Re: waiting for another thread without blocking resources...

From:
Lars Uffmann <aral@nurfuerspam.de>
Newsgroups:
comp.lang.c++
Date:
Fri, 15 Feb 2008 13:58:26 +0100
Message-ID:
<61lgitF1vtjmoU1@mid.dfncis.de>
Cholo Lennon wrote:

PS: Could you provide some code to check the library use?


boost::thread *THREAD_FileReceiver; // global variable
int GLB_listen = 0; // global
int GLB_listening = 0; // global

// event handler function
void OnToggleListen()
{
   if (!GLB_listen) {
     if (GLB_listening) {
       cout << "error: still ending thread" << endl;
return;
     }
     GLB_listen = 1; // set keepalive flag for thread
     cout << "starting thread" << endl;

     // this function is the threads main loop, receiving UDP packets
     THREAD_FileReceiver = new boost::thread(&listenForUDPFiles);

     // wait for thread to set GLB_Listening := 1 - how??

     // the following is the cmd button to toggle thread status
     mainWindow->cmdToggleListen->SetLabel ("Stop Listening");
   }
   else {
     if (!GLB_listening) {
       cout << "error: still starting thread" << endl;
return;
     }
     GLB_listen = 0; // unset keepalive flag for thread

     // send a UDP packet to get thread out of listening mode
     sendEndOfStream();

cout << "waiting for thread to end" << endl;
     THREAD_FileReceiver->join();
cout << "thread finished, GLB_listening = " << GLB_listening << endl;
     delete THREAD_FileReceiver;
     THREAD_FileReceiver = 0;

     // the following is the cmd button to toggle thread status
     mainWindow->cmdToggleListen->SetLabel ("Start Listening");
   }
}

---
this code just crashes after the join() call while without it, the code
would exit normally. However, then I have a possible race condition when
re-activating the thread. Are you able to make anything from that?

Thanks,

   Lars

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