提高:: ASIO异步状态 [英] boost::asio async condition

问题描述

的想法是能够与升压:: ASIO和一个线程池来取代多线程code，在一个消费者/生产者的问题。目前，每个消费者线程等待一个的boost :: condition_variable - 当生产者增加了一些到队列中，它调用 notify_one / notify_all 通知所有消费者。当你（可能）有1K +消费者现在会发生什么？线程将不能扩展！

The idea is to be able to replace multithreaded code with boost::asio and a thread pool, on a consumer/producer problem. Currently, each consumer thread waits on a boost::condition_variable - when a producer adds something to the queue, it calls notify_one/notify_all to notify all the consumers. Now what happens when you (potentially) have 1k+ consumers? Threads won't scale!

我决定用的boost :: ASIO ，但后来我遇到了一个事实，即它不具备条件变量。然后 async_condition_variable 诞生了：

I decided to use boost::asio, but then I ran into the fact that it doesn't have condition variables. And then async_condition_variable was born:

class async_condition_variable
{
private:
    boost::asio::io_service& service_;
    typedef boost::function<void ()> async_handler;
    std::queue<async_handler> waiters_;

public:
    async_condition_variable(boost::asio::io_service& service) : service_(service)
    {
    }

    void async_wait(async_handler handler)
    {
        waiters_.push(handler);
    }

    void notify_one()
    {
        service_.post(waiters_.front());
        waiters_.pop();
    }

    void notify_all()
    {
        while (!waiters_.empty()) {
            notify_one();
        }
    }
};

基本上，每个消费者会叫 async_condition_variable ::等待（...）。然后，生产者最终将调用 async_condition_variable :: notify_one（）或 async_condition_variable :: notify_all（）。每个消费者的手柄会被调用，要么在条件或调用行为 async_condition_variable ::等待（...）一次。这是可行的还是我疯了吗？应该执行什么样的锁（互斥）的，鉴于这将在一个线程池来运行？

Basically, each consumer would call async_condition_variable::wait(...). Then, a producer would eventually call async_condition_variable::notify_one() or async_condition_variable::notify_all(). Each consumer's handle would be called, and would either act on the condition or call async_condition_variable::wait(...) again. Is this feasible or am I being crazy here? What kind of locking (mutexes) should be performed, given the fact that this would be run on a thread pool?

P.S：是的，这是一个多问题:)一个RFC（请求注解）。

P.S.: Yes, this is more a RFC (Request for Comments) than a question :).

推荐答案

有需要在事件发生时要做事情的清单。有一个函数的东西添加到列表中，并从该名单中删除一些功能。然后，当事件发生时，有一个池的线程现在需要做的作业列表上工作。你并不需要专门的线程等待事件。

Have a list of things that need to be done when an event occurs. Have a function to add something to that list and a function to remove something from that list. Then, when the event occurs, have a pool of threads work on the list of jobs that now need to be done. You don't need threads specifically waiting for the event.

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