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  • Trigger Event after values have been commited for validation purposes

    - by www.jefferyfernandez.id.au
    I have a Flex component with a form and on creationComplete, I load some data onto the form textInputs. After the Form TextInputs have got their values, I want to trigger an event so the Parent of the component can validate the values on the TextInputs and based on the validation results, I perform some enable/disable of other interfaces. I have the following dispatch code: this.dispatchEvent(new PersonalDetailsEvent(PersonalDetailsEvent.LOADED_DATA_EVENT)); The event is dispatched and is captured by the parent. But upon performing the validation, some TextInputs always fail the validation. I thought it could be because of a race condition and so I used callLater() with same results. So in the end I am now using a timer to dispatch the event which is not ideal. Does anyone have a solution to this problem. It is really annoying that a timer needs to be used for this scenario.

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  • Thread Suicide on Shutdown?

    - by yar
    I have a java.util.Timer running at a fixed interval. I have added a Runtime#addShutdownHook and it shuts down when the VM ends normally or abnormally. However, it keeps the VM alive when a main terminates, unless I insist by doing a System.exit in the main. Is there any way for me to check if I'm the last Thread standing, or some other way to avoid altering a main that would exit normally on finish? Note: I know a lot of people believe that java.util.Timer is deprecated (it's not), but unless your alternative helps me solve this problem...

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  • Is MSDN referencing a system.thread, a worker thread, an io thread or all three?

    - by w0051977
    Please see the warning below taken from the StreamWriter class specification (http://msdn.microsoft.com/en-us/library/system.io.streamwriter.aspx): "Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe." I understand that a W3WC process contains two thread pools i.e. worker threads and I/O threads. A worker thread could contain many threads of its own (if the application creates its own System.Thread instances). Does the warning only relate to System.Threads or does it relate to worker threads and I/O threads as well I.e. as the instance variables of the streamwriter class are not thread safe then does this mean that there would be problems if multiple worker threads access it eg if two users on two different web clients attempt to write to the log file at the same time, then could one lock out the other?

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  • (conditional) Multiple Event Handlers C#

    - by gjk
    A portion of my program requires a "flag" retrieval, that is I am fetching a value that is either True or False, and based on this return value two things could follow. 1) The flag is true, aka "go ahead", and I retrieve data from a database. 2) The flag is false, and I want to prevent the data from being retrieved. Now, this check has to be performed before any function that would call upon the database in question. I decided to implement this check in the form of an event handler attached to GUI objects that would trigger this data inquiry. This check event handler is called first upon necessary events, and my question is: How do I stop subsequent event handlers from firing if the FIRST event handler (my flag checker) comes up FALSE? Thanks

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  • Thread Synchronization and Synchronization Primitives

    When considering synchronization in an application, the decision truly depends on what the application and its worker threads are going to do. I would use synchronization if two or more threads could possibly manipulate the same instance of an object at the same time. An example of this in C# can be demonstrated through the use of storing data in a static object. A static object is initialized once per application and the data within the object can be accessed by all threads. I would use the synchronization primitives to prevent any data from being manipulated by multiple threads simultaneously. This would reduce any data corruption from occurring within the object. On the other hand if all the threads used non static objects and were independent of the other tasks there would be no need to use synchronization. Synchronization Primitives in C#: Basic Blocking Locking Signaling Non-Blocking Synchronization Constructs The Basic Blocking methods include Sleep, Join, and Task.Wait.  These methods force threads to wait until other threads have completed. In addition, these methods can also force a thread to wait a set amount of time before continuing to work.   The Locking primitive prevents a thread from entering a critical section of code while another thread is in the same critical section.  If another thread attempts to enter a locked code, it will wait, until the code block is released. The Signaling primitive allows a thread to temporarily pause work until receiving a notification from another thread that it is ok to continue working. The Signaling primitive removes the need for polling.The Non-Blocking Synchronization Constructs protect access to a common field by calling upon processor primitives.

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  • Simple Mouse Move Event in F# with Winforms

    - by MarkPearl
    This evening I had the pleasure of reading one of ThomasP’s blog posts on first class events. It was an excellent read, and I thought I would make a brief derivative of his post to explore some of the basics. In Thomas’s post he has a form with an ellipse on it that when he clicks on the ellipse it pops up a message box with the button clicked… awesome. Something that got me on the post though was the code similar to the one below… // React to Mouse Move events on the form let evtMessages = frm.MouseMove |> Event.map (fun mi -> mi.Location.ToString()) |> Event.map (sprintf "Hey, you clicked on the ellipse.\nUsing: %s") |> Event.add (MessageBox.Show >> ignore) The MessageBox is a function with a string passed into it. What if I wanted to rather change a mutable value holder instead, how would the syntax go for that? Immediately the thought came to me of anonymous functions. I’ve used them before to do something like this… let HelloPerson personName = "Hello " + personName |> fun(x) -> Console.WriteLine(x) So using the same approach I adapted the event code to instead of showing a Message Box with a string passed in to it, to rather change the forms header. |> Event.map (sprintf "Your mouse position is %s") |> Event.add(fun(x) -> frm.Text <- x) Okay… it looks a bit weird with the –> x <- syntax, but makes sense and works… The next thing I wanted to do was change Thomas’s code sample from having an ellipse, and reacting to the position of the mouse and click, to rather trigger the event whenever the mouse moved. This simple involved removing some filtering code. Finally I wanted the code to work as a FSharp Project without having to run through the F# interactive. To achieve this I just needed to find out how to trigger the window event loop. This can be achieved with the code below… // Program eventloop while frm.Created do Application.DoEvents()   So lets look at the complete code sample… #light open System open System.Drawing open System.Windows.Forms // Create the main form let frm = new Form(ClientSize=Size(600,400)) // React to Mouse Move events on the form let evtMessages = frm.MouseMove |> Event.map (fun mi -> mi.Location.ToString()) |> Event.map (sprintf "Your mouse position is %s") |> Event.add(fun(x) -> frm.Text <- x) // Show the form frm.Show() // Program eventloop while frm.Created do Application.DoEvents()

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  • Android Touch Event Collision Detection

    - by chrissb
    I'm relatively new to both Java and Android, so hopefully the problem I'm having is stemming from something pretty minor that I've overlooked. I've got a (very early stage) game that I've started working on, for Android using Java. At this stage, when the user touches the screen, if they touched a point at which there is an enemy, the enemies health is decreased and they become immobile (for the current implementation at least). The issue that I'm having is that the touch detection doesn't always seem to work. I've got a testing sprite set up that goes to the eventX and eventY coordinates of the touch down event, and it always seems to collide with the enemy object. Yet, the enemy doesn't always register as being hit, and sometimes a hit is registered when the sprite indicates the touch coordinates were outside of the enemies bounding box. I realise that this probably doesn't mean much without any code, so here's what I've got so far. Be gentle, as this is literally my first attempt at something more than basic movement etc. First off, the MainGamePanel class registers the touch event, and informs the levelmanager class (which is what I set up to monitor/handle enemies) public boolean onTouchEvent(MotionEvent event) { if (event.getAction() == MotionEvent.ACTION_DOWN){ levelManager.handleActionDown((int)event.getX(), (int)event.getY()); targetX=event.getX(); targetY=event.getY(); } if (event.getAction() == MotionEvent.ACTION_MOVE) { //the gestures } if (event.getAction() == MotionEvent.ACTION_UP) { //touch was released } return true; } From there, in the levelmanager class the touch event is passed on to all of the enemies within a list array: public static void handleActionDown(int eventX,int eventY){ hit=false; for (enemy1 en : enemy1array){ en.handleActionDown(eventX, eventY); } } The rest of the collision code is handled within the enemies handleActionDown function: public void handleActionDown(int eventX, int eventY) { if(eventX>this.x-enemy1bitmap.getWidth() && eventX<this.x+enemy1bitmap.getWidth() && eventY>this.y-enemy1bitmap.getHeight() && eventY<this.x+enemy1bitmap.getHeight()){ takeDamage(1); levelmanager.setHit(); } } I should probably be using getWidth()/2 and getHeight()/2 for it to be more accurate, but I expanded the area to test this - although I've noticed no improvement. At this stage, the games detection over whether or not the enemy is hit is spotty at best. Generally it takes two or three attempts before a collision is successfully registered, even though the sprite that is being used for testing and set to the eventX and eventY coordinates always indicates that the collision should have worked. Hopefully someone can steer me in the right direction here, and if more information is needed, ask away! Cheers, -Chris

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  • Image container instead of event object in image load event handler

    - by avok00
    I stumbled upon a very strange thing. In FF 3.6 (not tested others yet) I add onload handler to an image like this: imgRef.addEventListener("load", activateLink, false); When load event fires, in activateLink(evt) the evt paramater is not an event, but the "a" tag that contains the image. Why is this? function activateLink(evt) { // evt turns out to be a refference to <a> tag (HTMLAnchorElement) that contains the image. // Actually two of them. Both dynamically added with addElement. } I remembered another fact that may be relevant. I have multiple images with the same src that all have registered this same event handler activateLink. Could this be the problem?

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  • ReSharper C# Live Template for Declaring Routed Event

    - by Bart Read
    Here's another WPF ReSharper Live Template for you. This one is for declaring standalone routed events of any type. Again, it's pretty simple:        #region $EVENTNAME$ Routed Event       public static readonly RoutedEvent $EVENTNAME$Event = EventManager.RegisterRoutedEvent(            "$EVENTNAME$",           RoutingStrategy.$ROUTINGSTRATEGY$,           typeof( $EVENTHANDLERDELEGATE$ ),           typeof( $DECLARINGTYPE$ ) );       public event $EVENTHANDLERDELEGATE$ $EVENTNAME$       {           add { AddHandler( $EVENTNAME$Event, value ); }           remove { RemoveHandler( $EVENTNAME$Event, value ); }       }       protected virtual void On$EVENTNAME$()       {           RaiseEvent( new $EVENTARGSTYPE$( $EVENTNAME$Event, this ) );           $END$       }       #endregion Here are my previous posts along the same lines: ReSharper C# Live Template for Read-Only Dependency Property and Routed Event Boilerplate ReSharper C# Live Template for Dependency Property and Property Change Routed Event Boilerplate Code Enjoy! Technorati Tags: resharper,live template,c#,routed event,wpf,boilerplate,code generation

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  • Introduction to Extended Events

    - by extended_events
    For those fighting with all the Extended Event terminology, let's step back and have a small overall Introduction to Extended Events. This post will give you a simplified end to end view through some of the elements in Extended Events. Before we start, let’s review the first Extented Events that we are going to use: -          Events: The SQL Server code is populated with event calls that, by default, are disabled. Adding events to a session enables those event calls. Once enabled, they will execute the set of functionality defined by the session. -          Target: This is an Extended Event Object that can be used to log event information. Also it is important to understand the following Extended Event concept: -          Session: Server Object created by the user that defines functionality to be executed every time a set of events happen.   It’s time to write a small “Hello World” using Extended Events. This will help understand the above terms. We will use: -          Event sqlserver. error_reported: This event gets fired every time that an error happens in the server. -          Target package0.asynchronous_file_target: This target stores the event data in disk. -          Session: We will create a session that sends all the error_reported events to the ring buffer. Before we get started, a quick note: Don’t run this script in a production environment. Even though, we are going just going to be raise very low severity user errors, we don't want to introduce noise in our servers. -- TRIES TO ELIMINATE PREVIOUS SESSIONS BEGIN TRY       DROP EVENT SESSION test_session ON SERVER END TRY BEGIN CATCH END CATCH GO   -- CREATES THE SESSION CREATE EVENT SESSION test_session ON SERVER ADD EVENT sqlserver.error_reported ADD TARGET package0.asynchronous_file_target -- CONFIGURES THE FILE TARGET (set filename = 'c:\temp\data1.xel' , metadatafile = 'c:\temp\data1.xem') GO   -- STARTS THE SESSION ALTER EVENT SESSION test_session ON SERVER STATE = START GO   -- GENERATES AN ERROR RAISERROR (N'HELLO WORLD', -- Message text.            1, -- Severity,            1, 7, 3, N'abcde'); -- Other parameters GO   -- STOPS LISTENING FOR THE EVENT ALTER EVENT SESSION test_session ON SERVER STATE = STOP GO   -- REMOVES THE EVENT SESSION FROM THE SERVER DROP EVENT SESSION test_session ON SERVER GO -- REMOVES THE EVENT SESSION FROM THE SERVER select CAST(event_data as XML) as event_data from sys.fn_xe_file_target_read_file ('c:\temp\data1*.xel','c:\temp\data1*.xem', null, null) This query will output the event data with our first hello world in the Extended Event format: <event name="error_reported" package="sqlserver" id="100" version="1" timestamp="2010-02-27T03:08:04.210Z"><data name="error"><value>50000</value><text /></data><data name="severity"><value>1</value><text /></data><data name="state"><value>1</value><text /></data><data name="user_defined"><value>true</value><text /></data><data name="message"><value>HELLO WORLD</value><text /></data></event> More on parsing event data in this post: Reading event data 101 Now let's move that lets move on to the other three Extended Event objects: -          Actions. This Extended Objects actions get executed before events are published (stored in buffers to be transferred to the targets). Currently they are used additional data (like the TSQL Statement related to an event, the session, the user) or generate a mini dump.   -          Predicates: Predicates express are logical expressions that specify what predicates to fire (E.g. only listen to errors with a severity greater than 16). This are composed of two Extended Objects: o   Predicate comparators: Defines an operator for a pair of values. Examples: §  Severity > 16 §  error_message = ‘Hello World!!’ o   Predicate sources: These are values that can be also used by the predicates. They are generic data that isn’t usually provided in the event (similar to the actions). §  Sqlserver.username = ‘Tintin’ As logical expressions they can be combined using logical operators (and, or, not).  Note: This pair always has to be first an event field or predicate source and then a value         Let’s do another small Example. We will trigger errors but we will use the ones that have severity >= 10 and the error message != ‘filter’. To verify this we will use the action sql_text that will attach the sql statement to the event data: -- TRIES TO ELIMINATE PREVIOUS SESSIONS BEGIN TRY       DROP EVENT SESSION test_session ON SERVER END TRY BEGIN CATCH END CATCH GO   -- CREATES THE SESSION CREATE EVENT SESSION test_session ON SERVER ADD EVENT sqlserver.error_reported       (ACTION (sqlserver.sql_text) WHERE severity = 2 and (not (message = 'filter'))) ADD TARGET package0.asynchronous_file_target -- CONFIGURES THE FILE TARGET (set filename = 'c:\temp\data2.xel' , metadatafile = 'c:\temp\data2.xem') GO   -- STARTS THE SESSION ALTER EVENT SESSION test_session ON SERVER STATE = START GO   -- THIS EVENT WILL BE FILTERED BECAUSE SEVERITY != 2 RAISERROR (N'PUBLISH', 1, 1, 7, 3, N'abcde'); GO -- THIS EVENT WILL BE FILTERED BECAUSE MESSAGE = 'FILTER' RAISERROR (N'FILTER', 2, 1, 7, 3, N'abcde'); GO -- THIS ERROR WILL BE PUBLISHED RAISERROR (N'PUBLISH', 2, 1, 7, 3, N'abcde'); GO   -- STOPS LISTENING FOR THE EVENT ALTER EVENT SESSION test_session ON SERVER STATE = STOP GO   -- REMOVES THE EVENT SESSION FROM THE SERVER DROP EVENT SESSION test_session ON SERVER GO -- REMOVES THE EVENT SESSION FROM THE SERVER select CAST(event_data as XML) as event_data from sys.fn_xe_file_target_read_file ('c:\temp\data2*.xel','c:\temp\data2*.xem', null, null)   This last statement will output one event with the following data: <event name="error_reported" package="sqlserver" id="100" version="1" timestamp="2010-03-05T23:15:05.481Z">   <data name="error">     <value>50000</value>     <text />   </data>   <data name="severity">     <value>2</value>     <text />   </data>   <data name="state">     <value>1</value>     <text />   </data>   <data name="user_defined">     <value>true</value>     <text />   </data>   <data name="message">     <value>PUBLISH</value>     <text />   </data>   <action name="sql_text" package="sqlserver">     <value>-- THIS ERROR WILL BE PUBLISHED RAISERROR (N'PUBLISH', 2, 1, 7, 3, N'abcde'); </value>     <text />   </action> </event> If you see more events, check if you have deleted previous event files. If so, please run   -- Deletes previous event files EXEC SP_CONFIGURE GO EXEC SP_CONFIGURE 'xp_cmdshell', 1 GO RECONFIGURE GO XP_CMDSHELL 'del c:\temp\data*.xe*' GO   or delete them manually.   More Info on Events: Extended Event Events More Info on Targets: Extended Event Targets More Info on Sessions: Extended Event Sessions More Info on Actions: Extended Event Actions More Info on Predicates: Extended Event Predicates Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Showing Egde Shaped Event Duration in StreamInsight using Debugger

    Whilst writing some courseware I wanted to be able to see the start and end times of Edge shaped events from within the debugger.  A quick recap on Edge events At the start of the event you do not know the end time and most probably cannot work it out or you should be using one of the other shapes. You enqueue an event (Start Edge) with the start time and payload of the event.  The end time of the event is set to infinity When you see the end edge come through, you enqueue another event (End Edge) with the previous start time and payload and restate the event’s end time.  This is the Retract Event All seems simple enough.  The problem is the debugger is a little shy about showing you what you need but you can get it to show you everything by also reading this article Here’s what I mean. Here is what the Event Debugger looks like by default when viewing 2 complete edge events.  Notice how all the end times are set to infinity   The above does not tell you for how long an event was valid.  I then add the “NewEndTime” column to the debugger output and there I can now see the duration of events.  You will see the Retract events (End Edge) have the same start time and payload as their respective start events (Start Edge)   You can follow the exact same logic when looking at Interval shape events.  They look a little different on the output adapter but using this article you can easily see what is happening.

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  • Boost::thread mutex issue: Try to lock, access violation

    - by user1419305
    I am currently learning how to multithread with c++, and for that im using boost::thread. I'm using it for a simple gameengine, running three threads. Two of the threads are reading and writing to the same variables, which are stored inside something i call PrimitiveObjects, basicly balls, plates, boxes etc. But i cant really get it to work, i think the problem is that the two threads are trying to access the same memorylocation at the same time, i have tried to avoid this using mutex locks, but for now im having no luck, this works some times, but if i spam it, i end up with this exception: First-chance exception at 0x00cbfef9 in TTTTT.exe: 0xC0000005: Access violation reading location 0xdddddded. Unhandled exception at 0x77d315de in TTTTT.exe: 0xC0000005: Access violation reading location 0xdddddded. These are the functions inside the object that im using for this, and the debugger is also blaming them for the exception. void PrimitiveObj::setPos(glm::vec3 in){ boost::mutex mDisposingMutex; boost::try_mutex::scoped_try_lock lock(mDisposingMutex); if ( lock) { position = in; boost::try_mutex::scoped_try_lock unlock(mDisposingMutex); } } glm::vec3 PrimitiveObj::getPos(){ boost::mutex myMutex; boost::try_mutex::scoped_try_lock lock(myMutex); if ( lock) { glm::vec3 curPos = position; boost::try_mutex::scoped_try_lock unlock(myMutex); return curPos; } return glm::vec3(0,0,0); } Any ideas?

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  • MMGR Questions, code use and thread-saftey

    - by chadb
    1) Is MMGR thread safe? 2) I was hoping someone could help me understand some code. I am looking at something where a macro is used, but I don't understand the macro. I know it contains a function call and an if check, however, the function is a void function. How does wrapping "(m_setOwner (FILE,_LINE_,FUNCTION),false)" ever change return types? #define someMacro (m_setOwner(__FILE__,__LINE__,__FUNCTION__),false) ? NULL : new ... void m_setOwner(const char *file, const unsigned int line, const char *func); 3) What is the point of the reservoir? 4) On line 770 ("void *operator new(size_t reportedSize)" there is the line "// ANSI says: allocation requests of 0 bytes will still return a valid value" Who/what is ANSI in this context? Do they mean the standards? 5) This is more of C++ standards, but where does "reportedSize" come from for "void *operator new(size_t reportedSize)"? 6) Is this the code that is actually doing the allocation needed? "au-actualAddress = malloc(au-actualSize);"

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  • Is it safe to use a boolean flag to stop a thread from running in C#

    - by Lirik
    My main concern is with the boolean flag... is it safe to use it without any synchronization? I've read in several places that it's atomic. class MyTask { private ManualResetEvent startSignal; private CountDownLatch latch; private bool running; MyTask(CountDownLatch latch) { running = false; this.latch = latch; startSignal = new ManualResetEvent(false); } // A method which runs in a thread public void Run() { startSignal.WaitOne(); while(running) { startSignal.WaitOne(); //... some code } latch.Signal(); } public void Stop() { running = false; startSignal.Set(); } public void Start() { running = true; startSignal.Set(); } public void Pause() { startSignal.Reset(); } public void Resume() { startSignal.Set(); } } Is this a safe way to design a task? Any suggestions, improvements, comments? Note: I wrote my custom CountDownLatch class in case you're wondering where I'm getting it from.

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  • WPF -- Event Threading, GUI updating question

    - by LSTayon
    I'm trying to send two events to the main window so that I can show some kind of animation that will let the user know that I'm updating the data. This is an ObservableCollection object so the OnPropertyChanged is immediately picked up by the bindings on the main window. The sleep is only in there so that the user can see the animation. However, the first OnPropetyChanged is never seen. I'm assuming this is because we're in a single thread here and the timer_Tick has to finish before the GUI updates. Any suggetions? In VB6 land we would use a DoEvents or a Form.Refresh. Thanks! private void timer_Tick(object sender, EventArgs e) { Loading = "Before: " + DateTime.Now.ToString(); OnPropertyChanged("Loading"); LoadData(); Thread.Sleep(1000); //Loading = Visibility.Hidden; Loading = "After: " + DateTime.Now.ToString(); OnPropertyChanged("Loading"); }

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  • Is there a straightforward way to have a thread-local instance variable?

    - by Dan Tao
    With the ThreadStatic attribute I can have a static member of a class with one instance of the object per thread. This is really handy for achieving thread safety using types of objects that don't guarantee thread-safe instance methods (e.g., System.Random). It only works for static members, though. Is there any straightforward way to declare a class member as thread-local, meaning, each class instance gets an object per thread?

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  • Non-Dom Element Event Binding with jQuery

    - by Rick Strahl
    Yesterday I had a short discussion with Dave Reed on Twitter regarding setting up fake ‘events’ on objects that are hookable. jQuery makes it real easy to bind events on DOM elements and with a little bit of extra work (that I didn’t know about) you can also set up binding to non-DOM element ‘event’ bindings. Assume for a second that you have a simple JavaScript object like this: var item = { sku: "wwhelp" , foo: function() { alert('orginal foo function'); } }; and you want to be notified when the foo function is called. You can use jQuery to bind the handler like this: $(item).bind("foo", function () { alert('foo Hook called'); } ); Binding alone won’t actually cause the handler to be triggered so when you call: item.foo(); you only get the ‘original’ message. In order to fire both the original handler and the bound event hook you have to use the .trigger() function: $(item).trigger("foo"); Now if you do the following complete sequence: var item = { sku: "wwhelp" , foo: function() { alert('orginal foo function'); } }; $(item).bind("foo", function () { alert('foo hook called'); } ); $(item).trigger("foo"); You’ll see the ‘hook’ message first followed by the ‘original’ message fired in succession. In other words, using this mechanism you can hook standard object functions and chain events to them in a way similar to the way you can do with DOM elements. The main difference is that the ‘event’ has to be explicitly triggered in order for this to happen rather than just calling the method directly. .trigger() relies on some internal logic that checks for event bindings on the object (attached via an expando property) which .trigger() searches for in its bound event list. Once the ‘event’ is found it’s called prior to execution of the original function. This is pretty useful as it allows you to create standard JavaScript objects that can act as event handlers and are effectively hookable without having to explicitly override event definitions with JavaScript function handlers. You get all the benefits of jQuery’s event methods including the ability to hook up multiple events to the same handler function and the ability to uniquely identify each specific event instance with post fix string names (ie. .bind("MyEvent.MyName") and .unbind("MyEvent.MyName") to bind MyEvent). Watch out for an .unbind() Bug Note that there appears to be a bug with .unbind() in jQuery that doesn’t reliably unbind an event and results in a elem.removeEventListener is not a function error. The following code demonstrates: var item = { sku: "wwhelp", foo: function () { alert('orginal foo function'); } }; $(item).bind("foo.first", function () { alert('foo hook called'); }); $(item).bind("foo.second", function () { alert('foo hook2 called'); }); $(item).trigger("foo"); setTimeout(function () { $(item).unbind("foo"); // $(item).unbind("foo.first"); // $(item).unbind("foo.second"); $(item).trigger("foo"); }, 3000); The setTimeout call delays the unbinding and is supposed to remove the event binding on the foo function. It fails both with the foo only value (both if assigned only as “foo” or “foo.first/second” as well as when removing both of the postfixed event handlers explicitly. Oddly the following that removes only one of the two handlers works: setTimeout(function () { //$(item).unbind("foo"); $(item).unbind("foo.first"); // $(item).unbind("foo.second"); $(item).trigger("foo"); }, 3000); this actually works which is weird as the code in unbind tries to unbind using a DOM method that doesn’t exist. <shrug> A partial workaround for unbinding all ‘foo’ events is the following: setTimeout(function () { $.event.special.foo = { teardown: function () { alert('teardown'); return true; } }; $(item).unbind("foo"); $(item).trigger("foo"); }, 3000); which is a bit cryptic to say the least but it seems to work more reliably. I can’t take credit for any of this – thanks to Dave Reed and Damien Edwards who pointed out some of these behaviors. I didn’t find any good descriptions of the process so thought it’d be good to write it down here. Hope some of you find this helpful.© Rick Strahl, West Wind Technologies, 2005-2010Posted in jQuery  

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  • Event Driven Programming 101

    - by JHarley1
    Good Morning, I previously asked the Q. of how Event Handlers Work (which I got a great answer for). I would now like to understand the basics of how are events are associated with on-screen objects? An explanation of how Events are associated with on Screen Objects: The application registers the Event, the Event Handler and the Component with the GUI Server. When an Event is detected the GUI Server has to link an Event to a Window and then to a Component, it then consults the Event / Component Table to identify which Handler (s) to be executed. I am having problems finding resources/papers that have mention of this process - especially of a Event / Component Table - can anyone clarify?

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  • Synchronizing issue: I want the main thread to be run before another thread but it sometimes doesn´t

    - by Rox
    I have done my own small concurrency framework (just for learning purposes) inspired by the java.util.concurrency package. This is about the Callable/Future mechanism. My code below is the whole one and is compilable and very easy to understand. My problem is that sometimes I run into a deadlock where the first thread (the main thread) awaits for a signal from the other thread. But then the other thread has already notified the main thread before the main thread went into waiting state, so the main thread cannot wake up. FutureTask.get() should always be run before FutureTask.run() but sometimes the run() method (which is called by new thread) runs before the get() method (which is called by main thread). I don´t know how I can prevent that. This is a pseudo code of how I want the two threads to be run. //From main thread: Executor.submit().get() (in get() the main thread waits for new thread to notify) ->submit() calls Executor.execute(FutureTask object) -> execute() starts new thread -> new thread shall notify `main thread` I cannot understand how the new thread can start up and run faster than the main thread that actually starts the new thread. Main.java: public class Main { public static void main(String[] args) { new ExecutorServiceExample(); } public Main() { ThreadExecutor executor = new ThreadExecutor(); Integer i = executor.submit(new Callable<Integer>() { @Override public Integer call() { return 10; } }).get(); System.err.println("Value: "+i); } } ThreadExecutor.java: public class ThreadExecutor { public ThreadExecutor() {} protected <V> RunnableFuture<V> newTaskFor(Callable c) { return new FutureTask<V>(c); } public <V> Future<V> submit(Callable<V> task) { if (task == null) throw new NullPointerException(); RunnableFuture<V> ftask = newTaskFor(task); execute(ftask); return ftask; } public void execute(Runnable r) { new Thread(r).start(); } } FutureTask.java: import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.ReentrantLock; import java.util.logging.Level; import java.util.logging.Logger; public class FutureTask<V> implements RunnableFuture<V> { private Callable<V> callable; private volatile V result; private ReentrantLock lock = new ReentrantLock(); private Condition condition = lock.newCondition(); public FutureTask(Callable callable) { if (callable == null) throw new NullPointerException(); this.callable = callable; } @Override public void run() { acquireLock(); System.err.println("RUN"+Thread.currentThread().getName()); V v = this.callable.call(); set(v); condition.signal(); releaseLock(); } @Override public V get() { acquireLock(); System.err.println("GET "+Thread.currentThread().getName()); try { condition.await(); } catch (InterruptedException ex) { Logger.getLogger(FutureTask.class.getName()).log(Level.SEVERE, null, ex); } releaseLock(); return this.result; } public void set(V v) { this.result = v; } private void acquireLock() { lock.lock(); } private void releaseLock() { lock.unlock(); } } And the interfaces: public interface RunnableFuture<V> extends Runnable, Future<V> { @Override void run(); } public interface Future<V> { V get(); } public interface Callable<V> { V call(); }

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  • Several client waiting for the same event

    - by ff8mania
    I'm developing a communication API to be used by a lot of generic clients to communicate with a proprietary system. This proprietary system exposes an API, and I use a particular classes to send and wait messages from this system: obviously the system alert me that a message is ready using an event. The event is named OnMessageArrived. My idea is to expose a simple SendSyncMessage(message) method that helps the user/client to simply send a message and the method returns the response. The client: using ( Communicator c = new Communicator() ) { response = c.SendSync(message); } The communicator class is done in this way: public class Communicator : IDisposable { // Proprietary system object ExternalSystem c; String currentRespone; Guid currentGUID; private readonly ManualResetEvent _manualResetEvent; private ManualResetEvent _manualResetEvent2; String systemName = "system"; String ServerName = "server"; public Communicator() { _manualResetEvent = new ManualResetEvent(false); //This methods are from the proprietary system API c = SystemInstance.CreateInstance(); c.Connect(systemName , ServerName); } private void ConnectionStarter( object data ) { c.OnMessageArrivedEvent += c_OnMessageArrivedEvent; _manualResetEvent.WaitOne(); c.OnMessageArrivedEvent-= c_OnMessageArrivedEvent; } public String SendSync( String Message ) { Thread _internalThread = new Thread(ConnectionStarter); _internalThread.Start(c); _manualResetEvent2 = new ManualResetEvent(false); String toRet; int messageID; currentGUID = Guid.NewGuid(); c.SendMessage(Message, "Request", currentGUID.ToString()); _manualResetEvent2.WaitOne(); toRet = currentRespone; return toRet; } void c_OnMessageArrivedEvent( int Id, string root, string guid, int TimeOut, out int ReturnCode ) { if ( !guid.Equals(currentGUID.ToString()) ) { _manualResetEvent2.Set(); ReturnCode = 0; return; } object newMessage; c.FetchMessage(Id, 7, out newMessage); currentRespone = newMessage.ToString(); ReturnCode = 0; _manualResetEvent2.Set(); } } I'm really noob in using waithandle, but my idea was to create an instance that sends the message and waits for an event. As soon as the event arrived, checks if the message is the one I expect (checking the unique guid), otherwise continues to wait for the next event. This because could be (and usually is in this way) a lot of clients working concurrently, and I want them to work parallel. As I implemented my stuff, at the moment if I run client 1, client 2 and client 3, client 2 starts sending message as soon as client 1 has finished, and client 3 as client 2 has finished: not what I'm trying to do. Can you help me to fix my code and get my target? Thanks!

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  • A script that writes errors and should create a event-error

    - by helmich
    this if it works should check the internet connection if there is a connection it does nothing. if there isn't a connection it should write a error in a txtfile if that happend 5 times it should create a error but it doesn't I will show you the whole code that i have now and the piece of code that i want in a loop. I can't get it in the way i want. I want it to creat 1 Event-error after 5 times writing to the file. this is the whole code i will put the code i want in a loop under it strDirectory = "Z:\text2" strFile = "\foutmelding.txt" strText = "De connectie is verbroken" strWebsite = "www.helmichbeens.com" If PingSite(strWebsite) Then WScript.Quit 'Website is pingable - no further action required Set objFSO = CreateObject("Scripting.FileSystemObject") RecordSingleEvent Dim fout For fout = 1 To 5 : Do If fout = 5 Then Exit Do Set WshShell = WScript.CreateObject("WScript.Shell") Call WshShell.LogEvent(1, "Test Event") Loop While False : next '------------------------------------ 'Record a single event in a text file '------------------------------------ Sub RecordSingleEvent If Not objFSO.FolderExists(strDirectory) Then objFSO.CreateFolder(strDirectory) Set objTextFile = objFSO.OpenTextFile(strDirectory & strFile, 8, True) objTextFile.WriteLine(Now & strText) objTextFile.Close End sub '---------------- 'Ping my web site '---------------- Function PingSite( myWebsite ) Set objHTTP = CreateObject( "WinHttp.WinHttpRequest.5.1" ) objHTTP.Open "GET", "http://" & myWebsite & "/", False objHTTP.SetRequestHeader "User-Agent", "Mozilla/4.0 (compatible; MyApp 1.0; Windows NT 5.1)" On Error Resume Next objHTTP.Send PingSite = (objHTTP.Status = 200) On Error Goto 0 End Function '----------------------------------------------- 'Counts the number of lines inside the text file '----------------------------------------------- Function EventCount(fout) strData = objFSO.OpenTextFile(strDirectory & strFile,ForReading).ReadAll arrLines = Split(strData,vbCrLf) EventCount = UBound(arrLines) End Function This is the whole code, and it doesnt work correctly becaus it creats a event-log rightaway and it should do that after the script has written 5 times to the textfile here is the code that writes to a textfile Sub RecordSingleEvent If Not objFSO.FolderExists(strDirectory) Then objFSO.CreateFolder(strDirectory) Set objTextFile = objFSO.OpenTextFile(strDirectory & strFile, 8, True) objTextFile.WriteLine(Now & strText) objTextFile.Close End sub and here is the code but this part doesnt not work or atleast i think it is this part Dim fout For fout = 1 To 5 : Do If fout = 5 Then Exit Do Set WshShell = WScript.CreateObject("WScript.Shell") Call WshShell.LogEvent(1, "Test Event") Loop While False : next Function EventCount(fout) strData = objFSO.OpenTextFile(strDirectory & strFile,ForReading).ReadAll arrLines = Split(strData,vbCrLf) EventCount = UBound(arrLines) End Function this is the not working part and I don't know what to do anymore so can you please take a look at it tank you very much. btw: this code can be very usefull for a network administrator

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  • Win32 Event vs Semaphore

    - by JP
    Basically I need a replacement for Condition Variable and SleepConditionVariableCS because it only support Vista and UP. (For C++) Some suggested to use Semaphore, I also found CreateEvent. Basically, I need to have on thread waiting on WaitForSingleObject, until something one or more others thread tell me there is something to do. In which context should I use a Semaphore vs an Win Event? Thanks

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