c++多线程，一个很清晰的包含类定义的多线程实例

红太狼 2022-08-14 01:35 99阅读 0赞

/*  file Main.cpp
     *
     *  This program is an adaptation of the code Rex Jaeschke showed in
     *  Listing 1 of his Oct 2005 C/C++ User's Journal article entitled
     *  "C++/CLI Threading: Part I".  I changed it from C++/CLI (managed)
     *  code to standard C++.
     *
     *  One hassle is the fact that C++ must employ a free (C) function
     *  or a static class member function as the thread entry function.
     *
     *  This program must be compiled with a multi-threaded C run-time
     *  (/MT for LIBCMT.LIB in a release build or /MTd for LIBCMTD.LIB
     *  in a debug build).
     *
     *                                      John Kopplin  7/2006
     */
    
    
    #include <stdio.h>
    #include <string>             // for STL string class
    #include <windows.h>          // for HANDLE
    #include <process.h>          // for _beginthread()
    
    using namespace std;
    
    
    class ThreadX
    {
    private:
      int loopStart;
      int loopEnd;
      int dispFrequency;
    
    public:
      string threadName;
    
      ThreadX( int startValue, int endValue, int frequency )
      {
        loopStart = startValue;
        loopEnd = endValue;
        dispFrequency = frequency;
      }
    
      // In C++ you must employ a free (C) function or a static
      // class member function as the thread entry-point-function.
      // Furthermore, _beginthreadex() demands that the thread
      // entry function signature take a single (void*) and returned
      // an unsigned.
      static unsigned __stdcall ThreadStaticEntryPoint(void * pThis)
      {
          ThreadX * pthX = (ThreadX*)pThis;   // the tricky cast
          pthX->ThreadEntryPoint();           // now call the true entry-point-function
    
          // A thread terminates automatically if it completes execution,
          // or it can terminate itself with a call to _endthread().
    
          return 1;          // the thread exit code
      }
    
      void ThreadEntryPoint()
      {
         // This is the desired entry-point-function but to get
         // here we have to use a 2 step procedure involving
         // the ThreadStaticEntryPoint() function.
    
        for (int i = loopStart; i <= loopEnd; ++i)
        {
          if (i % dispFrequency == 0)
          {
              printf( "%s: i = %d\n", threadName.c_str(), i );
          }
        }
        printf( "%s thread terminating\n", threadName.c_str() );
      }
    };
    
    
    int main()
    {
        // All processes get a primary thread automatically. This primary
        // thread can generate additional threads.  In this program the
        // primary thread creates 2 additional threads and all 3 threads
        // then run simultaneously without any synchronization.  No data
        // is shared between the threads.
    
        // We instantiate an object of the ThreadX class. Next we will
        // create a thread and specify that the thread is to begin executing
        // the function ThreadEntryPoint() on object o1. Once started,
        // this thread will execute until that function terminates or
        // until the overall process terminates.
    
        ThreadX * o1 = new ThreadX( 0, 1000000, 20000 );
    
        // When developing a multithreaded WIN32-based application with
        // Visual C++, you need to use the CRT thread functions to create
        // any threads that call CRT functions. Hence to create and terminate
        // threads, use _beginthreadex() and _endthreadex() instead of
        // the Win32 APIs CreateThread() and EndThread().
    
        // The multithread library LIBCMT.LIB includes the _beginthread()
        // and _endthread() functions. The _beginthread() function performs
        // initialization without which many C run-time functions will fail.
        // You must use _beginthread() instead of CreateThread() in C programs
        // built with LIBCMT.LIB if you intend to call C run-time functions.
    
        // Unlike the thread handle returned by _beginthread(), the thread handle
        // returned by _beginthreadex() can be used with the synchronization APIs.
    
        HANDLE   hth1;
        unsigned  uiThread1ID;
    
        hth1 = (HANDLE)_beginthreadex( NULL,         // security
                                       0,            // stack size
                                       ThreadX::ThreadStaticEntryPoint,
                                       o1,           // arg list
                                       CREATE_SUSPENDED,  // so we can later call ResumeThread()
                                       &uiThread1ID );
    
        if ( hth1 == 0 )
            printf("Failed to create thread 1\n");
    
        DWORD   dwExitCode;
    
        GetExitCodeThread( hth1, &dwExitCode );  // should be STILL_ACTIVE = 0x00000103 = 259
        printf( "initial thread 1 exit code = %u\n", dwExitCode );
    
        // The System::Threading::Thread object in C++/CLI has a "Name" property.
        // To create the equivalent functionality in C++ I added a public data member
        // named threadName.
    
        o1->threadName = "t1";
    
        ThreadX * o2 = new ThreadX( -1000000, 0, 20000 );
    
        HANDLE   hth2;
        unsigned  uiThread2ID;
    
        hth2 = (HANDLE)_beginthreadex( NULL,         // security
                                       0,            // stack size
                                       ThreadX::ThreadStaticEntryPoint,
                                       o2,           // arg list
                                       CREATE_SUSPENDED,  // so we can later call ResumeThread()
                                       &uiThread2ID );
    
        if ( hth2 == 0 )
            printf("Failed to create thread 2\n");
    
        GetExitCodeThread( hth2, &dwExitCode );  // should be STILL_ACTIVE = 0x00000103 = 259
        printf( "initial thread 2 exit code = %u\n", dwExitCode );
    
        o2->threadName = "t2";
    
        // If we hadn't specified CREATE_SUSPENDED in the call to _beginthreadex()
        // we wouldn't now need to call ResumeThread().
    
        ResumeThread( hth1 );   // serves the purpose of Jaeschke's t1->Start()
    
        ResumeThread( hth2 );
    
        // In C++/CLI the process continues until the last thread exits.
        // That is, the thread's have independent lifetimes. Hence
        // Jaeschke's original code was designed to show that the primary
        // thread could exit and not influence the other threads.
    
        // However in C++ the process terminates when the primary thread exits
        // and when the process terminates all its threads are then terminated.
        // Hence if you comment out the following waits, the non-primary
        // threads will never get a chance to run.
    
        WaitForSingleObject( hth1, INFINITE );
        WaitForSingleObject( hth2, INFINITE );
    
        GetExitCodeThread( hth1, &dwExitCode );
        printf( "thread 1 exited with code %u\n", dwExitCode );
    
        GetExitCodeThread( hth2, &dwExitCode );
        printf( "thread 2 exited with code %u\n", dwExitCode );
    
        // The handle returned by _beginthreadex() has to be closed
        // by the caller of _beginthreadex().
    
        CloseHandle( hth1 );
        CloseHandle( hth2 );
    
        delete o1;
        o1 = NULL;
    
        delete o2;
        o2 = NULL;
    
        printf("Primary thread terminating.\n");
    }