#include <Windows.h>
#include <process.h>
#include <iostream>
using namespace std;
// write线程写了之后,read1、read2、read3才能读,且只有3个线程都读完之后,write函数才能向buffer中写
CRITICAL_SECTION cs;
typedef struct
{
HANDLE h1;
HANDLE h2;
HANDLE h3;
HANDLE h4;
int a;
} PARAMS, *PPARAMS;
void read1(PVOID pvoid)
{
while (TRUE)
{
volatile PPARAMS pparams = (PPARAMS)pvoid;
WaitForSingleObject(pparams->h2, INFINITE); //一直等待,直到h2指代的对象被触发
EnterCriticalSection(&cs);
cout << "线程1开始读取...\n";
cout << (pparams->a) <<endl;
LeaveCriticalSection(&cs);
Sleep(1000);
ReleaseSemaphore(pparams->h3, 1, NULL);
ReleaseSemaphore(pparams->h1, 1, NULL); //释放一个信号量
}
}
void read2(PVOID pvoid)
{
while (TRUE)
{
volatile PPARAMS pparams = (PPARAMS)pvoid;
WaitForSingleObject(pparams->h3, INFINITE);
EnterCriticalSection(&cs);
cout << "线程2开始读取...\n";
cout << (pparams->a) << endl;
LeaveCriticalSection(&cs);
Sleep(1000);
ReleaseSemaphore(pparams->h4, 1, NULL);
ReleaseSemaphore(pparams->h1, 1, NULL); //释放一个信号量
}
}
void read3(PVOID pvoid)
{
while (TRUE)
{
volatile PPARAMS pparams = (PPARAMS)pvoid;
WaitForSingleObject(pparams->h4, INFINITE);
EnterCriticalSection(&cs);
cout << "线程3开始读取...\n";
cout << (pparams->a) << endl;
LeaveCriticalSection(&cs);
Sleep(1000);
ReleaseSemaphore(pparams->h1,1, NULL); //释放一个信号量,h1, 加1
}
}
void write(PVOID pvoid)
{
while (TRUE)
{
volatile PPARAMS pparams = (PPARAMS)pvoid;
WaitForSingleObject(pparams->h1, INFINITE); // 等到后,就减去一个信号
WaitForSingleObject(pparams->h1, INFINITE);
WaitForSingleObject(pparams->h1, INFINITE);
cout << "======================\n";
cout << "写线程开始写入...\n";
pparams->a = rand()%256;
cout << "写入" << (pparams->a) << endl;
ReleaseSemaphore(pparams->h2, 1, NULL);
// ReleaseSemaphore(pparams->h3, 1, NULL);
// ReleaseSemaphore(pparams->h4, 1, NULL);
}
}
int main()
{
PARAMS params;
params.h1 = CreateSemaphore(NULL, 3, 3, NULL); //最开始有3,最大有3
params.h2 = CreateSemaphore(NULL, 0, 1, NULL); //最开始有0,最大有1
params.h3 = CreateSemaphore(NULL, 0, 1, NULL); //最开始有0,最大有1
params.h4 = CreateSemaphore(NULL, 0, 1, NULL); //最开始有0,最大有1
InitializeCriticalSection(&cs);
_beginthread(read1, 0, ¶ms);
_beginthread(read2, 0, ¶ms);
_beginthread(read3, 0, ¶ms);
_beginthread(write, 0, ¶ms);
// HANDLE hEvent;
// hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
// WaitForSingleObject(hEvent, INFINITE);
int a;
cin>>a;
DeleteCriticalSection(&cs);
// system("pause");
return 0;
}