是否提高::绑定事业开销？ [英] Does boost::bind cause overhead?

问题描述

我目前工作的网络软件。它有一个主类，服务器这显然重新presents的服务器实例。

I am currently working on network software. It has one main class, server which obviously represents a server instance.

A 服务器实例可以发送请求，并通知用户用回调的响应。

A server instance can send requests and the user is notified of the response by a callback.

在code是这样的：

class server
{
  public:
    typedef boost::function<void (int duration)> callback_func;

    void send_request(endpoint& ep, callback_func cb);
};

现在让我们说，作为一个用户我想回调了解调用它的情况下，我可以做以下的事情：

Now let's say that, as a user I want to the callback to know about the instance that called it, I can do the following thing:

void mycallback(const server& sv, int duration) { ... }

server sv;
sv.send_request("localhost", boost::bind(&mycallback, boost::ref(sv), _1));

但我不知道：有没有什么开销，这样做？在调用 myCallBack函数会有什么比使用较慢的常规打电话？

But I wonder: is there any overhead doing so ? Will the calls to mycallback be any slower than using a "regular" call ?

感谢您。

的脚踏注：当然，我可以改变我的的typedef 为：的typedef的boost ::功能＆LT;无效（const的服务器和放大器; SV， INT持续时间）＆GT; callback_func; ，如果的boost ::绑定造成任何显著的开销，这可能是什么，我会做到底。我只是想知道是什么费用意味着使用的boost ::绑定的的

Foot note: I could of course change my typedef to: typedef boost::function<void (const server& sv, int duration)> callback_func; and if boost::bind cause any significant overhead, that's probably what I will do in the end. I would just like to know what costs implies the use of boost::bind.

推荐答案

当然，这会导致开销。它所做的是，它会创建一个存储绑定参数并有一个运营商算符（）你用剩下的参数来调用。现在，这是显著？我不知道，因为这只是一个字。让1000万个请求，并测量它。你是唯一一个谁可以告诉我们，如果这方面的开销是给你显著与否。

Of course it causes overhead. What it does is that it creates a functor that stores the bound parameters and has an operator() that you call with the remaining arguments. Now, is this significant? I don't know, because that is just a word. Make 10 million requests and measure it. You are the only one who can tell if this overhead is significant to you or not.

另外，我面临着类似的问题。由于我没有真正需要的代表，我可以摆脱函数指针。但我发现一个有趣的基准也提到了一些替代实现，所有的人都具有更好的性能比的boost ::功能。这是以便携性的成本，在执行某些情况下丑陋的，非标准的黑客（但换来一个非常不错的表现）。

Also, I faced a similar problem. Since I didn't really need delegates, I could get away with function pointers. But I found an interesting benchmark which also mentions some alternative implementation, all of them with better performance than boost::function. This comes at the cost of portability and in some cases ugly, non-standard hacks in the implementation (but a really good performance in return).

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