什么是Linux下的C ++等价物的AutoResetEvent？

问题描述

的AutoResetEvent的MSDN中说明

我想要的端口在C＃中实施，以C ++在Linux下一个线程池。我不知道我应该使用哪种功能有类似的行为来的AutoResetEvent。

I'm trying to port a Thread Pool implemented in C# to C++ under Linux. I don't know which functions I should use that have similar behaviors to "AutoResetEvent".

推荐答案

这是的AutoResetEvent是最类似于一个二进制信号。人们说：条件变量都没有错本身，而是条件变量被用在类似的情况下，而不是类似的对象。您可以在条件变量之上实现的（未命名）的AutoResetEvent：

An AutoResetEvent is most akin to a binary semaphore. People saying "conditional variables" aren't wrong per se, but condition variables are used in similar situations, rather than being similar objects. You can implement an (unnamed) AutoResetEvent on top of condition variables:

#include <pthread.h>
#include <stdio.h>

class AutoResetEvent
{
  public:
  explicit AutoResetEvent(bool initial = false);

  ~AutoResetEvent();
  void Set();
  void Reset();

  bool WaitOne();

  private:
  AutoResetEvent(const AutoResetEvent&);
  AutoResetEvent& operator=(const AutoResetEvent&); // non-copyable
  bool flag_;
  pthread_mutex_t protect_;
  pthread_cond_t signal_;
};

AutoResetEvent::AutoResetEvent(bool initial)
: flag_(initial)
{
  pthread_mutex_init(&protect_, NULL);
  pthread_cond_init(&signal_, NULL);
}

void AutoResetEvent::Set()
{
  pthread_mutex_lock(&protect_);
  flag_ = true;
  pthread_mutex_unlock(&protect_);
  pthread_cond_signal(&signal_);
}

void AutoResetEvent::Reset()
{
  pthread_mutex_lock(&protect_);
  flag_ = false;
  pthread_mutex_unlock(&protect_);
}

bool AutoResetEvent::WaitOne()
{
  pthread_mutex_lock(&protect_);
  while( !flag_ ) // prevent spurious wakeups from doing harm
    pthread_cond_wait(&signal_, &protect_);
  flag_ = false; // waiting resets the flag
  pthread_mutex_unlock(&protect_);
  return true;
}

AutoResetEvent::~AutoResetEvent()
{
  pthread_mutex_destroy(&protect_);
  pthread_cond_destroy(&signal_);
}


AutoResetEvent event;

void *otherthread(void *)
{
  event.WaitOne();
  printf("Hello from other thread!\n");
  return NULL;
}


int main()
{
  pthread_t h;
  pthread_create(&h, NULL, &otherthread, NULL);
  printf("Hello from the first thread\n");
  event.Set();

  pthread_join(h, NULL);
  return 0;
}

但是，如果你需要一个名为自动复位的事件，你可能会想看看信号量，并可能有一个稍微困难的时候，你的翻译code。无论哪种方式，我会看仔细的为pthreads的平台上，条件变量和自动复位事件的文件是不一样的，并不具有相同的行为。

If however, you need named auto reset events, you'll likely want to look at semaphores, and may have a slightly more difficult time translating your code. Either way I would look careful at the documentation for pthreads on your platform, condition variables and auto reset events are not the same and do not behave the same.

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