Search Results

Search found 16237 results on 650 pages for 'lock free'.

Page 396/650 | < Previous Page | 392 393 394 395 396 397 398 399 400 401 402 403  | Next Page >

  • Shared value in parallel python

    - by Jonathan
    Hey all- I'm using ParallelPython to develop a performance-critical script. I'd like to share one value between the 8 processes running on the system. Please excuse the trivial example but this illustrates my question. def findMin(listOfElements): for el in listOfElements: if el < min: min = el import pp min = 0 myList = range(100000) job_server = pp.Server() f1 = job_server.submit(findMin, myList[0:25000]) f2 = job_server.submit(findMin, myList[25000:50000]) f3 = job_server.submit(findMin, myList[50000:75000]) f4 = job_server.submit(findMin, myList[75000:100000]) The pp docs don't seem to describe a way to share data across processes. Is it possible? If so, is there a standard locking mechanism (like in the threading module) to confirm that only one update is done at a time? l = Lock() if(el < min): l.acquire if(el < min): min = el l.release I understand I could keep a local min and compare the 4 in the main thread once returned, but by sharing the value I can do some better pruning of my BFS binary tree and potentially save a lot of loop iterations. Thanks- Jonathan

    Read the article

  • Thread implemented as a Singleton

    - by rocknroll
    Hi all, I have a commercial application made with C,C++/Qt on Linux platform. The app collects data from different sensors and displays them on GUI. Each of the protocol for interfacing with sensors is implemented using singleton pattern and threads from Qt QThreads class. All the protocols except one work fine. Each protocol's run function for thread has following structure: void <ProtocolClassName>::run() { while(!mStop) //check whether screen is closed or not { mutex.lock() while(!waitcondition.wait(&mutex,5)) { if(mStop) return; } //Code for receiving and processing incoming data mutex.unlock(); } //end while } Hierarchy of GUI. 1.Login screen. 2. Screen of action. When a user logs in from login screen, we enter the action screen where all data is displayed and all the thread's for different sensors start. They wait on mStop variable in idle time and when data arrives they jump to receiving and processing data. Incoming data for the problem protocol is 117 bytes. In the main GUI threads there are timers which when timeout, grab the running instance of protocol using <ProtocolName>::instance() function Check the update variable of singleton class if its true and display the data. When the data display is done they reset the update variable in singleton class to false. The problematic protocol has the update time of 1 sec, which is also the frame rate of protocol. When I comment out the display function it runs fine. But when display is activated the application hangs consistently after 6-7 hours. I have asked this question on many forums but haven't received any worthwhile suggestions. I Hope that here I will get some help. Also, I have read a lot of literature on Singleton, multithreading, and found that people always discourage the use of singletons especially in C++. But in my application I can think of no other design for implementation. Thanks in advance A Hapless programmer

    Read the article

  • How can I implement a proper counter bean with EJB 3.0?

    - by Aaron Digulla
    I have this entity bean: import javax.persistence.*; @Entity public class CounterTest { private int id; private int counter; @Id public int getId() { return id; } public void setId(int id) { this.id = id; } public int getCounter() { return counter; } public void setCounter(int counter) { this.counter = counter; } } and this stateful bean to increment a counter: import java.rmi.RemoteException; import javax.ejb.*; import javax.persistence.*; @Stateful public class CounterTestBean implements CounterTestRemote { @PersistenceContext(unitName = "JavaEE") EntityManager manager; public void initDB() { CounterTest ct = new CounterTest(); ct.setNr(1); ct.setWert(1); manager.persist(ct); } public boolean testCounterWithLock() { try { CounterTest ct = manager.find(CounterTest.class, 1); manager.lock(ct, LockModeType.WRITE); int wert = ct.getWert(); ct.setWert(wert + 1); manager.flush(); return true; } catch (Throwable t) { return false; } } } When I call testCounterWithLock() from three threads 500 times each, the counter gets incremented between 13 and 1279 times. How do I fix this code so that it is incremented 1500 times?

    Read the article

  • Are local variables in Fortran 77 static or stack dynamic?

    - by mm2887
    For my programming languages class one hw problem asks: Are local variables in FORTRAN static or stack dynamic? Are local variables that are INITIALIZED to a default value static or stack dynamic? Show me some code with an explanation to back up your answer. Hint: The easiest way to check this is to have your program test the history sensitivity of a subprogram. Look at what happens when you initialize the local variable to a value and when you don’t. You may need to call more than one subprogram to lock in your answer with confidence. I wrote a few subroutines: - create a variable - print the variable - initialize the variable to a value - print the variable again Each successive call to the subroutine prints out the same random value for the variable when it is uninitialized and then it prints out the initialized value. What is this random value when the variable is uninitialized? Does this mean Fortran uses the same memory location for each call to the subroutine or it dynamically creates space and initializes the variable randomly? My second subroutine also creates a variable, but then calls the first subroutine. The result is the same except the random number printed of the uninitialized variable is different. I am very confused. Please help! Thank you so much.

    Read the article

  • Custom Modal Window in WPF?

    - by Dan Bryant
    I have a WPF application where I'd like to create a custom pop-up that has modal behavior. I've been able to hack up a solution using an equivalent to 'DoEvents', but is there a better way to do this? Here is what I have currently: private void ShowModalHost(FrameworkElement element) { //Create new modal host var host = new ModalHost(element); //Lock out UI with blur WindowSurface.Effect = new BlurEffect(); ModalSurface.IsHitTestVisible = true; //Display control in modal surface ModalSurface.Children.Add(host); //Block until ModalHost is done while (ModalSurface.IsHitTestVisible) { DoEvents(); } } private void DoEvents() { var frame = new DispatcherFrame(); Dispatcher.BeginInvoke(DispatcherPriority.Background, new DispatcherOperationCallback(ExitFrame), frame); Dispatcher.PushFrame(frame); } private object ExitFrame(object f) { ((DispatcherFrame)f).Continue = false; return null; } public void CloseModal() { //Remove any controls from the modal surface and make UI available again ModalSurface.Children.Clear(); ModalSurface.IsHitTestVisible = false; WindowSurface.Effect = null; } Where my ModalHost is a user control designed to host another element with animation and other support.

    Read the article

  • Can you force a crash if a write occurs to a given memory location with finer than page granularity?

    - by Joseph Garvin
    I'm writing a program that for performance reasons uses shared memory (alternatives have been evaluated, and they are not fast enough for my task, so suggestions to not use it will be downvoted). In the shared memory region I am writing many structs of a fixed size. There is one program responsible for writing the structs into shared memory, and many clients that read from it. However, there is one member of each struct that clients need to write to (a reference count, which they will update atomically). All of the other members should be read only to the clients. Because clients need to change that one member, they can't map the shared memory region as read only. But they shouldn't be tinkering with the other members either, and since these programs are written in C++, memory corruption is possible. Ideally, it should be as difficult as possible for one client to crash another. I'm only worried about buggy clients, not malicious ones, so imperfect solutions are allowed. I can try to stop clients from overwriting by declaring the members in the header they use as const, but that won't prevent memory corruption (buffer overflows, bad casts, etc.) from overwriting. I can insert canaries, but then I have to constantly pay the cost of checking them. Instead of storing the reference count member directly, I could store a pointer to the actual data in a separate mapped write only page, while keeping the structs in read only mapped pages. This will work, the OS will force my application to crash if I try to write to the pointed to data, but indirect storage can be undesirable when trying to write lock free algorithms, because needing to follow another level of indirection can change whether something can be done atomically. Is there any way to mark smaller areas of memory such that writing them will cause your app to blow up? Some platforms have hardware watchpoints, and maybe I could activate one of those with inline assembly, but I'd be limited to only 4 at a time on 32-bit x86 and each one could only cover part of the struct because they're limited to 4 bytes. It'd also make my program painful to debug ;)

    Read the article

  • Invalid Cast Exception in ASP.NET but not in WinForms

    - by Shadow Scorpion
    I have a problem in this code: public static T[] GetExtras <T>(Type[] Types) { List<T> Res = new List<T>(); foreach (object Current in GetExtras(typeof(T), Types)) { Res.Add((T)Current);//this is the error } return Res.ToArray(); } public static object[] GetExtras(Type ExtraType, Type[] Types) { lock (ExtraType) { if (!ExtraType.IsInterface) return new object[] { }; List<object> Res = new List<object>(); bool found = false; found = (ExtraType == typeof(IExtra)); foreach (Type CurInterFace in ExtraType.GetInterfaces()) { if (found = (CurInterFace == typeof(IExtra))) break; } if (!found) return new object[] { }; foreach (Type CurType in Types) { found = false; if (!CurType.IsClass) continue; foreach (Type CurInterface in CurType.GetInterfaces()) { try { if (found = (CurInterface.FullName == ExtraType.FullName)) break; } catch { } } try { if (found) Res.Add(Activator.CreateInstance(CurType)); } catch { } } return Res.ToArray(); } } When I'm using this code in windows application it works! But I cant use it on ASP page. Why?

    Read the article

  • Trouble with jquery email form submitHandler

    - by Robert
    Here is the code I'm using for the submitHandler: submitHandler: function() { $('.holder').fadeOut('slow'); $('#loading').fadeIn('slow'); $.post('email.php',{name:$('#em_name').val(), email:$('#em_email').val(), message:$('#em_message').val()}, function(data){ $('#loading').css({display:'none'}); if( data == 'success') { $('#callback').show().append('Message delivered successfully'); $('#emailform').slideUp('slow'); } else { $('#callback').show().append('Sorry but your message could not be sent, try again later'); } }); } This isn't working when used in conjunction with this php: <?php $name = stripcslashes($_POST['name']); $emailAddr = stripcslashes($_POST['email']); $message = stripcslashes($_POST['message']); $email = "Message: $message \r \n From: $name \r \n Reply to: $emailAddr"; $to = '[email protected]'; $subject = 'Message from example'; //validate the email address on the server side if(eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $emailAddr) ) { //if successful lets send the message mail($to, $subject, $email); echo('success'); //return success callback } else { echo('An invalid email address was entered'); //email was not valid } ?> Does anyone have any suggestions as to why this isn't working like it should. It seems to just lock up when I submit. Any help would be appreciated. Thanks!

    Read the article

  • Pitfalls and practical Use-Cases: Toplink, Hibernate, Eclipse Link, Ibatis ...

    - by Martin K.
    I worked a lot with Hibernate as my JPA implementation. In most cases it works fine! But I have also seen a lot of pitfalls: Remoting with persisted Objects is difficult, because Hibernate replaces the Java collections with its own collection implementation. So the every client must have the Hibernate .jar libraries. You have to take care on LazyLoading exceptions etc. One way to get around this problem is the use of webservices. Dirty checking is done against the Database without any lock. "Delayed SQL", causes that the data access isn't ACID compliant. (Lost data...) Implict Updates So we don't know if an object is modified or not (commit causes updates). Are there similar issues with Toplink, Eclipse Link and Ibatis? When should I use them? Have they a similar performance? Are there reasons to choose Eclipse Link/Toplink... over Hibernate?

    Read the article

  • Are there some cases where Python threads can safely manipulate shared state?

    - by erikg
    Some discussion in another question has encouraged me to to better understand cases where locking is required in multithreaded Python programs. Per this article on threading in Python, I have several solid, testable examples of pitfalls that can occur when multiple threads access shared state. The example race condition provided on this page involves races between threads reading and manipulating a shared variable stored in a dictionary. I think the case for a race here is very obvious, and fortunately is eminently testable. However, I have been unable to evoke a race condition with atomic operations such as list appends or variable increments. This test exhaustively attempts to demonstrate such a race: from threading import Thread, Lock import operator def contains_all_ints(l, n): l.sort() for i in xrange(0, n): if l[i] != i: return False return True def test(ntests): results = [] threads = [] def lockless_append(i): results.append(i) for i in xrange(0, ntests): threads.append(Thread(target=lockless_append, args=(i,))) threads[i].start() for i in xrange(0, ntests): threads[i].join() if len(results) != ntests or not contains_all_ints(results, ntests): return False else: return True for i in range(0,100): if test(100000): print "OK", i else: print "appending to a list without locks *is* unsafe" exit() I have run the test above without failure (100x 100k multithreaded appends). Can anyone get it to fail? Is there another class of object which can be made to misbehave via atomic, incremental, modification by threads? Do these implicitly 'atomic' semantics apply to other operations in Python? Is this directly related to the GIL?

    Read the article

  • Modify Executing Jar file

    - by pinkynobrain
    Hello Stack Overflow friends. I have a simple problem which i fear doesnt have a simple solution and i need advice as to how to proceed. I am developing a java application packaged as and executable JAR but it requires to modify some of its JAR file contents during execution. At this stage i hit a problem because some OS lock the file preventing writes to it. It is essential that the user sees an updated version of the jar file by the time the application exits allthough i can be pretty flexible as to how to achieve this. A clean and efficient solution is obviously prefereable but portability is the only hard requirement. The following are three approaches i can see to solving the problem, feel free to comment on them or suggest others. Tell Java to unlock the JAR file for writing(this doesnt seem possible but it would be the easyest solution) Copy the executable class files to a tempory file on application startup, use a class loader to load these files and unload the ones from the initial JAR file.(Not had much experience with the classloaders but hopefully the JVM would then be smart enough to realize that the original JAR is nolonger in use and so unlock it) Put a Second executable JAR File inside the First, on startup extract the inner jar to e temporaryfile, invoke a new java process and pass it the location of the Outer JAR, first process exits, second process modifys the Outer jar unincumbered.(This will work but im not sure there is a platform independant way of one java app invoking another) I know this is a weird question but any help would be appreciated.

    Read the article

  • Locking behaviour is different via network shares

    - by MattH
    I have been trying to lock a file so that other cloned services cannot access the file. I then read the file, and then move the file when finished. The Move is allowed by using FileShare.Delete. However in later testing, we found that this approach does not work if we are looking at a network share. I appreciate my approach may not have been the best, but my specific question is: Why does the below demo work against the local file, but not against the network file? The more specific you can be the better, as I've found very little information in my searches that indicates network shares behave differently to local disks. string sourceFile = @"C:\TestFile.txt"; string localPath = @"C:\MyLocalFolder\TestFile.txt"; string networkPath = @"\\MyMachine\MyNetworkFolder\TestFile.txt"; File.WriteAllText(sourceFile, "Test data"); if (!File.Exists(localPath)) File.Copy(sourceFile, localPath); foreach (string path in new string[] { localPath, networkPath }) { using (FileStream fsLock = File.Open(path, FileMode.Open, FileAccess.ReadWrite, (FileShare.Read | FileShare.Delete))) { string target = path + ".out"; File.Move(path, target); //This is the point of failure, when working with networkPath if (File.Exists(target)) File.Delete(target); } if (!File.Exists(path)) File.Copy(sourceFile, path); }

    Read the article

  • How to synchronize placing an object in JNDI across processes?

    - by indra
    I am trying to place an object in JNDI, so that only one of the progam should be able to place it in JNDI. is there any global lock that can be used in J2EE environment. Is RMI can be used for this purpose? please provide any reference links. Thanks in advance. Also, what is NameAlreadyBoundexception? I am trying to use it as a method to synchronize, i.e, only one program places it in JNDI and if other trying to bind should get that exception. But when i am testing the multiple binding I am not getting the Exception.And second binding is done. look up is giving the second object bound. here is my code: private static String JNDI_NAME = "java:comp/env/test/something"; public class TestJNDI { private static String JNDI_NAME = "java:comp/env/test/something"; public static void main(String[] args) throws NamingException { Hashtable env = new Hashtable(); env.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory"); env.put(Context.PROVIDER_URL,"t3://127.0.0.1:7001"); Context ctx = new InitialContext(env); System.out.println("Initial Context created"); String obj1 = "obj1"; String obj2 = "obj2"; try{ ctx.bind(JNDI_NAME, obj1); System.out.println("Bind Sucess"); }catch(NameAlreadyBoundException ne ){ // already bound System.out.println("Name already bound"); } ctx.close(); Context ctx2 = new InitialContext(env); try{ // Second binding to the same name not giving the Exception?? ctx2.bind(JNDI_NAME, obj2); System.out.println("Re Bind Sucess"); }catch(NameAlreadyBoundException ne ){ // already bound System.out.println("Name already bound"); } String lookedUp = (String) ctx2.lookup(JNDI_NAME); System.out.println("LookedUp Object"+lookedUp); ctx2.close(); } }

    Read the article

  • How to pass binary data between two apps using Content Provider?

    - by Viktor
    I need to pass some binary data between two android apps using Content Provider (sharedUserId is not an option). I would prefer not to pass the data (a savegame stored as a file, small in size < 20k) as a file (ie. overriding openFile()) since this would necessitate some complicated temp-file scheme to cope with concurrency with several content provider accesses and a running game. I would like to read the file into memory under a mutex lock and then pass the binary array in the simplest way possible. How do I do this? It seems creating a file in memory is not a possibility due to the return type of openFile(). query() needs to return a Cursor. Using MatrixCursor is not possible since it applies toString() to all stored objects when reading it. What do I need to do? Implement a custom Cursor? This class has 30 abstract methods. Do I read the file, put it in a SQLite db and return the cursor? The complexity of this seemingly simple task is mindboggling.

    Read the article

  • Strategies for serializing an object for auditing/logging purpose in .NET?

    - by Jiho Han
    Let's say I have an application that processes messages. Messages are just objects in this case that implements IMessage interface which is just a marker. In this app, if a message fails to process, then I want to log it, first of all for auditing and troubleshooting purposes. Secondly I might want to use it for re-processing. Ideally, I want the message to be serialized into a format that is human-readable. The first candidate is XML although there are others like JSON. If I were to serialize the messages as XML, I want to know whether the message object is XML-serializable. One way is to reflect on the type and to see if it has a parameter-less constructor and the other is to require IXmlSerializable interface. I'm not too happy with either of these approaches. There is a third option which is to try to serialize it and catch exceptions. This doesn't really help - I want to, in some way, stipulate that IMessage (or a derived type) should be xml-serializable. The reflection route has obvious disadvantages such as security, performance, etc. IXmlSerializable route locks down my messages to one format, when in the future, I might want to change the serialization format to be JSON. The other thing is even the simplest objects now must implement ReadXml and WriteXml methods. Is there a route that involves the least amount of work that lets me serialize an arbitrary object (as long as it implements the marker interface) into XML but not lock future messages into XML?

    Read the article

  • Atomic Instructions and Variable Update visibility

    - by dsimcha
    On most common platforms (the most important being x86; I understand that some platforms have extremely difficult memory models that provide almost no guarantees useful for multithreading, but I don't care about rare counter-examples), is the following code safe? Thread 1: someVariable = doStuff(); atomicSet(stuffDoneFlag, 1); Thread 2: while(!atomicRead(stuffDoneFlag)) {} // Wait for stuffDoneFlag to be set. doMoreStuff(someVariable); Assuming standard, reasonable implementations of atomic ops: Is Thread 1's assignment to someVariable guaranteed to complete before atomicSet() is called? Is Thread 2 guaranteed to see the assignment to someVariable before calling doMoreStuff() provided it reads stuffDoneFlag atomically? Edits: The implementation of atomic ops I'm using contains the x86 LOCK instruction in each operation, if that helps. Assume stuffDoneFlag is properly cleared somehow. How isn't important. This is a very simplified example. I created it this way so that you wouldn't have to understand the whole context of the problem to answer it. I know it's not efficient.

    Read the article

  • How to make Facebook Authentication from Silverlight secure?

    - by SondreB
    I have the following scenario I want to complete: Website running some HTTP(S) services that returns data for a user. Same website is additionally hosting a Silverlight 4 app which calls these services. The Silverlight app is integrating with Facebook using the Facebook Developer Toolkit (http://facebooktoolkit.codeplex.com/). I have not fully decided whether I want Facebook-integration to be a "opt-in" option such as Spotify, or if I want to "lock" down my service with Facebook-only authentication. That's another discussion. How do I protect my API Key and Secret that I receive from Facebook in a Silverlight app? To me it's obvious that this is impossible as the code is running on the client, but is there a way I can make it harder or should I just live with the fact that third parties could potentially "act" as my own app? Using the Facebook Developer Toolkit, there is a following C# method in Silverlight that is executed from the JavaScript when the user has fully authenticated with Facebook using the Facebook Connect APIs. [ScriptableMember] public void LoggedIn(string sessionKey, string secret, int expires, long userId) { this.SessionKey = sessionKey; this.UserId = userId; Obvious the problem here is the fact that JavaScript is injection the userId, which is nothing but a simple number. This means anyone could potentially inject a different userId in JavaScript and have my app think it's someone else. This means someone could hijack the data within the services running on my website. The alternative that comes to mind is authenticating the users on my website, this way I'm never exposing any secrets and I can return an auth-cookie to the users after the initial authentication. Though this scenario doesn't work very well in an out-of-browser scenario where the user is running the Silverlight app locally and not from my website.

    Read the article

  • Creating a service (SERVICE_ACCEPT_SESSIONCHANGE)

    - by Ron
    Hi there, I am trying to create a service following the example documented in the link below: http://msdn.microsoft.com/en-us/library/bb540475(v=VS.85).aspx What I am interested in is to be able to catch user "lock" and "unlock" workstation events. Using the code on from the example provided, I modified the following: Line 15: Original: VOID WINAPI SvcCtrlHandler( DWORD ); Modified: DWORD WINAPI SvcCtrlHandler( DWORD, DWORD, LPVOID, LPVOID ); Line 141: Original: gSvcStatusHandle = RegisterServiceCtrlHandler( SVCNAME, SvcCtrlHandler); Modified: gSvcStatusHandle = RegisterServiceCtrlHandlerEx( SVCNAME, SvcCtrlHandler, NULL); Line 244: Original: SvcStatus.dwControlsAccepted = SERVICE_ACCEPT_STOP; Modified: gSvcStatus.dwControlsAccepted = SERVICE_ACCEPT_STOP|SERVICE_ACCEPT_SESSIONCHANGE; Line 266: Original: VOID WINAPI SvcCtrlHandler( DWORD dwCtrl ) { // Handle the requested control code. switch(dwCtrl) { case SERVICE_CONTROL_STOP: ReportSvcStatus(SERVICE_STOP_PENDING, NO_ERROR, 0); // Signal the service to stop. SetEvent(ghSvcStopEvent); ReportSvcStatus(gSvcStatus.dwCurrentState, NO_ERROR, 0); return; case SERVICE_CONTROL_INTERROGATE: break; default: break; } }` Modified: DWORD WINAPI SvcCtrlHandler( DWORD dwControl, DWORD dwEventType, LPVOID lpEventData, LPVOID lpContext ) { DWORD dwErrorCode = NO_ERROR; switch(dwControl) { case SERVICE_CONTROL_STOP: ReportSvcStatus(SERVICE_STOP_PENDING, NO_ERROR, 0); // Signal the service to stop. SetEvent(ghSvcStopEvent); ReportSvcStatus(gSvcStatus.dwCurrentState, NO_ERROR, 0); break; case SERVICE_CONTROL_INTERROGATE: break; case SERVICE_CONTROL_SESSIONCHANGE: ReportSvcStatus(gSvcStatus.dwCurrentState, NO_ERROR, 0); break; default: break; } return dwErrorCode; } With the changes above, my service compiled and install fine. But when I try to start my service on my Windows 2000 machine, it does not start properly (it will be stuck on the "starting" status) Can anyone please advise? Thank you in advance, Ron

    Read the article

  • cross-platform scripting for windows, Linux, MacOS X

    - by karolrvn
    Hi. I'm looking for cross-platform scripting (language) for windows, Linux, MacOS X. I'm tired of .bat / bash . I would like to do things like for example ,,lock workstation'' at automatic login (I had this in X-Window but the solution was pretty ugly; now, I would like that on MS Windows and not that ugly :-) ). Generally: automate tasks. Or would I be better off with Windows Scripting Host? PowerShell also comes to mind, but that's seems to Windows-only for my taste. Can languages like Python, Ruby, (Java?) interact (elegantly? sensibly?) with WSH? Also things like DBUS, DCOM, etc come to mind as part of the picture. Currently I use a mixture of Java, .bat, bash, Ruby, Scala; some VBA for Excel. Which sometimes gets pretty ugly. I would like a cross-platform general solution with/using ,,native'' parts close to OS-specifics. Like e.g. Ruby driving some Windows-specific stuff (just a guess). What do You use? TIA

    Read the article

  • Iphone: TabView + TableView

    - by OneTrickPonySoft
    I think I'm missing something simple, but I can't figure out exactly what it is. I'm trying to set up an App with a UITabViewController, and one of the Tabs will have a UITableView and UISearchBar (but no Navigation Controller). I set up the UITabViewController with all the tabs in interface builder, and the views are in their own xib files. The xib file for the tab with the UITableView is set up and connected as follows. Stuff in the browser: File's owner (Class is my custom class that is a child of UITableViewController) view - View View (class UIView, reference view - File's owner) contains: UITableView (if i try and set references to the data source / delegate, the app breaks) UISearchBar (unconfigured at the moment) This setup displays all the items and doesn't lock up, but I can't assign a DataSource without it crashing when i try and load the tab with the UITableView. What should I do to get data into this table, either in IB or code? My ideas are as follows: Implement custom UITableView class, hook up to table view in IB or to custom tableviewcontroller in Xcode. Pound head or laptop against the wall until it works. Update: Here's the error the simulator pushes to the console when I connect the Tableview's data source and delegate to File Owner (who's class is my custom tableviewcontroller). 2/14/09 6:59:12 PM TabBarWillbeRight[33172] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[UIViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x523760'

    Read the article

  • ADO/SQL Server: What is the error code for "timeout expired"?

    - by Ian Boyd
    i'm trying to trap a "timeout expired" error from ADO. When a timeout happens, ADO returns: Number: 0x80040E31 (DB_E_ABORTLIMITREACHED in oledberr.h) SQLState: HYT00 NativeError: 0 The NativeError of zero makes sense, since the timeout is not a function of the database engine (i.e. SQL Server), but of ADO's internal timeout mechanism. The Number (i.e. the COM hresult) looks useful, but the definition of DB_E_ABORTLIMITREACHED in oledberr.h says: Execution stopped because a resource limit was reached. No results were returned. This error could apply to things besides "timeout expired" (some potentially server-side), such as a governor that limits: CPU usage I/O reads/writes network bandwidth and stops a query. The final useful piece is SQLState, which is a database-independent error code system. Unfortunately the only reference for SQLState error codes i can find have no mention of HYT00. What to do? What do do? Note: i can't trust 0x80040E31 (DB_E_ABORTLIMITREACHED) to mean "timeout expired", anymore than i could trust 0x80004005 (E_UNSPECIFIED_ERROR) to mean "Transaction was deadlocked on lock resources with another process and has been chosen as the deadlock victim". My pseudo-question becomes: does anyone have documentation on what the SQLState "HYT000" means? And my real question still remains: How can i specifically trap an ADO timeout expired exception thrown by ADO? Gotta love the questions where the developer is trying to "do the right thing", but nobody knows how to do the right thing. Also gotta love how googling for DB_E_ABORTLIMITREACHED and this question is #9, with MSDN nowhere to be found. Update 3 From the OLEdb ICommand.Execute reference: DB_E_ABORTLIMITREACHED Execution has been aborted because a resource limit has been reached. For example, a query timed out. No results have been returned. "For example", meaning not an exhaustive list.

    Read the article

  • Python pixel manipulation library

    - by silinter
    So I'm going through the beginning stages of producing a game in Python, and I'm looking for a library that is able to manipulate pixels and blit them relatively fast. My first thought was pygame, as it deals in pure 2D surfaces, but it only allows pixel access through pygame.get_at(), pygame.set_at() and pygame.get_buffer(), all of which lock the surface each time they're called, making them slow to use. I can also use the PixelArray and surfarray classes, but they are locked for the duration of their lifetimes, and the only way to blit them to a surface is to either copy the pixels to a new surface, or use surfarray.blit_array, which requires creating a subsurface of the screen and blitting it to that, if the array is smaller than the screen (if it's bigger I can just use a slice of the array, which is no problem). I don't have much experience with PyOpenGL or Pyglet, but I'm wondering if there is a faster library for doing pixel manipulation in, or if there is a faster method, in Pygame, for doing pixel manupilation. I did some work with SDL and OpenGL in C, and I do like the idea of adding vertex/fragment shaders to my program. My program will chiefly be dealing in loading images and writing/reading to/from surfaces.

    Read the article

  • PocketPC c++ windows message processing recursion problem

    - by user197350
    Hello, I am having a problem in a large scale application that seems related to windows messaging on the Pocket PC. What I have is a PocketPC application written in c++. It has only one standard message loop. while (GetMessage (&msg, NULL, 0, 0)) { { TranslateMessage (&msg); DispatchMessage (&msg); } } We also have standard dlgProc's. In the switch of the dlgProc, we will call a proprietary 3rd party API. This API uses a socket connection to communicate with another process. The problem I am seeing is this: whenever two of the same messages come in quickly (from the user clicking the screen twice too fast and shouldn't be) it seems as though recursion is created. Windows begins processing the first message, gets the api into a thread safe state, and then jumps to process the next (identical ui) message. Well since the second message also makes the API call, the call fails because it is locked. Because of the design of this legacy system, the API will be locked until the recursion comes back out (which also is triggered by the user; so it could be locked the entire working day). I am struggling to figure out exactly why this is happening and what I can do about it. Is this because windows recognizes the socket communication will take time and preempts it? Is there a way I can force this API call to complete before preemption? Is there a way I can slow down the message processing or re-queue the message to ensure the first will execute (capturing it and doing a PostMessage back to itself didnt work). We don't want to lock the ui down while the first call completes. Any insight is greatly appreciated! Thanks!!

    Read the article

  • Calling QAxWidget method outside of the GUI thread

    - by user304361
    I'm beginning to wonder if this is impossible, but I thought I'd ask in case there's a clever way to get around the problems I'm having. I have a Qt application that uses an ActiveX control. The control is held by a QAxWidget, and the QAxWidget itself is contained within another QWidget (I needed to add additional signals/slots to the widget, and I couldn't just subclass QAxWidget because the class doesn't permit that). When I need to interact with the ActiveX control, I call a method of the QWidget, which in turn calls the dynamicCall method of the QAxWidget in order to invoke the appropriate method of the ActiveX control. All of that is working fine. However, one method of the ActiveX control takes several seconds to return. When I call this method, my entire GUI locks up for a few seconds until the method returns. This is undesirable. I'd like the ActiveX control to go off and do its processing by itself and come back to me when it's done without locking up the Qt GUI. I've tried a few things without success: Creating a new QThread and calling QAxWidget::dynamicCall from the new thread Connecting a signal to the appropriate slot method of the QAxWidget and calling the method using signals/slots instead of using dynamicCall Calling QAxWidget::dynamicCall using QtConcurrent::run Nothing seems to affect the behavior. No matter how or where I use dynamicCall (or trigger the appropriate slot of the QAxWidget), the GUI locks until the ActiveX control completes its operation. Is there any way to detach this ActiveX processing from the Qt GUI thread so that the GUI doesn't lock up while the ActiveX control is running a method? Is there something clever I can do with QAxBase or QAxObject to get my desired results?

    Read the article

  • How does one decrypt a PDF with an owner password, but no user password?

    - by Tony Meyer
    Although the PDF specification is available from Adobe, it's not exactly the simplest document to read through. PDF allows documents to be encrypted so that either a user password and/or an owner password is required to do various things with the document (display, print, etc). A common use is to lock a PDF so that end users can read it without entering any password, but a password is required to do anything else. I'm trying to parse PDFs that are locked in this way (to get the same privileges as you would get opening them in any reader). Using an empty string as the user password doesn't work, but it seems (section 3.5.2 of the spec) that there has to be a user password to create the hash for the admin password. What I would like is either an explanation of how to do this, or any code that I can read (ideally Python, C, or C++, but anything readable will do) that does this so that I can understand what I'm meant to be doing. Standalone code, rather than reading through (e.g.) the gsview source, would be best.

    Read the article

< Previous Page | 392 393 394 395 396 397 398 399 400 401 402 403  | Next Page >