To write a program that runs in multi-threading on Windows, first include "proces.h".
#include <process.h> |
The function unsigned func (LPVOID) runs in the thread is defined in the following format.
unsigned __stdcall func (LPVOID pParam) {
// The work this thread should do.
_endthreadex(0);
return 0;
}
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For programs that operate in multi-threading, exclusive control must be needed in critical sections where conflicts may occur. We use Mutex for this purpose. We create a mutex as a variable that can be refered from any thread, and we decide that only the thread that acquire the right of the mutex can enter the critical section.
Handle mutex;
int main(int argc, char** argv) {
mutex = CreateMutex(NULL, FALSE, NULL); // create mutex
if (GetLastError() == ERROR_ALREADY_EXISTS) throw ERROR;
...(abbreviated)...
}
unsigned __stdcall func (LPVOID pParam) {
...(abbreviated)...
DWORD ret = WaitForSingleObject(mutex, INFINITE); // acquire the right of Mutex
if (ret == WAIT_FAILED) throw ERROR;
...(abbreviated)... // critical section
ReleaseMutex(mutex); // release the right of Mutex
...(abbreviated)...
_endthreadex(0);
return 0;
}
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To start N threads in the main thead, write as follows. _beginthreadex() function is used to start a thread, and WaitForMultipleObjects() function is used to wait for all threads to finish.
HANDLE hThread[N ] = { 0 };
hThread[0] = (HANDLE) _beginthreadex(NULL,0, functionName1,NULL,0,NULL); // create thread to call function1
if (hThread[0] == 0) throw Error ;
...(abbreviated)... // create threads of 2〜(N-2)
hThread[N -1] = (HANDLE) _beginthreadex(NULL,0,functionName>N,NULL,0,NULL); // create thread to call functionN
if (hThread[N -1] == 0) throw Error ;
...(abbreviated)... // Job for the main thread
DWORD ret = WaitForMultipleObjects(N ,hThread,TRUE,INFINITE); // wait for all threads to finish
if (ret == WAIT_FAILED) throw Error ;
return 0;
}
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If you define USE_THREAD constant before including NtKinect.h, the functions and variables of NtKinect for multi-thread become effective.