使用线程本地存储

线程本地存储（TLS）使同一进程的多个线程能够使用由TlsAlloc函数分配的索引来存储和检索线程本地的值。在此示例中，在进程启动时分配索引。当每个线程启动时，它会分配一个动态内存块，并使用TlsSetValue函数在TLS槽中存储指向此内存的指针。CommonFunc函数使用TlsGetValue函数来访问与调用线程本地的索引相关联的数据。在每个线程终止之前，它会释放其动态内存。在进程终止之前，它会调用TlsFree来释放索引。

#include  
#include  

#define THREADCOUNT 4 
DWORD dwTlsIndex; 

VOID ErrorExit(LPSTR); 

VOID CommonFunc(VOID) 
{ 
   LPVOID lpvData; 

// Retrieve a data pointer for the current thread. 

   lpvData = TlsGetValue(dwTlsIndex); 
   if ((lpvData == 0) && (GetLastError() != ERROR_SUCCESS)) 
      ErrorExit("TlsGetValue error"); 

// Use the data stored for the current thread. 

   printf("common: thread %d: lpvData=%lx\n", 
      GetCurrentThreadId(), lpvData); 

   Sleep(5000); 
} 

DWORD WINAPI ThreadFunc(VOID) 
{ 
   LPVOID lpvData; 

// Initialize the TLS index for this thread. 

   lpvData = (LPVOID) LocalAlloc(LPTR, 256); 
   if (! TlsSetValue(dwTlsIndex, lpvData)) 
      ErrorExit("TlsSetValue error"); 

   printf("thread %d: lpvData=%lx\n", GetCurrentThreadId(), lpvData); 

   CommonFunc(); 

// Release the dynamic memory before the thread returns. 

   lpvData = TlsGetValue(dwTlsIndex); 
   if (lpvData != 0) 
      LocalFree((HLOCAL) lpvData); 

   return 0; 
} 

int main(VOID) 
{ 
   DWORD IDThread; 
   HANDLE hThread[THREADCOUNT]; 
   int i; 

// Allocate a TLS index. 

   if ((dwTlsIndex = TlsAlloc()) == TLS_OUT_OF_INDEXES) 
      ErrorExit("TlsAlloc failed"); 

// Create multiple threads. 

   for (i = 0; i < THREADCOUNT; i++) 
   { 
      hThread[i] = CreateThread(NULL, // default security attributes 
         0,                           // use default stack size 
         (LPTHREAD_START_ROUTINE) ThreadFunc, // thread function 
         NULL,                    // no thread function argument 
         0,                       // use default creation flags 
         &IDThread);              // returns thread identifier 

   // Check the return value for success. 
      if (hThread[i] == NULL) 
         ErrorExit("CreateThread error\n"); 
   } 

   for (i = 0; i < THREADCOUNT; i++) 
      WaitForSingleObject(hThread[i], INFINITE); 

   TlsFree(dwTlsIndex);

   return 0; 
} 

VOID ErrorExit (LPSTR lpszMessage) 
{ 
   fprintf(stderr, "%s\n", lpszMessage); 
   ExitProcess(0); 
}

相关话题

在动态链接库中使用线程本地存储