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  • Non-blocking MySQL updates with java?

    - by justkevin
    For a multiplayer game I'm working on I'd like to record events to the mysql database without blocking the game update thread so that if the database is busy or a table is locked the game doesn't stop running while it waits for a write. What's the best way to accomplish this? I'm using c3p0 to manage the database connection pool. My best idea so far is to add query update strings to a synchronized list with an independent thread checking the list every 100ms and executing the queries it finds there.

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  • Syntax error in SWIG using __thread keyword

    - by user366838
    I am trying to make some code thread safe for use with pthreads. This code is written in C++, but is linked to using SWIG. g++ compiles this correctly, but when swig tries to create a wrapper, I get: fast_alloc.hh:109: Error: Syntax error in input(3) The original, unsafe code that compiles correctly is: static void *freeLists[Num_Buckets]; and the error occurs when I change it to: static __thread void *freeLists[Num_Buckets]; I have made other parts thread safe adding "__thread", for example, this works: static __thread unsigned newCount[Num_Buckets];

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  • Components are not longer resizable after moving

    - by Junior Software Developer
    Hi guys My question relates to swing programming. I want to enlarge a component (component x) by removing it from its parent panel (component a) and adding it in one of component a's parent (component b). Before that, I call setVisible(false) on all components in b. After that I want to make this back by removing it from b and adding on a. After that all components are not longer resizable. Why that? An easy example: import java.awt.BorderLayout; import java.awt.Color; import java.awt.Component; import java.awt.Dimension; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JTabbedPane; public class SwingTest { private static ViewPanel layer1; private static JFrame frame; private static JTabbedPane tabbedPane; private static ViewPanel root; public static void main(String[] args) { frame = new JFrame(); frame.setLayout(new BorderLayout()); frame.setMinimumSize(new Dimension(800, 600)); root = new ViewPanel(); root.setBackground(Color.blue); root.setPreferredSize(new Dimension(400, 600)); root.setLayout(new BorderLayout()); root.add(new JLabel("blue area")); layer1 = new ViewPanel(); layer1.setBackground(Color.red); layer1.setPreferredSize(new Dimension(400, 600)); layer1.setLayout(new BorderLayout()); tabbedPane = new JTabbedPane(); tabbedPane.add("A", new JLabel("A label")); tabbedPane.setPreferredSize(new Dimension(400, 600)); layer1.add(tabbedPane); root.add(layer1); frame.add(root, BorderLayout.NORTH); frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); frame.pack(); frame.setVisible(true); Thread t = new Thread() { @Override public void run() { try { Thread.sleep(8000); System.out.println("start"); for (Component c : root.getComponents()) { c.setVisible(false); } layer1.remove(tabbedPane); root.add(tabbedPane); Thread.sleep(8000); root.remove(tabbedPane); layer1.add(tabbedPane); for (Component c : root.getComponents()) { c.setVisible(true); c.repaint(); } } catch (InterruptedException e) { //... } } }; t.start(); } }

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  • Using static mutex in a class

    - by Dmitry Yudakov
    I have a class that I can have many instances of. Inside it creates and initializes some members from a 3rd party library (that use some global variables) and is not thread-safe. I thought about using static boost::mutex, that would be locked in my class constructor and destructor. Thus creating and destroying instances among my threads would be safe for the 3rd party members. class MyClass { static boost::mutex mx; // 3rd party library members public: MyClass(); ~MyClass(); }; MyClass::MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // create and init 3rd party library stuff } MyClass::~MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // destroy 3rd party library stuff } I cannot link because I receive error: undefined reference to `MyClass::mx` Do I need some special initialization of such static member? Is the whole conception of static mutex wrong?

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  • Reading and writing C++ vector to a file

    - by JB
    For some graphics work I need to read in a large amount of data as quickly as possible and would ideally like to directly read and write the data structures to disk. Basically I have a load of 3d models in various file formats which take too long to load so I want to write them out in their "prepared" format as a cache that will load much faster on subsequent runs of the program. Is it safe to do it like this? My worries are around directly reading into the data of the vector? I've removed error checking, hard coded 4 as the size of the int and so on so that i can give a short working example, I know it's bad code, my question really is if it is safe in c++ to read a whole array of structures directly into a vector like this? I believe it to be so, but c++ has so many traps and undefined behavour when you start going low level and dealing directly with raw memory like this. I realise that number formats and sizes may change across platforms and compilers but this will only even be read and written by the same compiler program to cache data that may be needed on a later run of the same program. #include <fstream> #include <vector> using namespace std; struct Vertex { float x, y, z; }; typedef vector<Vertex> VertexList; int main() { // Create a list for testing VertexList list; Vertex v1 = {1.0f, 2.0f, 3.0f}; list.push_back(v1); Vertex v2 = {2.0f, 100.0f, 3.0f}; list.push_back(v2); Vertex v3 = {3.0f, 200.0f, 3.0f}; list.push_back(v3); Vertex v4 = {4.0f, 300.0f, 3.0f}; list.push_back(v4); // Write out a list to a disk file ofstream os ("data.dat", ios::binary); int size1 = list.size(); os.write((const char*)&size1, 4); os.write((const char*)&list[0], size1 * sizeof(Vertex)); os.close(); // Read it back in VertexList list2; ifstream is("data.dat", ios::binary); int size2; is.read((char*)&size2, 4); list2.resize(size2); // Is it safe to read a whole array of structures directly into the vector? is.read((char*)&list2[0], size2 * sizeof(Vertex)); }

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  • WF State Persistence Collision.

    - by jlafay
    How does WF service handle possible between WF runtime persisting/resuming and a client call calling the next service method/activity in the workflow? I'm new to WF and I'm developing a back-end service that will be put into production for internal use at work. How does WF handles such a scenario? Does it restart the WF runtime on a separate thread than the thread that is concurrently storing state?

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  • How to specify pessimistic lock with Criteria API?

    - by Reddy
    I am retrieving a list of objects in hibernate using Criteria API. However I need lock on those objects as another thread executing at the same time will get the exact objects and only one of the thread will succeed in absence of a pessimistic lock. I tried like below, but it is not working. List esns=session.createCriteria(Reddy_Pool.class) .add(Restrictions.eq("status", "AVAILABLE")) .add(Restrictions.eq("name", "REDDY2")) .addOrder(Order.asc("id")) .setMaxResults(n) .setLockMode(LockMode.PESSIMISTIC_WRITE) //not working at all .list();

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  • MySQL Sub-query.. Doesn't provide proper information after 3 entries into table.

    - by Chris Keefer
    After I get 3 rows in my forum_threads table this no longer does it's job; to organize a list of active forum threads and put the most recently responded-to thread at the top of the list, followed by second most recent posted-to thread, followed by third, fourth, etc. Like I said, the query works wonders up until there is a fourth row added to forum_threads. SELECT forum_threads.*, forum_posts.thread_id FROM forum_threads INNER JOIN (SELECT MAX(id) AS id, thread_id as thread_id FROM forum_posts group by thread_id order by id DESC) forum_posts ON forum_threads.id = forum_posts.thread_id

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  • When is the onPreExecute called on an AsyncTask running parallely or concurrently?

    - by Debarshi Dutta
    I am using Android HoneyComb.I need to execute some tasks parallely and I am using AsyncTask's public final AsyncTask executeOnExecutor (Executor exec, Params... params) method.In each separate thread I am computing some values and I need to store then in an ArrayList.I must then sort all the values in the arrayList and then display it in the UI.Now my question is if one of the thread gets completed earlier than the other then will it immediately call the onPostExecute method or onPostExecute method will be called after all the background threads have been completed?MY program implementation depends on what occurs here.

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  • android playback suddenly stopping...

    - by user306517
    I have an app that is streaming audio content and sometimes it just stops all of the suddent. the logcat windows shows -- AudioHardware pcm playback is going to standby and that's it. I saw on another thread (pun intended) that someone was saying it was because he was using too many threads. Could that really be causing this? Could i give the audio thread higher priority? Anyway to prevent the audio hardware pcm from going to standby?

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  • Good computer science lecture series

    - by joemoe
    Since we have a thread on books.. what are your recommendations of publicly accessible video lecture series related to programming, computer science, or mathematics? Please post specific courses, not websites with courses. :) This is the video equivalent of this thread: http://stackoverflow.com/questions/194812/list-of-freely-available-programming-books

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  • C++/CLI HTTP Proxy problems...

    - by darkantimatter
    Hi, I'm trying(very hard) to make a small HTTP Proxy server which I can use to save all communications to a file. Seeing as I dont really have any experience in the area, I used a class from codeproject.com and some associated code to get started (It was made in the old CLI syntax, so I converted it). I couldn't get it working, so I added lots more code to make it work (threads etc), and now it sort of works. Basically, it recieves something from a client (I just configured Mozilla Firefox to route its connections through this proxy) and then routes it to google.com. After it sends Mozilla's data to google, recieves a responce, and sends that to Mozilla. This works fine, but then the proxy fails to recieve any data from Mozilla. It just loops in the Sleep(50) section. Anyway, heres the code: ProxyTest.cpp: #include "stdafx.h" #include "windows.h" #include "CHTTPProxy.h" public ref class ClientThread { public: System::Net::Sockets::TcpClient ^ pClient; CHttpProxy ^ pProxy; System::Int32 ^ pRecieveBufferSize; System::Threading::Thread ^ Thread; ClientThread(System::Net::Sockets::TcpClient ^ sClient, CHttpProxy ^ sProxy, System::Int32 ^ sRecieveBufferSize) { pClient = sClient; pProxy = sProxy; pRecieveBufferSize = sRecieveBufferSize; }; void StartReading() { Thread = gcnew System::Threading::Thread(gcnew System::Threading::ThreadStart(this,&ClientThread::ThreadEntryPoint)); Thread->Start(); }; void ThreadEntryPoint() { char * bytess; bytess = new char[(int)pRecieveBufferSize]; memset(bytess, 0, (int)pRecieveBufferSize); array<unsigned char> ^ bytes = gcnew array<unsigned char>((int)pRecieveBufferSize); array<unsigned char> ^ sendbytes; do { if (pClient->GetStream()->DataAvailable) { try { do { Sleep(100); //Lets wait for whole packet to get cached (If it even does...) unsigned int k = pClient->GetStream()->Read(bytes, 0, (int)pRecieveBufferSize); //Read it for(unsigned int i=0; i<(int)pRecieveBufferSize; i++) bytess[i] = bytes[i]; Console::WriteLine("Packet Received:\n"+gcnew System::String(bytess)); pProxy->SendToServer(bytes,pClient->GetStream()); //Now send it to google! pClient->GetStream()->Flush(); } while(pClient->GetStream()->DataAvailable); } catch (Exception ^ e) { break; } } else { Sleep(50); //It just loops here because it thinks mozilla isnt sending anything if (!(pClient->Connected)) break; }; } while (pClient->GetStream()->CanRead); delete [] bytess; pClient->Close(); }; }; int main(array<System::String ^> ^args) { System::Collections::Generic::Stack<ClientThread ^> ^ Clients = gcnew System::Collections::Generic::Stack<ClientThread ^>(); System::Net::Sockets::TcpListener ^ pTcpListener = gcnew System::Net::Sockets::TcpListener(8080); pTcpListener->Start(); System::Net::Sockets::TcpClient ^ pTcpClient; while (1) { pTcpClient = pTcpListener->AcceptTcpClient(); //Wait for client ClientThread ^ Client = gcnew ClientThread(pTcpClient, gcnew CHttpProxy("www.google.com.au", 80), pTcpClient->ReceiveBufferSize); //Make a new object for this client Client->StartReading(); //Start the thread Clients->Push(Client); //Add it to the list }; pTcpListener->Stop(); return 0; } CHTTPProxy.h, from http://www.codeproject.com/KB/IP/howtoproxy.aspx with a lot of modifications: //THIS FILE IS FROM http://www.codeproject.com/KB/IP/howtoproxy.aspx. I DID NOT MAKE THIS! BUT I HAVE MADE SEVERAL MODIFICATIONS! #using <mscorlib.dll> #using <SYSTEM.DLL> using namespace System; using System::Net::Sockets::TcpClient; using System::String; using System::Exception; using System::Net::Sockets::NetworkStream; #include <stdio.h> ref class CHttpProxy { public: CHttpProxy(System::String ^ szHost, int port); System::String ^ m_host; int m_port; void SendToServer(array<unsigned char> ^ Packet, System::Net::Sockets::NetworkStream ^ sendstr); }; CHttpProxy::CHttpProxy(System::String ^ szHost, int port) { m_host = gcnew System::String(szHost); m_port = port; } void CHttpProxy::SendToServer(array<unsigned char> ^ Packet, System::Net::Sockets::NetworkStream ^ sendstr) { TcpClient ^ tcpclnt = gcnew TcpClient(); try { tcpclnt->Connect(m_host,m_port); } catch (Exception ^ e ) { Console::WriteLine(e->ToString()); return; } // Send it if ( tcpclnt ) { NetworkStream ^ networkStream; networkStream = tcpclnt->GetStream(); int size = Packet->Length; networkStream->Write(Packet, 0, size); array<unsigned char> ^ bytes = gcnew array<unsigned char>(tcpclnt->ReceiveBufferSize); char * bytess = new char[tcpclnt->ReceiveBufferSize]; Sleep(500); //Wait for responce do { unsigned int k = networkStream->Read(bytes, 0, (int)tcpclnt->ReceiveBufferSize); //Read from google for(unsigned int i=0; i<k; i++) { bytess[i] = bytes[i]; if (bytess[i] == 0) bytess[i] = ' '; //Dont terminate the string if (bytess[i] < 8) bytess[i] = ' '; //Somethings making the computer beep, and its not 7?!?! }; Console::WriteLine("\n\nAbove packet sent to google. Google Packet Received:\n"+gcnew System::String(bytess)); sendstr->Write(bytes,0,k); //Send it to mozilla Console::WriteLine("\n\nAbove packet sent to client..."); //Sleep(1000); } while(networkStream->DataAvailable); delete [] bytess; } return; } Any help would be much appreciated, I've tried for hours.

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  • Django Generating RSS feed with description

    - by Issy
    Hey Guys, I am trying to generate a full rss feed, however when loading the feed in Mail, it just shows the title, with a read more link at the bottom. I have tried several different options. But none seem to work. I would like to generate the feed with a combination of several feeds in my modl. Here is the code i have tried: class LatestEvents(Feed): description_template = "events_description.html" def title(self): return "%s Events" % SITE.name def link(self): return '/events/' def items(self): events = list(Event.objects.all().order_by('-published_date')[:5]) return events author_name = 'Latest Events' def item_pubdate(self, item): return item.published_date And in my template which is stored in TEMPLATE_ROOT/feeds/ {{ obj.description|safe }} <h1>Event Location Details</h1> {{ obj.location|safe }} Even if i hard code the description it does not work.

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  • SQL ORDER BY thing1 ASC, thing2 DESC not working

    - by William
    it puts item1 down as DESC for some reason. edit: $sql_result = mysql_query("SELECT post, name, trip, Thread, sticky FROM (SELECT MIN(ID) AS min_id, MAX(ID) AS max_id, MAX(Date) AS max_date FROM test_posts GROUP BY Thread ) t_min_max INNER JOIN test_posts ON test_posts.ID = t_min_max.min_id WHERE Board=".$board." ORDER BY sticky ASC, max_date DESC", $db); http://prime.programming-designs.com/test_forum/viewboard.php?board=0&page=3

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  • Which is more robust and scalable method?

    - by Dhruv Arya
    I am implementing a distributed chat system, in this system we have the following options : Make the client and server running at each node run as separate threads. The server acting as the receiver will be running as the daemon thread and the client taking the user input as a normal thread. Fork two processes one for the client and one for the server. I am not able to reason out with which one to proceed. Any insight would be great !

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  • Code optimization - Unused methods

    - by Yochai Timmer
    How can I tell if a method will never be used ? I know that for dll files and libraries you can't really know if someone else (another project) will ever use the code. In general I assume that anything public might be used somewhere else. But what about private methods ? Is it safe to assume that if I don't see an explicit call to that method, it won't be used ? I assume that for private methods it's easier to decide. But is it safe to decide it ONLY for private methods ?

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  • Implementing the procducer-consumer pattern with .NET 4.0

    - by bitbonk
    With alle the new paralell programming features in .NET 4.0, what would be a a simple and fast way to implement the producer-consumer pattern (where at least one thread is producing/enqueuing task items and another thread executes/dequeues these tasks). Can we benfit from all these new APIs? What is your preferred implementation of this pattern?

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  • Is it multitasking?

    - by Newbie
    Consider the below program myThread = new Thread( new ThreadStart( delegate { Method1(); Method2(); } ) ); Is it that 2 threads are getting called parallely(multitasking) or a single thread is calling the methods sequentially? It's urgent.

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  • How to change label content with timers throwing InvalidOperationException.

    - by Guru
    Hi there, I'm making an application and I'm using a timer in that application to change label content in WPF C# .NET. In timer elapsed event I'm writing the following code lblTimer.Content = "hello"; but its throwing an InvalidOperationException and gives a message "The calling thread cannot access this object because a different thread owns it." I'm using .NET framework 3.5 and WPF with C#. Please help me. Thanks in advance.

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  • Should I start to use CSS 3 & HTML 5?

    - by LeonixSolutions
    I fear this may sound subjective, sorry. I am wondering how "safe" it is to use CSS3 & HTML5 in a commercial app. I really want the power that they give, but am obviously wary that they are not completely standardized. If it helps any I can probably enforce the use of Chrome as the browser; I can likely offer FireFox as an alternative. I personally do not want to let the user choose their own browser and can probably enforce my choice in a corporate environment which is already heavily biased towards Google. I suppose that if I can enforce a Chrome only policy & carefully test before release then my only worry is that some "behaviour" may change in future. Would you risk it, or would play safe (or go with an alternative, such as a Java app, forgetting the browser)?

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  • NSThread and memory management

    - by misfit153
    Imagine I create and execute an NSThread object using detachNewThreadSelector:toTarget:withObject:. The method executed by the thread might look like this: - (void)search { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // perform a lengthy search here. [pool release]; } I then might use the cancel method to kill the thread while it's running, before the pool gets released. What happens to the NSAutoreleasePool object? I suppose it will leak, won't it?

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  • Parameter passed by const reference returned by const reference.

    - by Alien01
    Hello, I was reading C++ Faq Second Edition , faq number 32.08 . FAQ says that parameter passed by const reference and returned by const reference can cause dangling reference. But it is ok if parameter is passed by reference and returned by reference. I got it that it is unsafe in case of const reference but how is it safe in case when parameter is non const reference. Last line of FAQ says "Note that if a function accepts a parameter by non-const reference (for example, f(string& s)), returning a copy of this reference parameter is safe because a temporary cannot be passed by non-const reference." Need some insight on this!!

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