Search Results

Search found 4335 results on 174 pages for 'wait'.

Page 141/174 | < Previous Page | 137 138 139 140 141 142 143 144 145 146 147 148  | Next Page >

• How to track the touch vector?

  - by mystify

  I need to calculate the direction of dragging a touch, to determine if the user is dragging up the screen, or down the screen. Actually pretty simple, right? But: 1) Finger goes down, you get -touchesBegan:withEvent: called 2) Must wait until finger moves, and -touchesMoved:withEvent: gets called 3) Problem: At this point it's dangerous to tell if the user did drag up or down. My thoughts: Check the time and accumulate calculates vectors until it's secure to tell the direction of touch. Easy? No. Think about it: What if the user holds the finger down for 5 minutes on the same spot, but THEN decides to move up or down? BANG! Your code would fail, because it tried to determine the direction of touch when the finger didn't move really. Problem 2: When the finger goes down and stays at the same spot for a few seconds because the user is a bit in the wind and thinks about what to do now, you'll get a lot of -touchesMoved:withEvent: calls very likely, but with very minor changes in touch location. So my next thought: Do the accumulation in -touchesMoved:withEvent:, but only if a certain threshold of movement has been exceeded. I bet you have some better concepts in place?

  Read the article

• Parse large XML file w/ script or use BioPython API ?

  - by jeremy04

  Hey guys this is my first question on here. I'm trying to make a local copy of the UniprotKB in SQL. The UniprotKB is 2.1GB, and it comes in XML and a special text format used by SwissProt Here are my options: 1) Use a SAX parser (XML) - I chose Ruby, and Nokogiri. I started writing the parser, but my initial reaction: how would I map the XML schema to the SAX parser? 2) BioPython - I already have BioSQL/Biopython installed, which literally created my SQL schema for me, and I was able to successfully insert one SwissProt/Uniprot txt file into the database. I'm running it right now (crosses fingers) on the entire 2.1gb. Here is the code I'm running: from Bio import SeqIO from BioSQL import BioSeqDatabase from Bio import SwissProt server = BioSeqDatabase.open_database(driver = "MySQLdb", user = "root", passwd = "", host="localhost", db = "bioseqdb") db = server["uniprot"] iterator = SeqIO.parse(open("/path/to/uniprot_sprot.dat", "r"), "swiss") db.load(iterator) server.commit() Edit: it's now crashing because the transactions are getting locked (since the tables are Innodb) Error Number: 1205 Lock wait timeout exceeded; try restarting transaction. I'm using MySQL version: 5.1.43 Should I switch my database to Postgrelsql ?

  Read the article

• [C#] Two System.Drawing methods manifest slow drawing or flickery: Solutions? or Other Options?

  - by Luke Mcneice

  Hi all, I am doing a little graphing via the System.Drawing and im having a few problems. I'm holding data in a Queue and i'm drawing(graphing) out that data onto three picture boxes this method fills the picture box then scrolls the graph across. so not to draw on top of the previous drawings (and graduly looking messier) i found 2 solutions to draw the graph. Call plot.Clear(BACKGOUNDCOLOR) before the draw loop [block commented] although this causes a flicker to appear from the time it takes to do the actual drawing loop. call plot.DrawLine(channelPen[5], j, 140, j, 0); just before each drawline [commented] although this causes the drawing to start ok then slow down very quickly to a crawl as if a wait command had been placed before the draw command. Here is the Code for reference: /*plotx.Clear(BACKGOUNDCOLOR) ploty.Clear(BACKGOUNDCOLOR) plotz.Clear(BACKGOUNDCOLOR)*/ for (int j = 1; j < 599; j++) { if (j > RealTimeBuffer.Count - 1) break; QueueEntity past = RealTimeBuffer.ElementAt(j - 1); QueueEntity current = RealTimeBuffer.ElementAt(j); if (j == 1) { //plotx.DrawLine(channelPen[5], 0, 140, 0, 0); //ploty.DrawLine(channelPen[5], 0, 140, 0, 0); //plotz.DrawLine(channelPen[5], 0, 140, 0, 0); } //plotx.DrawLine(channelPen[5], j, 140, j, 0); plotx.DrawLine(channelPen[0], j - 1, (((past.accdata.X - 0x7FFF) / 256) + 64), j, (((current.accdata.X - 0x7FFF) / 256) + 64)); //ploty.DrawLine(channelPen[5], j, 140, j, 0); ploty.DrawLine(channelPen[1], j - 1, (((past.accdata.Y - 0x7FFF) / 256) + 64), j, (((current.accdata.Y - 0x7FFF) / 256) + 64)); //plotz.DrawLine(markerPen, j, 140, j, 0); plotz.DrawLine(channelPen[2], j - 1, (((past.accdata.Z - 0x7FFF) / 256) + 94), j, (((current.accdata.Z - 0x7FFF) / 256) + 94)); } Is there any tricks to avoid these overheads? If not would there be any other/better solutions?

  Read the article

• Ensuring that all callbacks were completed before sending a new request through a DuplexChannel usin

  - by Etan

  I am experiencing some issues when using a Callback in a WCF project. First, the server invokes some function Foo on the client which then forwards the request to a Windows Forms GUI: GUI CLASS delegate void DoForward(); public void ForwardToGui() { if (this.cmdSomeButton.InvokeRequired) { DoForward d = new DoForward(ForwardToGui); this.Invoke(d); } else { Process(); // sets result variable in callback class as soon as done } } } CALLBACK CLASS object _m = new object(); private int _result; public int result { get { return _result; } set { _result = value; lock(_m) { Monitor.PulseAll(_m); } } } [OperationContract] public int Foo() { result = 0; Program.Gui.ForwardToGui(); lock(_m) { Monitor.Wait(_m, 30000); } return result; } The problem now is that the user should be able to cancel the process, which doesn't work properly: SERVER INTERFACE [OperationContract] void Cleanup(); GUI CLASS private void Gui_FormClosed(object sender, EventArgs e) { Program.callbackclass.nextAction = -1; // so that the monitor pulses and Foo() returns Program.server.Cleanup(); } The problem with this is that Cleanup() hangs. However, when I close the form when Process() is not running, it works properly. The source seems to be that the Cleanup() is called before the monitor pulses etc and therefore a new request is sent to the server before the last request from the server has not yet been responded. How can I solve this problem? How can I ensure before calling Cleanup() that no Foo() is currently being executed?

  Read the article

• In threads, WaitForMultipleObjects never returns if set to INFINITE

  - by AKN

  Let say I have three thread handles HandleList[0] = hThread1; HandleList[1] = hThread2; HandleList[2] = hThread3; /*All the above are of type HANDLE*/ Before closing the application, I want the thread to get its task done. So I want to make app wait till thread completes. So I do, WaitForMultipleObjects(3, HandleList, TRUE, INFINITE ); By this I'm able to make the thread, complete its task. But control never move to next line after the call to WaitForMultileObjects irrespective of all thread completing its task. If I use, some seconds instead of INFINITE, it comes to next line after that many secs, irrspective of whether thread completes its task or not. WaitForMultipleObjects(3, HandleList, TRUE, 10000 ); My problem here is, I'm can't go for seconds, as I may not be sure whether the threads will complete its task with the given time. To list my problem in simple words, I want all my thread to finish the task, before I close my app. How can I achieve it using WaitForMultipleObjects API?

  Read the article

• How to prevent the other threads from accessing a method when one thread is accessing a method?

  - by geeta

  I want to search for a string in 10 files and write the matching lines to a single file. I wrote the matching lines from each file to 10 output files(o/p file1,o/p file2...) and then copied those to a single file using 10 threads. But the output single file has mixed output(one line from o/p file1,another line from o/p file 2 etc...) because its accessed simultaneously by many threads. If I wait for all threads to complete and then write the single file it will be much slower. I want the output file to be written by one thread at a time. What should i do? My source code:(only writing to single file method) public void WriteSingle(File output_file,File final_output) throws IOException { synchronized(output_file){ System.out.println("Writing Single file"); FileOutputStream fo = new FileOutputStream(final_output,true); FileChannel fi = fo.getChannel(); FileInputStream fs = new FileInputStream(output_file); FileChannel fc = fs.getChannel(); int maxCount = (64 * 1024 * 1024) - (32 * 1024); long size = fc.size(); long position = 0; while (position < size) { position += fc.transferTo(position, maxCount, fi); } } }

  Read the article

• How do I make a HTTP POST request to an url from within a c++ dll?

  - by tjorriemorrie

  Hi, there's an open-source application I need to use. It allows you to use a custom dll. Unfortunately, I can't code c++; i don't like it; it don't want to learn it. I do know PHP very well however, thus you can see that I'll rather do my logic within a PHP application. Thus I'm thinking about posting the data from c++/dll to a url on my localhost. (i have my local server set up, that's not the problem). I need to post a large amount of variables (thus a POST and not GET request required). The return value will only be one (int)variable, either 0, 1 or 2. So I need a c++ function that: 1) will post variables to an url. 2) Wait for, and receive the answer. The data type can be in xml, soap, json, whatever, doesn't matter. Is there anyone that can write a little c++ http function for me? pretty please? ;)

  Read the article

• What is the correct high level schema.org microdata itemtype for a retail brand/company homepage?

  - by kpowz

  I'd like to hear which schema.org itemtype others would recommend using or have used in the case of completing a retail brand's company homepage microdata. Take for example TOMS's shoes: Example #1 - Using /Corporation as the high-level itemtype one can include a lot of great /Organization microdata, but nothing about the retail store. <html itemscope='itemscope' itemtype="http://schema.org/Website> <head></head> <body itemscope='itemscope' itemtype="http://schema.org/Corporation> various microdata here probably including Product microdata </body> </html> NOTE: the only schema.org property specific to /Corporation is tickerSymbol & TOMS doesn't have one. Example #2 - This code would work if TOMS started their own channel of physical retail stores & each location had it's own homepage. However, for TOMS's.com, although accurate schematically & more descriptive at the face, this is incorrect microdata markup for TOMS.com, because /ShoeStore derives from /LocalBusiness - which must represent a physical place. <html itemscope='itemscope' itemtype='http://schema.org/Website'> <head></head> <body itemscope='itemscope' itemtype='http://schema.org/ShoeStore'> a whole bunch of jabber here </body> </html> NOTE: Since TOMS is virtual & thus can't be a /Store this means you lose really cool properties like 'currenciesAccepted', 'paymentAccepted' & 'priceRange'. Is this just a 'sit and wait' situation until more schemas are approved for 'virtual places' or is there a validation-passing way to get the best of both worlds?

  Read the article

• How can I save an ASP.NET IFRAME from a custom entity's OnSave event, reliably?

  - by Forgotten Semicolon

  I have a custom ASP.NET solution deployed to the ISV directory of an MS Dynamics CRM 4.0 application. We have created a custom entity, whose data entry requires more dynamism than is possible through the form builder within CRM. To accomplish this, we have created an ASP.NET form surfaced through an IFRAME on the entity's main form. Here is how the saving functionality is currently laid out: There is an ASP.NET button control on the page that saves the entity when clicked. This button is hidden by CSS. The button click event is triggered from the CRM OnSave javascript event. The event fires and the entity is saved. Here are the issues: When the app pool is recycled, the first save (or few) may: not save be delayed (ie. the interface doesn't show an update, until the page has been refreshed after a few sec) Save and Close/New may not save For issue 1.1 and 2, what seems to be happening is that while the save event is fired for the custom ASP.NET page, the browser has moved on/refreshed the page, invalidating the request to the server. This results in the save not actually completing. Right now, this is mitigated with a kludge javascript delay loop for a few seconds after calling the button save event, inside the entity OnSave event. Is there any way to have the OnSave event wait for a callback from the IFRAME?

  Read the article

• Can no longer debug ActiveX controls in Visual Studio 2008

  - by Phenglei Kai

  For a long time I would throw up a DebugBreak() or ASSERT(false) in the startup code of my ActiveX control, load up IE, go to a localhost page hosting my control, wait for the dialog to show up, then debug my application. I could also launch it under the debugger by setting IE as the container. I tried again for the first time in 2 months and now this no longer works. If I use the ASSERT(false) method, when I get the Visual C++ Debug dialog and click "retry", IE simply closes without any debugger activity. When I try launching from VS2008 and hoping the DebugBreak() will kick in after I load the page, VS2008 does break, but it says either the "RPC Server is Unavailable" or the "RPC Client Call failed." I am never allowed to have my application in the debugger and it doesn't show up in the modules list of VS. The stack trace in VS2008 only contains Microsoft DLLs and modules and not a hint of my code. I assume it's something I've picked up through Windows Update that broke this. Has anyone else ever seen this issue and know how to make it go away? As it stands, I'm now completely unable to debug my ActiveX control.

  Read the article

• How to determine loading status of images not attached to the DOM

  - by Rookwood

  I am working on a bit of javascript to plot data on a <canvas. The data points are marked by one of several different (small) image files. I am attempting to have the plot method wait until all the images are loaded. My best attempt thus far is such: var icon = { left : { air : new Image(), bone : new Image(), }, right : { air: new Image(), bone : new Image(), }, }; icon.left.air.src = option.imgPath + 'left.air.png'; icon.right.air.src = option.imgPath + 'right.air.png'; icon.left.bone.src = option.imgPath + 'left.bone.png'; icon.right.bone.src = option.imgPath + 'right.bone.png'; function main() { Canvas.draw(); // Make sure our image icons are loaded before we try to plot $(icon.left.air).load(function() { $(icon.right.air).load(function() { $(icon.left.bone).load(function() { $(icon.right.bone).load(function() { Data.plot(); }); }); }); }); } This works as expected most of the time. On occasion, it will fail and no data will be plotted. Inserting several console.log() statements shows that the script will silently stop working through the series of .load() statements, though code that comes after will be executed. My questions are as follows: Am I approaching this the right way? Is there a way to attach an event to my icon object that will fire once all of the images inside are loaded? This is a jquery plugin, so obviously jquery-based solutions are just as acceptable as vanilla javascript.

  Read the article

• writing a meta refresh method for rails

  - by aaronstacy

  I want a method in app/controllers/application.rb that can prepend/append text to whatever template gets rendered. Of course I can't call render twice w/o getting a double render error, so is this possible? I want to redirect after a delay using a meta refresh. Here's what I've got: app/controllers/application_controller.rb: def redirect_after_delay (url, delay) @redirect_delay = delay @redirect_url = url render end app/views/layouts/application.html.erb <!DOCTYPE html> <html lang="en"> <head> <%= yield :refresh_tag %> </head> <body> <%= yield %> </body> </html> So then if I want to add a redirect-after-delay, I add the following to 1) my controller and 2) the action's view: app/controllers/my_controller.rb def my_action redirect_after_delay 'http://www.google.com', 3 if some_condition end app/views/my_controller/my_action.html.erb <% content_for :refresh_tag do %> <meta http-equiv='refresh' content='<%=@redirect_delay%>;url=<%=@redirect_url%>'> <% end %> <h1>Please wait while you are redirected...</h1> Since the content_for block never changes, is it possible to do this in some generic way so that I don't have to put <%= yield :refresh_tag %> in each template? (e.g. could redirect_after_delay add it into whatever template is going to be rendered?)

  Read the article

• How to refresh jQuery Selector Value after an execution?

  - by Devyn

  Hi, I have like this. $(document).ready(function() { var $clickable_pieces = $('.chess_piece').parent(); $($clickable_pieces).addClass('selectee'); // add selectee class var $selectee = $('.chess_square.selectee'); // wait for click $($selectee).bind('click',function(){ $('.chess_square.selected').removeClass('selected'); $(this).addClass('selected'); { ........... } }); I initially inject 'selectee' class to all div which has 'chess_piece' class then I select DIVs with that class $('.chess_square.selectee'). <div id="clickable"> <div id="div1" class="chess_square"> </div> <div id="div2" class="chess_square selectee"> <div id="sub1" class="chess_piece queen"></div> </div> <div id="div3" class="chess_square"> </div> </div> There are two type of DIV element with class named 'chess_square selectee' and 'chess_square' which doesn't meant to be clickable. I move around Sub DIV of 'rps_square selectee' from DIV2 to DIV1 and add and remove classes to be exactly same like this. The meaning is Queen Piece is moved from Div2 to Div1. <div id="div1" class="chess_square selectee"> <div id="sub1" class="chess_piece queen"></div> </div> <div id="div2" class="chess_square"> </div> <div id="div3" class="chess_square"> </div> However, the problem is jQuery doesn't update var $selectee = $('.rps_square.selectee');. Even though I changed class names, DIV1 is not clickable and DIV2 is still clickable. By the way, I've used jQuery UI selectable but doesn't refresh either.

  Read the article

• How can I get an NPC to move randomly in XNA?

  - by Fishwaffles

  I basically want a character to walk in one direction for a while, stop, then go in another random direction. Right now my sprites look but don't move, randomly very quickly in all directions then wait and have another seizure. I will post the code I have so far in case that is useful. class NPC: Mover { int movementTimer = 0; public override Vector2 direction { get { Random rand = new Random(); int randDirection = rand.Next(8); Vector2 inputDirection = Vector2.Zero; if (movementTimer >= 50) { if (randDirection == 4) { inputDirection.X -= 1; movingLeft = true; } else movingLeft = false; if (randDirection == 1) { inputDirection.X += 1; movingRight = true; } else movingRight = false; if (randDirection == 2) { inputDirection.Y -= 1; movingUp = true; } else movingUp = false; if (randDirection == 3) { inputDirection.Y += 25; movingDown = true; } else movingDown = false; if (movementTimer >= 100) { movementTimer = 0; } } return inputDirection * speed; } } public NPC(Texture2D textureImage, Vector2 position, Point frameSize, int collisionOffset, Point currentFrame, Point sheetSize, Vector2 speed) : base(textureImage, position, frameSize, collisionOffset, currentFrame, sheetSize, speed) { } public NPC(Texture2D textureImage, Vector2 position, Point frameSize, int collisionOffset, Point currentFrame, Point sheetSize, Vector2 speed, int millisecondsPerframe) : base(textureImage, position, frameSize, collisionOffset, currentFrame, sheetSize, speed, millisecondsPerframe) { } public override void Update(GameTime gameTime, Rectangle clientBounds) { movementTimer++; position += direction; if (position.X < 0) position.X = 0; if (position.Y < 0) position.Y = 0; if (position.X > clientBounds.Width - frameSize.X) position.X = clientBounds.Width - frameSize.X; if (position.Y > clientBounds.Height - frameSize.Y) position.Y = clientBounds.Height - frameSize.Y; base.Update(gameTime, clientBounds); } }

  Read the article

• _beginthreadx and socket

  - by user638197

  hi, i have a question about the _beginthreadx function In the third and fourth parameter: if i have this line to create the thread hThread=(HANDLE)_beginthreadex(0,0, &RunThread, &m_socket,CREATE_SUSPENDED,&threadID ); m_socket is the socket that i want inside the thread (fourth parameter) and i have the RunThread function (third parameter) in this way static unsigned __stdcall RunThread (void* ptr) { return 0; } It is sufficient to create the thread independently if m_socket has something or not? Thanks in advance Thank you for the response Ciaran Keating helped me understand better the thread I'll explain a little more the situation I´m creating the tread in this function inside a class public: void getClientsConnection() { numberOfClients = 1; SOCKET temporalSocket = NULL; firstClient = NULL; secondClient = NULL; while (numberOfClients < 2) { temporalSocket = SOCKET_ERROR; while (temporalSocket == SOCKET_ERROR) { temporalSocket = accept(m_socket, NULL, NULL); //----------------------------------------------- HANDLE hThread; unsigned threadID; hThread=(HANDLE)_beginthreadex(0,0, &RunThread, &m_socket,CREATE_SUSPENDED,&threadID ); WaitForSingleObject( hThread, INFINITE ); if(!hThread) printf("ERROR AL CREAR EL HILO: %ld\n", WSAGetLastError()); //----------------------------------------------- } if(firstClient == NULL) { firstClient = temporalSocket; muebleC1 = temporalSocket; actionC1 = temporalSocket; ++numberOfClients; printf("CLIENTE 1 CONECTADO\n"); } else { secondClient = temporalSocket; muebleC2 = temporalSocket; actionC2 = temporalSocket; ++numberOfClients; printf("CLIENTE 2 CONECTADO\n"); } } } What i'm trying to do is to have the socket inside the thread while wait for a client connection Is this feasible as i have the code of the thread? I can change the state of the thread that is not a problem Thanks again

  Read the article

• Why Backbone.js isn't binding my event

  - by Saif Bechan

  I have a router like this, as main entry point: window.AppRouter = Backbone.Router.extend({ routes: { '': 'login' }, login: function(){ userLoginView = new UserLoginView(); } }); var appRouter = new AppRouter; Backbone.history.start({pushState: true}); I have a model/collection/view like this: window.User = Backbone.Model.extend({}); window.Users = Backbone.Collection.extend({ model: User }); window.UserLoginView = Backbone.View.extend({ events: { 'click #login-button': 'loginAction' }, initialize: function(){ _.bindAll(this, 'render', 'loginAction'); }, loginAction: function(){ var uid = $("#login-username").val(); var pwd = $("#login-password").val(); var user = new User({uid:uid, pwd:pwd}); } }); And body of my HTML looks like this: <form action="#" method="POST" id="login-form"> <p> <label for="login-username">username</label> <input type="text" id="login-username" autofocus /> </p> <p> <label for="login-password">password</label> <input type="password" id="login-password" /> </p> <a id="login-button" href="#">Inloggen</a> </form> Note: The HTML comes from Node.js using express.js, should I maybe wait for a document ready event somewhere? Edit: I have tried this, create the view when ready, did not solve the problem. $(function(){ userLoginView = new UserLoginView(); });

  Read the article

• AJAX: Permission denied to access property in iframe

  - by Muhammad Sajid

  Hi I created an php website which uses for AJAX post and was live at http://sprook.com.au/ but my client change it's domain to http://www.sprookit.net/ from his service provider Godaddy and now the firebug says: Permission denied to access property 'stopAjax' here stopAjax is my method name. script is there: <div class="post_area"> <form action="post.php" method="post" id="addVideo" enctype="multipart/form-data" target="post" onsubmit="return startAjax(this);"> <iframe id="post" name="post" src="#" style="width:0;height:0;border:0px solid #fff;"></iframe> <table width="860" border="0" cellspacing="0" cellpadding="0"> <tr> <td width="435">POST YOUR AD FREE<br /> <em>Paste embed code from YouTube</em></td> <td width="322"><input type="text" id="videoLink" name="videoLink" class="input_textbox" /> </td> <td width="95"><input type="submit" name="set_video_link" id="set_video_link" value="" class="submt_post" /> </td> </tr> <tr> <td>&nbsp;</td> <td><div id="process"> Connecting please wait <img src="images/loading.gif" /><br/> </div></td> </tr> </table> </form> </div> And all content comes from old domain i removed index file and it stoped working, therefore it is cleared that scripts run from old domain.

  Read the article

• CreateProcess() fails with an access violation

  - by John Doe

  My aim is to execute an external executable in my program. First, I used system() function, but I don't want the console to be seen to the user. So, I searched a bit, and found CreateProcess() function. However, when I try to pass a parameter to it, I don't know why, it fails. I took this code from MSDN, and changed a bit: #include <windows.h> #include <stdio.h> #include <tchar.h> void _tmain( int argc, TCHAR *argv[] ) { STARTUPINFO si; PROCESS_INFORMATION pi; ZeroMemory( &si, sizeof(si) ); si.cb = sizeof(si); ZeroMemory( &pi, sizeof(pi) ); /* if( argc != 2 ) { printf("Usage: %s [cmdline]\n", argv[0]); return; } */ // Start the child process. if( !CreateProcess( NULL, // No module name (use command line) L"c:\\users\\e\\desktop\\mspaint.exe", // Command line NULL, // Process handle not inheritable NULL, // Thread handle not inheritable FALSE, // Set handle inheritance to FALSE 0, // No creation flags NULL, // Use parent's environment block NULL, // Use parent's starting directory &si, // Pointer to STARTUPINFO structure &pi ) // Pointer to PROCESS_INFORMATION structure ) { printf( "CreateProcess failed (%d).\n", GetLastError() ); return; } // Wait until child process exits. WaitForSingleObject( pi.hProcess, INFINITE ); // Close process and thread handles. CloseHandle( pi.hProcess ); CloseHandle( pi.hThread ); } However, this code crated access violation somehow. Can I execute mspaint without showing user the console? Thank you very much.

  Read the article

• problem with implementing a simple work queue

  - by John Deerikio

  Hi all, I am having troubles with implementing a simple work queue. Doing some analysis, I am facing a subtle problem. The work queue is backed by a regular linked list. The code looks like this (simplified): 0. while (true) 1. while (enabled == true) 2. acquire lock on the list and get the next action to be executed (blocking operation) (store it in a local variable) 3. execute the action (outside the lock on the list on previous line) 4. get lock on this work queue 5. wait until this work queue has been notified (triggered when setEnabled(true) has been callled) The setEnabled(e) operation looks like this (simplified): enabled = e if (enabled == true) acquire lock on this work queue and do notify() Although this works, there is a condition in which a deadlock occurs. It happens in the following rare situation: while an action is being executed, setEnabled(false) is called just before step (4) is entered, setEnabled(true) is called now step (5) keeps waiting forever, because this work queue has already been notified How do I solve this? I have been looking at this for some time, but I cannot come up with a solution. Please note I am fairly new to thread synchronization. Thanks a lot.

  Read the article

• Does waitpid yield valid status information for a child process that has already exited?

  - by dtrebbien

  If I fork a child process, and the child process exits before the parent even calls waitpid, then is the exit status information that is set by waitpid still valid? If so, when does it become not valid; i.e., how do I ensure that I can call waitpid on the child pid and continue to get valid exit status information after an arbitrary amount of time, and how do I "clean up" (tell the OS that I am no longer interested in the exit status information for the finished child process)? I was playing around with the following code, and it appears that the exit status information is valid for at least a few seconds after the child finishes, but I do not know for how long or how to inform the OS that I won't be calling waitpid again: #include <assert.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/wait.h> int main() { pid_t pid = fork(); if (pid < 0) { fprintf(stderr, "Failed to fork\n"); return EXIT_FAILURE; } else if (pid == 0) { // code for child process _exit(17); } else { // code for parent sleep(3); int status; waitpid(pid, &status, 0); waitpid(pid, &status, 0); // call `waitpid` again just to see if the first call had an effect assert(WIFEXITED(status)); assert(WEXITSTATUS(status) == 17); } return EXIT_SUCCESS; }

  Read the article

• cross-platform development for mobile devices

  - by user924

  What language/framework is best worth learning for mobile application development? My specific situation is that I'm very familiar with Java and C++ (I especially love Qt), but have limited experience with other languages. Some options I'm considering: 1) Learn Objective-C and all the iPhone-specific tools I do have access to a mac. The downside here is I'm restricted to the iPhone, so I'd have to rewrite almost everything if I wanted to branch off into another mobile device (or move later to a cross-platform framework). Even after knowing Objective-C, it seems like other frameworks might be more efficient/faster to code in? 2) Use some existing cross-platform framework for development I've looked at rhomobile, but I only have limited experience with Ruby (and at first glance, it might be a little pricey comapred to other options). Appcelerator also looks popular and nice, but it uses html/css/javascript. Airplaysdk looks good, but it's new and I haven't been able to see much written about it (is it worth going for?). 3) Wait for something better to come along How far away is Qt for the iPhone? That would be ideal, but it isn't available now. So what do you recommend? Productivity/efficiency is my top priority, although learning a useful language for the long term would also be okay. Thanks

  Read the article

• C# Step by Step Execution

  - by Sheldon

  Hi. I'm building an app that uses and scanner API and a image to other format converter. I have a method (actually a click event) that do this: private void ButtonScan&Parse_Click(object sender, EventArgs e) { short scan_result = scanner_api.Scan(); if (scan_result == 1) parse_api.Parse(); // This will check for a saved image the scanner_api stores on disk, and then convert it. } The problem is that the if condition (scan_result == 1) is evaluated inmediatly, so it just don't work. How can I force the CLR to wait until the API return the convenient result. NOTE Just by doing something like: private void ButtonScan&Parse_Click(object sender, EventArgs e) { short scan_result = scanner_api.Scan(); MessageBox.Show("Result = " + scan_result); if (scan_result == 1) parse_api.Parse(); // This will check for a saved image the scanner_api stores on disk, and then convert it. } It works and display the results. Is there a way to do this, how? Thank you very much!

  Read the article

• Fibonacci in C works great with 1 - 18 but 19 does nothing at all...

  - by shevron

  Yeah right... we are forced to programm some good old C at our university... ;) So here's my problem: We got the assignment to program a little program that show a fibonacci sequence from 1 to n 1 to 18 works great. But from 19 the program does nothing at all and just exit as it's done. I can not find the error... so please give me a hint. :) #include #include #include #include int main(int argc, char **argv) { pid_t pid; int fib[argc]; int i, size; size = strtol(argv[1], NULL, 0L); fib[0] = 0; fib[1] = 1; pid = fork(); printf("size = %d \n", size); if(pid == 0){ for(i = 2; i 0){ // Parent, because pid 0 wait(NULL); printf("\n"); exit(1); } } Thanks already!

  Read the article

• How does the receiver of a cipher text know the IV used for encryption?

  - by PatrickL

  If a random IV is used in encrypting plain text, how does the receiver of the cipher text know what the IV is in order to decrypt it? This is a follow-up question to a response to the previous stackoverflow question on IVs here. The IV allows for plaintext to be encrypted such that the encrypted text is harder to decrypt for an attacker. Each bit of IV you use will double the possibilities of encrypted text from a given plain text. The point is that the attacker doesn't know what the IV is and therefore must compute every possible IV for a given plain text to find the matching cipher text. In this way, the IV acts like a password salt. Most commonly, an IV is used with a chaining cipher (either a stream or block cipher). ... So, if you have a random IV used to encrypt the plain text, how do you decrypt it? Simple. Pass the IV (in plain text) along with your encrypted text. Wait. You just said the IV is randomly generated. Then why pass it as plain text along with the encrypted text?

  Read the article

• Queueing method calls - any idea how?

  - by TomTom

  I write a heavily asynchronseous application. I am looking for a way to queue method calls, similar to what BeginInvoke / EndInvoke does.... but on my OWN queue. The reaqson is that I am having my own optimized message queueing system using a threadpool but at the same time making sure every component is single threaded in the requests (i.e. one thread only handles messages for a component). I Have a lot of messages going back and forth. For limited use, I would really love to be able to just queue a message call with parameters, instead of having to define my own parameter, method wrapping / unwrapping just for the sake of doing a lot of admnistrative calls. I also do not always want to bypass the queue, and I definitely do not want the sending service to wait for the other service to respond. Anyone knows of a way to intercept a method call? Some way to utilize TransparentProxy / Virtual Proxy for this? ;) ServicedComponent? I would like this to be as little overhead as possible ;)

  Read the article

< Previous Page | 137 138 139 140 141 142 143 144 145 146 147 148  | Next Page >