ThreadPrio1Example

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    // -------- Start of File -------- //
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    // ----------------------------------------------------------- //
    // C++ Source Code File Name: testprog.cpp
    // Compiler Used: MSVC, BCC32, GCC, HPUX aCC, SOLARIS CC
    // Produced By: DataReel Software Development Team
    // File Creation Date: 03/25/2000
    // Date Last Modified: 06/17/2016
    // Copyright (c) 2001-2016 DataReel Software Development
    // ----------------------------------------------------------- //
    // ------------- Program Description and Details ------------- //
    // ----------------------------------------------------------- //
    /*
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
    USA

    Test program demonstrating how to change thread priorities.
    */
    // ----------------------------------------------------------- //
    #include "gxdlcode.h"

    #if defined (__USE_ANSI_CPP__) // Use the ANSI Standard C++ library
    #include <iostream>
    using namespace std; // Use unqualified names for Standard C++ library
    #else // Use the old iostream library by default
    #include <iostream.h>
    #endif // __USE_ANSI_CPP__

    #include <stdlib.h>
    #include "gxthread.h"
    #include "gxcond.h"

    #ifdef __MSVC_DEBUG__
    #include "leaktest.h"
    #endif

    // For safe condition variable usage, must use a Boolean predicate and
    // a mutex with the condition.
    int is_locked = 1; // Block the threads initially in this example
    gxCondition cond;
    gxMutex mutex;

    void PrintThreadStatus(gxThread_t *thread)
    {
      cout << "Thread OID: " << (int)thread->GetObjectID() << ", "
           << thread->ThreadPriorityMessage() << ", "
           << thread->ThreadPriorityClassMessage() << "\n" << flush;
    }

    void HandleThreadError(gxThread_t *thread)
    {
      cout << "Error setting thread " << thread->GetObjectID()
           << " priority" << "\n" << flush;
      cout << thread->ThreadExceptionMessage() << "\n" << flush;
      cout << "Setting priority back to normal" << "\n" << flush;
      thread->SetThreadPriority(gxTHREAD_PRIORITY_NORMAL);
      thread->SetThreadPriorityClass(gxTHREAD_PRIORITY_CLASS_OTHER);
    }

    class SimpleThread : public gxThread
    {
    private: // Base class interface
      void *ThreadEntryRoutine(gxThread_t *thread);
    };

    void *SimpleThread::ThreadEntryRoutine(gxThread_t *thread)
    {
      int num = *((int *)thread->GetThreadParm());

      // Serialize access to the shared resource.
      mutex.MutexLock();

      int num_try = 0;
      while(is_locked != 0) {
        if(++num_try < 255) {
          cout << "Thread " << num << " execution blocked..." << "\n" << flush;
          cond.ConditionWait(&mutex);
        }
        else {
          cout << "Thread " << num << " could not wait for condition"
    	   << "\n" << flush;
          mutex.MutexUnlock();
          return 0;
        }
      }

      // Tell other threads to wait until shared resource is available
      is_locked = 1;

      // ********** Enter Critical Section ******************* //
      PrintThreadStatus(thread);
      // ********** Leave Critical Section ******************* //

      // Tell other threads shared resource is available
      is_locked = 0;

      // Wake up the next thread waiting on this condition
      cond.ConditionSignal();
      mutex.MutexUnlock();

      return 0;
    }

    // Main thread of execution
    int main()
    {
    #ifdef __MSVC_DEBUG__
      InitLeakTest();
    #endif

      SimpleThread t;

      const int NUM_THREADS = 10;
      gxThread_t *thread[NUM_THREADS];

      int i, rv;

      // Create the threads in a blocked state
      for(i = 0; i < NUM_THREADS; i++) {
        thread[i] = t.CreateThread((void *)&i);
        thread[i]->SetObjectID(i); // Assign an arbitrary object ID

        // Check for any errors created during thread creation
        if(thread[i]->GetThreadError() != gxTHREAD_NO_ERROR)
          cout << thread[i]->ThreadExceptionMessage() << "\n" << flush;
      }

      // Change some of the thread priorities and policies before executing them
      rv = t.SetThreadPriority(thread[NUM_THREADS-1], gxTHREAD_PRIORITY_HIGH);
      if(rv != 0) HandleThreadError(thread[NUM_THREADS-1]);

      rv = t.SetThreadPriority(thread[NUM_THREADS-2], gxTHREAD_PRIORITY_HIGH,
    			   gxTHREAD_PRIORITY_CLASS_FIFO);
      if(rv != 0) HandleThreadError(thread[NUM_THREADS-2]);

      rv = t.SetThreadPriority(thread[NUM_THREADS-3], gxTHREAD_PRIORITY_HIGH,
    			   gxTHREAD_PRIORITY_CLASS_RR);
      if(rv != 0) HandleThreadError(thread[NUM_THREADS-3]);

      rv = t.SetThreadPriority(thread[0], gxTHREAD_PRIORITY_LOW);
      if(rv != 0) HandleThreadError(thread[0]);

      rv = t.SetThreadPriority(thread[1], gxTHREAD_PRIORITY_LOW,
    			   gxTHREAD_PRIORITY_CLASS_FIFO);
      if(rv != 0) HandleThreadError(thread[1]);

      rv = t.SetThreadPriority(thread[2], gxTHREAD_PRIORITY_LOW,
    			   gxTHREAD_PRIORITY_CLASS_RR);
      if(rv != 0) HandleThreadError(thread[2]);

      // Reset lock and wake up all the waiters
      is_locked = 0;
      cond.ConditionBroadcast();

      // Wait for all the threads to finish before exiting
      for(i = 0; i < NUM_THREADS; i++) t.JoinThread(thread[i]);

      // Cleanup all the gxThread_t pointers
      for(i = 0; i < NUM_THREADS; i++) {
        rv = t.DestroyThread(thread[i]);
        if(rv != 0) {
          cout << "Error destroying thread!" << "\n" << flush;
        }
      }

      return 0; // Exit the process
    }
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