1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193
|
/* 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");
}
|