死锁

第一个写死锁的程序，不多说了，说多了都是泪。。。权当留念。。。

#include

#include

#include

#include

#include

#include

#include

volatile LONG cntR, cntW, waitR;

HANDLE mutexR, mutexW;

HANDLE readEvent, writeEvent;

int val;

DWORD WINAPI ReaderThread(PVOID pvParam);

DWORD WINAPI WriterThread(PVOID pvParam);

void initRand();

int main(int argc, char **argv){

HANDLE flag;

DWORD threadId;

val = 0;

mutexR = CreateMutex(NULL, 0, NULL);

mutexW = CreateMutex(NULL, 0, NULL);

writeEvent = CreateEvent(NULL, 0, true, NULL);

readEvent = CreateEvent(NULL, 1, true, NULL);

while (true){

srand(time(NULL));

int r = rand() % 4;

if (r == 0){

flag = CreateThread(NULL, 0, WriterThread, NULL, 0,&threadId);

if (flag)

printf("Writer thread %d created...\n", threadId);

else

printf("Error %d while creating Writer thread\n",GetLastError());

CloseHandle(flag);

}

else{

flag = CreateThread(NULL, 0, ReaderThread, NULL, 0,&threadId);

if (flag)

printf("Reader thread %d created...\n", threadId);

else

printf("Error %d while creating Reader thread\n",GetLastError());

CloseHandle(flag);

}

Sleep(1000);

}

}

DWORD WINAPI ReaderThread(PVOID pvParam){

InterlockedAdd(&waitR, 1);

WaitForSingleObject(readEvent, INFINITE);

InterlockedAdd(&waitR, -1);

ResetEvent(writeEvent);

WaitForSingleObject(mutexR, INFINITE);

cntR++;

int threadId = GetCurrentThreadId();

printf("This is reader %d, val = %d\n", threadId, val);

ReleaseMutex(mutexR);

Sleep(1500);

WaitForSingleObject(mutexR, INFINITE);

cntR--;

printf("Reader %d leaving, still %d readers reading, %dreaders waiting\n\n", threadId, cntR, waitR);

if (cntR == 0)

SetEvent(writeEvent);

ReleaseMutex(mutexR);

return 0;

}

DWORD WINAPI WriterThread(PVOID pvParam){

WaitForSingleObject(mutexW, INFINITE);

cntW++;

ReleaseMutex(mutexW);

//不能用InterlockedIncrement(&cntW);必须用同一种内核同步对象来控制

ResetEvent(readEvent);

WaitForSingleObject(writeEvent, INFINITE);

int threadId = GetCurrentThreadId();

initRand();

val = rand();

printf("This is %d writing, val equals %d\n", threadId,val);

Sleep(3500);

WaitForSingleObject(mutexW, INFINITE);

cntW--;

if (cntW == 0)

SetEvent(readEvent);

printf("Writer %d leaving, %d writers waiting\n\n", threadId,cntW);

ReleaseMutex(mutexW);

return 0;

}

void initRand(){

// 如果支持高性能精度计数器，则使用其初始化随机种子(微秒级)

LARGE_INTEGER nFrequency;

if (::QueryPerformanceFrequency(&nFrequency))

{

LARGE_INTEGER nStartCounter;

QueryPerformanceCounter(&nStartCounter);

srand((unsigned)nStartCounter.LowPart);

}

else // 否则使用当前系统时间初始化随机种子(毫秒级)

{

timeb stb;

ftime(&stb);

srand((unsigned)stb.millitm);

}

}