queueuserworkitem - Page 3

Is the below thread pool implementation correct(C#3.0)

- by Newbie

Hi Experts, For the first time ever I have implemented thread pooling and I found it to be working. But I am not very sure about the way I have done is the appropriate way it is supposed to be. Would you people mind in spending some valuable time to check and let me know if my approach is correct or not? If you people find that the approach is incorrect , could you please help me out in writing the correct version. I have basicaly read How to use thread pool and based on what ever I have understood I have developed the below program as per my need public class Calculation { #region Private variable declaration ManualResetEvent[] factorManualResetEvent = null; #endregion public void Compute() { factorManualResetEvent = new ManualResetEvent[2]; for (int i = 0; i < 2; i++){ factorManualResetEvent[i] = new ManualResetEvent(false); ThreadPool.QueueUserWorkItem(ThreadPoolCallback, i);} //Wait for all the threads to complete WaitHandle.WaitAll(factorManualResetEvent); //Proceed with the next task(s) NEXT_TASK_TO_BE_EXECUTED(); } #region Private Methods // Wrapper method for use with thread pool. public void ThreadPoolCallback(Object threadContext) { int threadIndex = (int)threadContext; Method1(); Method2(); factorManualResetEvent[threadIndex].Set(); } private void Method1 () { //Code of method 1} private void Method2 () { //Code of method 2 } #endregion }

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Problem in thread pool implementation(C#3.0)

- by Newbie

Hi Experts, I have done the below thread pool program but the problem is that the WaitCallBackMethod(here ThreadPoolCallback) is getting called 2 times(which ideally should be called 1ce). what is the misktake I am making? public class Calculation { #region Private variable declaration ManualResetEvent[] factorManualResetEvent = null; #endregion public void Compute() { factorManualResetEvent = new ManualResetEvent[2]; for (int i = 0; i < 2; i++){ factorManualResetEvent[i] = new ManualResetEvent(false); ThreadPool.QueueUserWorkItem(ThreadPoolCallback, i);} //Wait for all the threads to complete WaitHandle.WaitAll(factorManualResetEvent); //Proceed with the next task(s) NEXT_TASK_TO_BE_EXECUTED(); } #region Private Methods // Wrapper method for use with thread pool. public void ThreadPoolCallback(Object threadContext) { int threadIndex = (int)threadContext; Method1(); Method2(); factorManualResetEvent[threadIndex].Set(); } private void Method1 () { //Code of method 1} private void Method2 () { //Code of method 2 } #endregion } I am using C#3.0 Thanks

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.NET 4: “Slim”-style performance boost!

- by Vitus

RTM version of .NET 4 and Visual Studio 2010 is available, and now we can do some test with it. Parallel Extensions is one of the most valuable part of .NET 4.0. It’s a set of good tools for easily consuming multicore hardware power. And it also contains some “upgraded” sync primitives – Slim-version. For example, it include updated variant of widely known ManualResetEvent. For people, who don’t know about it: you can sync concurrency execution of some pieces of code with this sync primitive. Instance of ManualResetEvent can be in 2 states: signaled and non-signaled. Transition between it possible by Set() and Reset() methods call. Some shortly explanation: Thread 1 Thread 2 Time mre.Reset(); mre.WaitOne(); //code execution 0 //wating //code execution 1 //wating //code execution 2 //wating //code execution 3 //wating mre.Set(); 4 //code execution //… 5 Upgraded version of this primitive is ManualResetEventSlim. The idea in decreasing performance cost in case, when only 1 thread use it. Main concept in the “hybrid sync schema”, which can be done as following: internal sealed class SimpleHybridLock : IDisposable { private Int32 m_waiters = 0; private AutoResetEvent m_waiterLock = new AutoResetEvent(false); public void Enter() { if (Interlocked.Increment(ref m_waiters) == 1) return; m_waiterLock.WaitOne(); } public void Leave() { if (Interlocked.Decrement(ref m_waiters) == 0) return; m_waiterLock.Set(); } public void Dispose() { m_waiterLock.Dispose(); } } It’s a sample from Jeffry Richter’s book “CLR via C#”, 3rd edition. Primitive SimpleHybridLock have two public methods: Enter() and Leave(). You can put your concurrency-critical code between calls of these methods, and it would executed in only one thread at the moment. Code is really simple: first thread, called Enter(), increase counter. Second thread also increase counter, and suspend while m_waiterLock is not signaled. So, if we don’t have concurrent access to our lock, “heavy” methods WaitOne() and Set() will not called. It’s can give some performance bonus. ManualResetEvent use the similar idea. Of course, it have more “smart” technics inside, like a checking of recursive calls, and so on. I want to know a real difference between classic ManualResetEvent realization, and new –Slim. I wrote a simple “benchmark”: class Program { static void Main(string[] args) { ManualResetEventSlim mres = new ManualResetEventSlim(false); ManualResetEventSlim mres2 = new ManualResetEventSlim(false); ManualResetEvent mre = new ManualResetEvent(false); long total = 0; int COUNT = 50; for (int i = 0; i < COUNT; i++) { mres2.Reset(); Stopwatch sw = Stopwatch.StartNew(); ThreadPool.QueueUserWorkItem((obj) => { //Method(mres, true); Method2(mre, true); mres2.Set(); }); //Method(mres, false); Method2(mre, false); mres2.Wait(); sw.Stop(); Console.WriteLine("Pass {0}: {1} ms", i, sw.ElapsedMilliseconds); total += sw.ElapsedMilliseconds; } Console.WriteLine(); Console.WriteLine("==============================="); Console.WriteLine("Done in average=" + total / (double)COUNT); Console.ReadLine(); } private static void Method(ManualResetEventSlim mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } } private static void Method2(ManualResetEvent mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } } } I use 2 concurrent thread (the main thread and one from thread pool) for setting and resetting ManualResetEvents, and try to run test COUNT times, and calculate average execution time. Here is the results (I get it on my dual core notebook with T7250 CPU and Windows 7 x64): ManualResetEvent ManualResetEventSlim Difference is obvious and serious – in 10 times! So, I think preferable way is using ManualResetEventSlim, because not always on calling Set() and Reset() will be called “heavy” methods for working with Windows kernel-mode objects. It’s a small and nice improvement! ;)

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.NET 1.0 ThreadPool Question

- by dotnet-practitioner

I am trying to spawn a thread to take care of DoWork task that should take less than 3 seconds. Inside DoWork its taking 15 seconds. I want to abort DoWork and transfer the control back to main thread. I have copied the code as follows and its not working. Instead of aborting DoWork, it still finishes DoWork and then transfers the control back to main thread. What am I doing wrong? class Class1 { /// <summary> /// The main entry point for the application. /// </summary> /// private static System.Threading.ManualResetEvent[] resetEvents; [STAThread] static void Main(string[] args) { resetEvents = new ManualResetEvent[1]; int i = 0; resetEvents[i] = new ManualResetEvent(false); ThreadPool.QueueUserWorkItem(new WaitCallback(DoWork),(object)i); Thread.CurrentThread.Name = "main thread"; Console.WriteLine("[{0}] waiting in the main method", Thread.CurrentThread.Name); DateTime start = DateTime.Now; DateTime end ; TimeSpan span = DateTime.Now.Subtract(start); //abort dowork method if it takes more than 3 seconds //and transfer control to the main thread. do { if (span.Seconds < 3) WaitHandle.WaitAll(resetEvents); else resetEvents[0].Set(); end = DateTime.Now; span = end.Subtract(start); }while (span.Seconds < 2); Console.WriteLine(span.Seconds); Console.WriteLine("[{0}] all done in the main method",Thread.CurrentThread.Name); Console.ReadLine(); } static void DoWork(object o) { int index = (int)o; Thread.CurrentThread.Name = "do work thread"; //simulate heavy duty work. Thread.Sleep(15000); //work is done.. resetEvents[index].Set(); Console.WriteLine("[{0}] do work finished",Thread.CurrentThread.Name); } }

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Trying to run multiple HTTP requests in parallel, but being limited by Windows (registry)

- by Nailuj

I'm developing an application (winforms C# .NET 4.0) where I access a lookup functionality from a 3rd party through a simple HTTP request. I call an url with a parameter, and in return I get a small string with the result of the lookup. Simple enough. The challenge is however, that I have to do lots of these lookups (a couple of thousands), and I would like to limit the time needed. Therefore I would like to run requests in parallel (say 10-20). I use a ThreadPool to do this, and the short version of my code looks like this: public void startAsyncLookup(Action<LookupResult> returnLookupResult) { this.returnLookupResult = returnLookupResult; foreach (string number in numbersToLookup) { ThreadPool.QueueUserWorkItem(lookupNumber, number); } } public void lookupNumber(Object threadContext) { string numberToLookup = (string)threadContext; string url = @"http://some.url.com/?number=" + numberToLookup; WebClient webClient = new WebClient(); Stream responseData = webClient.OpenRead(url); LookupResult lookupResult = parseLookupResult(responseData); returnLookupResult(lookupResult); } I fill up numbersToLookup (a List<String>) from another place, call startAsyncLookup and provide it with a call-back function returnLookupResult to return each result. This works, but I found that I'm not getting the throughput I want. Initially I thought it might be the 3rd party having a poor system on their end, but I excluded this by trying to run the same code from two different machines at the same time. Each of the two took as long as one did alone, so I could rule out that one. A colleague then tipped me that this might be a limitation in Windows. I googled a bit, and found amongst others this post saying that by default Windows limits the number of simultaneous request to the same web server to 4 for HTTP 1.0 and to 2 for HTTP 1.1 (for HTTP 1.1 this is actually according to the specification (RFC2068)). The same post referred to above also provided a way to increase these limits. By adding two registry values to [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings] (MaxConnectionsPerServer and MaxConnectionsPer1_0Server), I could control this myself. So, I tried this (sat both to 20), restarted my computer, and tried to run my program again. Sadly though, it didn't seem to help any. I also kept an eye on the Resource Monitor (see screen shot) while running my batch lookup, and I noticed that my application (the one with the title blacked out) still only was using two TCP connections. So, the question is, why isn't this working? Is the post I linked to using the wrong registry values? Is this perhaps not possible to "hack" in Windows any longer (I'm on Windows 7)? Any ideas would be highly appreciated :) And just in case anyone should wonder, I have also tried with different settings for MaxThreads on ThreadPool (everyting from 10 to 100), and this didn't seem to affect my throughput at all, so the problem shouldn't be there either.

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Help with Silverlight Sockets and Message delivery

- by pixel3cs

There are 4 months since I stopped developing my Silverlight Multiplayer Chess game. The problem was a bug wich I couldn't reproduce. Sice I got some free time this week I managed to discover the problem and I am now able to reproduce the bug. It seems that if I send 10 messages from client, one after another, with no delay between them, just like in the below example // when I press Enter, the client will 10 messages with no delay between them private void textBox_KeyDown(object sender, KeyEventArgs e) { if (e.Key == Key.Enter && textBox.Text.Length > 0) { for (int i = 0; i < 10; i++) { MessageBuilder mb = new MessageBuilder(); mb.Writer.Write((byte)GameCommands.NewChatMessageInTable); mb.Writer.Write(string.Format("{0}{2}: {1}", ClientVars.PlayerNickname, textBox.Text, i)); SendChatMessageEvent(mb.GetMessage()); //System.Threading.Thread.Sleep(100); } textBox.Text = string.Empty; } } // the method used by client to send a message to server public void SendData(Message message) { if (socket.Connected) { SocketAsyncEventArgs myMsg = new SocketAsyncEventArgs(); myMsg.RemoteEndPoint = socket.RemoteEndPoint; byte[] buffer = message.Buffer; myMsg.SetBuffer(buffer, 0, buffer.Length); socket.SendAsync(myMsg); } else { string err = "Server does not respond. You are disconnected."; socket.Close(); uiContext.Post(this.uiClient.ProcessOnErrorData, err); } } // the method used by server to receive data from client private void OnDataReceived(IAsyncResult async) { ClientSocketPacket client = async.AsyncState as ClientSocketPacket; int count = 0; try { if (client.Socket.Connected) count = client.Socket.EndReceive(async); // THE PROBLEM IS HERE // IF SERVER WAS RECEIVE ALL MESSAGES SEPARATELY, ONE BY ONE, THE COUNT // WAS ALWAYS 15, BUT BECAUSE THE SERVER RECEIVE 3 MESSAGES IN 1, THE COUNT // IS SOMETIME 45 } catch { HandleException(client); } client.MessageStream.Write(client.Buffer, 0, count); Message message; while (client.MessageStream.Read(out message)) { message.Tag = client; ThreadPool.QueueUserWorkItem(new WaitCallback(this.processingThreadEvent.ServerGotData), message); totalReceivedBytes += message.Buffer.Length; } try { if (client.Socket.Connected) client.Socket.BeginReceive(client.Buffer, 0, client.Buffer.Length, 0, new AsyncCallback(OnDataReceived), client); } catch { HandleException(client); } } there are sent only 3 big messages, and every big message contain 3 or 4 small messages. This is not the behavior I want. If I put a 100 milliseconds delay between message delivery, everything is work fine, but in a real world scenario users can send messages to server even at 1 millisecond between them. Are there any settings to be done in order to make the client send only one message at a time, or Even if I receive 3 messages in 1, are they full messages all the time (I dont't want to receive 2.5 messages in one big message) ? because if they are, I can read them and treat this new situation

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Typesafe fire-and-forget asynchronous delegate invocation in C#

- by LBushkin

I recently found myself needing a typesafe "fire-and-forget" mechanism for running code asynchronously. Ideally, what I would want to do is something like: var myAction = (Action)(() => Console.WriteLine("yada yada")); myAction.FireAndForget(); // async invocation Unfortunately, the obvious choice of calling BeginInvoke() without a corresponding EndInvoke() does not work - it results in a slow resource leak (since the asyn state is held by the runtime and never released ... it's expecting an eventual call to EndInvoke(). I also can't run the code on the .NET thread pool because it may take a very long time to complete (it's advised to only run relatively short-lived code on the thread pool) - this makes it impossible to use the ThreadPool.QueueUserWorkItem(). Initially, I only needed this behavior for methods whose signature matches Action, Action<...>, or Func<...>. So I put together a set of extension methods (see listing below) that let me do this without running into the resource leak. There are overloads for each version of Action/Func. Unfortunately, I now want to port this code to .NET 4 where the number of generic parameters on Action and Func have been increased substantially. Before I write a T4 script to generate these, I was also hoping to find a simpler more elegant way to do this. Any ideas are welcome. public static class AsyncExt { public static void FireAndForget( this Action action ) { action.BeginInvoke(OnActionCompleted, action); } public static void FireAndForget<T1>( this Action<T1> action, T1 arg1 ) { action.BeginInvoke(arg1, OnActionCompleted<T1>, action); } public static void FireAndForget<T1,T2>( this Action<T1,T2> action, T1 arg1, T2 arg2 ) { action.BeginInvoke(arg1, arg2, OnActionCompleted<T1, T2>, action); } public static void FireAndForget<TResult>(this Func<TResult> func, TResult arg1) { func.BeginInvoke(OnFuncCompleted<TResult>, func); } public static void FireAndForget<T1,TResult>(this Func<T1, TResult> action, T1 arg1) { action.BeginInvoke(arg1, OnFuncCompleted<T1,TResult>, action); } // more overloads of FireAndForget<..>() for Action<..> and Func<..> private static void OnActionCompleted( IAsyncResult result ) { var action = (Action)result.AsyncState; action.EndInvoke(result); } private static void OnActionCompleted<T1>( IAsyncResult result ) { var action = (Action<T1>)result.AsyncState; action.EndInvoke( result ); } private static void OnActionCompleted<T1,T2>(IAsyncResult result) { var action = (Action<T1,T2>)result.AsyncState; action.EndInvoke(result); } private static void OnFuncCompleted<TResult>( IAsyncResult result ) { var func = (Func<TResult>)result.AsyncState; func.EndInvoke( result ); } private static void OnFuncCompleted<T1,TResult>(IAsyncResult result) { var func = (Func<T1, TResult>)result.AsyncState; func.EndInvoke(result); } // more overloads of OnActionCompleted<> and OnFuncCompleted<> }

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Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host

- by xnoor

i have an update server that sends client updates through TCP port 12000, the sending of a single file is successful only the first time, but after that i get an error message on the server "Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host", if i restart the update service on the server, it works again only one, i have normal multithreaded windows service SERVER CODE namespace WSTSAU { public partial class ApplicationUpdater : ServiceBase { private Logger logger = LogManager.GetCurrentClassLogger(); private int _listeningPort; private int _ApplicationReceivingPort; private string _setupFilename; private string _startupPath; public ApplicationUpdater() { InitializeComponent(); } protected override void OnStart(string[] args) { init(); logger.Info("after init"); Thread ListnerThread = new Thread(new ThreadStart(StartListener)); ListnerThread.IsBackground = true; ListnerThread.Start(); logger.Info("after thread start"); } private void init() { _listeningPort = Convert.ToInt16(ConfigurationSettings.AppSettings["ListeningPort"]); _setupFilename = ConfigurationSettings.AppSettings["SetupFilename"]; _startupPath = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase).Substring(6); } private void StartListener() { try { logger.Info("Listening Started"); ThreadPool.SetMinThreads(50, 50); TcpListener listener = new TcpListener(_listeningPort); listener.Start(); while (true) { TcpClient c = listener.AcceptTcpClient(); ThreadPool.QueueUserWorkItem(ProcessReceivedMessage, c); } } catch (Exception ex) { logger.Error(ex.Message); } } void ProcessReceivedMessage(object c) { try { TcpClient tcpClient = c as TcpClient; NetworkStream Networkstream = tcpClient.GetStream(); byte[] _data = new byte[1024]; int _bytesRead = 0; _bytesRead = Networkstream.Read(_data, 0, _data.Length); MessageContainer messageContainer = new MessageContainer(); messageContainer = SerializationManager.XmlFormatterByteArrayToObject(_data, messageContainer) as MessageContainer; switch (messageContainer.messageType) { case MessageType.ApplicationUpdateMessage: ApplicationUpdateMessage appUpdateMessage = new ApplicationUpdateMessage(); appUpdateMessage = SerializationManager.XmlFormatterByteArrayToObject(messageContainer.messageContnet, appUpdateMessage) as ApplicationUpdateMessage; Func<ApplicationUpdateMessage, bool> HandleUpdateRequestMethod = HandleUpdateRequest; IAsyncResult cookie = HandleUpdateRequestMethod.BeginInvoke(appUpdateMessage, null, null); bool WorkerThread = HandleUpdateRequestMethod.EndInvoke(cookie); break; } } catch (Exception ex) { logger.Error(ex.Message); } } private bool HandleUpdateRequest(ApplicationUpdateMessage appUpdateMessage) { try { TcpClient tcpClient = new TcpClient(); NetworkStream networkStream; FileStream fileStream = null; tcpClient.Connect(appUpdateMessage.receiverIpAddress, appUpdateMessage.receiverPortNumber); networkStream = tcpClient.GetStream(); fileStream = new FileStream(_startupPath + "\\" + _setupFilename, FileMode.Open, FileAccess.Read); FileInfo fi = new FileInfo(_startupPath + "\\" + _setupFilename); BinaryReader binFile = new BinaryReader(fileStream); FileUpdateMessage fileUpdateMessage = new FileUpdateMessage(); fileUpdateMessage.fileName = fi.Name; fileUpdateMessage.fileSize = fi.Length; MessageContainer messageContainer = new MessageContainer(); messageContainer.messageType = MessageType.FileProperties; messageContainer.messageContnet = SerializationManager.XmlFormatterObjectToByteArray(fileUpdateMessage); byte[] messageByte = SerializationManager.XmlFormatterObjectToByteArray(messageContainer); networkStream.Write(messageByte, 0, messageByte.Length); int bytesSize = 0; byte[] downBuffer = new byte[2048]; while ((bytesSize = fileStream.Read(downBuffer, 0, downBuffer.Length)) > 0) { networkStream.Write(downBuffer, 0, bytesSize); } fileStream.Close(); tcpClient.Close(); networkStream.Close(); return true; } catch (Exception ex) { logger.Info(ex.Message); return false; } finally { } } protected override void OnStop() { } } i have to note something that my windows service (server) is multithreaded.. i hope anyone can help with this

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First toe in the water with Object Databases : DB4O

- by REA_ANDREW

I have been wanting to have a play with Object Databases for a while now, and today I have done just that. One of the obvious choices I had to make was which one to use. My criteria for choosing one today was simple, I wanted one which I could literally wack in and start using, which means I wanted one which either had a .NET API or was designed/ported to .NET. My decision was between two being: db4o MongoDb I went for db4o for the single reason that it looked like I could get it running and integrated the quickest. I am making a Blogging application and front end as a project with which I can test and learn with these object databases. Another requirement which I thought I would mention is that I also want to be able to use the said database in a shared hosting environment where I cannot install, run and maintain a server instance of said object database. I can do exactly this with db4o. I have not tried to do this with MongoDb at time of writing. There are quite a few in the industry now and you read an interesting post about different ones and how they are used with some of the heavy weights in the industry here : http://blog.marcua.net/post/442594842/notes-from-nosql-live-boston-2010 In the example which I am building I am using StructureMap as my IOC. To inject the object for db4o I went with a Singleton instance scope as I am using a single file and I need this to be available to any thread on in the process as opposed to using the server implementation where I could open and close client connections with the server handling each one respectively. Again I want to point out that I have chosen to stick with the non server implementation of db4o as I wanted to use this in a shared hosting environment where I cannot have such servers installed and run. public static class Bootstrapper { public static void ConfigureStructureMap() { ObjectFactory.Initialize(x => x.AddRegistry(new MyApplicationRegistry())); } } public class MyApplicationRegistry : Registry { public const string DB4O_FILENAME = "blog123"; public string DbPath { get { return Path.Combine(Path.GetDirectoryName(Assembly.GetAssembly(typeof(IBlogRepository)).Location), DB4O_FILENAME); } } public MyApplicationRegistry() { For<IObjectContainer>().Singleton().Use( () => Db4oEmbedded.OpenFile(Db4oEmbedded.NewConfiguration(), DbPath)); Scan(assemblyScanner => { assemblyScanner.TheCallingAssembly(); assemblyScanner.WithDefaultConventions(); }); } } So my code above is the structure map plumbing which I use for the application. I am doing this simply as a quick scratch pad to play around with different things so I am simply segregating logical layers with folder structure as opposed to different assemblies. It will be easy if I want to do this with any segment but for the purposes of example I have literally just wacked everything in the one assembly. You can see an example file structure I have on the right. I am planning on testing out a few implementations of the object databases out there so I can program to an interface of IBlogRepository One of the things which I was unsure about was how it performed under a multi threaded environment which it will undoubtedly be used 9 times out of 10, and for the reason that I am using the db context as a singleton, I assumed that the library was of course thread safe but I did not know as I have not read any where in the documentation, again this is probably me not reading things correctly. In short though I threw together a simple test where I simply iterate to a limit each time kicking a common task off with a thread from a thread pool. This task simply created and added an random Post and added it to the storage. The execution of the threads I put inside the Setup of the Test and then simply ensure the number of posts committed to the database is equal to the number of iterations I made; here is the code I used to do the multi thread jobs: [TestInitialize] public void Setup() { var sw = new System.Diagnostics.Stopwatch(); sw.Start(); var resetEvent = new ManualResetEvent(false); ThreadPool.SetMaxThreads(20, 20); for (var i = 0; i < MAX_ITERATIONS; i++) { ThreadPool.QueueUserWorkItem(delegate(object state) { var eventToReset = (ManualResetEvent)state; var post = new Post { Author = MockUser, Content = "Mock Content", Title = "Title" }; Repository.Put(post); var counter = Interlocked.Decrement(ref _threadCounter); if (counter == 0) eventToReset.Set(); }, resetEvent); } WaitHandle.WaitAll(new[] { resetEvent }); sw.Stop(); Console.WriteLine("{0:00}.{1:00} seconds", sw.Elapsed.Seconds, sw.Elapsed.Milliseconds); } I was not doing this to test out the speed performance of db4o but while I was doing this I could not help but put in a StopWatch and see out of sheer interest how fast it would take to insert a number of Posts. I tested it out in this case with 10000 inserts of a small, simple POCO and it resulted in an average of: 899.36 object inserts / second. Again this is just simple crude test which came out of my curiosity at how it performed under many threads when using the non server implementation of db4o. The spec summary of the computer I used is as follows: With regards to the actual Repository implementation itself, it really is quite straight forward and I have to say I am very surprised at how easy it was to integrate and get up and running. One thing I have noticed in the exposure I have had so far is that the Query returns IList<T> as opposed to IQueryable<T> but again I have not looked into this in depth and this could be there already and if not they have provided everything one needs to make there own repository. An example of a couple of methods from by db4o implementation of the BlogRepository is below: public class BlogRepository : IBlogRepository { private readonly IObjectContainer _db; public BlogRepository(IObjectContainer db) { _db = db; } public void Put(DomainObject obj) { _db.Store(obj); } public void Delete(DomainObject obj) { _db.Delete(obj); } public Post GetByKey(object key) { return _db.Query<Post>(post => post.Key == key).FirstOrDefault(); } … Anyways I hope to get a few more implementations going of the object databases and literally just get familiarized with them and the concept of no sql databases. Cheers for now, Andrew

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C# XP Sound QuickFix

- by ikurtz

I have this: ThreadPool.QueueUserWorkItem(new WaitCallback(FireAttackProc), fireResult); and FireAttackProc: private void FireAttackProc(Object stateInfo) { // Process Attack/Fire (local) lock (_procLock) { // build status message String status = "(Away vs. Home)"; // get Fire Result state info FireResult fireResult = (FireResult)stateInfo; // update home grid with attack information GameModel.HomeCellStatusSet(fireResult.FireGridLocation, Cell.cellState.Lock); this.Invoke(new Action(delegate() { RefreshHomeGrid(); })); status = status + "(Attack Coordinate: (" + GameModel.alphaCoords(fireResult.FireGridLocation.Column) + "," + fireResult.FireGridLocation.Row + "))(Result: "; // play audio data if true if (audio) { String Letters; Stream stream; SoundPlayer player; Letters = GameModel.alphaCoords(fireResult.FireGridLocation.Column); stream = Properties.Resources.ResourceManager.GetStream("_" + Letters); player = new System.Media.SoundPlayer(stream); player.PlaySync(); Letters = fireResult.FireGridLocation.Row.ToString(); stream = Properties.Resources.ResourceManager.GetStream("__" + Letters); player = new System.Media.SoundPlayer(stream); player.PlaySync(); stream.Dispose(); player.Dispose(); } if (audio) { SoundPlayer fire = new SoundPlayer(Properties.Resources.fire); fire.PlaySync(); fire.Dispose(); } // deal with hit/miss switch (fireResult.Hit) { case true: this.Invoke(new Action(delegate() { GameModel.HomeCellStatusSet(fireResult.FireGridLocation, Cell.cellState.Hit); status = status + "(Hit)"; })); if (audio) { SoundPlayer hit = new SoundPlayer(Properties.Resources.firehit); hit.PlaySync(); hit.Dispose(); } break; case false: this.Invoke(new Action(delegate() { GameModel.HomeCellStatusSet(fireResult.FireGridLocation, Cell.cellState.Miss); status = status + "(Miss)"; })); GameModel.PlayerNextTurn = NietzscheBattleshipsGameModel.GamePlayers.Home; if (audio) { SoundPlayer miss = new SoundPlayer(Properties.Resources.firemiss); miss.PlaySync(); miss.Dispose(); } break; } // refresh home grid with updated data this.Invoke(new Action(delegate() { RefreshHomeGrid(); })); GameToolStripStatusLabel.Text = status + ")"; // deal with ship destroyed if (fireResult.ShipDestroyed) { status = status + "(Destroyed: " + GameModel.getShipDescription(fireResult.DestroyedShipType) + ")"; if (audio) { Stream stream; SoundPlayer player; stream = Properties.Resources.ResourceManager.GetStream("_home"); player = new System.Media.SoundPlayer(stream); player.PlaySync(); player.Dispose(); stream.Dispose(); string ShipID = fireResult.DestroyedShipType.ToString(); stream = Properties.Resources.ResourceManager.GetStream("_" + ShipID); player = new System.Media.SoundPlayer(stream); player.PlaySync(); player.Dispose(); stream.Dispose(); stream = Properties.Resources.ResourceManager.GetStream("_destroyed"); player = new System.Media.SoundPlayer(stream); player.PlaySync(); player.Dispose(); stream.Dispose(); } } // deal with win condition if (fireResult.Win) { if (audio) { Stream stream; SoundPlayer player; stream = Properties.Resources.ResourceManager.GetStream("_home"); player = new System.Media.SoundPlayer(stream); player.PlaySync(); player.Dispose(); stream = Properties.Resources.ResourceManager.GetStream("_loses"); player = new System.Media.SoundPlayer(stream); player.PlaySync(); player.Dispose(); } GameModel.gameContracts = new GameContracts(); } // update status message if (fireResult.Hit) { if (!fireResult.Win) { status = status + "(Turn: Away)"; LockGUIControls(); } } // deal with turn logic if (GameModel.PlayerNextTurn == NietzscheBattleshipsGameModel.GamePlayers.Home) { this.Invoke(new Action(delegate() { if (!fireResult.Win) { status = status + "(Turn: Home)"; AwayTableLayoutPanel.Enabled = true; } })); } // deal with win condition if (fireResult.Win) { this.Invoke(new Action(delegate() { status = status + "(Game: Home Loses)"; CancelToolStripMenuItem.Enabled = false; NewToolStripMenuItem.Enabled = true; LockGUIControls(); })); } // display completed status message GameToolStripStatusLabel.Text = status + ")"; } } The issue is this: Under Vista/win7 the sound clips in the FireAttackProc plays. But under XP the logic contained within FireAttackProc gets executed but none of the sound clips play. Is there a quick solution to this so the sound will play under XP? I ask for a quick solution because i am happy being able to execute fully in Vista/Win7 but would be great if there was a quick solution so it would be XP compitable also. Thank you.

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