std :: boost :: asio :: post/disp使用哪个io_context? [英] Which io_context does std::boost::asio::post / dispatch use?

问题描述

使用boost :: asio 1.66时，我在文档中读到，boost::asio::post不推荐用于boost::asio::post，与boost::asio::io_context::dispatch相同.因为在它们之前是io_context成员函数的位置，并且当然需要在某些io_context上下文中执行处理程序，即executor我的问题是:

While using boost::asio 1.66 I read in the documentation that boost::asio::io_context::post is deprecated for boost::asio::post, same for boost::asio::io_context::dispatch. Because before they where member functions of the io_context before, and of course the handler needs to be executed in the context of some io_context i.e. executor my question is:

boost :: asio :: io_context :: post最简单的重载如何知道要使用哪个io_context即executor?

How does boost::asio::io_context::post simplest overload know which io_context i.e. executor to use?

template< typename CompletionToken> DEDUCED post(CompletionToken && token);的文档指出

通过执行get_associated_executor(handler)获得处理程序的关联执行程序对象ex.

Obtains the handler's associated executor object ex by performing get_associated_executor(handler).

但是get_associated_executor的文档也不清楚.我的猜测是由于 Template参数扣除，它可以以某种方式在当前执行的处理程序中获取它，但是我想确保，而且，如果我在a之外调用post，这还不够. boost :: asio处理程序.

But the documentation of get_associated_executor does not make it clear to me either. My guess is due to the Template argument deduction it can grab it somehow in the currently executed handler, but I want to make sure and also, this wouldn't suffice if I call post outside of a boost::asio handler.

推荐答案

• get()

  • get()

  如果T具有嵌套类型executor_type，则返回t.get_executor().否则返回ex.

  If T has a nested type executor_type, returns t.get_executor(). Otherwise returns ex.

  executor_type

  如果T具有嵌套类型executor_type，则T :: executor_type.否则为执行人.

  If T has a nested type executor_type, T::executor_type. Otherwise Executor.

  如果处理程序类型¹具有嵌套的executor_type类型，则假定调用token.get()将返回要使用的正确执行程序.

  If your handler type¹ has a nested executor_type type, then it is assumed that calling token.get() will return the correct executor to use.

  如果传递的是可传递消息的普通可调用对象，而未指定执行者/执行上下文，则将获得执行上下文的默认构造实例:boost::asio::system_executor.

  If you pass a vanilla calleable to post without specifying an executor/execution context you will get a default-constructed instance of an execution context: boost::asio::system_executor.

  此操作的目的是使用自定义处理程序类型来实现DoTheRightThing.例如.如果您在链上发布内容，则处理程序将被包装为特定于链实现的类型.然后，associated_executor特质和同上的get_executor()成员函数将进行协调，以直接指向该链的执行程序.

  The purpose of this is for the implementation to DoTheRightThing with custom handler types. E.g. if you post something on a strand, the handler will be wrapped in a type specific to the strand implementation. The associated_executor trait and ditto get_executor() member function will then coordinate to direct to the executor for that strand.

  ¹或任何令牌，以防您的调用模型不同(例如收益上下文)

  ¹ or any token, in case your call model is different, like a yield context

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