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//
// system_executor.hpp
// ~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#ifndef ASIO_SYSTEM_EXECUTOR_HPP
#define ASIO_SYSTEM_EXECUTOR_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#include "asio/detail/push_options.hpp"
namespace asio {
class system_context;
/// An executor that uses arbitrary threads.
/**
* The system executor represents an execution context where functions are
* permitted to run on arbitrary threads. The post() and defer() functions
* schedule the function to run on an unspecified system thread pool, and
* dispatch() invokes the function immediately.
*/
class system_executor
{
public:
/// Obtain the underlying execution context.
system_context& context() const ASIO_NOEXCEPT;
/// Inform the executor that it has some outstanding work to do.
/**
* For the system executor, this is a no-op.
*/
void on_work_started() const ASIO_NOEXCEPT
{
}
/// Inform the executor that some work is no longer outstanding.
/**
* For the system executor, this is a no-op.
*/
void on_work_finished() const ASIO_NOEXCEPT
{
}
/// Request the system executor to invoke the given function object.
/**
* This function is used to ask the executor to execute the given function
* object. The function object will always be executed inside this function.
*
* @param f The function object to be called. The executor will make
* a copy of the handler object as required. The function signature of the
* function object must be: @code void function(); @endcode
*
* @param a An allocator that may be used by the executor to allocate the
* internal storage needed for function invocation.
*/
template <typename Function, typename Allocator>
void dispatch(ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
/// Request the system executor to invoke the given function object.
/**
* This function is used to ask the executor to execute the given function
* object. The function object will never be executed inside this function.
* Instead, it will be scheduled to run on an unspecified system thread pool.
*
* @param f The function object to be called. The executor will make
* a copy of the handler object as required. The function signature of the
* function object must be: @code void function(); @endcode
*
* @param a An allocator that may be used by the executor to allocate the
* internal storage needed for function invocation.
*/
template <typename Function, typename Allocator>
void post(ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
/// Request the system executor to invoke the given function object.
/**
* This function is used to ask the executor to execute the given function
* object. The function object will never be executed inside this function.
* Instead, it will be scheduled to run on an unspecified system thread pool.
*
* @param f The function object to be called. The executor will make
* a copy of the handler object as required. The function signature of the
* function object must be: @code void function(); @endcode
*
* @param a An allocator that may be used by the executor to allocate the
* internal storage needed for function invocation.
*/
template <typename Function, typename Allocator>
void defer(ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
/// Compare two executors for equality.
/**
* System executors always compare equal.
*/
friend bool operator==(const system_executor&,
const system_executor&) ASIO_NOEXCEPT
{
return true;
}
/// Compare two executors for inequality.
/**
* System executors always compare equal.
*/
friend bool operator!=(const system_executor&,
const system_executor&) ASIO_NOEXCEPT
{
return false;
}
};
} // namespace asio
#include "asio/detail/pop_options.hpp"
#include "asio/impl/system_executor.hpp"
#endif // ASIO_SYSTEM_EXECUTOR_HPP
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