Semaphore上的WaitForSingleObject

问题描述

我正在使用信号量进行消费者/生产者同步。

当消费者需要使用资源时，它会在资源计数器信号量上调用WaitForSingleObject。

信号量用一个简单的包装类实现：

I'm using a Semaphore for a Consumer/Producer synchronization.
When the consumer needs to use a resource, it calls WaitForSingleObject on the resource counter semaphore.
The semaphore is implemented with a simple wrapper class:

CSyncroSemaphore::CSyncroSemaphore() {
	hSemaphore = NULL;
}

void CSyncroSemaphore::Create(int maxCount)
{
	hSemaphore = CreateSemaphore(NULL, 0, maxCount, NULL);
	if (hSemaphore == NULL) 
		throw CStringException("Error createing semaphore:%08x", GetLastError());
	
}

CSyncroSemaphore::~CSyncroSemaphore(void)
{
	CloseHandle(hSemaphore);
}

void CSyncroSemaphore::Release(int releaseCount,bool &overflow)
{
	BOOL ris;
	overflow=false;
	if ((ris=ReleaseSemaphore(hSemaphore,releaseCount,nullptr))==FALSE) {
		if (GetLastError() == ERROR_TOO_MANY_POSTS) {
			overflow = true;
			return;
		}
		throw CStringException("Error releasing semaphore:%08x", GetLastError());
	}
}

void CSyncroSemaphore::Wait(int waitTime, bool &timeout)
{
	timeout = false;
	DWORD  hr;
	if (hr = WaitForSingleObject(hSemaphore, waitTime) != WAIT_OBJECT_0) {
		if (hr == WAIT_TIMEOUT) {
			timeout = true;
			return;
		}
		throw CStringException("Error wiaitng for semaphore:%08x", hr);
	}
}

奇怪的是，在wait函数中，我从WaitForSingleObject获得返回值1 ，具有Timeout Expired的含义。 GetLastError返回S_OK。



我将我的代码更改为：

The strangeness is that in the wait function I get a return value of 1 from WaitForSingleObject, with the meaning of Timeout Expired. GetLastError returns S_OK.

I changed my code to:

if (hr == WAIT_TIMEOUT || hr==1) {
    timeout = true;
    return;
}

一切正常。

根据MSDN，返回值为1可以只被解释为WAIT_OBJECT_1，但这似乎不正确。



我错过了什么吗？



谢谢提前，

Fabio

And everything works fine.
According to MSDN a return value of 1 could only be interpreted as WAIT_OBJECT_1, but this seems not true.

Am I missing something?

Thanks in advance,
Fabio

推荐答案

Quote：

if（hr = WaitForSingleObject（hSemaphore，waitTime）！= WAIT_OBJECT_0）

if (hr = WaitForSingleObject(hSemaphore, waitTime) != WAIT_OBJECT_0)

你可能意味着

You probably meant

if ( ( hr = WaitForSingleObject(hSemaphore, waitTime)) != WAIT_OBJECT_0)

你知道 = = 运算符的优先级高于 = 1。

You know == operator has higher precedence than = one.

这篇关于Semaphore上的WaitForSingleObject的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！