ThreadPool1Example

    // ------------------------------- //
    // -------- 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 used to the basic functionality of the Thread Pool
    class.
    */
    // ----------------------------------------------------------- //
    #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 "thrpool.h"
    #include "gthreadt.h"

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

    void PausePrg()
    // Pause the program and wait for the user to press enter.
    {
      // Pause the program until enter is pressed
      cout << "\n" << flush;
      cout << "Press Enter to continue..." << "\n" << flush;
      cin.get();
    }

    void ScrollForward(thrPool &pool)
    {
      cout << "Walking through the pool..." << "\n" << flush;
      thrPoolNode *ptr = pool.GetHead();
      while(ptr) {
        cout << (char)ptr->GetThreadPtr()->GetObjectID() << ' ';
        ptr = ptr->GetNext();
      }
      cout << "\n" << flush;
    }

    void RewindPool(thrPool &pool)
    {
      cout << "Walking through the pool in a backward direction..."
           << "\n" << flush;
      thrPoolNode *ptr = pool.GetTail();

      // Walk through the pool in a backward direction
      while(ptr) {
        cout << (char)ptr->GetThreadPtr()->GetObjectID() << ' ';
        ptr = ptr->GetPrev();
      }

      cout << "\n" << flush;
    }

    int main()
    {
    #ifdef __MSVC_DEBUG__
      InitLeakTest();
    #endif

      thrPool pool;
      thrPoolNode *ptr;

      cout << "Loading data elements into the pool..." << "\n" << flush;
      thrPoolNode *na = new thrPoolNode;
      thrPoolNode *nb = new thrPoolNode;
      thrPoolNode *nc = new thrPoolNode;
      thrPoolNode *nd = new thrPoolNode;
      thrPoolNode *n1 = new thrPoolNode;
      thrPoolNode *n2 = new thrPoolNode;
      thrPoolNode *n3 = new thrPoolNode;
      thrPoolNode *n4 = new thrPoolNode;

      // Allocating some memory buffers
      const unsigned num_blocks = 9;
      gxThread_t *buf[num_blocks];
      unsigned i;
      for(i = 0; i < num_blocks; i++) {
        buf[i] = new gxThread_t;
        // Set an arbitary object ID stating starting with ASCII character 'A'
        buf[i]->SetObjectID(65+i);
      }

      na->SetThreadPtr(buf[0]);
      nb->SetThreadPtr(buf[1]);
      nc->SetThreadPtr(buf[2]);
      nd->SetThreadPtr(buf[3]);

      // Load some pool elements
      pool.InsertAfter(pool.GetHead(), na);
      pool.InsertAfter(na, nb);
      pool.InsertAfter(nb, nc);
      pool.InsertAfter(nc, nd);

      n1->SetThreadPtr(buf[4]);
      n2->SetThreadPtr(buf[5]);
      n3->SetThreadPtr(buf[6]);
      n4->SetThreadPtr(buf[7]);

      // Testing insert functions
      pool.InsertBefore(na, n1);
      pool.InsertBefore(nc, n2);
      pool.InsertAfter(nb, n3);
      pool.InsertAfter(nd, n4);

      // Reordering the pool
      pool.MoveToBack(na);
      pool.MoveAfter(na, nc);
      pool.MoveBefore(nc, nb);
      pool.MoveAfter(nc, nd);
      pool.MoveAfter(nd, n2);
      pool.MoveBefore(n2, n1);
      pool.MoveAfter(n2, n3);
      pool.MoveAfter(n3, n4);

      ScrollForward(pool);
      RewindPool(pool);

      PausePrg();

      cout << "Adding another item to the pool..." << "\n" << flush;
      ptr = pool.AddThread(buf[8]);
      ScrollForward(pool);

      PausePrg();

      cout << "Moving pool item to the front of the pool" << "\n" << flush;
      pool.MoveToFront(ptr);
      ScrollForward(pool);

      cout << "Moving item to the back of the pool..." << "\n" << flush;
      pool.MoveToBack(ptr);
      ScrollForward(pool);

      PausePrg();

      cout << "Removing the head of the pool..." << "\n" << flush;
      ptr = pool.GetHead();
      gxThread_t *tptr = pool.RemoveNode(ptr);
      if(tptr) delete tptr; // Prevent memory leaks
      ScrollForward(pool);

      cout << "Removing the tail of the pool..." << "\n" << flush;
      ptr = pool.GetTail();
      tptr = pool.RemoveNode(ptr);
      if(tptr) delete tptr; // Prevent memory leaks
      ScrollForward(pool);

      PausePrg();
      cout << "Testing for memory leaks..." << "\n" << flush;
      unsigned len = sizeof(gxThread_t);
      const unsigned num_to_allocate = 1000; // 1000 * 1000;
      const unsigned mem_bufs = (sizeof(thrPoolNode) + len) * num_to_allocate;
      cout << "Allocating " << mem_bufs << " bytes..." << "\n" << flush;

      // Clear the thread pool without checking the status of each thread
      pool.ClearPool();

      unsigned count1 = 0;
      unsigned count2 = 0;
      for(i = 0; i < num_to_allocate; ++i) {
        gxThread_t *sbuf = new gxThread_t;
        count1 += sizeof(sbuf);
        if(!sbuf) {
          cout << "Memory allocation error at " << (count1+count2) << " bytes"
    	   << "\n" << flush;
          break;
        }

        count2 += sizeof(thrPoolNode);
        if(!pool.AddThread(sbuf))  {
          cout << "Memory allocation error at " << (count1+count2) << " bytes"
    	   << "\n" << flush;
          break;
        }
      }
      cout << "Done" << "\n" << flush;
      PausePrg();

      cout << "Releasing memory allocated back to the heap..." << "\n" << flush;

      while(!pool.IsEmpty()) {
        // Clear the pool, giving the application a chance to check the
        // status of each thread.
        gxThread_t *t = pool.RemoveTail();
        if(t) {
          // Process the thread and release any memory the thread is holding
          // ...
          delete t;
        }
      }
      pool.MakeEmpty(); // The thread pool is no empty

      PausePrg();

      cout << "Exiting..." << "\n" << flush;
      cout << "\n" << flush;
      return 0;
    }
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