提高:: ASIO :: deadline_timer :: async_wait不触发回调 [英] boost::asio::deadline_timer::async_wait not firing callback

问题描述

我有一个提升 io_service对象运行在一个线程中，我想6秒后某个事件发生到客户端火在该线程回调，并重置该客户端的计时器，如果它已经在运行。

I have a boost io_service running in a thread, and I would like to fire a callback in that thread 6 seconds after a certain event happens to a client, and reset the timer for that client if it is already running.

我保持了 unordered_map＆LT;字符串的shared_ptr＆LT; deadline_timer＆GT;方式＆gt; 为每个客户端的定时器

I maintain a unordered_map<string, shared_ptr<deadline_timer>> with a timer for each client.

不过，在设置 async_wait ，我的回调不火的时间获分配金额后（ io_service对象 IS运行），它也不火（有错误code）当我复位指针（它应该调用析构函数为现有的定时器，使其发布到服务）。我该如何解决这个问题？

However, upon setting async_wait, my callback does not fire after the alloted amount of time (the io_service IS running), neither does it fire (with an error code) when I reset the pointer (which should call the destructor for the existing timer, causing it to post to the service). How can I fix this?

这是我的code的相关部分：

This is the relevant part of my code:

auto it = timersByClientId.find(clientId);
if (it == timersByClientId.end())
{
    onLogonChangeCallback(clientId, true);
    timersByClientId[clientId].reset(
        new boost::asio::deadline_timer(replyService, boost::posix_time::seconds(6))
    );
    it = timersByClientId.find(clientId);
}
else
{
    // Cancel current wait operation (should fire the callback with an error code)
    it->second.reset(
        new boost::asio::deadline_timer(replyService, boost::posix_time::seconds(6))
    );
}
it->second->async_wait([this, clientId](const boost::system::error_code& err) {
    if (!err)
    {
        onLogonChangeCallback(clientId, false);
    }
});

如果它改变任何东西，我在Visual C ++ 2010运行并提高1.47.0。

If it changes anything, I'm running under Visual C++ 2010 and boost 1.47.0.

推荐答案

您code /外观/没关系十岁上下。

Your code /looks/ okay-ish.

我不知道你是如何达成的结论是，你的完成处理程序不会的[...]火（有错误code）当我复位指针的。您忽略此情况下（没有在拉姆达没有其他分支）。

I'm not sure how you are reaching the conclusion that your completion handler doesn't "[...] fire (with an error code) when I reset the pointer". You are ignoring this case (there is no else branch in the lambda).

如何更清晰地写什么逻辑？

How about writing the logic more clearly?

void foo(int clientId) {
    shared_timer& timer = timersByClientId[clientId];

    if (!timer) 
        onLogonChangeCallback(clientId, true);

    timer = make_timer(); // reset

    timer->async_wait([this, clientId](const boost::system::error_code& err) {
        if (!err)
            onLogonChangeCallback(clientId, false);
    });
}

下面是一个完整的演示与其他分支，让你看到是怎么回事。我以为1服务线程。

Here's a full demo with that else branch to let you see what is going on. I assumed 1 service thread.

看它的 住在Coliru

See it Live On Coliru.

测试负载是在0.5秒〜16账户100届活动。总运行时间为1.5秒〜因为我已经减少了会话有效期从6秒到1秒的Coliru。

The test load is 100 session activities on 16 accounts in ~0.5s. The total running time is ~1.5s because I have reduced the session expiration from 6s to 1s for Coliru.

如果你不想LogonManager的析构函数等待所有会话到期，然后加入后台线程之前清除会话表：

If you didn't want the destructor of LogonManager to wait for all sessions to expire, then clear the session table before joining the background thread:

~LogonMonitor() {
    work = boost::none;
    timersByClientId.clear();
    background.join();
}

完整列表

#include <boost/asio.hpp>
#include <boost/thread.hpp>
#include <boost/optional.hpp>
#include <boost/make_shared.hpp>

struct LogonMonitor {
    LogonMonitor() 
        : work(io_service::work(replyService)), background([this]{ replyService.run(); })
    { }

    ~LogonMonitor() {
        work = boost::none;
        // timersByClientId.clear();
        background.join();
    }

    void foo(int clientId) {
        shared_timer& timer = timersByClientId[clientId];

        if (!timer) 
            onLogonChangeCallback(clientId, true);

        timer = make_timer(); // reset

        timer->async_wait([this, clientId](const boost::system::error_code& err) {
            if (!err)
                onLogonChangeCallback(clientId, false);
            else
                std::cout << "(cancel " << clientId << " timer)" << std::endl;
        });
    }

  private:
    using io_service   = boost::asio::io_service;
    using timer        = boost::asio::deadline_timer;
    using shared_timer = boost::shared_ptr<timer>;

    io_service replyService;
    boost::optional<io_service::work> work;
    boost::thread background;

    std::map<int, shared_timer> timersByClientId;

    shared_timer make_timer() { 
        return boost::make_shared<timer>(replyService, boost::posix_time::seconds(/*6*/1)); 
    }

    void onLogonChangeCallback(int clientId, bool newLogon) 
    {
        std::cout << __FUNCTION__ << "(" << clientId << ", " << newLogon << ")" << std::endl;
    }
};

int main()
{
    LogonMonitor instance;
    for (int i = 0; i < 100; ++i)
    {
        instance.foo(rand() % 16);
        boost::this_thread::sleep_for(boost::chrono::milliseconds(rand() % 10));
    }
}

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