg_read(key=key, value=value, d_post=d_post, b_exact=b_exact) # end of the kwargs for loop else: if self.has_limit(): # THIS SEEMS TO GET HIT SOMETIMES IF YOU CONSTANTLY REFRESH THE API PAGE, EVEN THOUGH # THE LINE IN THE FOR LOOP WHICH UPDATES s_query DOESN'T GET HIS AND THUS self.process_kwarg_read ALSO # DOESN'T GET HIT SO NEITHER DOES limit = [0,1] s_query = '%swith limit[%s,%s](limit,%s),' % (s_query, self.limit[0], self.limit[1], kwargs['limit']) d_post[self.post_name] = d_post[self.post_name][self.limit[0]:self.limit[1]] if d_post[self.post_name].count() == 0: d_post['status'] = 0 d_post['statusmsg'] = '%s not found with query: {%s}' % (self.post_name, s_query) else: d_post['status'] = 1 d_post['statusmsg'] = '%s %s found with query: {%s}' % (d_post[self.post_name].count(), self.post_name, s_query) except: e = sys.exc_info()[1] d_post['status'] = 0 d_post['statusmsg'] = 'error: %s' % e d_post[self.post_name] = [] return d_post class HoursDetailHandler(BaseApiHandler): #allowed_methods = ('GET',) model = HoursDetail exclude = () post_name = 'hours_detail' def process_kwarg_read(self, key, value, d_post, b_exact): if ... # I have several if/elif statements here that check for other things... # 'self.limit =' only shows up in the following elif: elif key == 'limit': order_by = 'clock_time' if value == 'last': order_by = '-clock_time' d_post[self.post_name] = d_post[self.post_name].order_by(order_by) # TO GET HERE, THE ONLY PLACE IN CODE WHERE self.limit IS SET, YOU MUST HAVE GONE THROUGH # THE value == None CHECK???? self.limit = [0, 1] else: raise NameError def read(self, request, *args, **kwargs): # empid is required, so make sure it exists before running BaseApiHandler's read method if not('empid' in kwargs and kwargs['empid'] <> None and kwargs['empid'] >= 0): return {'status':0,'statusmsg':'empid cannot be empty'} else: return BaseApiHandler.read(self, request, *args, **kwargs) Does anyone have a clue how else self.limit might be getting set to [0, 1] ? Am I misunderstanding kwargs or loops or anything in Python?

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• How do I create an instance of this class in Android?

  - by Lloyd Banks

  I was wondering if it is possible to create an instance of this class (from the link, which creates a listview) from another class so that I can call on either lazyadapter.java or customizedlistview.java (not sure which one) to inflate that same listview. Is this possible? This is what I tried (obviously incorrect): CustomizedListView clv = new CustomizedListView(); clv.onCreate(...); source: http://www.androidhive.info/2012/02/android-custom-listview-with-image-and-text/ LazyAdapter.java import java.util.ArrayList; import java.util.HashMap; import android.app.Activity; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.TextView; public class LazyAdapter extends BaseAdapter { private Activity activity; private ArrayList&lt;HashMap&lt;String, String&gt;&gt; data; private static LayoutInflater inflater=null; public ImageLoader imageLoader; public LazyAdapter(Activity a, ArrayList&lt;HashMap&lt;String, String&gt;&gt; d) { activity = a; data=d; inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); imageLoader=new ImageLoader(activity.getApplicationContext()); } public int getCount() { return data.size(); } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { View vi=convertView; if(convertView==null) vi = inflater.inflate(R.layout.list_row, null); TextView title = (TextView)vi.findViewById(R.id.title); // title TextView artist = (TextView)vi.findViewById(R.id.artist); // artist name TextView duration = (TextView)vi.findViewById(R.id.duration); // duration ImageView thumb_image=(ImageView)vi.findViewById(R.id.list_image); // thumb image HashMap&lt;String, String&gt; song = new HashMap&lt;String, String&gt;(); song = data.get(position); // Setting all values in listview title.setText(song.get(CustomizedListView.KEY_TITLE)); artist.setText(song.get(CustomizedListView.KEY_ARTIST)); duration.setText(song.get(CustomizedListView.KEY_DURATION)); imageLoader.DisplayImage(song.get(CustomizedListView.KEY_THUMB_URL), thumb_image); return vi; } } CustomizedListView.java import java.util.ArrayList; import java.util.HashMap; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.ListView; public class CustomizedListView extends Activity { // All static variables static final String URL = "http://api.androidhive.info/music/music.xml"; // XML node keys static final String KEY_SONG = "song"; // parent node static final String KEY_ID = "id"; static final String KEY_TITLE = "title"; static final String KEY_ARTIST = "artist"; static final String KEY_DURATION = "duration"; static final String KEY_THUMB_URL = "thumb_url"; ListView list; LazyAdapter adapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ArrayList&lt;HashMap&lt;String, String&gt;&gt; songsList = new ArrayList&lt;HashMap&lt;String, String&gt;&gt;(); XMLParser parser = new XMLParser(); String xml = parser.getXmlFromUrl(URL); // getting XML from URL Document doc = parser.getDomElement(xml); // getting DOM element NodeList nl = doc.getElementsByTagName(KEY_SONG); // looping through all song nodes &lt;song&gt; for (int i = 0; i &lt; nl.getLength(); i++) { // creating new HashMap HashMap&lt;String, String&gt; map = new HashMap&lt;String, String&gt;(); Element e = (Element) nl.item(i); // adding each child node to HashMap key =&gt; value map.put(KEY_ID, parser.getValue(e, KEY_ID)); map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE)); map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST)); map.put(KEY_DURATION, parser.getValue(e, KEY_DURATION)); map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL)); // adding HashList to ArrayList songsList.add(map); } list=(ListView)findViewById(R.id.list); // Getting adapter by passing xml data ArrayList adapter=new LazyAdapter(this, songsList); list.setAdapter(adapter); // Click event for single list row list.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id) { } }); } }

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• Of these 3 methods for reading linked lists from shared memory, why is the 3rd fastest?

  - by Joseph Garvin

  I have a 'server' program that updates many linked lists in shared memory in response to external events. I want client programs to notice an update on any of the lists as quickly as possible (lowest latency). The server marks a linked list's node's state_ as FILLED once its data is filled in and its next pointer has been set to a valid location. Until then, its state_ is NOT_FILLED_YET. I am using memory barriers to make sure that clients don't see the state_ as FILLED before the data within is actually ready (and it seems to work, I never see corrupt data). Also, state_ is volatile to be sure the compiler doesn't lift the client's checking of it out of loops. Keeping the server code exactly the same, I've come up with 3 different methods for the client to scan the linked lists for changes. The question is: Why is the 3rd method fastest? Method 1: Round robin over all the linked lists (called 'channels') continuously, looking to see if any nodes have changed to 'FILLED': void method_one() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { Data* current_item = channel_cursors[i]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[i] = static_cast<Data*>(current_item->next_.get(segment)); } } } Method 1 gave very low latency when then number of channels was small. But when the number of channels grew (250K+) it became very slow because of looping over all the channels. So I tried... Method 2: Give each linked list an ID. Keep a separate 'update list' to the side. Every time one of the linked lists is updated, push its ID on to the update list. Now we just need to monitor the single update list, and check the IDs we get from it. void method_two() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { if(update_cursor->state_ == NOT_FILLED_YET) { continue; } ::uint32_t update_id = update_cursor->list_id_; Data* current_item = channel_cursors[update_id]; if(current_item->state_ == NOT_FILLED_YET) { std::cerr << "This should never print." << std::endl; // it doesn't continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[update_id] = static_cast<Data*>(current_item->next_.get(segment)); update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } } Method 2 gave TERRIBLE latency. Whereas Method 1 might give under 10us latency, Method 2 would inexplicably often given 8ms latency! Using gettimeofday it appears that the change in update_cursor-state_ was very slow to propogate from the server's view to the client's (I'm on a multicore box, so I assume the delay is due to cache). So I tried a hybrid approach... Method 3: Keep the update list. But loop over all the channels continuously, and within each iteration check if the update list has updated. If it has, go with the number pushed onto it. If it hasn't, check the channel we've currently iterated to. void method_three() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { std::size_t idx = i; ACQUIRE_MEMORY_BARRIER; if(update_cursor->state_ != NOT_FILLED_YET) { //std::cerr << "Found via update" << std::endl; i--; idx = update_cursor->list_id_; update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } Data* current_item = channel_cursors[idx]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } found_an_update = true; log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[idx] = static_cast<Data*>(current_item->next_.get(segment)); } } } The latency of this method was as good as Method 1, but scaled to large numbers of channels. The problem is, I have no clue why. Just to throw a wrench in things: if I uncomment the 'found via update' part, it prints between EVERY LATENCY LOG MESSAGE. Which means things are only ever found on the update list! So I don't understand how this method can be faster than method 2. The full, compilable code (requires GCC and boost-1.41) that generates random strings as test data is at: http://pastebin.com/e3HuL0nr

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• finding numbers of days between two date to make a dynamic columns

  - by Chandradyani

  Dear all, I have a select query that currently produces the following results: DoctorName Team 1 2 3 4 5 6 7 ... 31 Visited dr. As   A                             x    x ...      2 times dr. Sc   A                          x          ...      1 times dr. Gh   B                                  x ...      1 times dr. Nd   C                                     ... x    1 times Using the following query: DECLARE @startDate = '1/1/2010', @enddate = '1/31/2010' SELECT d.doctorname, t.teamname, MAX(CASE WHEN ca.visitdate = 1 THEN 'x' ELSE NULL END) AS 1, MAX(CASE WHEN ca.visitdate = 2 THEN 'x' ELSE NULL END) AS 2, MAX(CASE WHEN ca.visitdate = 3 THEN 'x' ELSE NULL END) AS 3, ... MAX(CASE WHEN ca.visitdate = 31 THEN 'x' ELSE NULL END) AS 31, COUNT(*) AS visited FROM CACTIVITY ca JOIN DOCTOR d ON d.id = ca.doctorid JOIN TEAM t ON t.id = ca.teamid WHERE ca.visitdate BETWEEN @startdate AND @enddate GROUP BY d.doctorname, t.teamname the problem is I want to make the column of date are dynamic for example if ca.visitdate BETWEEN '2/1/2012' AND '2/29/2012' so the result will be : DoctorName Team 1 2 3 4 5 6 7 ... 29 Visited dr. As   A                             x    x ...      2 times dr. Sc   A                          x          ...      1 times dr. Gh   B                                  x ...      1 times dr. Nd   C                                     ... x    1 times Can somebody help me how to get numbers of days between two date and help me revised the query so it can looping MAX(CASE WHEN ca.visitdate = 1 THEN 'x' ELSE NULL END) AS 1 as many as numbers of days? Please please

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• Python - Converting CSV to Objects - Code Design

  - by victorhooi

  Hi, I have a small script we're using to read in a CSV file containing employees, and perform some basic manipulations on that data. We read in the data (import_gd_dump), and create an Employees object, containing a list of Employee objects (maybe I should think of a better naming convention...lol). We then call clean_all_phone_numbers() on Employees, which calls clean_phone_number() on each Employee, as well as lookup_all_supervisors(), on Employees. import csv import re import sys #class CSVLoader: # """Virtual class to assist with loading in CSV files.""" # def import_gd_dump(self, input_file='Gp Directory 20100331 original.csv'): # gd_extract = csv.DictReader(open(input_file), dialect='excel') # employees = [] # for row in gd_extract: # curr_employee = Employee(row) # employees.append(curr_employee) # return employees # #self.employees = {row['dbdirid']:row for row in gd_extract} # Previously, this was inside a (virtual) class called "CSVLoader". # However, according to here (http://tomayko.com/writings/the-static-method-thing) - the idiomatic way of doing this in Python is not with a class-fucntion but with a module-level function def import_gd_dump(input_file='Gp Directory 20100331 original.csv'): """Return a list ('employee') of dict objects, taken from a Group Directory CSV file.""" gd_extract = csv.DictReader(open(input_file), dialect='excel') employees = [] for row in gd_extract: employees.append(row) return employees def write_gd_formatted(employees_dict, output_file="gd_formatted.csv"): """Read in an Employees() object, and write out each Employee() inside this to a CSV file""" gd_output_fieldnames = ('hrid', 'mail', 'givenName', 'sn', 'dbcostcenter', 'dbdirid', 'hrreportsto', 'PHFull', 'PHFull_message', 'SupervisorEmail', 'SupervisorFirstName', 'SupervisorSurname') try: gd_formatted = csv.DictWriter(open(output_file, 'w', newline=''), fieldnames=gd_output_fieldnames, extrasaction='ignore', dialect='excel') except IOError: print('Unable to open file, IO error (Is it locked?)') sys.exit(1) headers = {n:n for n in gd_output_fieldnames} gd_formatted.writerow(headers) for employee in employees_dict.employee_list: # We're using the employee object's inbuilt __dict__ attribute - hmm, is this good practice? gd_formatted.writerow(employee.__dict__) class Employee: """An Employee in the system, with employee attributes (name, email, cost-centre etc.)""" def __init__(self, employee_attributes): """We use the Employee constructor to convert a dictionary into instance attributes.""" for k, v in employee_attributes.items(): setattr(self, k, v) def clean_phone_number(self): """Perform some rudimentary checks and corrections, to make sure numbers are in the right format. Numbers should be in the form 0XYYYYYYYY, where X is the area code, and Y is the local number.""" if self.telephoneNumber is None or self.telephoneNumber == '': return '', 'Missing phone number.' else: standard_format = re.compile(r'^\+(?P<intl_prefix>\d{2})\((?P<area_code>\d)\)(?P<local_first_half>\d{4})-(?P<local_second_half>\d{4})') extra_zero = re.compile(r'^\+(?P<intl_prefix>\d{2})\(0(?P<area_code>\d)\)(?P<local_first_half>\d{4})-(?P<local_second_half>\d{4})') missing_hyphen = re.compile(r'^\+(?P<intl_prefix>\d{2})\(0(?P<area_code>\d)\)(?P<local_first_half>\d{4})(?P<local_second_half>\d{4})') if standard_format.search(self.telephoneNumber): result = standard_format.search(self.telephoneNumber) return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), '' elif extra_zero.search(self.telephoneNumber): result = extra_zero.search(self.telephoneNumber) return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), 'Extra zero in area code - ask user to remediate. ' elif missing_hyphen.search(self.telephoneNumber): result = missing_hyphen.search(self.telephoneNumber) return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), 'Missing hyphen in local component - ask user to remediate. ' else: return '', "Number didn't match recognised format. Original text is: " + self.telephoneNumber class Employees: def __init__(self, import_list): self.employee_list = [] for employee in import_list: self.employee_list.append(Employee(employee)) def clean_all_phone_numbers(self): for employee in self.employee_list: #Should we just set this directly in Employee.clean_phone_number() instead? employee.PHFull, employee.PHFull_message = employee.clean_phone_number() # Hmm, the search is O(n^2) - there's probably a better way of doing this search? def lookup_all_supervisors(self): for employee in self.employee_list: if employee.hrreportsto is not None and employee.hrreportsto != '': for supervisor in self.employee_list: if supervisor.hrid == employee.hrreportsto: (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = supervisor.mail, supervisor.givenName, supervisor.sn break else: (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = ('Supervisor not found.', 'Supervisor not found.', 'Supervisor not found.') else: (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = ('Supervisor not set.', 'Supervisor not set.', 'Supervisor not set.') #Is thre a more pythonic way of doing this? def print_employees(self): for employee in self.employee_list: print(employee.__dict__) if __name__ == '__main__': db_employees = Employees(import_gd_dump()) db_employees.clean_all_phone_numbers() db_employees.lookup_all_supervisors() #db_employees.print_employees() write_gd_formatted(db_employees) Firstly, my preamble question is, can you see anything inherently wrong with the above, from either a class design or Python point-of-view? Is the logic/design sound? Anyhow, to the specifics: The Employees object has a method, clean_all_phone_numbers(), which calls clean_phone_number() on each Employee object inside it. Is this bad design? If so, why? Also, is the way I'm calling lookup_all_supervisors() bad? Originally, I wrapped the clean_phone_number() and lookup_supervisor() method in a single function, with a single for-loop inside it. clean_phone_number is O(n), I believe, lookup_supervisor is O(n^2) - is it ok splitting it into two loops like this? In clean_all_phone_numbers(), I'm looping on the Employee objects, and settings their values using return/assignment - should I be setting this inside clean_phone_number() itself? There's also a few things that I'm sorted of hacked out, not sure if they're bad practice - e.g. print_employee() and gd_formatted() both use __dict__, and the constructor for Employee uses setattr() to convert a dictionary into instance attributes. I'd value any thoughts at all. If you think the questions are too broad, let me know and I can repost as several split up (I just didn't want to pollute the boards with multiple similar questions, and the three questions are more or less fairly tightly related). Cheers, Victor

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• Watching setTimeout loops so that only one is running at a time.

  - by DA

  I'm creating a content rotator in jQuery. 5 items total. Item 1 fades in, pauses 10 seconds, fades out, then item 2 fades in. Repeat. Simple enough. Using setTimeout I can call a set of functions that create a loop and will repeat the process indefinitely. I now want to add the ability to interrupt this rotator at any time by clicking on a navigation element to jump directly to one of the content items. I originally started going down the path of pinging a variable constantly (say every half second) that would check to see if a navigation element was clicked and, if so, abandon the loop, then restart the loop based on the item that was clicked. The challenge I ran into was how to actually ping a variable via a timer. The solution is to dive into JavaScript closures...which are a little over my head but definitely something I need to delve into more. However, in the process of that, I came up with an alternative option that actually seems to be better performance-wise (theoretically, at least). I have a sample running here: http://jsbin.com/uxupi/14 (It's using console.log so have fireBug running) Sample script: $(document).ready(function(){ var loopCount = 0; $('p#hello').click(function(){ loopCount++; doThatThing(loopCount); }) function doThatOtherThing(currentLoopCount) { console.log('doThatOtherThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatThing(currentLoopCount)},5000) } } function doThatThing(currentLoopCount) { console.log('doThatThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatOtherThing(currentLoopCount)},5000); } } }) The logic being that every click of the trigger element will kick off the loop passing into itself a variable equal to the current value of the global variable. That variable gets passed back and forth between the functions in the loop. Each click of the trigger also increments the global variable so that subsequent calls of the loop have a unique local variable. Then, within the loop, before the next step of each loop is called, it checks to see if the variable it has still matches the global variable. If not, it knows that a new loop has already been activated so it just ends the existing loop. Thoughts on this? Valid solution? Better options? Caveats? Dangers? UPDATE: I'm using John's suggestion below via the clearTimeout option. However, I can't quite get it to work. The logic is as such: var slideNumber = 0; var timeout = null; function startLoop(slideNumber) { ...do stuff here to set up the slide based on slideNumber... slideFadeIn() } function continueCheck(){ if (timeout != null) { // cancel the scheduled task. clearTimeout(timeout); timeout = null; return false; }else{ return true; } }; function slideFadeIn() { if (continueCheck){ // a new loop hasn't been called yet so proceed... // fade in the LI $currentListItem.fadeIn(fade, function() { if(multipleFeatures){ timeout = setTimeout(slideFadeOut,display); } }); }; function slideFadeOut() { if (continueLoop){ // a new loop hasn't been called yet so proceed... slideNumber=slideNumber+1; if(slideNumber==features.length) { slideNumber = 0; }; timeout = setTimeout(function(){startLoop(slideNumber)},100); }; startLoop(slideNumber); The above kicks of the looping. I then have navigation items that, when clicked, I want the above loop to stop, then restart with a new beginning slide: $(myNav).click(function(){ clearTimeout(timeout); timeout = null; startLoop(thisItem); }) If I comment out 'startLoop...' from the click event, it, indeed, stops the initial loop. However, if I leave that last line in, it doesn't actually stop the initial loop. Why? What happens is that both loops seem to run in parallel for a period. So, when I click my navigation, clearTimeout is called, which clears it.

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• click buttons error

  - by sara

  I will retrieve student information (id -number- name) from a database (MySQL) as a list view, each student have 2 buttons (delete - alert ) and radio buttons Every thing is ok, but how can I make an onClickListener, for example for the delete button because I try lots of examples, I heard that I can use (custom list or get view or direct onClickListener as in my code (but it is not working ) or Simple Cursor Adapter) I do not know what to use, I looked around for examples that can help me, but in my case but I did not find any so I hope this be reference for anyone have the same problem. this is my code which I use direct onClick with Simple Adapter public class ManageSection extends ListActivity { //ProgresogressDialog pDialog; private ProgressDialog pDialog; // Creating JSON Parser object // Creating JSON Parser object JSONParser jParser = new JSONParser(); //class boolean x =true; Button delete; ArrayList<HashMap<String, String>> studentList; //url to get all products list private static String url_all_student = "http://10.0.2.2/SmsPhp/view_student_info.php"; String cl; // JSON Node names private static final String TAG_SUCCESS = "success"; private static final String TAG_student = "student"; private static final String TAG_StudentID = "StudentID"; private static final String TAG_StudentNo = "StudentNo"; private static final String TAG_FullName = "FullName"; private static final String TAG_Avatar="Avatar"; HashMap<String, String> selected_student; // course JSONArray JSONArray student = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.manage_section); studentList = new ArrayList<HashMap<String, String>>(); ListView list1 = getListView(); list1.setAdapter(getListAdapter()); list1.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int pos, long l) { selected_student =(HashMap<String, String>) studentList.get(pos); //member of your activity. delete =(Button)view.findViewById(R.id.DeleteStudent); cl=selected_student.get(TAG_StudentID); Toast.makeText(getBaseContext(),cl,Toast.LENGTH_LONG).show(); delete.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { Log.d("id: ",cl); Toast.makeText(getBaseContext(),cl,Toast.LENGTH_LONG).show(); } }); } }); new LoadAllstudent().execute(); } /** * Background Async Task to Load all student by making HTTP Request * */ class LoadAllstudent extends AsyncTask<String, String, String> { /** * Before starting background thread Show Progress Dialog * */ @Override protected void onPreExecute() { super.onPreExecute(); pDialog = new ProgressDialog(ManageSection.this); pDialog.setMessage("Loading student. Please wait..."); pDialog.setIndeterminate(false); } /** * getting All student from u r l * */ @Override protected String doInBackground(String... args) { // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); // getting JSON string from URL JSONObject json = jParser.makeHttpRequest(url_all_student, "GET", params); // Check your log cat for JSON response Log.d("All student : ", json.toString()); try { // Checking for SUCCESS TAG int success = json.getInt(TAG_SUCCESS); if (success == 1) { // student found // Getting Array of course student = json.getJSONArray(TAG_student); // looping through All courses for (int i = 0; i < student.length(); i++)//course JSONArray { JSONObject c = student.getJSONObject(i); // read first // Storing each json item in variable String StudentID = c.getString(TAG_StudentID); String StudentNo = c.getString(TAG_StudentNo); String FullName = c.getString(TAG_FullName); // String Avatar = c.getString(TAG_Avatar); // creating new HashMap HashMap<String, String> map = new HashMap<String, String>(); // adding each child node to HashMap key => value map.put(TAG_StudentID, StudentID); map.put(TAG_StudentNo, StudentNo); map.put(TAG_FullName, FullName); // adding HashList to ArrayList studentList.add(map); } } else { x=false; } } catch (JSONException e) { e.printStackTrace(); } return null; } /** * After completing background task Dismiss the progress dialog * **/ protected void onPostExecute(String file_url) { // dismiss the dialog after getting all products pDialog.dismiss(); if (x==false) Toast.makeText(getBaseContext(),"no student" ,Toast.LENGTH_LONG).show(); ListAdapter adapter = new SimpleAdapter( ManageSection.this, studentList, R.layout.list_student, new String[] { TAG_StudentID, TAG_StudentNo,TAG_FullName}, new int[] { R.id.StudentID, R.id.StudentNo,R.id.FullName}); setListAdapter(adapter); // Updating parsed JSON data into ListView } } } So what do you think, why doesn't the delete button work? There is no error in my log cat. What is the alternative way ?.. what should I do ?

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• Yet another C# Deadlock Debugging Question

  - by Roo

  Hi All, I have a multi-threaded application build in C# using VS2010 Professional. It's quite a large application and we've experienced the classing GUI cross-threading and deadlock issues before, but in the past month we've noticed the appears to lock up when left idle for around 20-30 minutes. The application is irresponsive and although it will repaint itself when other windows are dragged in front of the application and over it, the GUI still appears to be locked... interstingly (unlike if the GUI thread is being used for a considerable amount of time) the Close, Maximise and minimise buttons are also irresponsive and when clicked the little (Not Responding...) text is not displayed in the title of the application i.e. Windows still seems to think it's running fine. If I break/pause the application using the debugger, and view the threads that are running. There are 3 threads of our managed code that are running, and a few other worker threads whom the source code cannot be displayed for. The 3 threads that run are: The main/GUI thread A thread that loops indefinitely A thread that loops indefinitely If I step into threads 2 and 3, they appear to be looping correctly. They do not share locks (even with the main GUI thread) and they are not using the GUI thread at all. When stepping into the main/GUI thread however, it's broken on Application.Run... This problem screams deadlock to me, but what I don't understand is if it's deadlock, why can't I see the line of code the main/GUI thread is hanging on? Any help will be greatly appreciated! Let me know if you need more information... Cheers, Roo -----------------------------------------------------SOLUTION-------------------------------------------------- Okay, so the problem is now solved. Thanks to everyone for their suggestions! Much appreciated! I've marked the answer that solved my initial problem of determining where on the main/UI thread the application hangs (I handn't turned off the "Enable Just My Code" option). The overall issue I was experiencing was indeed Deadlock, however. After obtaining the call-stack and popping the top half of it into Google I came across this which explains exactly what I was experiencing... http://timl.net/ This references a lovely guide to debugging the issue... http://www.aaronlerch.com/blog/2008/12/15/debugging-ui/ This identified a control I was constructing off the GUI thread. I did know this, however, and was marshalling calls correctly, but what I didn't realise was that behind the scenes this Control was subscribing to an event or set of events that are triggered when e.g. a Windows session is unlocked or the screensaver exits. These calls are always made on the main/UI thread and were blocking when it saw the call was made on the incorrect thread. Kim explains in more detail here... http://krgreenlee.blogspot.com/2007/09/onuserpreferencechanged-hang.html In the end I found an alternative solution which did not require this Control off the main/UI thread. That appears to have solved the problem and the application no longer hangs. I hope this helps anyone who's confronted by a similar problem. Thanks again to everyone on here who helped! (and indirectly, the delightful bloggers I've referenced above!) Roo -----------------------------------------------------SOLUTION II-------------------------------------------------- Aren't threading issues delightful...you think you've solved it, and a month down the line it pops back up again. I still believe the solution above resolved an issue that would cause simillar behaviour, but we encountered the problem again. As we spent a while debugging this, I thought I'd update this question with our (hopefully) final solution: The problem appears to have been a bug in the Infragistics components in the WinForms 2010.1 release (no hot fixes). We had been running from around the time the freeze issue appeared (but had also added a bunch of other stuff too). After upgrading to WinForms 2010.3, we've yet to reproduce the issue (deja vu). See my question here for a bit more information: 'http://stackoverflow.com/questions/4077822/net-4-0-and-the-dreaded-onuserpreferencechanged-hang'. Hans has given a nice summary of the general issue. I hope this adds a little to the suggestions/information surrounding the nutorious OnUserPreferenceChanged Hang (or whatever you'd like to call it). Cheers, Roo

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• how can i update view when fragment change?

  - by user1524393

  i have a activity that have 2 sherlockfragment in this The first two pages display fragments with custom list views which are built from xml from server using AsyncTask. However, when the app runs, only one list view is displayed, the other page is just blank public class VpiAbsTestActivity extends SherlockFragmentActivity { private static final String[] CONTENT = new String[] { "1","2"}; TestFragmentAdapter mAdapter; ViewPager mPager; PageIndicator mIndicator; protected void onCreate(Bundle savedInstanceState) { setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); super.onCreate(savedInstanceState); setContentView(R.layout.simple_tabs); mAdapter = new TestFragmentAdapter(getSupportFragmentManager()); mPager = (ViewPager)findViewById(R.id.pager); mPager.setAdapter(mAdapter); mIndicator = (TabPageIndicator)findViewById(R.id.indicator); mIndicator.setViewPager(mPager); mIndicator.notifyDataSetChanged(); } class TestFragmentAdapter extends FragmentPagerAdapter { private int mCount = CONTENT.length; public TestFragmentAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int position) { switch(position) { case 0: return new customlist(); case 1: return new customlistnotuser(); default: return null; } } @Override public int getCount() { return mCount; } public CharSequence getPageTitle(int position) { return VpiAbsTestActivity.CONTENT[position % VpiAbsTestActivity.CONTENT.length].toUpperCase(); } @Override public void destroyItem(View collection, int position, Object view) { ((ViewPager) collection).removeView((View) view); } } } what can i update viewpager when change pages ? the customlistnotuser page likes customlist page but not show public class customlistnotuser extends SherlockFragment { // All static variables static final String URL = "url"; // XML node keys static final String KEY_TEST = "test"; // parent node static final String KEY_ID = "id"; static final String KEY_TITLE = "title"; static final String KEY_Description = "description"; static final String KEY_DURATION = "duration"; static final String KEY_THUMB_URL = "thumb_url"; static final String KEY_PRICE = "price"; static final String KEY_URL = "url"; private ProgressDialog pDialog; ListView list; LazyAdapterbeth adapter; XMLParser parser = new XMLParser(); public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); } public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); new getFeed().execute(); } public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View thisfragment = inflater.inflate(R.layout.dovomi, container, false); return thisfragment; } private class getFeed extends AsyncTask<Void, Void, Document> { } protected Document doInBackground(Void... params) { XMLParser parser = new XMLParser(); String xml = parser.getXmlFromUrl(URL); // getting XML from URL Document doc = parser.getDomElement(xml); // getting DOM element return doc; } protected void onPostExecute(Document doc) { ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>(); NodeList nl = doc.getElementsByTagName(KEY_TEST); // looping through all song nodes <song> for (int i = 0; i < nl.getLength(); i++) { // creating new HashMap HashMap<String, String> map = new HashMap<String, String>(); Element e = (Element) nl.item(i); // adding each child node to HashMap key => value map.put(KEY_ID, parser.getValue(e, KEY_ID)); map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE)); map.put(KEY_Description, parser.getValue(e, KEY_Description)); map.put(KEY_DURATION, parser.getValue(e, KEY_DURATION)); map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL)); map.put(KEY_PRICE, parser.getValue(e, KEY_PRICE)); map.put(KEY_URL, parser.getValue(e, KEY_URL)); // adding HashList to ArrayList songsList.add(map); pDialog.dismiss(); } list=(ListView)getActivity().findViewById(R.id.list); // Getting adapter by passing xml data ArrayList adapter=new LazyAdapterbeth(getActivity(), songsList); list.setAdapter(adapter); // Click event for single list row list.setOnItemClickListener(new OnItemClickListener() {

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• Is multithreading the right way to go for my case?

  - by Julien Lebosquain

  Hello, I'm currently designing a multi-client / server application. I'm using plain good old sockets because WCF or similar technology is not what I need. Let me explain: it isn't the classical case of a client simply calling a service; all clients can 'interact' with each other by sending a packet to the server, which will then do some action, and possible re-dispatch an answer message to one or more clients. Although doable with WCF, the application will get pretty complex with hundreds of different messages. For each connected client, I'm of course using asynchronous methods to send and receive bytes. I've got the messages fully working, everything's fine. Except that for each line of code I'm writing, my head just burns because of multithreading issues. Since there could be around 200 clients connected at the same time, I chose to go the fully multithreaded way: each received message on a socket is immediately processed on the thread pool thread it was received, not on a single consumer thread. Since each client can interact with other clients, and indirectly with shared objects on the server, I must protect almost every object that is mutable. I first went with a ReaderWriterLockSlim for each resource that must be protected, but quickly noticed that there are more writes overall than reads in the server application, and switched to the well-known Monitor to simplify the code. So far, so good. Each resource is protected, I have helper classes that I must use to get a lock and its protected resource, so I can't use an object without getting a lock. Moreover, each client has its own lock that is entered as soon as a packet is received from its socket. It's done to prevent other clients from making changes to the state of this client while it has some messages being processed, which is something that will happen frequently. Now, I don't just need to protect resources from concurrent accesses. I must keep every client in sync with the server for some collections I have. One tricky part that I'm currently struggling with is the following: I have a collection of clients. Each client has its own unique ID. When a client connects, it must receive the IDs of every connected client, and each one of them must be notified of the newcomer's ID. When a client disconnects, every other client must know it so that its ID is no longer valid for them. Every client must always have, at a given time, the same clients collection as the server so that I can assume that everybody knows everybody. This way if I'm sending a message to client #1 telling "Client #2 has done something", I know that it will always be correctly interpreted: Client 1 will never wonder "but who is Client 2 anyway?". My first attempt for handling the connection of a new client (let's call it X) was this pseudo-code (remember that newClient is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("newClient with id X has connected"); } } clients.Add(newClient); newClient.Send("the list of other clients"); } Now imagine that in the same time, another client has sent a packet that translates into a message that must be broadcasted to every connected client, the pseudo-code will be something like this (remember that the current client - let's call it Y - is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("something"); } } } An obvious deadlock occurs here: on one thread X is locked, the clients lock has been entered, started looping through the clients, and at one moment must get Y's lock... which is already acquired on the second thread, itself waiting for the clients collection lock to be released! This is not the only case like this in the server application. There are other collections which must be kept in sync with the clients, some properties on a client can be changed by another one, etc. I tried other types of locks, lock-free mechanisms and a bunch of other things. Either there were obvious deadlocks when I'm using too much locks for safety, or obvious race conditions otherwise. When I finally find a good middle point between the two, it usually comes with very subtle race conditions / dead locks and other multi-threading issues... my head hurts very quickly since for any single line of code I'm writing I have to review almost the whole application to ensure everything will behave correctly with any number of threads. So here's my final question: how would you resolve this specific case, the general case, and more importantly: aren't I going the wrong way here? I have little problems with the .NET framework, C#, simple concurrency or algorithms in general. Still, I'm lost here. I know I could use only one thread processing the incoming requests and everything will be fine. However, that won't scale well at all with more clients... But I'm thinking more and more to go this simple way. What do you think? Thanks in advance to you, StackOverflow people which have taken the time to read this huge question. I really had to explain the whole context if I want to get some help.

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• Using methods on 2 input files - 2nd is printing multiple times - Java

  - by Aaa

  I have the following code to read in text, store in a hashmap as bigrams (with other methods to sort them by frequency and do v. v. basic additive smoothing. I had it working great for one language input file (english) and then I want to expand it for the second language input file (japanese - doens;t matter what it is I suppose) using the same methods but the Japanese bigram hashmap is printing out 3 times in a row with diff. values. I've tried using diff text in the input file, making sure there are no gaps in text etc. I've also put print statements at certain places in the Japanese part of the code to see if I can get any clues but all the print statements are printing each time so I can't work out if it is looping at a certain place. I have gone through it with a fine toothcomb but am obviously missing something and slowly going crazy here - any help would be appreciated. thanks in advance... package languagerecognition2; import java.lang.String; import java.io.InputStreamReader; import java.util.*; import java.util.Iterator; import java.util.List.*; import java.util.ArrayList; import java.util.AbstractMap.*; import java.lang.Object; import java.io.*; import java.util.Enumeration; import java.util.Arrays; import java.lang.Math; public class Main { /** public static void main(String[] args) { //training English ----------------------------------------------------------------- File file = new File("english1.txt"); StringBuffer contents = new StringBuffer(); BufferedReader reader = null; try { reader = new BufferedReader(new FileReader(file)); String test = null; //test = reader.readLine(); // repeat until all lines are read while ((test = reader.readLine()) != null) { test = test.toLowerCase(); char[] charArrayEng = test.toCharArray(); HashMap<String, Integer> hashMapEng = new HashMap<String, Integer>(bigrams(charArrayEng)); LinkedHashMap<String, Integer> sortedListEng = new LinkedHashMap<String, Integer>(sort(hashMapEng)); int sizeEng=sortedListEng.size(); System.out.println("Total count of English bigrams is " + sizeEng); LinkedHashMap<String, Integer> smoothedListEng = new LinkedHashMap<String, Integer>(smooth(sortedListEng, sizeEng)); //print linkedHashMap to check values Set set= smoothedListEng.entrySet(); Iterator iter = set.iterator ( ) ; System.out.println("Beginning English"); while ( iter.hasNext()) { Map.Entry entry = ( Map.Entry ) iter.next ( ) ; Object key = entry.getKey ( ) ; Object value = entry.getValue ( ) ; System.out.println( key+" : " + value); } System.out.println("End English"); }//end while }//end try catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (reader != null) { reader.close(); } } catch (IOException e) { e.printStackTrace(); } } //End training English----------------------------------------------------------- //Training japanese-------------------------------------------------------------- File file2 = new File("japanese1.txt"); StringBuffer contents2 = new StringBuffer(); BufferedReader reader2 = null; try { reader2 = new BufferedReader(new FileReader(file2)); String test2 = null; //repeat until all lines are read while ((test2 = reader2.readLine()) != null) { test2 = test2.toLowerCase(); char[] charArrayJap = test2.toCharArray(); HashMap<String, Integer> hashMapJap = new HashMap<String, Integer>(bigrams(charArrayJap)); //System.out.println( "bigrams stage"); LinkedHashMap<String, Integer> sortedListJap = new LinkedHashMap<String, Integer>(sort(hashMapJap)); //System.out.println( "sort stage"); int sizeJap=sortedListJap.size(); //System.out.println("Total count of Japanese bigrams is " + sizeJap); LinkedHashMap<String, Integer> smoothedListJap = new LinkedHashMap<String, Integer>(smooth(sortedListJap, sizeJap)); System.out.println( "smooth stage"); //print linkedHashMap to check values Set set2= smoothedListJap.entrySet(); Iterator iter2 = set2.iterator(); System.out.println("Beginning Japanese"); while ( iter2.hasNext()) { Map.Entry entry2 = ( Map.Entry ) iter2.next ( ) ; Object key = entry2.getKey ( ) ; Object value = entry2.getValue ( ) ; System.out.println( key+" : " + value); }//end while System.out.println("End Japanese"); }//end while }//end try catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (reader2 != null) { reader2.close(); } } catch (IOException e) { e.printStackTrace(); } } //end training Japanese--------------------------------------------------------- } //end main (inner)

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• Perl - Reading .txt files line-by-line and using compare function (printing non-matches only once)

  - by Kurt W

  I am really struggling and have spent about two full days on this banging my head against receiving the same result every time I run this perl script. I have a Perl script that connects to a vendor tool and stores data for ~26 different elements within @data. There is a foreach loop for @data that breaks the 26 elements into $e-{'element1'), $e-{'element2'), $e-{'element3'), $e-{'element4'), etc. etc. etc. I am also reading from the .txt files within a directory (line-by-line) and comparing the server names that exist within the text files with what exists in $e-{'element4'}. The Problem: Matches are working perfectly and only printing one line for each of the 26 elements when there is a match, however non-matches are producing one line for every entry within the .txt files (37 in all). So if there are 100 entries (each entry having 26 elements) stored within @data, then there are 100 x 37 entries being printed. So for every non-match in the: if ($e-{'element4'} eq '6' && $_ =~ /$e-{element7}/i) statement below, I am receiving a print out saying that there is not a match. 37 entries for the same identical 26 elements (because there are 37 total entries in all of the .txt files). The Goal: I need to print out only 1 line for each unique entry (a unique entry being $e-{element1} thru $e-{element26}). It is already printing one 1 line for matches, but it is printing out 37 entries when there is not a match. I need to treat matches and non-matches differently. Code: foreach my $e (@data) { # Open the .txt files stored within $basePath and use for comparison: opendir(DIRC, $basePath . "/") || die ("cannot open directory"); my @files=(readdir(DIRC)); my @MPG_assets = grep(/(.*?).txt/, @files); # Loop through each system name found and compare it with the data in SC for a match: foreach(@MPG_assets) { $filename = $_; open (MPGFILES, $basePath . "/" . $filename) || die "canot open the file"; while(<MPGFILES>) { if ($e->{'element4'} eq '6' && $_ =~ /$e->{'element7'}/i) { ## THIS SECTION WORKS PERFECTLY AND ONLY PRINTS MATCHES WHERE $_ ## (which contains the servernames (1 per line) in the .txt files) ## EQUALS $e->{'element7'}. print $e->{'element1'} . "\n"; print $e->{'element2'} . "\n"; print $e->{'element3'} . "\n"; print $e->{'element4'} . "\n"; print $e->{'element5'} . "\n"; # ... print $e->{'element26'} . "\n"; } else { ## **THIS SECTION DOES NOT WORK**. FOR EVERY NON-MATCH, THERE IS A ## LINE PRINTED WITH 26 IDENTICAL ELEMENTS BECAUSE ITS LOOPING THRU ## THE 37 LINES IN THE *.TXT FILES. print $e->{'element1'} . "\n"; print $e->{'element2'} . "\n"; print $e->{'element3'} . "\n"; print $e->{'element4'} . "\n"; print $e->{'element5'} . "\n"; # ... print $e->{'element26'} . "\n"; } # End of 'if ($e->{'element4'} eq..' statement } # End of while loop } # End of 'foreach(@MPG_assets)' } # End of 'foreach my $e (@data)' I think I need something to identical unique elements and define what fields make up a unique element but honestly I have tried everything I know. If you would be so kind to provide actual code fixes, that would be wonderful because I am headed to production with this script quite soon. Also. I am looking for code (ideally) that is very human-readable because I will need to document it so others can understand. Please let me know if you need additional information.

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• Informed TDD &ndash; Kata &ldquo;To Roman Numerals&rdquo;

  - by Ralf Westphal

  Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons.   PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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• Can't seem to get C TCP Server-Client Communications Right

  - by Zeesponge

  Ok i need some serious help here. I have to make a TCP Server Client. When the Client connects to server using a three stage handshake. AFterwards... while the Client is running in the terminal, the user enters linux shell commands like xinput list, ls -1, ect... something that uses standard output. The server accepts the commands and uses system() (in a fork() in an infinite loop) to run the commands and the standard output is redirected to the client, where the client prints out each line. Afterward the server sends a completion signal of "\377\n". In which the client goes back to the command prompt asking for a new command and closes its connection and exit()'s when inputting "quit". I know that you have to dup2() both the STDOUT_FILENO and STDERR_FILENO to the clients file descriptor {dup2(client_FD, STDOUT_FILENO). Everything works accept when it comes for the client to retrieve system()'s stdout and printing it out... all i get is a blank line with a blinking cursor (client waiting on stdin). I tried all kinds of different routes with no avail... If anyone can help out i would greatly appreciate it TCP SERVER CODE include #include <sys/socket.h> #include <stdio.h> #include <string.h> #include <netinet/in.h> #include <signal.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> //Prototype void handle_client(int connect_fd); int main() { int server_sockfd, client_sockfd; socklen_t server_len, client_len; struct sockaddr_in server_address; struct sockaddr_in client_address; server_sockfd = socket(AF_INET, SOCK_STREAM, 0); server_address.sin_family = AF_INET; server_address.sin_addr.s_addr = htonl(INADDR_ANY); server_address.sin_port = htons(9734); server_len = sizeof(server_address); bind(server_sockfd, (struct sockaddr *)&server_address, server_len); /* Create a connection queue, ignore child exit details and wait for clients. */ listen(server_sockfd, 10); signal(SIGCHLD, SIG_IGN); while(1) { printf("server waiting\n"); client_len = sizeof(client_address); client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_address, &client_len); if(fork() == 0) handle_client(client_sockfd); else close(client_sockfd); } } void handle_client(int connect_fd) { const char* remsh = "<remsh>\n"; const char* ready = "<ready>\n"; const char* ok = "<ok>\n"; const char* command = "<command>\n"; const char* complete = "<\377\n"; const char* shared_secret = "<shapoopi>\n"; static char server_msg[201]; static char client_msg[201]; static char commands[201]; int sys_return; //memset client_msg, server_msg, commands memset(&client_msg, 0, sizeof(client_msg)); memset(&server_msg, 0, sizeof(client_msg)); memset(&commands, 0, sizeof(commands)); //read remsh from client read(connect_fd, &client_msg, 200); //check remsh validity from client if(strcmp(client_msg, remsh) != 0) { errno++; perror("Error Establishing Handshake"); close(connect_fd); exit(1); } //memset client_msg memset(&client_msg, 0, sizeof(client_msg)); //write remsh to client write(connect_fd, remsh, strlen(remsh)); //read shared_secret from client read(connect_fd, &client_msg, 200); //check shared_secret validity from client if(strcmp(client_msg, shared_secret) != 0) { errno++; perror("Invalid Security Passphrase"); write(connect_fd, "no", 2); close(connect_fd); exit(1); } //memset client_msg memset(&client_msg, 0, sizeof(client_msg)); //write ok to client write(connect_fd, ok, strlen(ok)); // dup2 STDOUT_FILENO <= client fd, STDERR_FILENO <= client fd dup2(connect_fd, STDOUT_FILENO); dup2(connect_fd, STDERR_FILENO); //begin while... while read (client_msg) from server and >0 while(read(connect_fd, &client_msg, 200) > 0) { //check command validity from client if(strcmp(client_msg, command) != 0) { errno++; perror("Error, unable to retrieve data"); close(connect_fd); exit(1); } //memset client_msg memset(&client_msg, 0, sizeof(client_msg)); //write ready to client write(connect_fd, ready, strlen(ready)); //read commands from client read(connect_fd, &commands, 200); //run commands using system( ) sys_return = system(commands); //check success of system( ) if(sys_return < 0) { perror("Invalid Commands"); errno++; } //memset commands memset(commands, 0, sizeof(commands)); //write complete to client write(connect_fd, complete, sizeof(complete)); } } TCP CLIENT CODE #include <sys/types.h> #include <sys/socket.h> #include <stdio.h> #include <string.h> #include <netinet/in.h> #include <arpa/inet.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> #include "readline.c" int main(int argc, char *argv[]) { int sockfd; int len; struct sockaddr_in address; int result; const char* remsh = "<remsh>\n"; const char* ready = "<ready>\n"; const char* ok = "<ok>\n"; const char* command = "<command>\n"; const char* complete = "<\377\n"; const char* shared_secret = "<shapoopi>\n"; static char server_msg[201]; static char client_msg[201]; memset(&client_msg, 0, sizeof(client_msg)); memset(&server_msg, 0, sizeof(server_msg)); /* Create a socket for the client. */ sockfd = socket(AF_INET, SOCK_STREAM, 0); /* Name the socket, as agreed with the server. */ memset(&address, 0, sizeof(address)); address.sin_family = AF_INET; address.sin_addr.s_addr = inet_addr(argv[1]); address.sin_port = htons(9734); len = sizeof(address); /* Now connect our socket to the server's socket. */ result = connect(sockfd, (struct sockaddr *)&address, len); if(result == -1) { perror("ACCESS DENIED"); exit(1); } //write remsh to server write(sockfd, remsh, strlen(remsh)); //read remsh from server read(sockfd, &server_msg, 200); //check remsh validity from server if(strcmp(server_msg, remsh) != 0) { errno++; perror("Error Establishing Initial Handshake"); close(sockfd); exit(1); } //memset server_msg memset(&server_msg, 0, sizeof(server_msg)); //write shared secret text to server write(sockfd, shared_secret, strlen(shared_secret)); //read ok from server read(sockfd, &server_msg, 200); //check ok velidity from server if(strcmp(server_msg, ok) != 0 ) { errno++; perror("Incorrect security phrase"); close(sockfd); exit(1); } //? dup2 STDIN_FILENO = server socket fd? //dup2(sockfd, STDIN_FILENO); //begin while(1)/////////////////////////////////////// while(1){ //memset both msg arrays memset(&client_msg, 0, sizeof(client_msg)); memset(&server_msg, 0, sizeof(server_msg)); //print Enter Command, scan input, fflush to stdout printf("<<Enter Command>> "); scanf("%s", client_msg); fflush(stdout); //check quit input, if true close and exit successfully if(strcmp(client_msg, "quit") == 0) { printf("Exiting\n"); close(sockfd); exit(EXIT_SUCCESS); } //write command to server write(sockfd, command, strlen(command)); //read ready from server read(sockfd, &server_msg, 200); //check ready validity from server if(strcmp(server_msg, ready) != 0) { errno++; perror("Failed Server Communications"); close(sockfd); exit(1); } //memset server_msg memset(&server_msg, 0, sizeof(server_msg)); //begin looping and retrieving from stdin, //break loop at EOF or complete while((read(sockfd, server_msg, 200) != 0) && (strcmp(server_msg, complete) != 0)) { //while((fgets(server_msg, 4096, stdin) != EOF) || (strcmp(server_msg, complete) == 0)) { printf("%s", server_msg); memset(&server_msg, 0, sizeof(server_msg)); } } }

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• Moving items from one tableView to another tableView with extra's

  - by Totumus Maximus

  Let's say I have 2 UITableViews next to eachother on an ipad in landscape-mode. Now I want to move multiple items from one tableView to the other. They are allowed to be inserted on the bottom of the other tableView. Both have multiSelection activated. Now the movement itself is no problem with normal cells. But in my program each cell has an object which contains the consolidationState of the cell. There are 4 states a cell can have: Basic, Holding, Parent, Child. Basic = an ordinary cell. Holding = a cell which contains multiple childs but which wont be shown in this state. Parent = a cell which contains multiple childs and are shown directly below this cell. Child = a cell created by the Parent cell. The object in each cell also has some array which contains its children. The object also holds a quantityValue, which is displayed on the cell itself. Now the movement gets tricky. Holding and Parent cells can't move at all. Basic cells can move freely. Child cells can move freely but based on how many Child cells are left in the Parent. The parent will change or be deleted all together. If a Parent cell has more then 1 Child cell left it will stay a Parent cell. Else the Parent has no or 1 Child cell left and is useless. It will then be deleted. The items that are moved will always be of the same state. They will all be Basic cells. This is how I programmed the movement: *First I determine which of the tableViews is the sender and which is the receiver. *Second I ask all indexPathsForSelectedRows and sort them from highest row to lowest. *Then I build the data to be transferred. This I do by looping through the selectedRows and ask their object from the sender's listOfItems. *When I saved all the data I need I delete all the items from the sender TableView. This is why I sorted the selectedRows so I can start at the highest indexPath.row and delete without screwing up the other indexPaths. *When I loop through the selectedRows I check whether I found a cell with state Basic or Child. *If its a Basic cell I do nothing and just delete the cell. (this works fine with all Basic Cells) *If its a Child cell I go and check it's Parent cell immidiately. Since all Child cells are directly below the Parent cell and no other the the Parent's Childs are below that Parent I can safely get the path of the selected Childcell and move upwards and find it's Parent cell. When this Parent cell is found (this will always happen, no exceptions) it has to change accordingly. *The Parent cell will either be deleted or the object inside will have its quantity and children reduced. *After the Parent cell has changed accordingly the Child cell is deleted similarly like the Basic cells *After the deletion of the cells the receiver tableView will build new indexPaths so the movedObjects will have a place to go. *I then insert the objects into the listOfItems of the receiver TableView. The code works in the following ways: Only Basic cells are moved. Basic cells and just 1 child for each parent is moved. A single Basic/Child cell is moved. The code doesn't work when: I select more then 1 or all childs of some parent cell. The problem happens somewhere into updating the parent cells. I'm staring blindly at the code now so maybe a fresh look will help fix things. Any help will be appreciated. Here is the method that should do the movement: -(void)moveSelectedItems { UITableView *senderTableView = //retrieves the table with the data here. UITableView *receiverTableView = //retrieves the table which gets the data here. NSArray *selectedRows = senderTableView.indexPathsForSelectedRows; //sort selected rows from lowest indexPath.row to highest selectedRows = [selectedRows sortedArrayUsingSelector:@selector(compare:)]; //build up target rows (all objects to be moved) NSMutableArray *targetRows = [[NSMutableArray alloc] init]; for (int i = 0; i<selectedRows.count; i++) { NSIndexPath *path = [selectedRows objectAtIndex:i]; [targetRows addObject:[senderTableView.listOfItems objectAtIndex:path.row]]; } //delete rows at active for (int i = selectedRows.count-1; i >= 0; i--) { NSIndexPath *path = [selectedRows objectAtIndex:i]; //check what item you are deleting. act upon the status. Parent- and HoldingCells cant be selected so only check for basic and childs MyCellObject *item = [senderTableView.listOfItems objectAtIndex:path.row]; if (item.consolidatedState == ConsolidationTypeChild) { for (int j = path.row; j >= 0; j--) { MyCellObject *consolidatedItem = [senderTableView.listOfItems objectAtIndex:j]; if (consolidatedItem.consolidatedState == ConsolidationTypeParent) { //copy the consolidated item but with 1 less quantity MyCellObject *newItem = [consolidatedItem copyWithOneLessQuantity]; //creates a copy of the object with 1 less quantity. if (newItem.quantity > 1) { newItem.consolidatedState = ConsolidationTypeParent; [senderTableView.listOfItems replaceObjectAtIndex:j withObject:newItem]; } else if (newItem.quantity == 1) { newItem.consolidatedState = ConsolidationTypeBasic; [senderTableView.listOfItems removeObjectAtIndex:j]; MyCellObject *child = [senderTableView.listOfItems objectAtIndex:j+1]; child.consolidatedState = ConsolidationTypeBasic; [senderTableView.listOfItems replaceObjectAtIndex:j+1 withObject:child]; } else { [senderTableView.listOfItems removeObject:consolidatedItem]; } [senderTableView reloadData]; } } } [senderTableView.listOfItems removeObjectAtIndex:path.row]; } [senderTableView deleteRowsAtIndexPaths:selectedRows withRowAnimation:UITableViewRowAnimationTop]; //make new indexpaths for row animation NSMutableArray *newRows = [[NSMutableArray alloc] init]; for (int i = 0; i < targetRows.count; i++) { NSIndexPath *newPath = [NSIndexPath indexPathForRow:i+receiverTableView.listOfItems.count inSection:0]; [newRows addObject:newPath]; DLog(@"%i", i); //scroll to newest items [receiverTableView setContentOffset:CGPointMake(0, fmaxf(receiverTableView.contentSize.height - recieverTableView.frame.size.height, 0.0)) animated:YES]; } //add rows at target for (int i = 0; i < targetRows.count; i++) { MyCellObject *insertedItem = [targetRows objectAtIndex:i]; //all moved items will be brought into the standard (basic) consolidationType insertedItem.consolidatedState = ConsolidationTypeBasic; [receiverTableView.ListOfItems insertObject:insertedItem atIndex:receiverTableView.ListOfItems.count]; } [receiverTableView insertRowsAtIndexPaths:newRows withRowAnimation:UITableViewRowAnimationNone]; } If anyone has some fresh ideas of why the movement is bugging out let me know. If you feel like you need some extra information I'll be happy to add it. Again the problem is in the movement of ChildCells and updating the ParentCells properly. I could use some fresh looks and outsider ideas on this. Thanks in advance. *updated based on comments

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• Implementing an async "read all currently available data from stream" operation

  - by Jon

  I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a console's standard output Stream. Console output streams are of type FileStream; the implementation can cast to that, if needed. There is also an associated StreamReader already present to leverage. There is only one thing I need to implement in this class to achieve my desired functionality: an async "read all the data available this moment" operation. Reading to the end of the stream is not viable because the stream will not end unless the process closes the console output handle, and it will not do that because it is interactive and expecting input before continuing. I will be using that hypothetical async operation to implement event-based notification, which will be more convenient for my callers. The public interface of the class is this: public class ConsoleAutomator { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Remember that the goal here is to read all of the chunk and call event subscribers exactly once for each chunk. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream. private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer (in which case we know that there was no more data to be read during the last read operation), all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Never more than one event for each time data is available to be read Is almost agnostic to the buffer size The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this. Update: I definitely did not communicate the scenario well in my initial writeup. I have since revised the writeup quite a bit, but to be extra sure: The question is about how to implement an async "read all the data available this moment" operation. My apologies to the people who took the time to read and answer without me making my intent clear enough.

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• Implementing a robust async stream reader

  - by Jon

  I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output, but that is a detail and does not play an important role. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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• Implementing union of Set using basic java array

  - by lupindeterd

  Note: This is an assignment. Hi, Continuing with my Set implementation using Java basic array, I'm now struggling with the 3 to last function namely the union. import java.io.*; class Set { private int numberOfElements = 0; private String[] setElements = new String[5]; private int maxNumberOfElements = 5; // constructor for our Set class public Set(int numberOfE, int setE, int maxNumberOfE) { int numberOfElements = numberOfE; String[] setElements = new String[setE]; int maxNumberOfElements = maxNumberOfE; } // Helper method to shorten/remove element of array since we're using basic array instead of ArrayList or HashSet from collection interface :( static String[] removeAt(int k, String[] arr) { final int L = arr.length; String[] ret = new String[L - 1]; System.arraycopy(arr, 0, ret, 0, k); System.arraycopy(arr, k + 1, ret, k, L - k - 1); return ret; } int findElement(String element) { int retval = 0; for ( int i = 0; i < setElements.length; i++) { if ( setElements[i] != null && setElements[i].equals(element) ) { return retval = i; } retval = -1; } return retval; } void add(String newValue) { int elem = findElement(newValue); if( numberOfElements < maxNumberOfElements && elem == -1 ) { setElements[numberOfElements] = newValue; numberOfElements++; } } int getLength() { if ( setElements != null ) { return setElements.length; } else { return 0; } } String[] emptySet() { setElements = new String[0]; return setElements; } Boolean isFull() { Boolean True = new Boolean(true); Boolean False = new Boolean(false); if ( setElements.length == maxNumberOfElements ){ return True; } else { return False; } } Boolean isEmpty() { Boolean True = new Boolean(true); Boolean False = new Boolean(false); if ( setElements.length == 0 ) { return True; } else { return False; } } void remove(String newValue) { for ( int i = 0; i < setElements.length; i++) { if ( setElements[i].equals(newValue) ) { setElements = removeAt(i,setElements); } } } int isAMember(String element) { int retval = -1; for ( int i = 0; i < setElements.length; i++ ) { if (setElements[i] != null && setElements[i].equals(element)) { return retval = i; } } return retval; } void printSet() { for ( int i = 0; i < setElements.length; i++) { System.out.println("Member elements on index: "+ i +" " + setElements[i]); } } String[] getMember() { String[] tempArray = new String[setElements.length]; for ( int i = 0; i < setElements.length; i++) { if(setElements[i] != null) { tempArray[i] = setElements[i]; } } return tempArray; } Set union(Set x, Set y) { String[] newtemparray = new String[x.getLength]; newtemparray = x.getMember; return x; } } // This is the SetDemo class that will make use of our Set class class SetDemo { public static void main(String[] args) { //get input from keyboard BufferedReader keyboard; InputStreamReader reader; String temp = ""; reader = new InputStreamReader(System.in); keyboard = new BufferedReader(reader); try { System.out.println("Enter string element to be added" ); temp = keyboard.readLine( ); System.out.println("You entered " + temp ); } catch (IOException IOerr) { System.out.println("There was an error during input"); } /* ************************************************************************** * Test cases for our new created Set class. * ************************************************************************** */ Set setA = new Set(1,10,10); setA.add(temp); setA.add("b"); setA.add("b"); setA.add("hello"); setA.add("world"); setA.add("six"); setA.add("seven"); setA.add("b"); int size = setA.getLength(); System.out.println("Set size is: " + size ); Boolean isempty = setA.isEmpty(); System.out.println("Set is empty? " + isempty ); int ismember = setA.isAMember("sixb"); System.out.println("Element six is member of setA? " + ismember ); Boolean output = setA.isFull(); System.out.println("Set is full? " + output ); setA.printSet(); int index = setA.findElement("world"); System.out.println("Element b located on index: " + index ); setA.remove("b"); setA.emptySet(); int resize = setA.getLength(); System.out.println("Set size is: " + resize ); setA.printSet(); Set setB = new Set(0,10,10); Set SetA = setA.union(setB,setA); } } Ok the method in question will be the implementation of union. As such this: Set union(Set x, Set y) { String[] newtemparray = new String[x.getLength]; newtemparray = x.getMember; return x; } I got this error: symbol : variable getLength location: class Set String[] newtemparray = new String[x.getLength]; ^ d:\javaprojects\Set.java:122: cannot find symbol symbol : variable getMember location: class Set newtemparray = x.getMember; ^ 2 errors My approach for union would be: *) create temporary array of string with size of the object x length. *) store object x members to temporary array by looping the object and calling the getMember *) loop object y members and check if element exist against temporary array. *) discard if it exist/add if it is not there *) return obj x with the union array. thanks, lupin

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• XMLReader mysteriously fails when parsing document

  - by Valrus

  I have a php script that takes in some XML data and parses it, displaying various bits of information I pull out of it. This has been working fine for over 6 months, until recently it now fails mysteriously on a certain tag. The XML is generated from an outside source(a conferencing bridge), so I have no control over how it is built. I have put the xml through an online validator and it returned no errors. The code also works fine when I connect to another conferencing bridge and get the same output. I have been using XMLReader class so far and tried switching to SmipleXML, but it fails when I create the SimpleXML object using the data. Here is the snippet of where it fails while parsing: <CDR_SUMMARY> <FILE_VERSION>1001</FILE_VERSION> <NAME>Conference Title Hidden</NAME> <ID>10227</ID> <STATUS_STR>Auto_termination,_everybody_quit</STATUS_STR> <STATUS>4</STATUS> <GMT_OFFSET>-4</GMT_OFFSET> <START_TIME>2010-04-14T15:00:33</START_TIME> <DURATION> <HOUR>0</HOUR> <MINUTE>39</MINUTE> <SECOND>37</SECOND> </DURATION> <RESERVE_START_TIME>2010-04-14T15:00:33</RESERVE_START_TIME> <RESERVE_DURATION> <HOUR>12</HOUR> <MINUTE>0</MINUTE> <SECOND>0</SECOND> </RESERVE_DURATION> <MCU_FILE_NAME>c11</MCU_FILE_NAME> <FILE_SAVED>0</FILE_SAVED> <GMT_OFFSET_MINUTE>0</GMT_OFFSET_MINUTE> </CDR_SUMMARY> The <SOUND> opening tag is the last one read before failing. And this is my code: `public function processResponse($xml) { print "Processing List..."; $reader = new XMLReader($xml); try { $reader->setSchema("./schemas/response_trans_cdr_list.xsd"); } catch(Exception $e) { print "Exception:".$e->getMessage(); } //verify xml if($reader->xml($xml)) { while($reader->read()) { //$currentstring = $reader->readstring(); if($reader->name === "ACTION") { //into meat of resposnse while($reader->read()) { //print "Looping..."; //$currentstring = $reader->readInnerXML(); //print $currentstring; if($reader->nodeType == XMLReader::ELEMENT) { if($reader->name === "ID") { $this->conferenceIDs[$this->counter] = $reader->readString(); print "<BR>Conf ID found: ".$this->counter." ID: ".$this->conferenceIDs[$this->counter]; $this->counter += 1; } else if($reader->name === "START_TIME") { //conference start time. print "<BR>Start Time Found! "; $this->conferenceStarts[$this->counter-1] = $reader->readString(); } else if($reader->name === "NAME") { print "<BR> Name Found!"; $this->conferenceNames[$this->counter] = $reader->readString(); } else if($reader->name === "MCU_FILE_NAME") { print "<BR> MCU_FILE_NAME Found!"; //print $this->counter." File Name: ".$reader->readstring()."<BR>"; } else if($reader->name === "RESERVE_START_TIME") { print "<BR> RESERVE_START_TIME Found!"; } else if($reader->name === "FILE_VERSION") { print "<BR> FILE_VERSION Found!"; } else if($reader->name === "STATUS_STR") { print "<BR> STATUS_STR Found!"; } else if($reader->name === "STATUS") { print "<BR> STATUS Found!"; } else if($reader->name === "GMT_OFFSET") { print "<BR> GMT_OFFSET Found!"; } else if($reader->name === "DURATION") { print "<BR> DURATION Found!"; } else if($reader->name === "RESERVE_START_TIME") { print "<BR> RESERVE_START_TIME Found!"; } else if($reader->name === "RESERVE_DURATION") { print "<BR> RESERVE_DURATION Found!"; } else if($reader->name === "FILE_SAVED") { print "<BR> FILE_SAVED Found!"; } else if($reader->name === "GMT_OFFSET_MINUTE") { print "<BR> GMT_OFFSET_MINUTE Found!"; } else if($reader->name === "HOUR") { print "<BR> HOUR Found!"; } else if($reader->name === "MINUTE") { print "<BR> MINUTE Found!"; } else if($reader->name === "SECOND") { print "<BR> SECOND Found!"; } }else if($reader->nodeType == XMLReader::END_ELEMENT) { print "Close Element".$reader->name; } } print "End Action Loop"; } } } else { print "Error reading response: Bad XML returned"; } }` Anyone have any ideas what could be causing this failure? the code exits gracefully and I see the "End Action Loop" message in my output. It's like it just spontaneously exits the loop.

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• Implementing a robust async stream reader for a console

  - by Jon

  I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. Edit: There are comments below correctly stating that since the data is coming from a stream, there is absolutely nothing that the receiver can infer about the structure of the data unless it is fully prepared to parse it. What I am trying to do here is leverage the "flush the output" "structure" that the owner of the console imparts while writing on it. I am prepared to assume (better: allow my caller to have the option to assume) that the OS will pass me the data written between two flushes of the stream in exactly one piece. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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• Using glDrawElements does not draw my .obj file

  - by Hallik

  I am trying to correctly import an .OBJ file from 3ds Max. I got this working using glBegin() & glEnd() from a previous question on here, but had really poor performance obviously, so I am trying to use glDrawElements now. I am importing a chessboard, its game pieces, etc. The board, each game piece, and each square on the board is stored in a struct GroupObject. The way I store the data is like this: struct Vertex { float position[3]; float texCoord[2]; float normal[3]; float tangent[4]; float bitangent[3]; }; struct Material { float ambient[4]; float diffuse[4]; float specular[4]; float shininess; // [0 = min shininess, 1 = max shininess] float alpha; // [0 = fully transparent, 1 = fully opaque] std::string name; std::string colorMapFilename; std::string bumpMapFilename; std::vector<int> indices; int id; }; //A chess piece or square struct GroupObject { std::vector<Material *> materials; std::string objectName; std::string groupName; int index; }; All vertices are triangles, so there are always 3 points. When I am looping through the faces f section in the obj file, I store the v0, v1, & v2 in the Material-indices. (I am doing v[0-2] - 1 to account for obj files being 1-based and my vectors being 0-based. So when I get to the render method, I am trying to loop through every object, which loops through every material attached to that object. I set the material information and try and use glDrawElements. However, the screen is black. I was able to draw the model just fine when I looped through each distinct material with all the indices associated with that material, and it drew the model fine. This time around, so I can use the stencil buffer for selecting GroupObjects, I changed up the loop, but the screen is black. Here is my render loop. The only thing I changed was the for loop(s) so they go through each object, and each material in the object in turn. void GLEngine::drawModel() { glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); // Vertex arrays setup glEnableClientState( GL_VERTEX_ARRAY ); glVertexPointer(3, GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->position); glEnableClientState( GL_NORMAL_ARRAY ); glNormalPointer(GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->normal); glClientActiveTexture( GL_TEXTURE0 ); glEnableClientState( GL_TEXTURE_COORD_ARRAY ); glTexCoordPointer(2, GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->texCoord); glUseProgram(blinnPhongShader); objects = model.getObjects(); // Loop through objects... for( int i=0 ; i < objects.size(); i++ ) { ModelOBJ::GroupObject *object = objects[i]; // Loop through materials used by object... for( int j=0 ; j<object->materials.size() ; j++ ) { ModelOBJ::Material *pMaterial = object->materials[j]; glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, pMaterial->ambient); glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, pMaterial->diffuse); glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, pMaterial->specular); glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, pMaterial->shininess * 128.0f); // Draw faces, letting OpenGL loop through them glDrawElements( GL_TRIANGLES, pMaterial->indices.size(), GL_UNSIGNED_INT, &pMaterial->indices ); } } if (model.hasNormals()) glDisableClientState(GL_NORMAL_ARRAY); if (model.hasTextureCoords()) { glClientActiveTexture(GL_TEXTURE0); glDisableClientState(GL_TEXTURE_COORD_ARRAY); } if (model.hasPositions()) glDisableClientState(GL_VERTEX_ARRAY); glBindTexture(GL_TEXTURE_2D, 0); glUseProgram(0); glDisable(GL_BLEND); } I don't know what I am missing that's important. If it's also helpful, here is where I read a 'f' face line and store the info in the obj importer in the pMaterial-indices. else if (sscanf(buffer, "%d/%d/%d", &v[0], &vt[0], &vn[0]) == 3) // v/vt/vn { fscanf(pFile, "%d/%d/%d", &v[1], &vt[1], &vn[1]); fscanf(pFile, "%d/%d/%d", &v[2], &vt[2], &vn[2]); v[0] = (v[0] < 0) ? v[0] + numVertices - 1 : v[0] - 1; v[1] = (v[1] < 0) ? v[1] + numVertices - 1 : v[1] - 1; v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1; currentMaterial->indices.push_back(v[0]); currentMaterial->indices.push_back(v[1]); currentMaterial->indices.push_back(v[2]); Again, this worked drawing it all together only separated by materials, so I haven't changed code anywhere else except added the indices to the materials within objects, and the loop in the draw method. Before everything was showing up black, now with the setup as above, I am getting an unhandled exception write violation on the glDrawElements line. I did a breakpoint there, and there are over 600 elements in the pMaterial-indices array, so it's not empty, it has indices to use. When I set the glDrawElements like this, it gives me the black screen but no errors glDrawElements( GL_TRIANGLES, pMaterial->indices.size(), GL_UNSIGNED_INT, &pMaterial->indices[0] ); I have also tried adding this when I loop through the faces on import if ( currentMaterial->startIndex == -1 ) currentMaterial->startIndex = v[0]; currentMaterial->triangleCount++; And when drawing... //in draw method glDrawElements( GL_TRIANGLES, pMaterial->triangleCount * 3, GL_UNSIGNED_INT, model.getIndexBuffer() + pMaterial->startIndex );

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