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• Hibernate Communications Link Failure in Restlet-Hibernate Based Java application powered by MySQL

  - by Vatsala

  Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?)

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• dynamic module creation

  - by intuited

  I'd like to dynamically create a module from a dictionary, and I'm wondering if adding an element to sys.modules is really the best way to do this. EG context = { a: 1, b: 2 } import types test_context_module = types.ModuleType('TestContext', 'Module created to provide a context for tests') test_context_module.__dict__.update(context) import sys sys.modules['TestContext'] = test_context_module My immediate goal in this regard is to be able to provide a context for timing test execution: import timeit timeit.Timer('a + b', 'from TestContext import *') It seems that there are other ways to do this, since the Timer constructor takes objects as well as strings. I'm still interested in learning how to do this though, since a) it has other potential applications; and b) I'm not sure exactly how to use objects with the Timer constructor; doing so may prove to be less appropriate than this approach in some circumstances. EDITS/REVELATIONS/PHOOEYS/EUREKAE: I've realized that the example code relating to running timing tests won't actually work, because import * only works at the module level, and the context in which that statement is executed is that of a function in the testit module. In other words, the globals dictionary used when executing that code is that of main, since that's where I was when I wrote the code in the interactive shell. So that rationale for figuring this out is a bit botched, but it's still a valid question. I've discovered that the code run in the first set of examples has the undesirable effect that the namespace in which the newly created module's code executes is that of the module in which it was declared, not its own module. This is like way weird, and could lead to all sorts of unexpected rattlesnakeic sketchiness. So I'm pretty sure that this is not how this sort of thing is meant to be done, if it is in fact something that the Guido doth shine upon. The similar-but-subtly-different case of dynamically loading a module from a file that is not in python's include path is quite easily accomplished using imp.load_source('NewModuleName', 'path/to/module/module_to_load.py'). This does load the module into sys.modules. However this doesn't really answer my question, because really, what if you're running python on an embedded platform with no filesystem? I'm battling a considerable case of information overload at the moment, so I could be mistaken, but there doesn't seem to be anything in the imp module that's capable of this. But the question, essentially, at this point is how to set the global (ie module) context for an object. Maybe I should ask that more specifically? And at a larger scope, how to get Python to do this while shoehorning objects into a given module?

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• Killing Mysql processes staying in sleep command.

  - by Shino88

  Hey I am connecting a MYSQL database through hibernate and i seem to have processes that are not being killed after they are finished in the session. I have called flush and close on each session but when i check the server the last processes are still there with a sleep command. This is a new problem which i am having and was not the case yesterday. Is there any way i can ensure the killng of theses processes when i am done with a session. Below is an example of one of my classes. public JSONObject check() { //creates a new session needed to add elements to a database Session session = null; //holds the result of the check in the database JSONObject check = new JSONObject(); try{ //creates a new session needed to add elements to a database SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory(); session = sessionFactory.openSession(); if (justusername){ //query created to select a username from user table String hquery = "Select username from User user Where username = ? "; //query created Query query = session.createQuery(hquery); //sets the username of the query the values JSONObject contents query.setString(0, username); // executes query and adds username string variable String user = (String) query.uniqueResult(); //checks to see if result is found (null if not found) if (user == null) { //adds false to Jobject if not found check.put("indatabase", "false"); } else { check.put("indatabase", "true"); } //adds check to Jobject to say just to check username check.put("justusername", true); } else { //query created to select a username and password from user table String hquery = "Select username from User user Where username = :user and password = :pass "; Query query = session.createQuery(hquery); query.setString("user", username); query.setString("pass", password); String user = (String) query.uniqueResult(); if(user ==null) { check.put("indatabase", false); } else { check.put("indatabase", true); } check.put("justusername", false); } }catch(Exception e){ System.out.println(e.getMessage()); //logg.log(Level.WARNING, " Exception", e.getMessage()); }finally{ // Actual contact insertion will happen at this step session.flush(); session.close(); } //returns Jobject return check; }

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• What to Expect in Rails 4

  - by mikhailov

  Rails 4 is nearly there, we should be ready before it released. Most developers are trying hard to keep their application on the edge. Must see resources: 1) @sikachu talk: What to Expect in Rails 4.0 - YouTube 2) Rails Guides release notes: http://edgeguides.rubyonrails.org/4_0_release_notes.html There is a mix of all major changes down here: ActionMailer changes excerpt: Asynchronously send messages via the Rails Raise an ActionView::MissingTemplate exception when no implicit template could be found ActionPack changes excerpt Added controller-level etag additions that will be part of the action etag computation Add automatic template digests to all CacheHelper#cache calls (originally spiked in the cache_digests plugin) Add Routing Concerns to declare common routes that can be reused inside others resources and routes Added ActionController::Live. Mix it in to your controller and you can stream data to the client live truncate now always returns an escaped HTML-safe string. The option :escape can be used as false to not escape the result Added ActionDispatch::SSL middleware that when included force all the requests to be under HTTPS protocol ActiveModel changes excerpt AM::Validation#validates ability to pass custom exception to :strict option Changed `AM::Serializers::JSON.include_root_in_json' default value to false. Now, AM Serializers and AR objects have the same default behaviour Added ActiveModel::Model, a mixin to make Ruby objects work with AP out of box Trim down Active Model API by removing valid? and errors.full_messages ActiveRecord changes excerpt Use native mysqldump command instead of structure_dump method when dumping the database structure to a sql file. Attribute predicate methods, such as article.title?, will now raise ActiveModel::MissingAttributeError if the attribute being queried for truthiness was not read from the database, instead of just returning false ActiveRecord::SessionStore has been extracted from Active Record as activerecord-session_store gem. Please read the README.md file on the gem for the usage Fix reset_counters when there are multiple belongs_to association with the same foreign key and one of them have a counter cache Raise ArgumentError if list of attributes to change is empty in update_all Add Relation#load. This method explicitly loads the records and then returns self Deprecated most of the 'dynamic finder' methods. All dynamic methods except for find_by_... and find_by_...! are deprecated Added ability to ActiveRecord::Relation#from to accept other ActiveRecord::Relation objects Remove IdentityMap ActiveSupport changes excerpt ERB::Util.html_escape now escapes single quotes ActiveSupport::Callbacks: deprecate monkey patch of object callbacks Replace deprecated memcache-client gem with dalli in ActiveSupport::Cache::MemCacheStore Object#try will now return nil instead of raise a NoMethodError if the receiving object does not implement the method, but you can still get the old behavior by using the new Object#try! Object#try can't call private methods Add ActiveSupport::Deprecations.behavior = :silence to completely ignore Rails runtime deprecations What are the most important changes for you?

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• How can I stop Flash from changing indent when user Clicks on hyperlink in TextField?

  - by Paul Chernoch

  I have a TextField which I initialize by setting htmlText. The text has anchor tags (hyperlinks). When a user clicks on the hyperlink, the indentation of the second and subsequent lines in the paragraph changes. Why? How do I stop it? My html has an image at the beginning of the line, followed by the tag, followed by more text. To style the hyper links to look blue always and underlined when the mouse is over them, I do this: var css:StyleSheet = new StyleSheet(); css.parseCSS("a {color: #0000FF;} a:hover {text-decoration: underline;}"); stepText.styleSheet = css; stepText.htmlText = textToUse; stepText.visible = true; Here is a fragment of the html text (with newlines and exrta whitespace added to improve readability - originally it was one long line): <textformat indent="-37" blockindent="37" > <img src="media/interface/level-1-bullets/solid-circle.png" align="left" hspace="8" vspace="1"/> American Dental Association. (n.d.). <i>Cleaning your teeth and gums (oral hygiene)</i>. Retrieved 11/24/08, from <a href="http://www.ada.org/public/topics/cleaning_faq.asp" target="_blank">http://www.ada.org/public/topics/cleaning_faq.asp </a> </textformat> <br/> As it turns out, the text field is of a width such that it wraps and the second line starts with "Retrieved 11/24/08". Clicking on the hyper link causes this particular line to be indented. Subsequent paragraphs are not affected. ASIDE: The image is a list bullet about 37 pixels wide. (I used images instead of li tags because Flash does not allow nested lists, so I faked it using a series of images with varying amounts of whitespace to simulate three levels of indentation.) IDEA: I was thinking of changing all hyperlinks to use "event:" as the URL protocol, which causes a TextEvent.LINK event to be triggered instead of following the link. Then I would have to open the browser in a second call. I could use this event handler to set the html text to itself, which might clear the problem. (When I switch pages in my application and then come back to the page, everything is OKAY again.) PROBLEM: If I use the "event:" protocol and user tries the right-mouse button click, they will get an error, or so I am told. (See http://www.blog.lessrain.com/as3-texteventlink-and-contextmenu-incompatibilities/ ) I do not like this trade-off.

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• How do I tie a cmbBox that selects all drives (local and network) into a treeNode VB

  - by jpavlov

  How do i tie in a selected item from a cmbBox with a treeView? I am looking to just obtain the value of the one selected drive Thanks. Imports System Imports System.IO Imports System.IO.File Imports System.Windows.Forms Public Class F_Treeview_Demo Private Sub F_Treeview_Demo_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load ' Initialize the local directory treeview Dim nodeText As String = "" Dim sb As New C_StringBuilder With My.Computer.FileSystem 'Read in the number of drives For i As Integer = 0 To .Drives.Count - 1 '** Build the drive's node text sb.ClearText() sb.AppendText(.Drives(i).Name) cmbDrives.Items.Add(sb.FullText) Next End With ListRootNodes() End Sub Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click Application.Exit() End Sub Private Sub tvwLocalFolders_AfterSelect(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) _ Handles tvwLocalFolders.AfterSelect ' Display the path for the selected node Dim folder As String = tvwLocalFolders.SelectedNode.Tag lblLocalPath.Text = folder ListView1.Items.Clear() Dim childNode As TreeNode = e.Node.FirstNode Dim parentPath As String = AddChar(e.Node.Tag) End Sub Private Sub AddToList(ByVal nodes As TreeNodeCollection) For Each node As TreeNode In nodes If node.Checked Then ListView1.Items.Add(node.Text) ListView1.Items.Add(Chr(13)) AddToList(node.Nodes) End If Next End Sub Private Sub tvwLocalFolders_BeforeExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewCancelEventArgs) _ Handles tvwLocalFolders.BeforeExpand ' Display the path for the selected node lblLocalPath.Text = e.Node.Tag ' Populate all child nodes below the selected node Dim parentPath As String = AddChar(e.Node.Tag) tvwLocalFolders.BeginUpdate() Dim childNode As TreeNode = e.Node.FirstNode 'this i added Dim smallNode As TreeNode = e.Node.FirstNode Do While childNode IsNot Nothing ListLocalSubFolders(childNode, parentPath & childNode.Text) childNode = childNode.NextNode ''this i added ListLocalFiles(smallNode, parentPath & smallNode.Text) Loop tvwLocalFolders.EndUpdate() tvwLocalFolders.Refresh() ' Select the node being expanded tvwLocalFolders.SelectedNode = e.Node ListView1.Items.Clear() AddToList(tvwLocalFolders.Nodes) ListView1.Items.Add(Environment.NewLine) End Sub Private Sub ListRootNodes() ' Add all local drives to the Local treeview Dim nodeText As String = "" Dim sb As New C_StringBuilder With My.Computer.FileSystem For i As Integer = 0 To .Drives.Count - 1 '** Build the drive's node text sb.ClearText() sb.AppendText(.Drives(i).Name) nodeText = sb.FullText nodeText = Me.cmbDrives.SelectedItem '** Add the drive to the treeview Dim driveNode As TreeNode driveNode = tvwLocalFolders.Nodes.Add(nodeText) 'driveNode.Tag = .Drives(i).Name '** Add the next level of subfolders 'ListLocalSubFolders(driveNode, .Drives(i).Name) ListLocalSubFolders(driveNode, nodeText) 'driveNode = Nothing Next End With End Sub Private Sub ListLocalFiles(ByVal ParentNode As TreeNode, ByVal PParentPath As String) Dim FileNode As String = "" Try For Each FileNode In Directory.GetFiles(PParentPath) Dim smallNode As TreeNode smallNode = ParentNode.Nodes.Add(FilenameFromPath(FileNode)) With smallNode .ImageIndex = 0 .SelectedImageIndex = 1 .Tag = FileNode End With smallNode = Nothing Next Catch ex As Exception End Try End Sub Private Sub ListLocalSubFolders(ByVal ParentNode As TreeNode, _ ByVal ParentPath As String) ' Add all local subfolders below the passed Local treeview node Dim FolderNode As String = "" Try For Each FolderNode In Directory.GetDirectories(ParentPath) Dim childNode As TreeNode childNode = ParentNode.Nodes.Add(FilenameFromPath(FolderNode)) With childNode .ImageIndex = 0 .SelectedImageIndex = 1 .Tag = FolderNode End With childNode = Nothing Next Catch ex As Exception End Try End Sub Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbDrives.SelectedIndexChanged End Sub Private Sub lblLocalPath_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lblLocalPath.Click End Sub Private Sub grpLocalFileSystem_Enter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles grpLocalFileSystem.Enter End Sub Private Sub btn1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn1.Click ' lbl1.Text = End Sub Private Sub ListView1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListView1.SelectedIndexChanged End Sub End Class

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• Java loading user-specified classes at runtime

  - by user349043

  I'm working on robot simulation in Java (a Swing application). I have an abstract class "Robot" from which different types of Robots are derived, e.g. public class StupidRobot extends Robot { int m_stupidness; int m_insanityLevel; ... } public class AngryRobot extends Robot { float m_aggression; ... } As you can see, each Robot subclass has a different set of parameters. What I would like to do is control the simulation setup in the initial UI. Choose the number and type of Robots, give it a name, fill in the parameters etc. This is one of those times where being such a dinosaur programmer, and new to Java, I wonder if there is some higher level stuff/thinking that could help me here. So here is what I've got: (1) User Interface Scrolling list of Robot types on the left. "Add " and "<< Remove" buttons in the middle. Default-named scrolling list of Robots on the right. "Set Parameters" button underneath. (So if you wanted an AngryRobot, you'd select AngryRobot on the left list, click "Add" and "AngryRobot1" would show up on the right.) When selecting a Robot on the right, click "Set Parameters..." button which would call yet another model dialog where you'd fill in the parameters. Different dialog called for each Robot type. (2) Data structures an implementation As an end-product I think a HashMap would be most convenient. The keys would be Robot types and the accompanying object would be all of the parameters. The initializer could just retrieve each item one and a time and instantiate. Here's what the data structures would look like: enum ROBOT_TYPE {STUPID, ANGRY, etc} public class RobotInitializer { public ROBOT_TYPE m_type; public string m_name; public int[] m_int_params; public float[] m_float_params; etc. The initializer's constructor would create the appropriate length parameter arrays based on the type: public RobotInitializer(ROBOT_TYPE type, int[] int_array, float[] float_array, etc){ switch (type){ case STUPID: m_int_params = new int[STUPID_INT_PARAM_LENGTH]; System.arraycopy(int_array,0,m_int_params,0,STUPID_INT_PARAM_LENGTH); etc. Once all the RobotInitializers are instantiated, they are added to the HashMap. Iterating through the HashMap, the simulation initializer takes items from the Hashmap and instantiates the appropriate Robots. Is this reasonable? If not, how can it be improved? Thanks

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• jQuery action being called when selector isn't met?

  - by dougoftheabaci

  I've been working on a prototype for a client's web site and I've run into a rather significant snag. You can view the prototype here. As you can see, the way it works is you can scroll a set of slides horizontally and, by clicking one, open a stack containing yet more slides. If you then click again on an image in that stack it opens up a lightbox. Clicking on another stack or the close button will close that stack (and open another, as case may be). That all works great. However you get some weird behavior if you do the following: Click to open any stack. Click to open an image's light box (this works best if you click on the image that's level with the main list). Close the light box and the stack either by clicking the close button or clicking on another stack. Click back to the first stack. Instead of reopening the stack, you get the lightbox. This confuses me as the light box should only ever be called if there is a class on the containing UL and that class is removed when the lightbox is closed. I've checked and double-checked this, it's definitely missing. Here are the respective functions: $("ul.hide a.lightbox").live("click",function(){ $("ul.show").removeClass("show").addClass("hide"); $(this).parent().parent().removeClass("hide").addClass("show"); $("ul.hide").animate({opacity: 0.2}); $("ul.show").animate({opacity: 1}); $("#next").animate({opacity: 0.2}); $("#prev").animate({opacity: 0.2}); return false; }); $("ul.show a.lightbox").live("click",function(){ $(this).fancybox().trigger("click"); return false; }); As you can see, in order for the lightbox to be called the containing UL has to have the class of show. However, if you check it with Firebug it won't. For those who are curious, the added .trigger("click"); is because the lightbox will require a double-click to launch otherwise. Any idea how I can fix this?

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• Generating Unordered List with PHP + CodeIgniter from a MySQL Database

  - by Tim

  Hello Everyone, I am trying to build a dynamically generated unordered list in the following format using PHP. I am using CodeIgniter but it can just be normal php. This is the end output I need to achieve. <ul id="categories" class="menu"> <li rel="1"> Arts &amp; Humanities <ul> <li rel="2"> Photography <ul> <li rel="3"> 3D </li> <li rel="4"> Digital </li> </ul> </li> <li rel="5"> History </li> <li rel="6"> Literature </li> </ul> </li> <li rel="7"> Business &amp; Economy </li> <li rel="8"> Computers &amp; Internet </li> <li rel="9"> Education </li> <li rel="11"> Entertainment <ul> <li rel="12"> Movies </li> <li rel="13"> TV Shows </li> <li rel="14"> Music </li> <li rel="15"> Humor </li> </ul> </li> <li rel="10"> Health </li> And here is my SQL that I have to work with. -- -- Table structure for table `categories` -- CREATE TABLE IF NOT EXISTS `categories` ( `id` mediumint(8) NOT NULL auto_increment, `dd_id` mediumint(8) NOT NULL, `parent_id` mediumint(8) NOT NULL, `cat_name` varchar(256) NOT NULL, `cat_order` smallint(4) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; So I know that I am going to need at least 1 foreach loop to generate the first level of categories. What I don't know is how to iterate inside each loop and check for parents and do that in a dynamic way so that there could be an endless tree of children. Thanks for any help you can offer. Tim

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• Why oh why doesn't my asp.net treeview update?

  - by Brendan

  I'm using an ASP.net treeview on a page with a custom XmlDataSource. When the user clicks on a node of the tree, a detailsview pops up and edits a bunch of things about the underlying object. All this works properly, and the underlying object gets updated in my background object-management classes. Yay! However, my treeview just isn't updating the display. Either immediately (which i would like it to), or on full page re-load (which is the minimal useful level i need it to be at). Am i subclassing XmlDataSource poorly? I really don't know. Can anyone point me in a good direction? Thanks! The markup looks about like this (chaff removed): <data:DefinitionDataSource runat="server" ID="DefinitionTreeSource" RootDefinitionID="uri:1"></data:DefinitionDataSource> <asp:TreeView ID="TreeView" runat="server" DataSourceID="DefinitionTreeSource"> <DataBindings> <asp:TreeNodeBinding DataMember="definition" TextField="name" ValueField="id" /> </DataBindings> </asp:TreeView> <asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="Id" DataSourceID="DefinitionSource" DefaultMode="Edit"> <Fields> <asp:BoundField DataField="Name" HeaderText="Name" HeaderStyle-Wrap="false" SortExpression="Name" /> <asp:CommandField ShowCancelButton="False" ShowInsertButton="True" ShowEditButton="True" ButtonType="Button" /> </Fields> </asp:DetailsView> And the DefinitionTreeSource code looks like this: public class DefinitionDataSource : XmlDataSource { public string RootDefinitionID { get { if (ViewState["RootDefinitionID"] != null) return ViewState["RootDefinitionID"] as String; return null; } set { if (!Object.Equals(ViewState["RootDefinitionID"], value)) { ViewState["RootDefinitionID"] = value; DataBind(); } } } public DefinitionDataSource() { } public override void DataBind() { base.DataBind(); setData(); } private void setData() { String defXML = "<?xml version=\"1.0\" ?>"; Test.Management.TestManager.Definition root = Test.Management.TestManager.Definition.GetDefinitionById(RootDefinitionID); if (root != null) this.Data = defXML + root.ToXMLString(); else this.Data = defXML + "<definition id=\"null\" name=\"Set Root Node\" />"; } } }

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• Why are these two sql statements deadlocking? (Deadlock graph + details included).

  - by Pure.Krome

  Hi folks, I've got the following deadlock graph that describes two sql statements that are deadlocking each other. I'm just not sure how to analyse this and then fix up my sql code to prevent this from happening. Main deadlock graph Click here for a bigger image. Left side, details Click here for a bigger image. Right side, details Click here for a bigger image. What is the code doing? I'm reading in a number of files (eg. lets say 3, for this example). Each file contains different data BUT the same type of data. I then insert data into LogEntries table and then (if required) I insert or delete something from the ConnectedClients table. Here's my sql code. using (TransactionScope transactionScope = new TransactionScope()) { _logEntryRepository.InsertOrUpdate(logEntry); // Now, if this log entry was a NewConnection or an LostConnection, then we need to make sure we update the ConnectedClients. if (logEntry.EventType == EventType.NewConnection) { _connectedClientRepository.Insert(new ConnectedClient { LogEntryId = logEntry.LogEntryId }); } // A (PB) BanKick does _NOT_ register a lost connection .. so we need to make sure we handle those scenario's as a LostConnection. if (logEntry.EventType == EventType.LostConnection || logEntry.EventType == EventType.BanKick) { _connectedClientRepository.Delete(logEntry.ClientName, logEntry.ClientIpAndPort); } _unitOfWork.Commit(); transactionScope.Complete(); } Now each file has it's own UnitOfWork instance (which means it has it's own database connection, transaction and repository context). So i'm assuming this means there's 3 different connections to the db all happening at the same time. Finally, this is using Entity Framework as the repository, but please don't let that stop you from having a think about this problem. Using a profiling tool, the Isolation Level is Serializable. I've also tried ReadCommited and ReadUncommited, but they both error :- ReadCommited: same as above. Deadlock. ReadUncommited: different error. EF exception that says it expected some result back, but got nothing. I'm guessing this is the LogEntryId Identity (scope_identity) value that is expected but not retrieve because of the dirty read. Please help! PS. It's Sql Server 2008, btw.

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• I need help converting a C# string from one character encoding to another?

  - by Handleman

  According to Spolsky I can't call myself a developer, so there is a lot of shame behind this question... Scenario: From a C# application, I would like to take a string value from a SQL db and use it as the name of a directory. I have a secure (SSL) FTP server on which I want to set the current directory using the string value from the DB. Problem: Everything is working fine until I hit a string value with a "special" character - I seem unable to encode the directory name correctly to satisfy the FTP server. The code example below uses "special" character é as an example uses WinSCP as an external application for the ftps comms does not show all the code required to setup the Process "_winscp". sends commands to the WinSCP exe by writing to the process standardinput for simplicity, does not get the info from the DB, but instead simply declares a string (but I did do a .Equals to confirm that the value from the DB is the same as the declared string) makes three attempts to set the current directory on the FTP server using different string encodings - all of which fail makes an attempt to set the directory using a string that was created from a hand-crafted byte array - which works Process _winscp = new Process(); byte[] buffer; string nameFromString = "Sinéad O'Connor"; _winscp.StandardInput.WriteLine("cd \"" + nameFromString + "\""); buffer = Encoding.UTF8.GetBytes(nameFromString); _winscp.StandardInput.WriteLine("cd \"" + Encoding.UTF8.GetString(buffer) + "\""); buffer = Encoding.ASCII.GetBytes(nameFromString); _winscp.StandardInput.WriteLine("cd \"" + Encoding.ASCII.GetString(buffer) + "\""); byte[] nameFromBytes = new byte[] { 83, 105, 110, 130, 97, 100, 32, 79, 39, 67, 111, 110, 110, 111, 114 }; _winscp.StandardInput.WriteLine("cd \"" + Encoding.Default.GetString(nameFromBytes) + "\""); The UTF8 encoding changes é to 101 (decimal) but the FTP server doesn't like it. The ASCII encoding changes é to 63 (decimal) but the FTP server doesn't like it. When I represent é as value 130 (decimal) the FTP server is happy, except I can't find a method that will do this for me (I had to manually contruct the string from explicit bytes). Anyone know what I should do to my string to encode the é as 130 and make the FTP server happy and finally elevate me to level 1 developer by explaining the only single thing a developer should understand?

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• how to insert into database from stored procedure in log4net?

  - by Samreen

  I have to log thread context properties like this: string logFilePath = AppDomain.CurrentDomain.BaseDirectory + "log4netconfig.xml"; FileInfo finfo = new FileInfo(logFilePath); log4net.Config.XmlConfigurator.ConfigureAndWatch(finfo); ILog logger = LogManager.GetLogger("Exception.Logging"); log4net.ThreadContext.Properties["MESSAGE"] = exception.Message; log4net.ThreadContext.Properties["MODULE"] = "module1"; log4net.ThreadContext.Properties["COMPONENT"] = "component1"; logger.Debug("test"); and the configuration file is: <configuration> <configSections> <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,Log4net"/> </configSections> <log4net> <logger name="Exception.Logging" level="Debug"> <appender-ref ref="AdoNetAppender"/> </logger> <appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender"> <connectionString value="Data Source=xe;User ID=test;Password=test;" /> <connectionType value="System.Data.OracleClient.OracleConnection, System.Data.OracleClient, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" /> <bufferSize value="10000"/> <commandText value="Log_Exception_Pkg.Insert_Log" /> <commandType value="StoredProcedure" /> <parameter> <parameterName value="@p_Error_Message" /> <dbType value="String" /> <size value="255" /> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%property{MESSAGE}"/> </layout> </parameter> <parameter> <parameterName value="@p_Module" /> <dbType value="String" /> <size value="225" /> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%property{MODULE}"/> </layout> </parameter> <parameter> <parameterName value="@p_Component" /> <dbType value="String" /> <size value="225" /> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%property{COMPONENT}"/> </layout> </parameter> </appender> </log4net> </configuration> But its not inserting them in the database. How can I get that to work?

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• Security review of an authenticated Diffie Hellman variant

  - by mtraut

  EDIT I'm still hoping for some advice on this, i tried to clarify my intentions... When i came upon device pairing in my mobile communication framework i studied a lot of papers on this topic and and also got some input from previous questions here. But, i didn't find a ready to implement protocol solution - so i invented a derivate and as i'm no crypto geek i'm not sure about the security caveats of the final solution: The main questions are Is SHA256 sufficient as a commit function? Is the addition of the shared secret as an authentication info in the commit string safe? What is the overall security of the 1024 bit group DH I assume at most 2^-24 bit probability of succesful MITM attack (because of 24 bit challenge). Is this plausible? What may be the most promising attack (besides ripping the device out off my numb, cold hands) This is the algorithm sketch For first time pairing, a solution proposed in "Key agreement in peer-to-peer wireless networks" (DH-SC) is implemented. I based it on a commitment derived from: A fix "UUID" for the communicating entity/role (128 bit, sent at protocol start, before commitment) The public DH key (192 bit private key, based on the 1024 bit Oakley group) A 24 bit random challenge Commit is computed using SHA256 c = sha256( UUID || DH pub || Chall) Both parties exchange this commitment, open and transfer the plain content of the above values. The 24 bit random is displayed to the user for manual authentication DH session key (128 bytes, see above) is computed When the user opts for persistent pairing, the session key is stored with the remote UUID as a shared secret Next time devices connect, commit is computed by additionally hashing the previous DH session key before the random challenge. For sure it is not transfered when opening. c = sha256( UUID || DH pub || DH sess || Chall) Now the user is not bothered authenticating when the local party can derive the same commitment using his own, stored previous DH session key. After succesful connection the new DH session key becomes the new shared secret. As this does not exactly fit the protocols i found so far (and as such their security proofs), i'd be very interested to get an opinion from some more crypto enabled guys here. BTW. i did read about the "EKE" protocol, but i'm not sure what the extra security level is.

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• Hibernate - EhCache - Which region to Cache associations/sets/collections ??

  - by lifeisnotfair

  Hi all, I am a newcomer to hibernate. It would be great if someone could comment over the following query that i have: Say i have a parent class and each parent has multiple children. So the mapping file of parent class would be something like: parent.hbm.xml <hibernate-mapping > <class name="org.demo.parent" table="parent" lazy="true"> <cache usage="read-write" region="org.demo.parent"/> <id name="id" column="id" type="integer" length="10"> <generator class="native"> </generator> </id> <property name="name" column="name" type="string" length="50"/> <set name="children" lazy="true"> <cache usage="read-write" region="org.demo.parent.children" /> <key column="parent_id"/> <one-to-many class="org.demo.children"/> </set> </class> </hibernate-mapping> children.hbm.xml <hibernate-mapping > <class name="org.demo.children" table="children" lazy="true"> <cache usage="read-write" region="org.demo.children"/> <id name="id" column="id" type="integer" length="10"> <generator class="native"> </generator> </id> <property name="name" column="name" type="string" length="50"/> <many-to-one name="parent_id" column="parent_id" type="integer" length="10" not-null="true"/> </class> </hibernate-mapping> So for the set children, should we specify the region org.demo.parent.children where it should cache the association or should we use the cache region of org.demo.children where the children would be getting cached. I am using EHCache as the 2nd level cache provider. I tried to search for the answer to this question but couldnt find any answer in this direction. It makes more sense to use org.demo.children but I dont know in which scenarios one should use a separate cache region for associations/sets/collections as in the above case. Kindly provide your inputs also let me know if I am not clear in my question. Thanks all.

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• Minutia on Objective-C Categories and Extensions.

  - by Matt Wilding

  I learned something new while trying to figure out why my readwrite property declared in a private Category wasn't generating a setter. It was because my Category was named: // .m @interface MyClass (private) @property (readwrite, copy) NSArray* myProperty; @end Changing it to: // .m @interface MyClass () @property (readwrite, copy) NSArray* myProperty; @end and my setter is synthesized. I now know that Class Extension is not just another name for an anonymous Category. Leaving a Category unnamed causes it to morph into a different beast: one that now gives compile-time method implementation enforcement and allows you to add ivars. I now understand the general philosophies underlying each of these: Categories are generally used to add methods to any class at runtime, and Class Extensions are generally used to enforce private API implementation and add ivars. I accept this. But there are trifles that confuse me. First, at a hight level: Why differentiate like this? These concepts seem like similar ideas that can't decide if they are the same, or different concepts. If they are the same, I would expect the exact same things to be possible using a Category with no name as is with a named Category (which they are not). If they are different, (which they are) I would expect a greater syntactical disparity between the two. It seems odd to say, "Oh, by the way, to implement a Class Extension, just write a Category, but leave out the name. It magically changes." Second, on the topic of compile time enforcement: If you can't add properties in a named Category, why does doing so convince the compiler that you did just that? To clarify, I'll illustrate with my example. I can declare a readonly property in the header file: // .h @interface MyClass : NSObject @property (readonly, copy) NSString* myString; @end Now, I want to head over to the implementation file and give myself private readwrite access to the property. If I do it correctly: // .m @interface MyClass () @property (readonly, copy) NSString* myString; @end I get a warning when I don't synthesize, and when I do, I can set the property and everything is peachy. But, frustratingly, if I happen to be slightly misguided about the difference between Category and Class Extension and I try: // .m @interface MyClass (private) @property (readonly, copy) NSString* myString; @end The compiler is completely pacified into thinking that the property is readwrite. I get no warning, and not even the nice compile error "Object cannot be set - either readonly property or no setter found" upon setting myString that I would had I not declared the readwrite property in the Category. I just get the "Does not respond to selector" exception at runtime. If adding ivars and properties is not supported by (named) Categories, is it too much to ask that the compiler play by the same rules? Am I missing some grand design philosophy?

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• emacs: how do I use edebug on code that is defined in a macro?

  - by Cheeso

  I don't even know the proper terminology for this lisp syntax, so I don't know if the words I'm using to ask the question, make sense. But the question makes sense, I'm sure. So let me just show you. cc-mode (cc-fonts.el) has things called "matchers" which are bits of code that run to decide how to fontify a region of code. That sounds simple enough, but the matcher code is in a form I don't completely understand, with babckticks and comma-atsign and just comma and so on, and furthermore it is embedded in a c-lang-defcost, which itself is a macro. And I want to run edebug on that code. Look: (c-lang-defconst c-basic-matchers-after "Font lock matchers for various things that should be fontified after generic casts and declarations are fontified. Used on level 2 and higher." t `(;; Fontify the identifiers inside enum lists. (The enum type ;; name is handled by `c-simple-decl-matchers' or ;; `c-complex-decl-matchers' below. ,@(when (c-lang-const c-brace-id-list-kwds) `((,(c-make-font-lock-search-function (concat "\\<\\(" (c-make-keywords-re nil (c-lang-const c-brace-id-list-kwds)) "\\)\\>" ;; Disallow various common punctuation chars that can't come ;; before the '{' of the enum list, to avoid searching too far. "[^\]\[{}();,/#=]*" "{") '((c-font-lock-declarators limit t nil) (save-match-data (goto-char (match-end 0)) (c-put-char-property (1- (point)) 'c-type 'c-decl-id-start) (c-forward-syntactic-ws)) (goto-char (match-end 0))))))) I am reading up on lisp syntax to figure out what those things are and what to call them, but aside from that, how can I run edebug on the code that follows the comment that reads ;; Fontify the identifiers inside enum lists. ? I know how to run edebug on a defun - just invoke edebug-defun within the function's definition, and off I go. Is there a corresponding thing I need to do to edebug the cc-mode matcher code forms?

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• R: Plotting a graph with different colors of points based on advanced criteria

  - by balconydoor

  What I would like to do is a plot (using ggplot), where the x axis represent years which have a different colour for the last three years in the plot than the rest. The last three years should also meet a certain criteria and based on this the last three years can either be red or green. The criteria is that the mean of the last three years should be less (making it green) or more (making it red) than the 66%-percentile of the remaining years. So far I have made two different functions calculating the last three year mean: LYM3 <- function (x) { LYM3 <- tail(x,3) mean(LYM3$Data,na.rm=T) } And the 66%-percentile for the remaining: perc66 <- function(x) { percentile <- head(x,-3) quantile(percentile$Data, .66, names=F,na.rm=T) } Here are two sets of data that can be used in the calculations (plots), the first which is an example from my real data where LYM3(df1) < perc66(df1) and the second is just made up data where LYM3 perc66. df1<- data.frame(Year=c(1979:2010), Data=c(347261.87, 145071.29, 110181.93, 183016.71, 210995.67, 205207.33, 103291.78, 247182.10, 152894.45, 170771.50, 206534.55, 287770.86, 223832.43, 297542.86, 267343.54, 475485.47, 224575.08, 147607.81, 171732.38, 126818.10, 165801.08, 136921.58, 136947.63, 83428.05, 144295.87, 68566.23, 59943.05, 49909.08, 52149.11, 117627.75, 132127.79, 130463.80)) df2 <- data.frame(Year=c(1979:2010), Data=c(sample(50,29,replace=T),75,75,75)) Here’s my code for my plot so far: plot <- ggplot(df1, aes(x=Year, y=Data)) + theme_bw() + geom_point(size=3, aes(colour=ifelse(df1$Year<2008, "black",ifelse(LYM3(df1) < perc66(df1),"green","red")))) + geom_line() + scale_x_continuous(breaks=c(1980,1985,1990,1995,2000,2005,2010), limits=c(1978,2011)) plot As you notice it doesn’t really do what I want it to do. The only thing it does seem to do is that it turns the years before 2008 into one level and those after into another one and base the point colour off these two levels. Since I don’t want this year to be stationary either, I made another tiny function: fun3 <- function(x) { df <- subset(x, Year==(max(Year)-2)) df$Year } So the previous code would have the same effect as: geom_point(size=3, aes(colour=ifelse(df1$Year<fun3(df1), "black","red"))) But it still does not care about my colours. Why does it make the years into levels? And how come an ifelse function doesn’t work within another one in this case? How would it be possible to the arguments to do what I like? I realise this might be a bit messy, asking for a lot at the same time, but I hope my description is pretty clear. It would be helpful if someone could at least point me in the right direction. I tried to put the code for the plot into a function as well so I wouldn’t have to change the data frame at all functions within the plot, but I can’t get it to work. Thank you!

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• SQL Server - Get Inserted Record Identity Value when Using a View's Instead Of Trigger

  - by CuppM

  For several tables that have identity fields, we are implementing a Row Level Security scheme using Views and Instead Of triggers on those views. Here is a simplified example structure: -- Table CREATE TABLE tblItem ( ItemId int identity(1,1) primary key, Name varchar(20) ) go -- View CREATE VIEW vwItem AS SELECT * FROM tblItem -- RLS Filtering Condition go -- Instead Of Insert Trigger CREATE TRIGGER IO_vwItem_Insert ON vwItem INSTEAD OF INSERT AS BEGIN -- RLS Security Checks on inserted Table -- Insert Records Into Table INSERT INTO tblItem (Name) SELECT Name FROM inserted; END go If I want to insert a record and get its identity, before implementing the RLS Instead Of trigger, I used: DECLARE @ItemId int; INSERT INTO tblItem (Name) VALUES ('MyName'); SELECT @ItemId = SCOPE_IDENTITY(); With the trigger, SCOPE_IDENTITY() no longer works - it returns NULL. I've seen suggestions for using the OUTPUT clause to get the identity back, but I can't seem to get it to work the way I need it to. If I put the OUTPUT clause on the view insert, nothing is ever entered into it. -- Nothing is added to @ItemIds DECLARE @ItemIds TABLE (ItemId int); INSERT INTO vwItem (Name) OUTPUT INSERTED.ItemId INTO @ItemIds VALUES ('MyName'); If I put the OUTPUT clause in the trigger on the INSERT statement, the trigger returns the table (I can view it from SQL Management Studio). I can't seem to capture it in the calling code; either by using an OUTPUT clause on that call or using a SELECT * FROM (). -- Modified Instead Of Insert Trigger w/ Output CREATE TRIGGER IO_vwItem_Insert ON vwItem INSTEAD OF INSERT AS BEGIN -- RLS Security Checks on inserted Table -- Insert Records Into Table INSERT INTO tblItem (Name) OUTPUT INSERTED.ItemId SELECT Name FROM inserted; END go -- Calling Code INSERT INTO vwItem (Name) VALUES ('MyName'); The only thing I can think of is to use the IDENT_CURRENT() function. Since that doesn't operate in the current scope, there's an issue of concurrent users inserting at the same time and messing it up. If the entire operation is wrapped in a transaction, would that prevent the concurrency issue? BEGIN TRANSACTION DECLARE @ItemId int; INSERT INTO tblItem (Name) VALUES ('MyName'); SELECT @ItemId = IDENT_CURRENT('tblItem'); COMMIT TRANSACTION Does anyone have any suggestions on how to do this better? I know people out there who will read this and say "Triggers are EVIL, don't use them!" While I appreciate your convictions, please don't offer that "suggestion".

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• How to implement a caching model without violating MVC pattern?

  - by RPM1984

  Hi Guys, I have an ASP.NET MVC 3 (Razor) Web Application, with a particular page which is highly database intensive, and user experience is of the upmost priority. Thus, i am introducing caching on this particular page. I'm trying to figure out a way to implement this caching pattern whilst keeping my controller thin, like it currently is without caching: public PartialViewResult GetLocationStuff(SearchPreferences searchPreferences) { var results = _locationService.FindStuffByCriteria(searchPreferences); return PartialView("SearchResults", results); } As you can see, the controller is very thin, as it should be. It doesn't care about how/where it is getting it's info from - that is the job of the service. A couple of notes on the flow of control: Controllers get DI'ed a particular Service, depending on it's area. In this example, this controller get's a LocationService Services call through to an IQueryable<T> Repository and materialize results into T or ICollection<T>. How i want to implement caching: I can't use Output Caching - for a few reasons. First of all, this action method is invoked from the client-side (jQuery/AJAX), via [HttpPost], which according to HTTP standards should not be cached as a request. Secondly, i don't want to cache purely based on the HTTP request arguments - the cache logic is a lot more complicated than that - there is actually two-level caching going on. As i hint to above, i need to use regular data-caching, e.g Cache["somekey"] = someObj;. I don't want to implement a generic caching mechanism where all calls via the service go through the cache first - i only want caching on this particular action method. First thought's would tell me to create another service (which inherits LocationService), and provide the caching workflow there (check cache first, if not there call db, add to cache, return result). That has two problems: The services are basic Class Libraries - no references to anything extra. I would need to add a reference to System.Web here. I would have to access the HTTP Context outside of the web application, which is considered bad practice, not only for testability, but in general - right? I also thought about using the Models folder in the Web Application (which i currently use only for ViewModels), but having a cache service in a models folder just doesn't sound right. So - any ideas? Is there a MVC-specific thing (like Action Filter's, for example) i can use here? General advice/tips would be greatly appreciated.

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• PHP MySQL Zend-ACL - Find all inherited items (Children / Parents)

  - by Scoobler

  I have one MySQL DB table like the following, the resources table: id | name | type 1 | guest | user 2 | member | user 3 | moderator | user 4 | owner | user 5 | admin | user 6 | index | controller Onto the next table, the rules table: id | user_id | rule | resource_id | extras 1 | 2 | 3 | 1 | null 2 | 3 | 3 | 2 | null 3 | 4 | 3 | 3 | null 4 | 5 | 3 | 4 | null 5 | 6 | 1 | 1 | index,login,register 6 | 6 | 2 | 2 | login,register 7 | 6 | 1 | 2 | logout OK, sorry for the length, but I am trying to give a full picture of what I am trying to do. So the way it works, a role (aka user) can be granted (rule: 1) access to a controller, a role can inherit (rule: 3) access from another role or a role and be denied (rule: 2) access to a controller. (A user is a resource and a controller is a resource) Access to actions are granted / denied using the extras column. This all works, its not a problem with setting up the ACL within zend. What I am now trying to do is show the relationships; to do that I need to find the lowest level a role is granted access to a controller stopping if it has explicitly been removed. I plan on listing the roles. When I click a role, I want it to show all the controllers that role has access to. Then clicking on a controller shows the actions the role is allowed to do. So in the example above, a guest is allowed to view the index action of the index controller along with the login action. A member inherits the same access, but is then denied access to the login action and register action. A moderator inherits the rules of a member. So if I were to select the role moderator. I want to see the controller index listed. If I click on the controller, it should show the allowed actions as being action: index. (which was originally granted to the guest, but hasn't since been dissallowed) Is there any examples to doing this. I am obviously working with the Zend MVC (PHP) and MySQL. Even just a persudo code example would be a helpful starting point - this is one of the last parts of the jigsaw I am putting together. P.S. Obviously I have the ACL object - is it going to be easier to interigate that or is it better to do it my self via PHP/MySQL? The aim will be, show what a role can access which will then allow me to add or edit a role, controller and action in a GUI style (that is somewhat the easy bit) - currently I am updating the DB manually as I have been building the site.

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• Find the set of largest contiguous rectangles to cover multiple areas

  - by joelpt

  I'm working on a tool called Quickfort for the game Dwarf Fortress. Quickfort turns spreadsheets in csv/xls format into a series of commands for Dwarf Fortress to carry out in order to plot a "blueprint" within the game. I am currently trying to optimally solve an area-plotting problem for the 2.0 release of this tool. Consider the following "blueprint" which defines plotting commands for a 2-dimensional grid. Each cell in the grid should either be dug out ("d"), channeled ("c"), or left unplotted ("."). Any number of distinct plotting commands might be present in actual usage. . d . d c c d d d d c c . d d d . c d d d d d c . d . d d c To minimize the number of instructions that need to be sent to Dwarf Fortress, I would like to find the set of largest contiguous rectangles that can be formed to completely cover, or "plot", all of the plottable cells. To be valid, all of a given rectangle's cells must contain the same command. This is a faster approach than Quickfort 1.0 took: plotting every cell individually as a 1x1 rectangle. This video shows the performance difference between the two versions. For the above blueprint, the solution looks like this: . 9 . 0 3 2 8 1 1 1 3 2 . 1 1 1 . 2 7 1 1 1 4 2 . 6 . 5 4 2 Each same-numbered rectangle above denotes a contiguous rectangle. The largest rectangles take precedence over smaller rectangles that could also be formed in their areas. The order of the numbering/rectangles is unimportant. My current approach is iterative. In each iteration, I build a list of the largest rectangles that could be formed from each of the grid's plottable cells by extending in all 4 directions from the cell. After sorting the list largest first, I begin with the largest rectangle found, mark its underlying cells as "plotted", and record the rectangle in a list. Before plotting each rectangle, its underlying cells are checked to ensure they are not yet plotted (overlapping a previous plot). We then start again, finding the largest remaining rectangles that can be formed and plotting them until all cells have been plotted as part of some rectangle. I consider this approach slightly more optimized than a dumb brute-force search, but I am wasting a lot of cycles (re)calculating cells' largest rectangles and checking underlying cells' states. Currently, this rectangle-discovery routine takes the lion's share of the total runtime of the tool, especially for large blueprints. I have sacrificed some accuracy for the sake of speed by only considering rectangles from cells which appear to form a rectangle's corner (determined using some neighboring-cell heuristics which aren't always correct). As a result of this 'optimization', my current code doesn't actually generate the above solution correctly, but it's close enough. More broadly, I consider the goal of largest-rectangles-first to be a "good enough" approach for this application. However I observe that if the goal is instead to find the minimum set (fewest number) of rectangles to completely cover multiple areas, the solution would look like this instead: . 3 . 5 6 8 1 3 4 5 6 8 . 3 4 5 . 8 2 3 4 5 7 8 . 3 . 5 7 8 This second goal actually represents a more optimal solution to the problem, as fewer rectangles usually means fewer commands sent to Dwarf Fortress. However, this approach strikes me as closer to NP-Hard, based on my limited math knowledge. Watch the video if you'd like to better understand the overall strategy; I have not addressed other aspects of Quickfort's process, such as finding the shortest cursor-path that plots all rectangles. Possibly there is a solution to this problem that coherently combines these multiple strategies. Help of any form would be appreciated.

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• What web platform is right for me?

  - by egervari

  I've been looking at web frameworks like Rails, Grails, etc. I'm used to doing applications in Spring Framework with Hibernate... and I want something more productive. One of the things I realized is that while some of the things in Grails is sexy, there are some serious problems with it. Grails' controllers: 1) are implemented awfully. They don't seem to be able to extend from super classes at runtime. I tried this to add base actions and helper methods, and this seems to cause grails to blow up. 2) are based on an obsolete request parameters model (rather than form backing objects, which are much nicer). 3) are hard to test. Command objects are treated totally differently... and it's actually MUCH harder to write the test than it is to write the controller code. 4) Command objects operate totally differently. They are pre-validated and bound, which causes a lot of inconsistencies than basic parameter model. 5) Command objects are not reusable, and it's a pain in the rear to reuse most of the stuff from the domain classes, like constraints and fields. This is TRIVIAL to do in basic Spring. Why the hell was it not trivial to do in Grails? 6) The scaffolding that is generated is pure crap. It doesn't generalize inserts and updates... and it actually copy/pastes a pile of code in two views: create.gsp and edit.gsp. The views themselves are gargantuan piles of doggie do-do. This is further compounded by the fact that it uses low-level parameters and not objects. Integration tests are 30x slower than a Spring integration test. It is disgusting. Some mocking tests are so hard to write and aren't guaranteed to work when it's deployed, that I think it discourages fast, tdd test cycles. Most things seem to screw up grails while it's running, like adding a taglib, or anything really. The server restart problem wasn't solved at all. I'm starting to think going with Spring/Hibernate/Java is the only way to go. While there is a pretty big cost at startup, I know it'll eventually smooth out. It sucks I can't use a language like Scala... because idiomatically, it is so incompatible with Hibernate. This app is also not a run-of-the-mill UI over a database. It's got some of that, but it's not going to be a slouch. I am deathly scared of Grails now because of how crap it is in the Controller layer. Suggestions on what I can do?

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• Advice on "Invalid Pointer Operation" when using complex records

  - by Xaz

  Env: Delphi 2007 <JustificationI tend to use complex records quite frequently as they offer almost all of the advantages of classes but with much simpler handling.</Justification Anyhoo, one particularly complex record I have just implemented is trashing memory (later leading to an "Invalid Pointer Operation" error). This is an example of the memory trashing code: sSignature := gProfiles.Profile[_stPrimary].Signature.Formatted(True); On the second time i call it i get "Invalid Pointer Operation" It works OK if i call it like this: AProfile := gProfiles.Profile[_stPrimary]; ASignature := AProfile.Signature; sSignature := ASignature.Formatted(True); Background Code: gProfiles: TProfiles; TProfiles = Record private FPrimaryProfileID: Integer; FCachedProfile: TProfile; ... public < much code removed > property Profile[ProfileType: TProfileType]: TProfile Read GetProfile; end; function TProfiles.GetProfile(ProfileType: TProfileType): TProfile; begin case ProfileType of _stPrimary : Result := ProfileByID(FPrimaryProfileID); ... end; end; function TProfiles.ProfileByID(iID: Integer): TProfile; begin <snip> if LoadProfileOfID(iID, FCachedProfile) then begin Result := FCachedProfile; end else ... end; TProfile = Record private ... public ... Signature: TSignature; ... end; TSignature = Record private public PlainTextFormat : string; HTMLFormat : string; // The text to insert into a message when using this profile function Formatted(bHTML: boolean): string; end; function TSignature.Formatted(bHTML: boolean): string; begin if bHTML then result := HTMLFormat else result := PlainTextFormat; < SNIP MUCH CODE > end; OK, so I have a record within a record within a record, which is approaching Inception level confusion and I'm the first to admit is not really a good model. Clearly i am going to have to restructure it. What I would like from you gurus is a better understanding of why it is trashing the memory (something to do with the string object that is created then freed...) so that i can avoid making these kinds of errors in future. Thanks

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• NSNotifications vs delegate for multiple instances of same protocol

  - by Brent Traut

  I could use some architectural advice. I've run into the following problem a few times now and I've never found a truly elegant way to solve it. The issue, described at the highest level possible:I have a parent class that would like to act as the delegate for multiple children (all using the same protocol), but when the children call methods on the parent, the parent no longer knows which child is making the call. I would like to use loose coupling (delegates/protocols or notifications) rather than direct calls. I don't need multiple handlers, so notifications seem like they might be overkill. To illustrate the problem, let me try a super-simplified example: I start with a parent view controller (and corresponding view). I create three child views and insert each of them into the parent view. I would like the parent view controller to be notified whenever the user touches one of the children. There are a few options to notify the parent: Define a protocol. The parent implements the protocol and sets itself as the delegate to each of the children. When the user touches a child view, its view controller calls its delegate (the parent). In this case, the parent is notified that a view is touched, but it doesn't know which one. Not good enough. Same as #1, but define the methods in the protocol to also pass some sort of identifier. When the child tells its delegate that it was touched, it also passes a pointer to itself. This way, the parent know exactly which view was touched. It just seems really strange for an object to pass a reference to itself. Use NSNotifications. The parent defines a separate method for each of the three children and then subscribes to the "viewWasTouched" notification for each of the three children as the notification sender. The children don't need to attach themselves to the user dictionary, but they do need to send the notification with a pointer to themselves as the scope. Same as #4, but rather than using separate methods, the parent could just use one with a switch case or other branching along with the notification's sender to determine which path to take. Create multiple man-in-the-middle classes that act as the delegates to the child views and then call methods on the parent either with a pointer to the child or with some other differentiating factor. This approach doesn't seem scalable. Are any of these approaches considered best practice? I can't say for sure, but it feels like I'm missing something more obvious/elegant.

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