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• Why isn't my algorithm for find the biggest and smallest inputs working?

  - by Matt Ellen

  I have started a new job, and with it comes a new language: Ironpython. Thankfully a good language :D Before starting I got to grips with Python on the whole, but that was only a week's worth of learning. Now I'm writing actual code. I've been charged with writing an algorithm that finds the best input parameter to collect data with. The basic algorithm is (as I've been instructed): Set the input parameter to a good guess Start collecting data When data is available stop collecting find the highest point If the point before this (i.e. for the previous parameter value) was higher and the point before that was lower then we've found the max otherwise the input parameter is increased by the initial guess. goto 2 If the max is found then the min needs to be found. To do this the algorithm carries on increasing the input, but by 1/10 of the max, until the current point is greater than the previous point and the point before that is also greater. Once the min is found then the algorithm stops. Currently I have a simplified data generator outputting the sin of the input, so that I know that the min value should be PI and the max value should be PI/2 The main Python code looks like this (don't worry, this is just for my edification, I don't write real code like this): import sys sys.path.append(r"F:\Programming Source\C#\PythonHelp\PythonHelp\bin\Debug") import clr clr.AddReferenceToFile("PythonHelpClasses.dll") import PythonHelpClasses from PHCStruct import Helper from System import Math helper = Helper() def run(): b = PythonHelpClasses.Executor() a = PythonHelpClasses.HasAnEvent() b.Input = 0.0 helper.__init__() def AnEventHandler(e): b.Stop() h = helper h.lastLastVal, h.lastVal, h.currentVal = h.lastVal, h.currentVal, e.Number if h.lastLastVal < h.lastVal and h.currentVal < h.lastVal and h.NotPast90: h.NotPast90 = False h.bestInput = h.lastInput inputInc = 0.0 if h.NotPast90: inputInc = Math.PI/10.0 else: inputInc = h.bestInput/10.0 if h.lastLastVal > h.lastVal and h.currentVal > h.lastVal and h.NotPast180: h.NotPast180 = False if h.NotPast180: h.lastInput, b.Input = b.Input, b.Input + inputInc b.Start(a) else: print "Best input:", h.bestInput print "Last input:", h.lastInput b.Stop() a.AnEvent += AnEventHandler b.Start(a) PHCStruct.py: class Helper(): def __init__(self): self.currentVal = 0 self.lastVal = 0 self.lastLastVal = 0 self.NotPast90 = True self.NotPast180 = True self.bestInput = 0 self.lastInput = 0 PythonHelpClasses has two small classes I wrote in C# before I realised how to do it in Ironpython. Executor runs a delegate asynchronously while it's running member is true. The important code: public void Start(HasAnEvent hae) { running = true; RunDelegate r = new RunDelegate(hae.UpdateNumber); AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar = r.BeginInvoke(Input, ac, null); } public void Stop() { running = false; } public void UpdateDone(IAsyncResult ar) { RunDelegate r = (RunDelegate)((AsyncResult)ar).AsyncDelegate; r.EndInvoke(ar); if (running) { AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar2 = r.BeginInvoke(Input, ac, null); } } HasAnEvent has a function that generates the sin of its input and fires an event with that result as its argument. i.e.: public void UpdateNumber(double val) { AnEventArgs e = new AnEventArgs(Math.Sin(val)); System.Threading.Thread.Sleep(1000); if (null != AnEvent) { AnEvent(e); } } The sleep is in there just to slow things down a bit. The problem I am getting is that the algorithm is not coming up with the best input being PI/2 and the final input being PI, but I can't see why. Also the best and final inputs are different each time I run the programme. Can anyone see why? Also when the algorithm terminates the best and final inputs are printed to the screen multiple times, not just once. Can someone explain why?

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• How to log out from the Facebook in windows phone 7 using facebook api?

  - by Vijay

  I am trying to add Facebook into my application. I have try with a sample. public class FacebookLoginPageViewModel { private static WebBrowser _webBrowser; private Page _page; private const string ExtendedPermissions = "user_about_me,read_stream,publish_stream,user_birthday,offline_access,email"; private readonly FacebookClient _fb = new FacebookClient(); private const string AppId = "1XXX58XXXXXXXX9"; Uri url; public FacebookLoginPageViewModel(Panel container, Page page) { _page = page; _webBrowser = new WebBrowser(); var loginUrl = GetFacebookLoginUrl(AppId, ExtendedPermissions); url = loginUrl; container.Children.Add(_webBrowser); _webBrowser.Navigated += webBrowser_Navigated; _webBrowser.Navigate(loginUrl); } private Uri GetFacebookLoginUrl(string appId, string extendedPermissions) { var parameters = new Dictionary<string, object>(); parameters["client_id"] = appId; parameters["redirect_uri"] = "https://www.facebook.com/connect/login_success.html"; parameters["response_type"] = "token"; parameters["display"] = "touch"; // add the 'scope' only if we have extendedPermissions. if (!string.IsNullOrEmpty(extendedPermissions)) { // A comma-delimited list of permissions parameters["scope"] = extendedPermissions; } return _fb.GetLoginUrl(parameters); } void webBrowser_Navigated(object sender, System.Windows.Navigation.NavigationEventArgs e) { FacebookOAuthResult oauthResult; if (!_fb.TryParseOAuthCallbackUrl(e.Uri, out oauthResult)) { return; } if (oauthResult.IsSuccess) { var accessToken = oauthResult.AccessToken; LoginSucceded(accessToken); } else { // user cancelled MessageBox.Show(oauthResult.ErrorDescription); } } private void LoginSucceded(string accessToken) { var fb = new FacebookClient(accessToken); fb.GetCompleted += (o, e) => { if (e.Error != null) { Deployment.Current.Dispatcher.BeginInvoke(() => { MessageBox.Show(e.Error.Message); return; }); } var result = (IDictionary<string, object>)e.GetResultData(); var id = (string)result["id"]; var url = string.Format("/Views/FacebookInfoPage.xaml?access_token={0}&id={1}", accessToken, id); var rootFrame = (App.Current as App).RootFrame; Deployment.Current.Dispatcher.BeginInvoke(() => { rootFrame.Navigate(new Uri(url, UriKind.Relative)); }); }; fb.GetAsync("me?fields=id"); } This is working fine. But i want to Log out from the facebook when i click log out. How to achieve this? I have try with some examples. But it is not working for me. private void logout(object sender, RoutedEventArgs e) { webBrowser1.Navigated += new EventHandler<System.Windows.Navigation.NavigationEventArgs>(CheckForout); webBrowser1.Navigate(new Uri("http://m.facebook.com/logout.php?confirm=1")); webBrowser1.Visibility = Visibility.Visible; } private void CheckForout(object sender, System.Windows.Navigation.NavigationEventArgs e) { string fbLogoutDoc = webBrowser1.SaveToString(); Regex regex = new Regex ("\\<a href=\\\"/logout(.*)\\\".*data-sigil=\\\"logout\\\""); MatchCollection matches = regex.Matches(fbLogoutDoc); if (matches.Count > 0) { string finalLogout = string.Format("http://m.facebook.com/logout{0}", matches[0].Groups[1].ToString().Replace("amp;", "")); webBrowser1.Navigate(new Uri(finalLogout)); } } Please let me any idea to resolve this problem.

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• Windows Azure Service Bus Scatter-Gather Implementation

  - by Alan Smith

  One of the more challenging enterprise integration patterns that developers may wish to implement is the Scatter-Gather pattern. In this article I will show the basic implementation of a scatter-gather pattern using the topic-subscription model of the windows azure service bus. I’ll be using the implementation in demos, and also as a lab in my training courses, and the pattern will also be included in the next release of my free e-book the “Windows Azure Service Bus Developer Guide”. The Scatter-Gather pattern answers the following scenario. How do you maintain the overall message flow when a message needs to be sent to multiple recipients, each of which may send a reply? Use a Scatter-Gather that broadcasts a message to multiple recipients and re-aggregates the responses back into a single message. The Enterprise Integration Patterns website provides a description of the Scatter-Gather pattern here.   The scatter-gather pattern uses a composite of the publish-subscribe channel pattern and the aggregator pattern. The publish-subscribe channel is used to broadcast messages to a number of receivers, and the aggregator is used to gather the response messages and aggregate them together to form a single message. Scatter-Gather Scenario The scenario for this scatter-gather implementation is an application that allows users to answer questions in a poll based voting scenario. A poll manager application will be used to broadcast questions to users, the users will use a voting application that will receive and display the questions and send the votes back to the poll manager. The poll manager application will receive the users’ votes and aggregate them together to display the results. The scenario should be able to scale to support a large number of users.   Scatter-Gather Implementation The diagram below shows the overall architecture for the scatter-gather implementation.       Messaging Entities Looking at the scatter-gather pattern diagram it can be seen that the topic-subscription architecture is well suited for broadcasting a message to a number of subscribers. The poll manager application can send the question messages to a topic, and each voting application can receive the question message on its own subscription. The static limit of 2,000 subscriptions per topic in the current release means that 2,000 voting applications can receive question messages and take part in voting. The vote messages can then be sent to the poll manager application using a queue. The voting applications will send their vote messages to the queue, and the poll manager will receive and process the vote messages. The questions topic and answer queue are created using the Windows Azure Developer Portal. Each instance of the voting application will create its own subscription in the questions topic when it starts, allowing the question messages to be broadcast to all subscribing voting applications. Data Contracts Two simple data contracts will be used to serialize the questions and votes as brokered messages. The code for these is shown below.   [DataContract] public class Question {     [DataMember]     public string QuestionText { get; set; } }     To keep the implementation of the voting functionality simple and focus on the pattern implementation, the users can only vote yes or no to the questions.   [DataContract] public class Vote {     [DataMember]     public string QuestionText { get; set; }       [DataMember]     public bool IsYes { get; set; } }     Poll Manager Application The poll manager application has been implemented as a simple WPF application; the user interface is shown below. A question can be entered in the text box, and sent to the topic by clicking the Add button. The topic and subscriptions used for broadcasting the messages are shown in a TreeView control. The questions that have been broadcast and the resulting votes are shown in a ListView control. When the application is started any existing subscriptions are cleared form the topic, clients are then created for the questions topic and votes queue, along with background workers for receiving and processing the vote messages, and updating the display of subscriptions.   public MainWindow() {     InitializeComponent();       // Create a new results list and data bind it.     Results = new ObservableCollection<Result>();     lsvResults.ItemsSource = Results;       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Clear out any old subscriptions.     NamespaceManager = new NamespaceManager(serviceBusUri, credentials);     IEnumerable<SubscriptionDescription> subs =         NamespaceManager.GetSubscriptions(AccountDetails.ScatterGatherTopic);     foreach (SubscriptionDescription sub in subs)     {         NamespaceManager.DeleteSubscription(sub.TopicPath, sub.Name);     }       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Create the topic and queue clients.     ScatterGatherTopicClient =         factory.CreateTopicClient(AccountDetails.ScatterGatherTopic);     ScatterGatherQueueClient =         factory.CreateQueueClient(AccountDetails.ScatterGatherQueue);       // Start the background worker threads.     VotesBackgroundWorker = new BackgroundWorker();     VotesBackgroundWorker.DoWork += new DoWorkEventHandler(ReceiveMessages);     VotesBackgroundWorker.RunWorkerAsync();       SubscriptionsBackgroundWorker = new BackgroundWorker();     SubscriptionsBackgroundWorker.DoWork += new DoWorkEventHandler(UpdateSubscriptions);     SubscriptionsBackgroundWorker.RunWorkerAsync(); }     When the poll manager user nters a question in the text box and clicks the Add button a question message is created and sent to the topic. This message will be broadcast to all the subscribing voting applications. An instance of the Result class is also created to keep track of the votes cast, this is then added to an observable collection named Results, which is data-bound to the ListView control.   private void btnAddQuestion_Click(object sender, RoutedEventArgs e) {     // Create a new result for recording votes.     Result result = new Result()     {         Question = txtQuestion.Text     };     Results.Add(result);       // Send the question to the topic     Question question = new Question()     {         QuestionText = result.Question     };     BrokeredMessage msg = new BrokeredMessage(question);     ScatterGatherTopicClient.Send(msg);       txtQuestion.Text = ""; }     The Results class is implemented as follows.   public class Result : INotifyPropertyChanged {     public string Question { get; set; }       private int m_YesVotes;     private int m_NoVotes;       public event PropertyChangedEventHandler PropertyChanged;       public int YesVotes     {         get { return m_YesVotes; }         set         {             m_YesVotes = value;             NotifyPropertyChanged("YesVotes");         }     }       public int NoVotes     {         get { return m_NoVotes; }         set         {             m_NoVotes = value;             NotifyPropertyChanged("NoVotes");         }     }       private void NotifyPropertyChanged(string prop)     {         if(PropertyChanged != null)         {             PropertyChanged(this, new PropertyChangedEventArgs(prop));         }     } }     The INotifyPropertyChanged interface is implemented so that changes to the number of yes and no votes will be updated in the ListView control. Receiving the vote messages from the voting applications is done asynchronously, using a background worker thread.   // This runs on a background worker. private void ReceiveMessages(object sender, DoWorkEventArgs e) {     while (true)     {         // Receive a vote message from the queue         BrokeredMessage msg = ScatterGatherQueueClient.Receive();         if (msg != null)         {             // Deserialize the message.             Vote vote = msg.GetBody<Vote>();               // Update the results.             foreach (Result result in Results)             {                 if (result.Question.Equals(vote.QuestionText))                 {                     if (vote.IsYes)                     {                         result.YesVotes++;                     }                     else                     {                         result.NoVotes++;                     }                     break;                 }             }               // Mark the message as complete.             msg.Complete();         }       } }     When a vote message is received, the result that matches the vote question is updated with the vote from the user. The message is then marked as complete. A second background thread is used to update the display of subscriptions in the TreeView, with a dispatcher used to update the user interface. // This runs on a background worker. private void UpdateSubscriptions(object sender, DoWorkEventArgs e) {     while (true)     {         // Get a list of subscriptions.         IEnumerable<SubscriptionDescription> subscriptions =             NamespaceManager.GetSubscriptions(AccountDetails.ScatterGatherTopic);           // Update the user interface.         SimpleDelegate setQuestion = delegate()         {             trvSubscriptions.Items.Clear();             TreeViewItem topicItem = new TreeViewItem()             {                 Header = AccountDetails.ScatterGatherTopic             };               foreach (SubscriptionDescription subscription in subscriptions)             {                 TreeViewItem subscriptionItem = new TreeViewItem()                 {                     Header = subscription.Name                 };                 topicItem.Items.Add(subscriptionItem);             }             trvSubscriptions.Items.Add(topicItem);               topicItem.ExpandSubtree();         };         this.Dispatcher.BeginInvoke(DispatcherPriority.Send, setQuestion);           Thread.Sleep(3000);     } }       Voting Application The voting application is implemented as another WPF application. This one is more basic, and allows the user to vote “Yes” or “No” for the questions sent by the poll manager application. The user interface for that application is shown below. When an instance of the voting application is created it will create a subscription in the questions topic using a GUID as the subscription name. The application can then receive copies of every question message that is sent to the topic. Clients for the new subscription and the votes queue are created, along with a background worker to receive the question messages. The voting application is set to receiving mode, meaning it is ready to receive a question message from the subscription.   public MainWindow() {     InitializeComponent();       // Set the mode to receiving.     IsReceiving = true;       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Create a subcription for this instance     NamespaceManager mgr = new NamespaceManager(serviceBusUri, credentials);     string subscriptionName = Guid.NewGuid().ToString();     mgr.CreateSubscription(AccountDetails.ScatterGatherTopic, subscriptionName);       // Create the subscription and queue clients.     ScatterGatherSubscriptionClient = factory.CreateSubscriptionClient         (AccountDetails.ScatterGatherTopic, subscriptionName);     ScatterGatherQueueClient =         factory.CreateQueueClient(AccountDetails.ScatterGatherQueue);       // Start the background worker thread.     BackgroundWorker = new BackgroundWorker();     BackgroundWorker.DoWork += new DoWorkEventHandler(ReceiveMessages);     BackgroundWorker.RunWorkerAsync(); }     I took the inspiration for creating the subscriptions in the voting application from the chat application that uses topics and subscriptions blogged by Ovais Akhter here. The method that receives the question messages runs on a background thread. If the application is in receive mode, a question message will be received from the subscription, the question will be displayed in the user interface, the voting buttons enabled, and IsReceiving set to false to prevent more questing from being received before the current one is answered.   // This runs on a background worker. private void ReceiveMessages(object sender, DoWorkEventArgs e) {     while (true)     {         if (IsReceiving)         {             // Receive a question message from the topic.             BrokeredMessage msg = ScatterGatherSubscriptionClient.Receive();             if (msg != null)             {                 // Deserialize the message.                 Question question = msg.GetBody<Question>();                   // Update the user interface.                 SimpleDelegate setQuestion = delegate()                 {                     lblQuestion.Content = question.QuestionText;                     btnYes.IsEnabled = true;                     btnNo.IsEnabled = true;                 };                 this.Dispatcher.BeginInvoke(DispatcherPriority.Send, setQuestion);                 IsReceiving = false;                   // Mark the message as complete.                 msg.Complete();             }         }         else         {             Thread.Sleep(1000);         }     } }     When the user clicks on the Yes or No button, the btnVote_Click method is called. This will create a new Vote data contract with the appropriate question and answer and send the message to the poll manager application using the votes queue. The user voting buttons are then disabled, the question text cleared, and the IsReceiving flag set to true to allow a new message to be received.   private void btnVote_Click(object sender, RoutedEventArgs e) {     // Create a new vote.     Vote vote = new Vote()     {         QuestionText = (string)lblQuestion.Content,         IsYes = ((sender as Button).Content as string).Equals("Yes")     };       // Send the vote message.     BrokeredMessage msg = new BrokeredMessage(vote);     ScatterGatherQueueClient.Send(msg);       // Update the user interface.     lblQuestion.Content = "";     btnYes.IsEnabled = false;     btnNo.IsEnabled = false;     IsReceiving = true; }     Testing the Application In order to test the application, an instance of the poll manager application is started; the user interface is shown below. As no instances of the voting application have been created there are no subscriptions present in the topic. When an instance of the voting application is created the subscription will be displayed in the poll manager. Now that a voting application is subscribing, a questing can be sent from the poll manager application. When the message is sent to the topic, the voting application will receive the message and display the question. The voter can then answer the question by clicking on the appropriate button. The results of the vote are updated in the poll manager application. When two more instances of the voting application are created, the poll manager will display the new subscriptions. More questions can then be broadcast to the voting applications. As the question messages are queued up in the subscription for each voting application, the users can answer the questions in their own time. The vote messages will be received by the poll manager application and aggregated to display the results. The screenshots of the applications part way through voting are shown below. The messages for each voting application are queued up in sequence on the voting application subscriptions, allowing the questions to be answered at different speeds by the voters.

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• .NET Code Evolution

  - by Alois Kraus

  Originally posted on: http://geekswithblogs.net/akraus1/archive/2013/07/24/153504.aspxAt my day job I do look at a lot of code written by other people. Most of the code is quite good and some is even a masterpiece. And there is also code which makes you think WTF… oh it was written by me. Hm not so bad after all. There are many excuses reasons for bad code. Most often it is time pressure followed by not enough ambition (who cares) or insufficient training. Normally I do care about code quality quite a lot which makes me a (perceived) slow worker who does write many tests and refines the code quite a lot because of the design deficiencies. Most of the deficiencies I do find by putting my design under stress while checking for invariants. It does also help a lot to step into the code with a debugger (sometimes also Windbg). I do this much more often when my tests are red. That way I do get a much better understanding what my code really does and not what I think it should be doing. This time I do want to show you how code can evolve over the years with different .NET Framework versions. Once there was  time where .NET 1.1 was new and many C++ programmers did switch over to get rid of not initialized pointers and memory leaks. There were also nice new data structures available such as the Hashtable which is fast lookup table with O(1) time complexity. All was good and much code was written since then. At 2005 a new version of the .NET Framework did arrive which did bring many new things like generics and new data structures. The “old” fashioned way of Hashtable were coming to an end and everyone used the new Dictionary<xx,xx> type instead which was type safe and faster because the object to type conversion (aka boxing) was no longer necessary. I think 95% of all Hashtables and dictionaries use string as key. Often it is convenient to ignore casing to make it easy to look up values which the user did enter. An often followed route is to convert the string to upper case before putting it into the Hashtable. Hashtable Table = new Hashtable(); void Add(string key, string value) { Table.Add(key.ToUpper(), value); } This is valid and working code but it has problems. First we can pass to the Hashtable a custom IEqualityComparer to do the string matching case insensitive. Second we can switch over to the now also old Dictionary type to become a little faster and we can keep the the original keys (not upper cased) in the dictionary. Dictionary<string, string> DictTable = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase); void AddDict(string key, string value) { DictTable.Add(key, value); } Many people do not user the other ctors of Dictionary because they do shy away from the overhead of writing their own comparer. They do not know that .NET has for strings already predefined comparers at hand which you can directly use. Today in the many core area we do use threads all over the place. Sometimes things break in subtle ways but most of the time it is sufficient to place a lock around the offender. Threading has become so mainstream that it may sound weird that in the year 2000 some guy got a huge incentive for the idea to reduce the time to process calibration data from 12 hours to 6 hours by using two threads on a dual core machine. Threading does make it easy to become faster at the expense of correctness. Correct and scalable multithreading can be arbitrarily hard to achieve depending on the problem you are trying to solve. Lets suppose we want to process millions of items with two threads and count the processed items processed by all threads. A typical beginners code might look like this: int Counter; void IJustLearnedToUseThreads() { var t1 = new Thread(ThreadWorkMethod); t1.Start(); var t2 = new Thread(ThreadWorkMethod); t2.Start(); t1.Join(); t2.Join(); if (Counter != 2 * Increments) throw new Exception("Hmm " + Counter + " != " + 2 * Increments); } const int Increments = 10 * 1000 * 1000; void ThreadWorkMethod() { for (int i = 0; i < Increments; i++) { Counter++; } } It does throw an exception with the message e.g. “Hmm 10.222.287 != 20.000.000” and does never finish. The code does fail because the assumption that Counter++ is an atomic operation is wrong. The ++ operator is just a shortcut for Counter = Counter + 1 This does involve reading the counter from a memory location into the CPU, incrementing value on the CPU and writing the new value back to the memory location. When we do look at the generated assembly code we will see only inc dword ptr [ecx+10h] which is only one instruction. Yes it is one instruction but it is not atomic. All modern CPUs have several layers of caches (L1,L2,L3) which try to hide the fact how slow actual main memory accesses are. Since cache is just another word for redundant copy it can happen that one CPU does read a value from main memory into the cache, modifies it and write it back to the main memory. The problem is that at least the L1 cache is not shared between CPUs so it can happen that one CPU does make changes to values which did change in meantime in the main memory. From the exception you can see we did increment the value 20 million times but half of the changes were lost because we did overwrite the already changed value from the other thread. This is a very common case and people do learn to protect their  data with proper locking.   void Intermediate() { var time = Stopwatch.StartNew(); Action acc = ThreadWorkMethod_Intermediate; var ar1 = acc.BeginInvoke(null, null); var ar2 = acc.BeginInvoke(null, null); ar1.AsyncWaitHandle.WaitOne(); ar2.AsyncWaitHandle.WaitOne(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Intermediate did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Intermediate() { for (int i = 0; i < Increments; i++) { lock (this) { Counter++; } } } This is better and does use the .NET Threadpool to get rid of manual thread management. It does give the expected result but it can result in deadlocks because you do lock on this. This is in general a bad idea since it can lead to deadlocks when other threads use your class instance as lock object. It is therefore recommended to create a private object as lock object to ensure that nobody else can lock your lock object. When you read more about threading you will read about lock free algorithms. They are nice and can improve performance quite a lot but you need to pay close attention to the CLR memory model. It does make quite weak guarantees in general but it can still work because your CPU architecture does give you more invariants than the CLR memory model. For a simple counter there is an easy lock free alternative present with the Interlocked class in .NET. As a general rule you should not try to write lock free algos since most likely you will fail to get it right on all CPU architectures. void Experienced() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); t1.Wait(); t2.Wait(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Experienced did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Experienced() { for (int i = 0; i < Increments; i++) { Interlocked.Increment(ref Counter); } } Since time does move forward we do not use threads explicitly anymore but the much nicer Task abstraction which was introduced with .NET 4 at 2010. It is educational to look at the generated assembly code. The Interlocked.Increment method must be called which does wondrous things right? Lets see: lock inc dword ptr [eax] The first thing to note that there is no method call at all. Why? Because the JIT compiler does know very well about CPU intrinsic functions. Atomic operations which do lock the memory bus to prevent other processors to read stale values are such things. Second: This is the same increment call prefixed with a lock instruction. The only reason for the existence of the Interlocked class is that the JIT compiler can compile it to the matching CPU intrinsic functions which can not only increment by one but can also do an add, exchange and a combined compare and exchange operation. But be warned that the correct usage of its methods can be tricky. If you try to be clever and look a the generated IL code and try to reason about its efficiency you will fail. Only the generated machine code counts. Is this the best code we can write? Perhaps. It is nice and clean. But can we make it any faster? Lets see how good we are doing currently. Level Time in s IJustLearnedToUseThreads Flawed Code Intermediate 1,5 (lock) Experienced 0,3 (Interlocked.Increment) Master 0,1 (1,0 for int[2]) That lock free thing is really a nice thing. But if you read more about CPU cache, cache coherency, false sharing you can do even better. int[] Counters = new int[12]; // Cache line size is 64 bytes on my machine with an 8 way associative cache try for yourself e.g. 64 on more modern CPUs void Master() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Master, 0); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Master, Counters.Length - 1); t1.Wait(); t2.Wait(); Counter = Counters[0] + Counters[Counters.Length - 1]; if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Master did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Master(object number) { int index = (int) number; for (int i = 0; i < Increments; i++) { Counters[index]++; } } The key insight here is to use for each core its own value. But if you simply use simply an integer array of two items, one for each core and add the items at the end you will be much slower than the lock free version (factor 3). Each CPU core has its own cache line size which is something in the range of 16-256 bytes. When you do access a value from one location the CPU does not only fetch one value from main memory but a complete cache line (e.g. 16 bytes). This means that you do not pay for the next 15 bytes when you access them. This can lead to dramatic performance improvements and non obvious code which is faster although it does have many more memory reads than another algorithm. So what have we done here? We have started with correct code but it was lacking knowledge how to use the .NET Base Class Libraries optimally. Then we did try to get fancy and used threads for the first time and failed. Our next try was better but it still had non obvious issues (lock object exposed to the outside). Knowledge has increased further and we have found a lock free version of our counter which is a nice and clean way which is a perfectly valid solution. The last example is only here to show you how you can get most out of threading by paying close attention to your used data structures and CPU cache coherency. Although we are working in a virtual execution environment in a high level language with automatic memory management it does pay off to know the details down to the assembly level. Only if you continue to learn and to dig deeper you can come up with solutions no one else was even considering. I have studied particle physics which does help at the digging deeper part. Have you ever tried to solve Quantum Chromodynamics equations? Compared to that the rest must be easy ;-). Although I am no longer working in the Science field I take pride in discovering non obvious things. This can be a very hard to find bug or a new way to restructure data to make something 10 times faster. Now I need to get some sleep ….

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• (C#) Label.Text = Struct.Value (Microsoft.VisualStudio.Debugger.Runtime.CrossThreadMessagingException)

  - by Kyle

  I have an app that I'm working on that polls usage from an ISP (Download quota). I've tried threading this via 'new Thread(ThreaProc)' but that didn't work, now trying an IAsyncResult based approach which does the same thing... I've got no idea on how to rectify, please help? The need-to-know: // Global public delegate void AsyncPollData(ref POLLDATA pData); // Class scope: private POLLDATA pData; private void UpdateUsage() { AsyncPollData PollDataProc = new AsyncPollData(frmMain.PollUsage); IAsyncResult result = PollDataProc.BeginInvoke(ref pData, new AsyncCallback(UpdateDone), PollDataProc); } public void UpdateDone(IAsyncResult ar) { AsyncPollData PollDataProc = (AsyncPollData)ar.AsyncState; PollDataProc.EndInvoke(ref pData, ar); // The Exception occurs here: lblStatus.Text = pData.LastError; } public static void PollUsage(ref POLLDATA PData) { PData.LastError = "Some string"; return; }

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• WPF: Asynchronous progress bar

  - by SumGuy

  I'm trying to create a progress bar that will work asynchronously to the main process. I'm created a new event and invoked it however everytime I then try to perform operations on the progress bar I recieve the following error: "The calling thread cannot access this object because a different thread owns it" The following code is an attempt to send an instance of the progress bar to the event as an object, it obviously failed but it gives you an idea of what the code looks like. private event EventHandler importing; void MdbDataImport_importing(object sender, EventArgs e) { ProgressBar pb = (ProgressBar)sender; while (true) { if (pb.Value >= 200) pb.Value = 0; pb.Value += 10; } } private void btnImport_Click(object sender, RoutedEventArgs e) { importing += new EventHandler(MdbDataImport_importing); IAsyncResult aResult = null; aResult = importing.BeginInvoke(pbDataImport, null, null, null); importing.EndInvoke(aResult); } Does anyone have ideas of how to do this. Thanks in advance SumGuy.

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• SL3/SL4 - Ado.Net Data Services Error during new DataServiceCollection<T>(queryResponse)

  - by Soulhuntre

  Hey all, I have two functions in a SL project (VS2010) that do almost exactly the same thing, yet one throws an error and the other does not. It seems to be related to the projections, but I am unsure about the best way to resolve. The function that works is... public void LoadAllChunksExpandAll(DataHelperReturnHandler handler, string orderby) { DataServiceCollection<CmsChunk> data = null; DataServiceQuery<CmsChunk> theQuery = _dataservice .CmsChunks .Expand("CmsItemState") .AddQueryOption("$orderby", orderby); theQuery.BeginExecute( delegate(IAsyncResult asyncResult) { _callback_dispatcher.BeginInvoke( () => { try { DataServiceQuery<CmsChunk> query = asyncResult.AsyncState as DataServiceQuery<CmsChunk>; if (query != null) { //create a tracked DataServiceCollection from the result of the asynchronous query. QueryOperationResponse<CmsChunk> queryResponse = query.EndExecute(asyncResult) as QueryOperationResponse<CmsChunk>; data = new DataServiceCollection<CmsChunk>(queryResponse); handler(data); } } catch { handler(data); } } ); }, theQuery ); } This compiles and runs as expected. A very, very similar function (shown below) fails... public void LoadAllPagesExpandAll(DataHelperReturnHandler handler, string orderby) { DataServiceCollection<CmsPage> data = null; DataServiceQuery<CmsPage> theQuery = _dataservice .CmsPages .Expand("CmsChildPages") .Expand("CmsParentPage") .Expand("CmsItemState") .AddQueryOption("$orderby", orderby); theQuery.BeginExecute( delegate(IAsyncResult asyncResult) { _callback_dispatcher.BeginInvoke( () => { try { DataServiceQuery<CmsPage> query = asyncResult.AsyncState as DataServiceQuery<CmsPage>; if (query != null) { //create a tracked DataServiceCollection from the result of the asynchronous query. QueryOperationResponse<CmsPage> queryResponse = query.EndExecute(asyncResult) as QueryOperationResponse<CmsPage>; data = new DataServiceCollection<CmsPage>(queryResponse); handler(data); } } catch { handler(data); } } ); }, theQuery ); } Clearly the issue is the Expand projections that involve a self referencing relationship (pages can contain other pages). This is under SL4 or SL3 using ADONETDataServices SL3 Update CTP3. I am open to any work around or pointers to goo information, a Google search for the error results in two hits, neither particularly helpful that I can decipher. The short error is "An item could not be added to the collection. When items in a DataServiceCollection are tracked by the DataServiceContext, new items cannot be added before items have been loaded into the collection." The full error is... System.Reflection.TargetInvocationException was caught Message=Exception has been thrown by the target of an invocation. StackTrace: at System.RuntimeMethodHandle.InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) at System.Data.Services.Client.ClientType.ClientProperty.SetValue(Object instance, Object value, String propertyName, Boolean allowAdd) at System.Data.Services.Client.AtomMaterializer.ApplyItemsToCollection(AtomEntry entry, ClientProperty property, IEnumerable items, Uri nextLink, ProjectionPlan continuationPlan) at System.Data.Services.Client.AtomMaterializer.ApplyFeedToCollection(AtomEntry entry, ClientProperty property, AtomFeed feed, Boolean includeLinks) at System.Data.Services.Client.AtomMaterializer.MaterializeResolvedEntry(AtomEntry entry, Boolean includeLinks) at System.Data.Services.Client.AtomMaterializer.Materialize(AtomEntry entry, Type expectedEntryType, Boolean includeLinks) at System.Data.Services.Client.AtomMaterializer.DirectMaterializePlan(AtomMaterializer materializer, AtomEntry entry, Type expectedEntryType) at System.Data.Services.Client.AtomMaterializerInvoker.DirectMaterializePlan(Object materializer, Object entry, Type expectedEntryType) at System.Data.Services.Client.ProjectionPlan.Run(AtomMaterializer materializer, AtomEntry entry, Type expectedType) at System.Data.Services.Client.AtomMaterializer.Read() at System.Data.Services.Client.MaterializeAtom.MoveNextInternal() at System.Data.Services.Client.MaterializeAtom.MoveNext() at System.Linq.Enumerable.d_b11.MoveNext() at System.Data.Services.Client.DataServiceCollection1.InternalLoadCollection(IEnumerable1 items) at System.Data.Services.Client.DataServiceCollection1.StartTracking(DataServiceContext context, IEnumerable1 items, String entitySet, Func2 entityChanged, Func2 collectionChanged) at System.Data.Services.Client.DataServiceCollection1..ctor(DataServiceContext context, IEnumerable1 items, TrackingMode trackingMode, String entitySetName, Func2 entityChangedCallback, Func2 collectionChangedCallback) at System.Data.Services.Client.DataServiceCollection1..ctor(IEnumerable1 items) at Phinli.Dashboard.Silverlight.Helpers.DataHelper.<>c__DisplayClass44.<>c__DisplayClass46.<LoadAllPagesExpandAll>b__43() InnerException: System.InvalidOperationException Message=An item could not be added to the collection. When items in a DataServiceCollection are tracked by the DataServiceContext, new items cannot be added before items have been loaded into the collection. StackTrace: at System.Data.Services.Client.DataServiceCollection1.InsertItem(Int32 index, T item) at System.Collections.ObjectModel.Collection`1.Add(T item) InnerException: Thanks for any help!

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• install SSMSE 2008 after VS 2010

  - by snehalpatkar

  hi guys i have installed VS 2010 ultimate on windows 7 machine which by default install sql server 2008. now i want to install SSMSE 2008 i download the following file SQLEXPRWT_x86_ENU and tried to install it but it give me error. [Window Title] Program Compatibility Assistant [Main Instruction] This program has known compatibility issues [Expanded Information] After SQL Server Setup completes, you must apply SQL Server 2008 Service Pack 1 (SP1) or a later service pack before you run SQL Server 2008 on this version of Windows. [^] Hide details [ ] Don't show this message again [Check for solutions online] [Run program] [Cancel] TITLE: SQL Server Setup failure. SQL Server Setup has encountered the following error: Invoke or BeginInvoke cannot be called on a control until the window handle has been created.. BUTTONS: OK how to install SSMSE 2008 after installing VS 2010 please help

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• Avoiding .NET versioning hell

  - by moogs

  So sometimes (oftentimes!) you want to target a specific .NET version (say 3.0), but then due to some .NET service packs you get into problems like: Dispatcher.BeginInvoke(Delegate, Object[]) <-- this was added in 3.0 SP2 (3.0.30618 ) System.Threading.WaitHandle.WaitOne(Int32) <-- this was added in 3.5 SP1, 3.0 SP2, 2.0 SP2 Now, these are detected by the JIT compiler, so building against .NET 3.0 in Visual Studio won't guarante it will run on .NET 3.0 only systems. Short of confirming each and every function you use, or limiting your development environment to .NET 3.0 (which sucks since you have to develop for other projects too) what's the best way to avoid against using extensions? Thanks!

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• The correct way to Fire-and-Forget an asynchronous delegate

  - by Programming Hero

  Consider me rusty on the subject of asynchronous delegates. If I want to call a method asynchronously, in a fire-and-forget style, is this an appropriate way to do it? Action action = DoSomething; action.BeginInvoke(action.EndInvoke, null); The DoSomething() method catches all exceptions and deals with them internally. Is the call to EndInvoke appropriate? Required? Is there a clearer way to achieve the same behaviour?

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• C# Delegate Invoke Required Issue

  - by Goober

  Scenario I have a C# windows forms application that has a number of processes. These processes run on separate threads and all communicate back to the Main Form class with updates to a log window and a progress bar. I'm using the following code below, which up until now has worked fine, however, I have a few questions. Code delegate void SetTextCallback(string mxID, string text); public void UpdateLog(string mxID, string text) { if (txtOutput.InvokeRequired) { SetTextCallback d = new SetTextCallback(UpdateLog); this.BeginInvoke(d, new object[] { mxID, text }); } else { UpdateProgressBar(text); } } Question Will, calling the above code about 10 times a second, repeatedly, give me errors, exceptions or generally issues?.....Or more to the point, should it give me any of these problems? Occasionally I get OutofMemory Exceptions and the program always seems to crash around this bit of code......

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• .NET invoking against an arbitrary control.

  - by kerkeslager

  I have a method which takes in a .NET control and calls invoke against it like so: Form.Invoke(Target); However, I've run into an issue numerous times calling this method where due to timing or whatever, the form handle on the form doesn't exist, causing a Invoke or BeginInvoke cannot be called on a control until the window handle has been created error. In frustration, I jokingly changed the code to: MainForm.Invoke(Target); where MainForm is the main window of the application (the form handle for the main form is created at startup and remains active for the entire life cycle of the application). I ran all the tests and manually tested the application and everything seems to work fine despite the fact that this is used everywhere. So my question is, what exactly is the meaning of invoking against a specific control? Is there any downside to just always invoking against a control you know will be active? If not, why does .NET have you invoke against a control in the first place (instead of just creating a static GuiThread.InvokeOnGuiThread(Blah);)?

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• e.DetailsElement in silverlight

  - by prince23

  hi, is there any way i can write this code in a function() right now what is happening in function is it tells e.Row.DetailsVisibility e.DetailsElement.ActualHeight it is not able to find this it is telling is there any way i can get this e.DetailsElement.ActualHeight if (e.Row.DetailsVisibility == Visibility.Visible) { Dispatcher.BeginInvoke(() => { DataGrid datagrid = sender as DataGrid; if (datagrid != null) { datagrid.Tag = e.DetailsElement.ActualHeight; datagrid.Height = datagrid.ActualHeight + e.DetailsElement.ActualHeight; } } ); } else { DataGrid datagrid = sender as DataGrid; if(datagrid.Tag!=null) datagrid.Height = datagrid.ActualHeight - System.Convert.ToDouble(datagrid.Tag); } }

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• Best practice for controlling a busy GUI

  - by MPelletier

  Suppose a GUI (C#, WinForms) that performs work and is busy for several seconds. It will still have buttons that need to remain accessible, labels that will change, progress bars, etc. I'm using this approach currently to change the GUI when busy: //Generic delegates private delegate void SetControlValue<T>(T newValue); //... public void SetStatusLabelMessage(string message) { if (StatusLabel.InvokeRequired) StatusLabel.BeginInvoke(new SetControlValue<string>(SetStatusLabelMessage, object[] { message }); else StatusLabel.Text = message; } I've been using this like it's going out of style, yet I'm not quite certain this is proper. Creating the delegate (and reusing it) makes the whole thing cleaner (for me, at least), but I must know that I'm not creating a monster...

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• Asynchronous Silverlight WCF callback

  - by Matt

  I've created my own WCF service and I've successfully been able to talk to it via my Silverlight client. I ran into an interesting problem on my asynchronous callbacks though. When my callback is invoked, I can't update any UI controls with the dreaded invalid cross thread access Here's what my callback function looks like private void GetTimeCallBack( object sender, Talk.ClientBase<IService>.ClientEventArgs e ) { lblDisplay.Text = e.Object.ToString(); } A quick google search showed me that I have to do this instead. private void GetTimeCallBack( object sender, Talk.ClientBase<IService>.ClientEventArgs e ) { Dispatcher.BeginInvoke( () => lblDisplay.Text = e.Object.ToString() ); } Now everything works fine, but I wasn't expecting my callback to be running on a different thread. Will I always have to use the Dispatcher class in order to modify anything within my class or is this just limited to UI elements? I've not familiar with the Dispatcher class at all so I'm looking to understand it more.

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• RaisePropertyChanged for Windows Phone

  - by chief7

  I'm starting to use the MVVMLight framework and have a question about binding to properties in the ViewModel. I found that I have to call the RaisePropertyChanged method in the setter for the property in order for the View to be updated. And I have to call RaisePropertyChanged from through the dispatcher otherwise I get a thread access error. public string Lat { get { return _lat; } set { _lat = value; Deployment.Current.Dispatcher.BeginInvoke(() => RaisePropertyChanged("Lat")); } } This works but its a lot of code to get auto binding properties. Is there a helper to handle this more cleanly?

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• How to program asynchronous Windows Forms Applications?

  - by Nestor

  I'm writting a Windows Forms application in C# that performs a lot of long-running procedures. I need to program the application so that the GUI doesn't lock. What is the best way to program it? I know how to use the following: BeginInvoke/EndInvoke Calling Application.DoEvents() repeatedly (probably not a good idea) BackgroundWorker etc. But how to manage GUI state with call backs, etc... is not trivial. Are there solutions for this (in the form of patterns or libraries)?

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• Ignore errors when scanning for files in C:\

  - by Shane

  I am trying to search the C:\ drive for all files with a certain extension. I am using the following code which is working fine, however when it encounters an error the whole process stops rather than continuing with the scan. (running in backgroundworker, hence the invoke) Private Sub ScanFiles(ByVal rootFolder As String, ByVal fileExtension As String) 'Determine if the current folder contains any sub folders Dim subFolders() As String = System.IO.Directory.GetDirectories(rootFolder) For Each subFolder As String In subFolders ScanFiles(subFolder, fileExtension) Next For Each file As String In System.IO.Directory.GetFiles(rootFolder, fileExtension) lb.BeginInvoke(New AddValue(AddressOf AddItems), file) Next End Sub How can I make this code continue once an error is encountered? Thanks for your help.

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• WPF ItemsControl - how to know when the items finished loading, so that I can focus the first one?

  - by Tomáš Kafka

  Hi everyone, I have an ItemsControl in my View, that is bound to an ObservableCollection from ViewModel. The collection is filled, and afterwards an event from VM to view is raised (think search results and SearchFinished event). I would like to move keyboard focus to the first item in an ItemsControl, but when I do it in View's code-behind when handling SearchFinished, the items are not yet rendered (the collection is filled already, but wpf's rendering is asynchronous and didn't happen yet), so there is nothing to focus (Focus() needs to have the items' visual tree already constructed). I wanted to do (myItemsControl.ItemContainerGenerator.ContainerFromIndex(0) as UIElement).Focus();, but as the 0th item is not yet loaded, ContainerFromIndex(0) returns null. I tried delaying it with Dispatcher.BeginInvoke... with low priority, but that is dependent on exact timing and usually doesn't work. How can I wait until the first item in ItemsControl is Loaded?

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• Ramifications of CheckForIllegalCrossThreadCalls=false

  - by Ron Skufca

  I recently updated an application from VS2003 to VS2008 and I knew I would be dealing with a host of "Cross-thread operation not valid: Control 'myControl' accessed from a thread other than the thread it was created on" I am handling this in what I beleive is the correct way (see code sample below). I am running into numerous controls that are going to need a similar fix. Not wanting to have similar code for every label, textbox etc.. that are being accessed by a non UI thread. What are the ramifications of just setting the CheckForIllegalCrossThreadCalls = false for the entire app? I found a CodeProject article with various workarounds and a warning at the bottom to NOT set the property. I am looking for other opinions/experiences on this issue. private void ShowStatus(string szStatus) { try { if (this.statusBar1.InvokeRequired) { BeginInvoke(new MethodInvoker(delegate() { ShowStatus(szStatus); })); } else { statusBar1.Panels[0].Text = szStatus; } } catch (Exception ex) { LogStatus.WriteErrorLog(ex, "Error", "frmMNI.ShowStatus()"); } }

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• [WPF] The calling thread cannot access this object because a different thread owns it.

  - by zunyite

  Why I can't create CroppedBitmap in the following code ? I got an exception : The calling thread cannot access this object because a different thread owns it. public MainWindow() { InitializeComponent(); ThreadPool.QueueUserWorkItem((o) => { //load a large image file var bf = BitmapFrame.Create( new Uri("D:\\1172735642.jpg"), BitmapCreateOptions.DelayCreation | BitmapCreateOptions.IgnoreColorProfile, BitmapCacheOption.None); bf.Freeze(); Dispatcher.BeginInvoke( new Action(() => { CroppedBitmap cb = new CroppedBitmap(bf, new Int32Rect(1,1,5,5)); cb.Freeze(); //set Image's source to cb.... }), System.Windows.Threading.DispatcherPriority.ApplicationIdle); } ); }

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• Which async call use for DB connection and still responsive GUI?--

  - by Jade

  Hi, My application connects to MSSQL but sometimes it takes a while and the GUI is getting frozen. I would like to do the connection on the other thread, I guess BeginInvoke would be the best way (I know about background worker but I would like to learn this). I have studied MSDN page but I did not understand what is the best way to use? They also say that you can use only callback when the thread that called the async.method does not need to know the results...I dont understand it as I believe I can set some variable in the other thread to "pass" the result well. I would just need the GUI to be not frozen while the connection is being established. Thank you for your advice.

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• how to write silverlight threading function in another file or project

  - by Piyush

  I am using three tier architecture.I have SilverlightUI and UIController two projects.SilverlightUI contains only UI pages and controls while UIController contains all proxies of WCF services. Now I have created threads to update my controls dynamically and to do processing parallel.AS the requirement I want to define all functionality of threads in UIController projects.What should I do? Currenty what I am doing - private void Button_Click(object sender, RoutedEventArgs e) { StartThreads(); } private void StartThreads() { private Thread _thread1; _thread1 = new Thread(DoThread1); _thread1.Start(); } public static void DoThread1() { _data1.Dispatcher.BeginInvoke(delegate() { _data1.Text = _count1.ToString(); }); System.Threading.Thread.Sleep(1000); } I Want to write DoThread1() method in UIController project and call that function from here button_click()

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• c#: sms appears to have been sent, but stuck in phone outbox

  - by I__

  i wrote code to send an SMS using my gsm phone which is attached to the computer through com port. the code is below. the problem is i do see that it is in the outbox of the phone and it actually appears to have been sent, but when i contact the recipient they say that i have not received the message. i test the phone, and i create and send a message using only the phone and it works perfectly, however when i do this with my code, it APPEARS to have been sent, and i am getting all the correct AT COMMAND responses from the phone, but the message is actually NOT sent. here is the code: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; using System.IO.Ports; namespace WindowsFormsApplication1 { public partial class Form1 : Form { SerialPort serialPort1; int m_iTxtMsgState = 0; const int NUM_MESSAGE_STATES = 4; const string RESERVED_COM_1 = "COM1"; const string RESERVED_COM_4 = "COM4"; public Form1() { InitializeComponent(); this.Closing += new CancelEventHandler(Form1_Closing); } private void Form1_Load(object sender, EventArgs e) { serialPort1 = new SerialPort(GetUSBComPort()); if (serialPort1.IsOpen) { serialPort1.Close(); } serialPort1.Open(); //ThreadStart myThreadDelegate = new ThreadStart(ReceiveAndOutput); //Thread myThread = new Thread(myThreadDelegate); //myThread.Start(); this.serialPort1.DataReceived += new SerialDataReceivedEventHandler(sp_DataReceived); } private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e) { serialPort1.Close(); } private void SendLine(string sLine) { serialPort1.Write(sLine); sLine = sLine.Replace("\u001A", ""); consoleOut.Text += sLine; } public void DoWork() { ProcessMessageState(); } public void ProcessMessageState() { switch (m_iTxtMsgState) { case 0: m_iTxtMsgState = 1; SendLine("AT\r\n"); //NOTE: SendLine must be the last thing called in all of these! break; case 1: m_iTxtMsgState = 2; SendLine("AT+CMGF=1\r\n"); break; case 2: m_iTxtMsgState = 3; SendLine("AT+CMGW=" + Convert.ToChar(34) + "+9737387467" + Convert.ToChar(34) + "\r\n"); break; case 3: m_iTxtMsgState = 4; SendLine("A simple demo of SMS text messaging." + Convert.ToChar(26)); break; case 4: m_iTxtMsgState = 5; break; case 5: m_iTxtMsgState = NUM_MESSAGE_STATES; break; } } private string GetStoredSMSID() { return null; } /* //i dont think this part does anything private void serialPort1_DataReceived_1(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) { string response = serialPort1.ReadLine(); this.BeginInvoke(new MethodInvoker(() => textBox1.AppendText(response + "\r\n"))); } */ void sp_DataReceived(object sender, SerialDataReceivedEventArgs e) { try { Thread.Sleep(500); char[] msg; msg = new char[613]; int iNumToRead = serialPort1.BytesToRead; serialPort1.Read(msg, 0, iNumToRead); string response = new string(msg); this.BeginInvoke(new MethodInvoker(() => textBox1.AppendText(response + "\r\n"))); serialPort1.DiscardInBuffer(); if (m_iTxtMsgState == 4) { int pos_cmgw = response.IndexOf("+CMGW:"); string cmgw_num = response.Substring(pos_cmgw + 7, 4); SendLine("AT+CMSS=" + cmgw_num + "\r\n"); //stop listening to messages received } if (m_iTxtMsgState < NUM_MESSAGE_STATES) { ProcessMessageState(); } } catch { } } private void button1_Click(object sender, EventArgs e) { m_iTxtMsgState = 0; DoWork(); } private void button2_Click(object sender, EventArgs e) { string[] sPorts = SerialPort.GetPortNames(); foreach (string port in sPorts) { consoleOut.Text += port + "\r\n"; } } private string GetUSBComPort() { string[] sPorts = SerialPort.GetPortNames(); foreach (string port in sPorts) { if (port != RESERVED_COM_1 && port != RESERVED_COM_4) { return port; } } return null; } }

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• How to implement async pattern in windows forms application?

  - by Alkersan

  I'm using an MVC pattern in winforms application. I need to call remote service asynchronously. So On some event in View I invoke corresponding Presenter method. In Presenter I call BeginInvoke method of service. But to View must be updated only in Main Thread. I could actualy point CallBack to some function in View, and update it`s controls state, but this conflicts with MVP pattern - View must not be responsible for data it carries. This callback function must be in Presenter. But how then invoke View in Main Thread?

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