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• Problems related to showing MessageBox from non-GUI threads

  - by Hans Løken

  I'm working on a heavily data-bound Win.Forms application where I've found some strange behavior. The app has separate I/O threads receiving updates through asynchronous web-requests which it then sends to the main/GUI thread for processing and updating of application-wide data-stores (which in turn may be data-bound to various GUI-elements, etc.). The server at the other end of the web-requests requires periodic requests or the session times out. I've gone through several attempted solutions of dealing with thread-issues etc. and I've observed the following behavior: If I use Control.Invoke for sending updates from I/O-thread(s) to main-thread and this update causes a MessageBox to be shown the main form's message pump stops until the user clicks the ok-button. This also blocks the I/O-thread from continuing eventually leading to timeouts on the server. If I use Control.BeginInvoke for sending updates from I/O-thread(s) to main-thread the main form's message pump does not stop, but if the processing of an update leads to a messagebox being shown, the processing of the rest of that update is halted until the user clicks ok. Since the I/O-threads keep running and the message pump keeps processing messages several BeginInvoke's for updates may be called before the one with the message box is finished. This leads to out-of-sequence updates which is unacceptable. I/O-threads add updates to a blocking queue (very similar to http://stackoverflow.com/questions/530211/creating-a-blocking-queuet-in-net/530228#530228). GUI-thread uses a Forms.Timer that periodically applies all updates in the blocking queue. This solution solves both the problem of blocking I/O threads and sequentiality of updates i.e. next update will be never be started until previous is finished. However, there is a small performance cost as well as introducing a latency in showing updates that is unacceptable in the long run. I would like update-processing in the main-thread to be event-driven rather than polling. So to my question. How should I do this to: avoid blocking the I/O-threads guarantee that updates are finished in-sequence keep the main message pump running while showing a message box as a result of an update.

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• Spawn a multi-threaded Java program from a Windows command line program, spawner won't end until spa

  - by Ross Patterson

  Short version: How can I prevent a spawned Java process in Windows from blocking the spawning process from ending? Long version: I'm trying to spawn a multi-threaded Java program (Selenium RC, not that it should matter) from a program launched from the Windows command line (NAnt's <exec> task, again, not that it should matter). I'm doing it using the Windows "start" command, and the spawned process is started and runs correctly. The spawning process receives control back and finishes (NAnt says "BUILD SUCCEEDED"), but doesn't actually exit to the command line. When the spawned process finally terminates (could be hours later), the command process returns and the command line prompt occurs. For example: <target name="start_rc"> <exec program="cmd" failonerror="false" workingdir="${ross.p5.dir}\Tools\selenium\selenium-server-1.0.1" verbose="true"> <arg value="/C"/> <arg value="start"/> <arg value="java"/> <arg value="-jar"/> <arg path="${ross.p5.dir}\Tools\selenium\selenium-server-1.0.1\selenium-server.jar"/> <arg value="-userExtensions"/> <arg path="${ross.p5.dir}\Tools\selenium\selenium-server-1.0.1\user-extensions.js"/> <arg value="-browserSideLog"/> <arg value="-log"/> <arg value="${ross.p5.dir}\artifacts\selenium.log"/> <arg value="-debug"/> </exec> </target> Produces: C :\Ross>nant start_rc NAnt 0.86 (Build 0.86.2898.0; beta1; 12/8/2007) Copyright (C) 2001-2007 Gerry Shaw http://nant.sourceforge.net Buildfile: file:///C:/Ross/ross.build Target framework: Microsoft .NET Framework 3.5 Target(s) specified: start_rc start_rc: [exec] Starting 'cmd (/C start java -jar C:\p5\Tools\selenium\selenium-server-1.0.1\selenium-server.jar -userExtensions C:\p5\Tools\selenium\selenium-server-1.0.1\user-extensions.js -browserSideLog -log C:\p5\artifacts\selenium.log -debug)' in 'C:\p5\Tools\selenium\selenium-server-1.0.1' BUILD SUCCEEDED Total time: 4.1 seconds. ... and then nothing until I close the window where Java is running, then ... C:\Ross> Obviously something is preventing the nant process from terminating, but shouldn't the Windows START command prevent that?

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• Eclipse: How to convert a web project into an AspectJ project and weave and run it using the AJDT pl

  - by Kent

  What I want to do: I want to use the @Configured annotation with Spring. It requires AspectJ to be enabled. I thought that using the AJDT plugin for compile time weaving would solve this problem. Before installing the plug in the dependencies which were supposed to be injected into my @Configured object remained null. What I have done: Installed the AJDT: AspectJ Development Tools plug in for Eclipse 3.4. Right clicked on my web project and converted it into a AspectJ project. Enabled compile time weaving. What doesn't work: When I start the Tomcat 6 server now, I get an exception*. Other information: I haven't configured anything in the AspectJ Build and AspectJ Compiler parts of the project properties. JDT Weaving under Preferences says weaving is enabled. I still have Java build path and Java Compiler under project properties. And they look like I previously configured them (while the above two new entries are not configured). The icon of my @Configured object file looks like any other file (i.e. no indication of any aspect or such, which I think there should be). The file name is MailNotification.java (and not .aj), but I guess it should still work as I'm using a Spring annotation for AspectJ? I haven't found any tutorial or similar which teaches: How to turn a Spring web application project into an AspectJ project and weave aspects into the files using the AJDT plugin, all within Eclipse 3.4. If there is anything like that out there I would be very interested in knowing about it. What I would like to know: Where to go from here? I just want to use the @Configured annotation of Spring. I'm also using @Transactional which I think also needs AspectJ. If it is possible I would like to study AspectJ as little as possible as long as my needs are met. The subject seems interesting, but huge, all I want to do is use the above two mentioned Spring annotations. *** Exception when Tomcat 6 is started: Caused by: java.lang.IllegalStateException: ClassLoader [org.apache.catalina.loader.WebappClassLoader] does NOT provide an 'addTransformer(ClassFileTransformer)' method. Specify a custom LoadTimeWeaver or start your Java virtual machine with Spring's agent: -javaagent:spring-agent.jar at org.springframework.context.weaving.DefaultContextLoadTimeWeaver.setBeanClassLoader(DefaultContextLoadTimeWeaver.java:82) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1322) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473) ... 41 more

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• Validate a string in a table in SQL Server - CLR function or T-SQL (Question updated)

  - by Ashish Gupta

  I need to check If a column value (string) in SQL server table starts with a small letter and can only contain '_', '-', numbers and alphabets. I know I can use a SQL server CLR function for that. However, I am trying to implement that validation using a scalar UDF and could make very little here...I can use 'NOT LIKE', but I am not sure how to make sure I validate the string irrespective of the order of characters or in other words write a pattern in SQL for this. Am I better off using a SQL CLR function? Any help will be appreciated.. Thanks in advance Thank you everyone for their comments. This morning, I chose to go CLR function way. For the purpose of what I was trying to achieve, I created one CLR function which does the validation of an input string and have that called from a SQL UDF and It works well. Just to measure the performance of t-SQL UDF using SQL CLR function vs t- SQL UDF, I created a SQL CLR function which will just check if the input string contains only small letters, it should return true else false and have that called from a UDF (IsLowerCaseCLR). After that I also created a regular t-SQL UDF(IsLowerCaseTSQL) which does the same thing using the 'NOT LIKE'. Then I created a table (Person) with columns Name(varchar) and IsValid(bit) columns and populate that with names to test. Data :- 1000 records with 'Ashish' as value for Name column 1000 records with 'ashish' as value for Name column then I ran the following :- UPDATE Person Set IsValid=1 WHERE dbo.IsLowerCaseTSQL (Name) Above updated 1000 records (with Isvalid=1) and took less than a second. I deleted all the data in the table and repopulated the same with same data. Then updated the same table using Sql CLR UDF (with Isvalid=1) and this took 3 seconds! If update happens for 5000 records, regular UDF takes 0 seconds compared to CLR UDF which takes 16 seconds! I am very less knowledgeable on t-SQL regular expression or I could have tested my actual more complex validation criteria. But I just wanted to know, even I could have written that, would that have been faster than the SQL CLR function considering the example above. Are we using SQL CLR because we can implement we can implement lot richer logic which would have been difficult otherwise If we write in regular SQL. Sorry for this long post. I just want to know from the experts. Please feel free to ask if you could not understand anything here. Thank you again for your time.

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• How to configure maximum number of transport channels in WCF using basicHttpBinding?

  - by Hemant

  Consider following code which is essentially a WCF host: [ServiceContract (Namespace = "http://www.mightycalc.com")] interface ICalculator { [OperationContract] int Add (int aNum1, int aNum2); } [ServiceBehavior (InstanceContextMode = InstanceContextMode.PerCall)] class Calculator: ICalculator { public int Add (int aNum1, int aNum2) { Thread.Sleep (2000); //Simulate a lengthy operation return aNum1 + aNum2; } } class Program { static void Main (string[] args) { try { using (var serviceHost = new ServiceHost (typeof (Calculator))) { var httpBinding = new BasicHttpBinding (BasicHttpSecurityMode.None); serviceHost.AddServiceEndpoint (typeof (ICalculator), httpBinding, "http://172.16.9.191:2221/calc"); serviceHost.Open (); Console.WriteLine ("Service is running. ENJOY!!!"); Console.WriteLine ("Type 'stop' and hit enter to stop the service."); Console.ReadLine (); if (serviceHost.State == CommunicationState.Opened) serviceHost.Close (); } } catch (Exception e) { Console.WriteLine (e); Console.ReadLine (); } } } Also the WCF client program is: class Program { static int COUNT = 0; static Timer timer = null; static void Main (string[] args) { var threads = new Thread[10]; for (int i = 0; i < threads.Length; i++) { threads[i] = new Thread (Calculate); threads[i].Start (null); } timer = new Timer (o => Console.WriteLine ("Count: {0}", COUNT), null, 1000, 1000); Console.ReadLine (); timer.Dispose (); } static void Calculate (object state) { var c = new CalculatorClient ("BasicHttpBinding_ICalculator"); c.Open (); while (true) { try { var sum = c.Add (2, 3); Interlocked.Increment (ref COUNT); } catch (Exception ex) { Console.WriteLine ("Error on thread {0}: {1}", Thread.CurrentThread.Name, ex.GetType ()); break; } } c.Close (); } } Basically, I am creating 10 proxy clients and then repeatedly calling Add service method. Now if I run both applications and observe opened TCP connections using netstat, I find that: If both client and server are running on same machine, number of tcp connections are equal to number of proxy objects. It means all requests are being served in parallel. Which is good. If I run server on a separate machine, I observed that maximum 2 TCP connections are opened regardless of the number of proxy objects I create. Only 2 requests run in parallel. It hurts the processing speed badly. If I switch to net.tcp binding, everything works fine (a separate TCP connection for each proxy object even if they are running on different machines). I am very confused and unable to make the basicHttpBinding use more TCP connections. I know it is a long question, but please help!

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• Authlogic openid: getting undefined method openid_identifier? error in functional test

  - by usr

  I use Authlogic with the Authlogic-openid addon (I gem installed ruby- openid and script/plugin install git://github.com/rails/open_id_authentication.git) and get two errors. First when running functional test, I get an undefined method openid_identifier? message on a line in my new.html.erb file when running the UsersControllerTest. The line is: <% if @user.openid_identifier? %> When running script/console I can access this method without any problem. Second when testing the openid functionality and registering a new user to my application using openid and using my blogspot account for that I get the following in my log file: Generated checkid_setup request to http://www.blogger.com/openid-server.g with assocication ... Redirected to http://www.blogger.com/openid-server.g?openid.assoc_handle=... NoMethodError (You have a nil object when you didn't expect it! The error occurred while evaluating nil.call): app/controllers/users_controller.rb:44:in `create' /usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /usr/lib/ruby/1.8/webrick/httpserver.rb:65:in `run' /usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' /usr/lib/ruby/1.8/webrick/server.rb:162:in `start' /usr/lib/ruby/1.8/webrick/server.rb:162:in `start_thread' /usr/lib/ruby/1.8/webrick/server.rb:95:in `start' /usr/lib/ruby/1.8/webrick/server.rb:92:in `each' /usr/lib/ruby/1.8/webrick/server.rb:92:in `start' /usr/lib/ruby/1.8/webrick/server.rb:23:in `start' /usr/lib/ruby/1.8/webrick/server.rb:82:in `start' The code in the users_controller is straight forward: def create respond_to do |format| @user.save do |result| if result flash[:notice] = t('Thanks for signing up!') format.html { redirect_to :action => 'index' } format.xml { render :xml => @user, :status => :created, :location => @user } else format.html { render :action => "new" } format.xml { render :xml => @user.errors, :status => :unprocessable_entity } end end end end The line giving the error being @user.save do |result|... I feel I'm missing something pretty basic but I have been staring at this for too long because I can't find what it is. I checked with the code on Railscasts episodes 160 and 170 and the bones GitHub project but found nothing. Thanks for your help, usr

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• Is this asking too much of a browser?

  - by Matt Ball

  I'm embedding a large array in <script> tags in my HTML, like this (nothing surprising): <script> var largeArray = [/* lots of stuff in here */]; </script> In this particular example, the array has 210,000 elements. That's well below the theoretical maximum of 231 - by 4 orders of magnitude. Here's the fun part: if I save JS source for the array to a file, that file is 44 megabytes (46,573,399 bytes, to be exact). If you want to see for yourself, you can download it from my Dropbox. (All the data in there is canned, so much of it is repeated. This will not be the case in production.) Now, I'm really not concerned about serving that much data. My server gzips its responses, so it really doesn't take all that long to get the data over the wire. However, there is a really nasty tendency for the page, once loaded, to crash the browser. I'm not testing at all in IE (this is an internal tool). My primary targets are Chrome 8 and Firefox 3.6. In Firefox, I can see a reasonably useful error in the console: Error: script stack space quota is exhausted In Chrome, I simply get the sad-tab page: Cut to the chase, already Is this really too much data for our modern, "high-performance" browsers to handle? Is there anything I can do* to gracefully handle this much data? Incidentally, I was able to get this to work (read: not crash the tab) on-and-off in Chrome. I really thought that Chrome, at least, was made of tougher stuff, but apparently I was wrong... Edit 1 @Crayon: I wasn't looking to justify why I'd like to dump this much data into the browser at once. Short version: either I solve this one (admittedly not-that-easy) problem, or I have to solve a whole slew of other problems. I'm opting for the simpler approach for now. @various: right now, I'm not especially looking for ways to actually reduce the number of elements in the array. I know I could implement Ajax paging or what-have-you, but that introduces its own set of problems for me in other regards. @Phrogz: each element looks something like this: {dateTime:new Date(1296176400000), terminalId:'terminal999', 'General___BuildVersion':'10.05a_V110119_Beta', 'SSM___ExtId':26680, 'MD_CDMA_NETLOADER_NO_BCAST___Valid':'false', 'MD_CDMA_NETLOADER_NO_BCAST___PngAttempt':0} @Will: but I have a computer with a 4-core processor, 6 gigabytes of RAM, over half a terabyte of disk space ...and I'm not even asking for the browser to do this quickly - I'm just asking for it to work at all! ? *other than the obvious: sending less data to the browser

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• WPF Choppy Animation

  - by Chris Dunaway

  WPF Windows-XP SP3 I'm having a problem with a simple WPF animation. I use the following Xaml code (in XamlPad and also in a WPF project): <Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" > <Border Name="MyBorder" BorderThickness="10" BorderBrush="Blue" CornerRadius="10" Background="DarkRed" > <Rectangle Name="MyRectangle" Margin="10" StrokeDashArray="2.0,1.0" StrokeThickness="10" RadiusX="10" RadiusY="10" Stroke="Black" StrokeDashOffset="0"> <Rectangle.Triggers> <EventTrigger RoutedEvent="Rectangle.Loaded"> <BeginStoryboard> <Storyboard> <DoubleAnimation Storyboard.TargetName="MyRectangle" Storyboard.TargetProperty="StrokeDashOffset" From="0.0" To="3.0" Duration="0:0:1" RepeatBehavior="Forever" Timeline.DesiredFrameRate="30" /> </Storyboard> </BeginStoryboard> </EventTrigger> </Rectangle.Triggers> </Rectangle> </Border> </Page> It has the effect of causing the border to animate around the rectangle. After a fresh reboot of the machine, this animation is nice and smooth. However, I tend to leave my machine on all the time and after a period time elapses (I don't know how long), the animation starts stuttering and becomes choppy. I thought that it may be memory or resource issues, but after shutting down all other apps and any services that seem unnecessary, the stuttering still continues. However, after a system reboot, the animation is smooth again! I get the same symptoms in a WPF app or in XamlPad. In the case of the app, it doesn't seem to make any difference whether I run in the debugger or if I run the executable directly. I applied the patch at this link: http://support.microsoft.com/kb/981741 and I thought that it had taken care of the issue, but it seems not to have. I have seen some posts that might indicate that using transparency might affect animation, but as you can see, my xaml does not use transparency. Can anyone give me some suggestions on how to determine what the problem is? Are there any WPF diagnostic tools that might help? UPDATE: I have checked my video drivers and they are the latest version. (nVidia GeForce 8400 GS)

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• Ubuntu hard disk problem

  - by Henadzy

  Hello! I have got the error with a hard disk on Ubuntu 9.10. It slows down my system, applications have not been responding for a long time. But when I mount and use filesystem which placed on this hard disk at other computer it works properly. disk: SAMSUNG HD161HJ (SATA) syslog: Apr 25 00:28:25 vare6gin kernel: [ 885.773839] ata3.00: exception Emask 0x1 SAct 0x1e SErr 0x0 action 0x6 frozen Apr 25 00:28:25 vare6gin kernel: [ 885.773845] ata3.00: Ata error. fis:0x21 Apr 25 00:28:25 vare6gin kernel: [ 885.773861] ata3.00: cmd 60/08:08:3f:00:ad/00:00:10:00:00/40 tag 1 ncq 4096 in Apr 25 00:28:25 vare6gin kernel: [ 885.773864] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773871] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773877] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773890] ata3.00: cmd 60/18:10:9f:6b:ed/00:00:0e:00:00/40 tag 2 ncq 12288 in Apr 25 00:28:25 vare6gin kernel: [ 885.773893] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773900] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773904] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773918] ata3.00: cmd 60/08:18:3f:5f:ed/00:00:0e:00:00/40 tag 3 ncq 4096 in Apr 25 00:28:25 vare6gin kernel: [ 885.773921] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773927] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773932] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773946] ata3.00: cmd 60/08:20:67:c8:91/00:00:05:00:00/40 tag 4 ncq 4096 in Apr 25 00:28:25 vare6gin kernel: [ 885.773948] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773955] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773960] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773970] ata3: hard resetting link Apr 25 00:28:25 vare6gin kernel: [ 885.773974] ata3: nv: skipping hardreset on occupied port Apr 25 00:28:25 vare6gin kernel: [ 886.240073] ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Apr 25 00:28:25 vare6gin kernel: [ 886.256277] ata3.00: configured for UDMA/133 Apr 25 00:28:25 vare6gin kernel: [ 886.256305] ata3: EH complete Apr 25 00:28:27 vare6gin kernel: [ 888.176088] ata3: EH in SWNCQ mode,QC:qc_active 0xF sactive 0xF Apr 25 00:28:27 vare6gin kernel: [ 888.176099] ata3: SWNCQ:qc_active 0xF defer_bits 0x0 last_issue_tag 0x3 Apr 25 00:28:27 vare6gin kernel: [ 888.176102] dhfis 0xF dmafis 0x1 sdbfis 0x0 Apr 25 00:28:27 vare6gin kernel: [ 888.176109] ata3: ATA_REG 0x51 ERR_REG 0x40 Apr 25 00:28:27 vare6gin kernel: [ 888.176113] ata3: tag : dhfis dmafis sdbfis sacitve Apr 25 00:28:27 vare6gin kernel: [ 888.176120] ata3: tag 0x0: 1 1 0 1 Apr 25 00:28:27 vare6gin kernel: [ 888.176126] ata3: tag 0x1: 1 0 0 1 Apr 25 00:28:27 vare6gin kernel: [ 888.176131] ata3: tag 0x2: 1 0 0 1 Apr 25 00:28:27 vare6gin kernel: [ 888.176136] ata3: tag 0x3: 1 0 0 1

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• ArrayIndexOutOfBoundsException with custom Android Adapter for multiple views in ListView

  - by Dan Watling

  I am attempting to create a custom Adapter for my ListView since each item in the list can have a different view (a link, toggle, or radio group), but when I try to run the Activity that uses the ListView I receive an error and the app stops. The application is targeted for the Android 1.6 platform. The code: public class MenuListAdapter extends BaseAdapter { private static final String LOG_KEY = MenuListAdapter.class.getSimpleName(); protected List<MenuItem> list; protected Context ctx; protected LayoutInflater inflater; public MenuListAdapter(Context context, List<MenuItem> objects) { this.list = objects; this.ctx = context; this.inflater = (LayoutInflater)this.ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE); } @Override public View getView(int position, View convertView, ViewGroup parent) { Log.i(LOG_KEY, "Position: " + position + "; convertView = " + convertView + "; parent=" + parent); MenuItem item = list.get(position); Log.i(LOG_KEY, "Item=" + item ); if (convertView == null) { convertView = this.inflater.inflate(item.getLayout(), null); } return convertView; } @Override public boolean areAllItemsEnabled() { return false; } @Override public boolean isEnabled(int position) { return true; } @Override public int getCount() { return this.list.size(); } @Override public MenuItem getItem(int position) { return this.list.get(position); } @Override public long getItemId(int position) { return position; } @Override public int getItemViewType(int position) { Log.i(LOG_KEY, "getItemViewType: " + this.list.get(position).getLayout()); return this.list.get(position).getLayout(); } @Override public int getViewTypeCount() { Log.i(LOG_KEY, "getViewTypeCount: " + this.list.size()); return this.list.size(); } } The error I receive: java.lang.ArrayIndexOutOfBoundsException at android.widget.AbsListView$RecycleBin.addScrapView(AbsListView.java:3523) at android.widget.ListView.measureHeightOfChildren(ListView.java:1158) at android.widget.ListView.onMeasure(ListView.java:1060) at android.view.View.measure(View.java:7703) I do know that the application is returning from getView and everything seems in order. Any ideas on what could be causing this would be appreciated. Thanks, -Dan

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• Wiki-fying a text using LPeg

  - by Stigma

  Long story coming up, but I'll try to keep it brief. I have many pure-text paragraphs which I extract from a system and re-output in wiki format so that the copying of said data is not such an arduous task. This all goes really well, except that there are no automatic references being generated for the 'topics' we have pages for, which end up needing to be added by reading through all the text and adding it in manually by changing Topic to [[Topic]]. First requirement: each topic is only to be made clickable once, which is the first occurrence. Otherwise, it would become a really spammy linkfest, which would detract from readability. To avoid issues with topics that start with the same words Second requirement: overlapping topic names should be handled in such a way that the most 'precise' topic gets the link, and in later occurrences, the less precise topics do not get linked, since they're likely not correct. Example: topics = { "Project", "Mary", "Mr. Moore", "Project Omega"} input = "Mary and Mr. Moore work together on Project Omega. Mr. Moore hates both Mary and Project Omega, but Mary simply loves the Project." output = function_to_be_written(input) -- "[[Mary]] and [[Mr. Moore]] work together on [[Project Omega]]. Mr. Moore hates both Mary and Project Omega, but Mary simply loves the [[Project]]." Now, I quickly figured out a simple or complicated string.gsub() could not get me what I need to satisfy the second requirement, as it provides no way to say 'Consider this match as if it did not happen - I want you to backtrack further'. I need the engine to do something akin to: input = "abc def ghi" -- Looping over the input would, in this order, match the following strings: -- 1) abc def ghi -- 2) abc def -- 3) abc -- 4) def ghi -- 5) def -- 6) ghi Once a string matches an actual topic and has not been replaced before by its wikified version, it is replaced. If this topic has been replaced by a wikified version before, don't replace, but simply continue the matching at the end of the topic. (So for a topic "abc def", it would test "ghi" next in both cases.) Thus I arrive at LPeg. I have read up on it, played with it, but it is considerably complex, and while I think I need to use lpeg.Cmt and lpeg.Cs somehow, I am unable to mix the two properly to make what I want to do work. I am refraining from posting my practice attempts as they are of miserable quality and probably more likely to confuse anyone than assist in clarifying my problem. (Why do I want to use a PEG instead of writing a triple-nested loop myself? Because I don't want to, and it is a great excuse to learn PEGs.. except that I am in over my head a bit. Unless it is not possible with LPeg, the first is not an option.)

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• Geolocation SQL query not finding exact location

  - by Iridium52

  I have been testing my geolocation query for some time now and I haven't found any issues with it until now. I am trying to search for all cities within a given radius, often times I'm searching for cities surrounding a city using that city's coords, but recently I tried searching around a city and found that the city itself was not returned. I have these cities as an excerpt in my database: city latitude longitude Saint-Mathieu 45.316708 -73.516253 Saint-Édouard 45.233374 -73.516254 Saint-Michel 45.233374 -73.566256 Saint-Rémi 45.266708 -73.616257 But when I run my query around the city of Saint-Rémi, with the following query... SELECT tblcity.city, tblcity.latitude, tblcity.longitude, truncate((degrees(acos( sin(radians(tblcity.latitude)) * sin(radians(45.266708)) + cos(radians(tblcity.latitude)) * cos(radians(45.266708)) * cos(radians(tblcity.longitude - -73.616257) ) ) ) * 69.09*1.6),1) as distance FROM tblcity HAVING distance < 10 ORDER BY distance desc I get these results: city latitude longitude distance Saint-Mathieu 45.316708 -73.516253 9.5 Saint-Édouard 45.233374 -73.516254 8.6 Saint-Michel 45.233374 -73.566256 5.3 The town of Saint-Rémi is missing from the search. So I tried a modified query hoping to get a better result: SELECT tblcity.city, tblcity.latitude, tblcity.longitude, truncate(( 6371 * acos( cos( radians( 45.266708 ) ) * cos( radians( tblcity.latitude ) ) * cos( radians( tblcity.longitude ) - radians( -73.616257 ) ) + sin( radians( 45.266708 ) ) * sin( radians( tblcity.latitude ) ) ) ),1) AS distance FROM tblcity HAVING distance < 10 ORDER BY distance desc But I get the same result... However, if I modify Saint-Rémi's coords slighly by changing the last digit of the lat or long by 1, both queries will return Saint-Rémi. Also, if I center the query on any of the other cities above, the searched city is returned in the results. Can anyone shed some light on what may be causing my queries above to not display the searched city of Saint-Rémi? I have added a sample of the table (with extra fields removed) below. I'm using MySQL 5.0.45, thanks in advance. CREATE TABLE `tblcity` ( `IDCity` int(1) NOT NULL auto_increment, `City` varchar(155) NOT NULL default '', `Latitude` decimal(9,6) NOT NULL default '0.000000', `Longitude` decimal(9,6) NOT NULL default '0.000000', PRIMARY KEY (`IDCity`) ) ENGINE=MyISAM AUTO_INCREMENT=52743 DEFAULT CHARSET=latin1 AUTO_INCREMENT=52743; INSERT INTO `tblcity` (`city`, `latitude`, `longitude`) VALUES ('Saint-Mathieu', 45.316708, -73.516253), ('Saint-Édouard', 45.233374, -73.516254), ('Saint-Michel', 45.233374, -73.566256), ('Saint-Rémi', 45.266708, -73.616257);

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• How to Determine the Size of MSADO Command Parameters

  - by Adam

  I am new to MS ADO and trying to understand how to set the size on command parameters as created by the command.CreateParameter (Name, Type, Direction, Size, Value) The documentation says the following: Size Optional. A Long value that specifies the maximum length for the parameter value in characters or bytes. ... If you specify a variable-length data type in the Type argument, you must either pass a Size argument or set the Size property of the Parameter object before appending it to the Parameters collection; otherwise, an error occurs. 1.) What should one pass for fixed-size parameters? Is it a "don't care"? I was a bit confused by the example found here, in which they set size to 3 for an adInteger parameter with Value set to a variant of type VT_I2 pPrmByRoyalty->Type = adInteger; pPrmByRoyalty->Size = 3; pPrmByRoyalty->Direction = adParamInput; pPrmByRoyalty->Value = vtroyal; VT_I2 implies two bytes. A tagVARIANT struct is 16 bytes. How did they land on three? I see that the enum value for adInteger happens to be three, but I suspect that is just a coincidence. So it's a bit confusing what to pass for fixed-size parameters. The team I'm working with has always passed sizeof(int) for adInteger, and it seems to work. Is that correct? Now, for "variable-length" parameters: we are instructed by the documentation to pass "the maximum length .. in characters or bytes". 2.) For adVarChar, is it sufficient to pass the max width as defined in the database? 3.) What about the Wide types (e.g. adVarWChar)? Is it characters or bytes? 4.) How about adVariant, which could contain fixed- or variable-length data? 5.) Do arrays ever come into play here? (we don't pass them as parameters, just curious) Any references or personal insights are welcome.

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• WCF XmlSerializer assembly not speeding up first request

  - by Matt Dearing

  I am generating proxy classes to a clients java webservice wsdls and xsd files with svcutil. The first call made to each service proxy class takes a very long time. I was hoping to speed this up by generating the XmlSerializers assembly myself (based on the article How to: Improve the Startup Time of WCF Client Applications using the XmlSerializer), but when I do the first call to each service still takes the same amount of time. Here are the steps I am following: //generate strong name key file sn -k Blah.snk //generate the proxy class file svcutil blah.wsdl blah2.wsdl blah3.wsdl ... base.xsd blah.xsd ... /UseSerializerForFaults /ser:XmlSerializer /n:*,SomeNamespace /out:Blah.cs //compile the class into an assembly signing it with the strong name key file csc /target:library /keyfile:Blah.snk /out:Blah.dll Blah.cs //generate the XmlSerializer code this will give us Blah.XmlSerializers.dll.cs svcutil /t:xmlSerializer Blah.dll //compile the xmlserializer code into its own dll using the same key to sign it and referencing the original dll csc /target:library /keyfile:Blah.snk /out:Blah.XmlSerializers.dll Blah.XmlSerializers.dll.cs /r:Blah.dll I then create a standard Console application that references both Blah.dll and Blah.XmlSerializers.dll. I will then try something like: //BlahProxy is one of the generated service proxy classes BlahProxy p = new BlahProxy(); //this call takes 30ish seconds p.SomeMethod(); BlahProxy p2 = new BlahProxy(); //this call takes < 1 second p2.SomeMethod(); //BlahProx2y is one of the generated service proxy classes BlahProxy2 p3 = new BlahProxy2(); //this call takes 30ish seconds p3.SomeMethod(); BlahProxy2 p4 = new BlahProxy2(); //this call takes < 1 second p4.SomeMethod(); I know that the problem is not server side because I don't see the request made in Fiddler until around 29 seconds. Subsequent calls to each service take < 1 second, so thats why I was hoping the main slow down was the .net runtime generating the xmlserializer code itself, compiling it and loading the assembly. I figured this would be the reason the first call to each service is slow and the rest are fast. Unfortunatley, me generating the code myself is not speeding anything up. Does anyone see what I am doing wrong?

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• Asynchronous subprocess on Windows

  - by Stigma

  First of all, the overall problem I am solving is a bit more complicated than I am showing here, so please do not tell me 'use threads with blocking' as it would not solve my actual situation without a fair, FAIR bit of rewriting and refactoring. I have several applications which are not mine to modify, which take data from stdin and poop it out on stdout after doing their magic. My task is to chain several of these programs. Problem is, sometimes they choke, and as such I need to track their progress which is outputted on STDERR. pA = subprocess.Popen(CommandA, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE) # ... some more processes make up the chain, but that is irrelevant to the problem pB = subprocess.Popen(CommandB, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=pA.stdout ) Now, reading directly through pA.stdout.readline() and pB.stdout.readline(), or the plain read() functions, is a blocking matter. Since different applications output in different paces and different formats, blocking is not an option. (And as I wrote above, threading is not an option unless at a last, last resort.) pA.communicate() is deadlock safe, but since I need the information live, that is not an option either. Thus google brought me to this asynchronous subprocess snippet on ActiveState. All good at first, until I implement it. Comparing the cmd.exe output of pA.exe | pB.exe, ignoring the fact both output to the same window making for a mess, I see very instantaneous updates. However, I implement the same thing using the above snippet and the read_some() function declared there, and it takes over 10 seconds to notify updates of a single pipe. But when it does, it has updates leading all the way upto 40% progress, for example. Thus I do some more research, and see numerous subjects concerning PeekNamedPipe, anonymous handles, and returning 0 bytes available even though there is information available in the pipe. As the subject has proven quite a bit beyond my expertise to fix or code around, I come to Stack Overflow to look for guidance. :) My platform is W7 64-bit with Python 2.6, the applications are 32-bit in case it matters, and compatibility with Unix is not a concern. I can even deal with a full ctypes or pywin32 solution that subverts subprocess entirely if it is the only solution, as long as I can read from every stderr pipe asynchronously with immediate performance and no deadlocks. :)

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• user generated / user specific functions

  - by pedalpete

  I'm looking for the most elegant and secure method to do the following. I have a calendar, and groups of users. Users can add events to specific days on the calendar, and specify how long each event lasts for. I've had a few requests from users to add the ability for them to define that events of a specific length include a break, of a certain amount of time, or require that a specific amount of time be left between events. For example, if event is 2 hours, include a 20min break. for each event, require 30 minutes before start of next event. The same group that has asked for an event of 2 hours to include a 20 min break, could also require that an event 3 hours include a 30 minute break. In the end, what the users are trying to get is an elapsed time excluding breaks calculated for them. Currently I provide them a total elapsed time, but they are looking for a running time. However, each of these requests is different for each group. Where one group may want a 30 minute break during a 2 hour event, and another may want only 10 minutes for each 3 hour event. I was kinda thinking I could write the functions into a php file per group, and then include that file and do the calculations via php and then return a calculated total to the user, but something about that doesn't sit right with me. Another option is to output the groups functions to javascript, and have it run client-side, as I'm already returning the duration of the event, but where the user is part of more than one group with different rules, this seems like it could get rather messy. I currently store the start and end time in the database, but no 'durations', and I don't think I should be storing the calculated totals in the db, because if a group decides to change their calculations, I'd need to change it throughout the db. Is there a better way of doing this? I would just store the variables in mysql, but I don't see how I can then say to mysql to calculate based on those variables. I'm REALLY lost here. Any suggestions? I'm hoping somebody has done something similar and can provide some insight into the best direction. If it helps, my table contains eventid, user, group, startDate, startTime, endDate, endTime, type The json for the event which I return to the user is {"eventid":"'.$eventId.'", "user":"'.$userId.'","group":"'.$groupId.'","type":"'.$type.'","startDate":".$startDate.'","startTime":"'.$startTime.'","endDate":"'.$endDate.'","endTime":"'.$endTime.'","durationLength":"'.$duration.'", "durationHrs":"'.$durationHrs.'"} where for example, duration length is 2.5 and duration hours is 2:30.

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• XSLT Document function returns empty result on Maven POM

  - by user328618

  Greetings! I want to extract some properties from different Maven POMs in a XSLT via the document function. The script itself works fine but the document function returns an empty result for the POM as long as I have the xmlns="http://maven.apache.org/POM/4.0.0" in the project tag. If I remove it, everything works fine. Any idea how the make this work while leaving the xmlns attribute where it belongs or why this doesn't work with the attribute in place? Here comes the relevant portion of my XSLT: <xsl:template match="abcs"> <xsl:variable name="artifactCoordinate" select="abc"/> <xsl:choose> <xsl:when test="document(concat($artifactCoordinate,'-pom.xml'))"> <abc> <ID><xsl:value-of select="$artifactCoordinate"/></ID> <xsl:copy-of select="document(concat($artifactCoordinate,'-pom.xml'))/project/properties"/> </abc> </xsl:when> <xsl:otherwise> <xsl:message terminate="yes"> Transformation failed: POM "<xsl:value-of select="concat($artifactCoordinate,'-pom.xml')"/>" doesn't exist. </xsl:message> </xsl:otherwise> </xsl:choose> And, for completeness, a POM extract with the "bad" attribute: <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <!-- ... --> <properties> <proalpha.version>[5.2a]</proalpha.version> <proalpha.openedge.version>[10.1B]</proalpha.openedge.version> <proalpha.optimierer.version>[1.1]</proalpha.optimierer.version> <proalpha.sonic.version>[7.6.1]</proalpha.sonic.version> </properties> </project>

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• Advice on displaying and allowing editing of data using ASP.NET MVC?

  - by Remnant

  I am embarking upon my first ASP.NET MVC project and I would like to get some input on possible ways to display database data and general best practice. In short, the body of my webpage will show data from my database in a table like format, with each table row showing similar data. For example: Name Age Position Date Joined Jon Smith 23 Striker 18th Mar 2005 John Doe 38 Defender 3rd Jan 1988 In terms of functionality, primarily I’d like to give the user the ability to edit the data and, after the edit, commit the edit to the database and refresh the view.The reason I want to refresh the view is because the data is date ordered and I will need to re-sort if the user edits a date field. My main question is what architecture / tools would be best suited to this fulfil my requirements at a high level? From the research I have done so far my initial conclusions were: ADO.NET for data retrieval. This is something I have used before and feel comfortable with. I like the look of LINQ to SQL but don’t want to make the learning curve any steeper for my first outing into MVC land just yet. Partial Views to create a template and then iterate through a datatable that I have pulled back from my database model. jQuery to allow the user to edit data in the table, error check edited data entries etc. Also, my intial view was that caching the data would not be a key requirement here. The only field a user will be able to update is the field and, if they do, I will need to commit that data to the database immediately and then refresh the view (as the data is date sorted). Any thoughts on this? Alternatively, I have seen some jQuery plug-ins that emulate a datagrid and provide associated functionality. My first thoughts are that I do not need all the functionality that comes with these plug-ins (e.g. zebra striping, ability to sort by column using sort glyph in column headers etc .) and I don’t really see any benefit to this over and above the solution I have outlined above. Again, is there reason to reconsider this view? Finally, when a user edits a date , I will need to refresh the view. In order to do this I had been reading about Html.RenderAction and this seemed like it may be a better option than using Partial Views as I can incorporate application logic into the action method. Am I right to consider Html.RenderAction or have I misunderstood its usage? Hope this post is clear and not too long. I did consider separate posts for each topic (e.g. Partial View vs. Html.RenderAction, when to use jQury datagrid plug-in) but it feels like these issues are so intertwined that they need to be dealt with in contect of each other. Thanks

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• Enable real fixed positioning on Samsung Android browsers

  - by Mr. Shiny and New ??

  The Android browser, since 2.2, supports fixed positioning, at least under certain circumstances such as when scaling is turned off. I have a simple HTML file with no JS, but the fixed positioning on three Samsung phones I've tried is simply wrong. Instead of true fixed positioning, the header scrolls out of view then pops back into place after the scrolling is done. This doesn't happen on the Android SDK emulator for any configuration I've tested (2.2, 2.3, 2.3 x86, 4.0.4). It also doesn't happen when using the WebView in an app on the Samsung phones: in those cases the positioning works as expected. Is there a way to make the Samsung Android "stock" browser use real fixed positioning? I've tested: 1. Samsung Galaxy 551, Android 2.2 2. Samsung Galaxy S, Android 2.3 3. Samsung Galaxy S II, Android 2.3 Sample code: <html> <head> <meta name="viewport" content="initial-scale=1.0,maximum-scale=1.0,user-scalable=no,width=device-width,height=device-height"> <style> h1 { position: fixed; top: 0; left: 0; height: 32px; background-color: #CDCDCD; color: black; font-size: 32px; line-height: 32px; padding: 2px; width: 100%; margin: 0;} p { margin-top: 36px; } </style> </head> <body> <h1>Header</h1> <p>Long text goes here</p> </body> </html> The expected behaviour is that the grey header fills the top of the screen and stays put no matter how much you scroll. On Samsung Android browsers it seems to scroll out of view then pop back into place once the scrolling is done, as if the fixed-positioning is being simulated using Javascript, which it isn't. Edit Judging by the comments and "answers" it seems that maybe I wasn't clear on what I need. I am looking for a meta tag or css rule/hack or javascript toggle which turns off Samsung's broken fixed-positioning and turns on the Android browser's working fixed-positioning. I am not looking for a Javascript solution that adds broken fixed-positioning to a browser that has no support whatsoever; the Samsung fixed-positioning does that already, it just looks stupid.

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• Create a screen like the iPhone home screen with Scrollview and Buttons

  - by Anthony Chan

  Hi, I'm working on a project and need to create a screen similar to the iPhone home screen: A scrollview with multiple pages A bunch of icons When not in edit mode, swipe through different pages (even I started the touch on an icon) When not in edit mode, tap an icon to do something When in edit mode, drag the icon to swap places, and even swap to different pages When in edit mode, tap an icon to remove it Previously I read from several forums that I have to subclass UIScrollview in order to have touch input for the UIViews on top of it. So I subclassed it overriding the methods to handle touches: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { //If not dragging, send event to next responder if (!self.dragging) [self.nextResponder touchesBegan:touches withEvent:event]; else [super touchesBegan:touches withEvent:event]; } In general I've override the touchesBegan:, touchesMoved: and touchesEnded: methods similarly. Then in the view controller, I added to following code: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; UIView *hitView = (UIView *)touch.view; if ([hitView isKindOfClass:[UIView class]]) { [hitView doSomething]; NSLog(@"touchesBegan"); } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { // Some codes to move the icons NSLog(@"touchesMoved"); } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { NSLog(@"touchesEnded"); } When I run the app, I have the touchesBegan method detected correctly. However, when I tried to drag the icon, the icon just moved a tiny bit and then the page started to scroll. In console, it logged with 2 or 3 "touchesMoved" message only. However, I learned from another project that it should logged tonnes of "touchesMoved" message as long as I'm still dragging on the screen. (I'm suspecting I have the delaysContentTouches set to YES, so it delays a little bit when I tried to drag the icons. After that minor delay, it sends to signal back to the scrollview to scroll through the page. Please correct me if I'm wrong.) So if any help on the code to perform the above tasks would be greatly appreciated. I've stuck in this place for nearly a week with no hope. Thanks a lot.

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• Determine the 'Overtype' mode using Javascript

  - by Snorkpete

  We are creating a web app to replace an old-school green-screen application. In the green-screen app, as the user presses the Insert key to switch between overtype and insert modes, the cursor changes to indicate which input mode the user is currently in. In IE (which is the official browser of the company), overtype mode also works, but there's no visual indication as to whether overtype mode is on or not, until the user starts typing and possibly over-writes existing information unexpectedly. I'd like to put some sort of visual indicator on the screen if in overtype mode. How can you determine if the browser is in 'overtype mode' from Javascript? Is there some property or function i can query to determine if the browser is in overtype mode? Even an IE-specific solution would be helpful, since our corporate policy dictates the browser to use as IE7 (pure torture, btw). (I do know that one solution is to do check for key presses of the Insert key. However, it's a solution that I'd prefer to avoid since that method seems a bit flaky & error-prone because I can't guarantee what mode the user would be in BEFORE he/she hits my page. ) The reasoning behind this question: The functionality of this portion of the green-screen app is such that the user can select from a list of 'preformatted bodies of text'. crude eg. The excess for this policy is: $xxxxxx and max limit is:$xxxxxx Date of policy is: xx/xx/xxxx and expires : xx/xx/xxxx Some other irrelevant text After selecting this 'preformatted text', the user would then use overtype to replace the x's with actual values, without disturbing the alignment of the rest of the text. (To be clear, they can still edit any part of the 'preformatted text' if they so wished. It's just that usually, they just wish to replace specific portions of the text. Keeping the alignment is important since these sections of text can end up on printed documents.) Of course, the same effect can be achieved by just selecting the x's to replace first, but it would be helpful (with respect to easing the transition to the web app) to allow old methods of doing things to continue to work, while still allowing 'web methods' to be used by the more tech-savvy users. Essentially, we're trying to make the initial transition from the green-screen app to the web app be as seemless as possible to minimise the resistance from the long-time green-screeners.

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• NoHostAvailableException With Cassandra & DataStax Java Driver If Large ResultSet

  - by hughj

  The setup: 2-node Cassandra 1.2.6 cluster replicas=2 very large CQL3 table with no secondary index Rowkey is a UUID.randomUUID().toString() read consistency set to ONE Using DataStax java driver 1.0 The request: Attempting to do a table scan by "SELECT some-col from schema.table LIMIT nnn;" The fail: Once I go beyond a certain nnn LIMIT, I start to get NoHostAvailableExceptions from the driver. It reads like this: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.exceptions.NoHostAvailableException.copy(NoHostAvailableException.java:64) at com.datastax.driver.core.ResultSetFuture.extractCauseFromExecutionException(ResultSetFuture.java:214) at com.datastax.driver.core.ResultSetFuture.getUninterruptibly(ResultSetFuture.java:169) at com.jpmc.es.rtm.storage.impl.EventExtract.main(EventExtract.java:36) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:98) at com.datastax.driver.core.RequestHandler$1.run(RequestHandler.java:165) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) Given: This is probably not the most enlightened thing to do to a large table with millions of rows, but this is how I learn what not to do, so I would really appreciate someone who could volunteer how this kind of error can be debugged. For example, when this happens, there are no indications that the nodes in the cluster ever had an issue with the request (there is nothing in the logs on either node that indicate any timeout or failure). Also, I enabled the trace on the driver, which gives you some nice autotrace (ala Oracle) info as long as the query succeeds. But in this case, the driver blows a NoHostAvailableException and no ExecutionInfo is available, so tracing has not provided any benefit in this case. I also find it interesting that this does not seem to be recorded as a timeout (my JMX consoles tell me no timeouts have occurred). So, I am left not understanding WHERE the failure is actually occurring. I am left with the idea that it is the driver that is having a problem, but I don't know how to debug it (and I would really like to). I have read several posts from folks that state that query'g for resultSets 10000 rows is probably not a good idea, and I am willing to accept this, but I would like to understand what is causing the exception and where the exception is happening. FWIW, I also tried bumping the timeout properties in the cassandra.yaml, but this made no difference whatsoever. I welcome any suggestions, anecdotes, insults, or monetary contributions for my registration in the house of moron-developers. Regards!!

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• How to produce precisely-timed tone and silence in C#

  - by Bob Denny

  I have a C# project that plays Morse code for RSS feeds. I write it using Managed DirectX, only to discover that Managed DirectX is old and deprecated. The task I have is to play pure sine wave bursts interspersed with silence periods (the code) which are precisely timed as to their duration. I need to be able to call a function which plays a pure tone for so many milliseconds, then Thread.Sleep() then play another, etc. At its fastest, the tones and spaces can be as short as 40ms. It's working quite well in Managed DirectX. To get the precisely timed tone I create 1 sec. of sine wave into a secondary buffer, then to play a tone of a certain duration I seek forward to within x milliseconds of the end of the buffer then play. I've tried System.Media.SoundPlayer. It's a loser because you have to Play(), Sleep(), then Stop() for arbitrary tone lengths. The result is a tone that is too long, variable by CPU load. It takes an indeterminate amount of time to actually stop the tone. I then embarked on a lengthy attempt to use NAudio 1.3. I ended up with a memory resident stream providing the tone data, and again seeking forward leaving the desired length of tone remaining in the stream, then playing. This worked OK on the DirectSoundOut class for a while (see below) but the WaveOut class quickly dies with an internal assert saying that buffers are still on the queue despite PlayerStopped = true. This is odd since I play to the end then put a wait of the same duration between the end of the tone and the start of the next. You'd think that 80ms after starting Play of a 40 ms tone that it wouldn't have buffers on the queue. DirectSoundOut works well for a while, but its problem is that for every tone burst Play() it spins off a separate thread. Eventually (5 min or so) it just stops working. You can see thread after thread after thread exiting in the Output window while running the project in VS2008 IDE. I don't create new objects during playing, I just Seek() the tone stream then call Play() over and over, so I don't think it's a problem with orphaned buffers/whatever piling up till it's choked. I'm out of patience on this one, so I'm asking in the hopes that someone here has faced a similar requirement and can steer me in a direction with a likely solution. Thanks in advance...

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• List all possible combinations of k integers between 1...n (n choose k)

  - by Asaf R

  Hi, Out of no particular reason I decided to look for an algorithm that produces all possible choices of k integers between 1...n, where the order amongst the k integer doesn't matter (the n choose k thingy). From the exact same reason, which is no reason at all, I also implemented it in C#. My question is: Do you see any mistake in my algorithm or code? And, more importantly, can you suggest a better algorithm? Please pay more attention to the algorithm than the code itself. It's not the prettiest code I've ever written, although do tell if you see an error. EDIT: Alogirthm explained - We hold k indices. This creates k nested for loops, where loop i's index is indices[i]. It simulates k for loops where indices[i+1] belongs to a loop nested within the loop of indices[i]. indices[i] runs from indices[i - 1] + 1 to n - k + i + 1. CODE: public class AllPossibleCombination { int n, k; int[] indices; List<int[]> combinations = null; public AllPossibleCombination(int n_, int k_) { if (n_ <= 0) { throw new ArgumentException("n_ must be in N+"); } if (k_ <= 0) { throw new ArgumentException("k_ must be in N+"); } if (k_ > n_) { throw new ArgumentException("k_ can be at most n_"); } n = n_; k = k_; indices = new int[k]; indices[0] = 1; } /// <summary> /// Returns all possible k combination of 0..n-1 /// </summary> /// <returns></returns> public List<int[]> GetCombinations() { if (combinations == null) { combinations = new List<int[]>(); Iterate(0); } return combinations; } private void Iterate(int ii) { // // Initialize // if (ii > 0) { indices[ii] = indices[ii - 1] + 1; } for (; indices[ii] <= (n - k + ii + 1); indices[ii]++) { if (ii < k - 1) { Iterate(ii + 1); } else { int[] combination = new int[k]; indices.CopyTo(combination, 0); combinations.Add(combination); } } } } I apologize for the long question, it might be fit for a blog post, but I do want the community's opinion here. Thanks, Asaf

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• Custom NSView in NSMenuItem not receiving mouse events

  - by Dennis

  I have an NSMenu popping out of an NSStatusItem using popUpStatusItemMenu. These NSMenuItems show a bunch of different links, and each one is connected with setAction: to the openLink: method of a target. This arrangement has been working fine for a long time. The user chooses a link from the menu and the openLink: method then deals with it. Unfortunately, I recently decided to experiment with using NSMenuItem's setView: method to provide a nicer/slicker interface. Basically, I just stopped setting the title, created the NSMenuItem, and then used setView: to display a custom view. This works perfectly, the menu items look great and my custom view is displayed. However, when the user chooses a menu item and releases the mouse, the action no longer works (i.e., openLink: isn't called). If I just simply comment out the setView: call, then the actions work again (of course, the menu items are blank, but the action is executed properly). My first question, then, is why setting a view breaks the NSMenuItem's action. No problem, I thought, I'll fix it by detecting the mouseUp event in my custom view and calling my action method from there. I added this method to my custom view: - (void)mouseUp:(NSEvent *)theEvent { NSLog(@"in mouseUp"); } No dice! This method is never called. I can set tracking rects and receive mouseEntered: events, though. I put a few tests in my mouseEntered routine, as follows: if ([[self window] ignoresMouseEvents]) { NSLog(@"ignoring mouse events"); } else { NSLog(@"not ignoring mouse events"); } if ([[self window] canBecomeKeyWindow]) { dNSLog((@"canBecomeKeyWindow")); } else { NSLog(@"not canBecomeKeyWindow"); } if ([[self window] isKeyWindow]) { dNSLog((@"isKeyWindow")); } else { NSLog(@"not isKeyWindow"); } And got the following responses: not ignoring mouse events canBecomeKeyWindow not isKeyWindow Is this the problem? "not isKeyWindow"? Presumably this isn't good because Apple's docs say "If the user clicks a view that isn’t in the key window, by default the window is brought forward and made key, but the mouse event is not dispatched." But there must be a way do detect these events. HOW? Adding: [[self window] makeKeyWindow]; has no effect, despite the fact that canBecomeKeyWindow is YES.

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