Use Win32API to synchronize producer and consumer threads

Use Win32API to synchronize producer and consumer threads

Use win32 API to create a thread and create a semaphore for Thread Synchronization

Create semaphores

Syntax:

 

HANDLE semophore;semophore =  CreateSemaphore(lpSemaphoreAttributes, lInitialCount, lMaximumCount, lpName);

 

The following is a prototype of the CreateSemophore function:

 

Handle winapi CreateSemaphore (_ In_opt _ LPSECURITY_ATTRIBUTES lpSemaphoreAttributes, // attribute _ In _ LONG lInitialCount, // Initial Value _ In _ LONG lMaximumCount, // maximum value _ In_opt _ LPCTSTR lpName // The Name Of The semaphore object );

The function returns a HANDLE pointing to the semaphore object, which is a HANDLE object.

Wait and signal operations

The usage structure is generally as follows:

 

While (true) {WaitForSingleObject (semophore, INFINITE); // wait operation // ReleaseSemaphore (semophore, 1, NULL) in the critical section; // signal operation}

 

The prototype of the two functions is as follows:

 

DWORD WaitForSingleObject (HANDLE hHandle, // HANDLE, which can point to the semaphore or thread DWORD dwMilliseconds // Number of milliseconds to wait); BOOL ReleaseSemaphore (HANDLE hSemaphore, // HANDLE, pointing to the semaphore LONG lReleaseCount, // add value to the semaphore, which is generally 1 LPLONG lpPreviousCount // the pointer to the variable that saves the value before the semaphore );

Create thread

 

HANDLE producer; // The PRODUCER thread executes this function // pro_id thread idproducer = CreateThread (NULL, 0, PRODUCER, NULL, 0, & pro_id); // create a thread

 

Function prototype

 

Handle winapi CreateThread (_ In_opt _ LPSECURITY_ATTRIBUTES lpThreadAttributes, // pointer to thread attribute struct _ In _ SIZE_T dwStackSize, // The initialization size of the stack, 0 indicates the default size of _ In _ LPTHREAD_START_ROUTINE lpStartAddress, // The starting address, that is, the pointer of the thread function _ In_opt _ LPVOID lpParameter, // The pointer of the thread function parameter _ In _ DWORD dwCreationFlags, // controls the flag bit to be created. 0 indicates that the thread is executed immediately after creation, and create_suincluded indicates that the thread is created In the suincluded state, it is not executed until the ResumeThread is called. The STACK_SIZE_PARAM_IS_A_RESERVATION parameter specifies the size of the initial reserved stack. If this parameter is not specified, dwStackSize specifies the submitted size _ Out_opt _ LPDWORD lpThreadId // pointer to the thread id );

 

The producer consumer thread synchronization code is as follows:

# Include
 
  
# Include
  
   
# Define QUEUE_LENGTH 10 // buffer length HANDLE full_sem; // full semaphores HANDLE empty_sem; // empty semaphores struct Msg {int I ;}; // message structure Msg MsgQueue [QUEUE_LENGTH]; // buffer int head = 0; // queue header int tail = 0; // queue tail dword winapi consumer (LPVOID lpParameter) {// consumer thread for (int I = 0; I ++) {WaitForSingleObject (full_sem, INFINITE); // wait operation // WaitForSingleObject (mutex, INFINITE ); // multiple consumers need to add mutex semaphores int val = MsgQueue [head]. i; head = (head + 1) % QUEUE_LENGTH; // ReleaseSemaphore (mutex, 1, NULL); // signal operation std: cout <"CONSUMER:" <