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- //
- // system_executor.hpp
- // ~~~~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2015 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/scheduler.hpp"
- #include "asio/detail/thread_group.hpp"
- #include "asio/execution_context.hpp"
- #include "asio/is_executor.hpp"
-
- #include "asio/detail/push_options.hpp"
-
- namespace asio {
-
- /// 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.
- execution_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;
- }
-
- private:
- struct thread_function;
-
- // Hidden implementation of the system execution context.
- struct context_impl
- : public execution_context
- {
- // Constructor creates all threads in the system thread pool.
- ASIO_DECL context_impl();
-
- // Destructor shuts down all threads in the system thread pool.
- ASIO_DECL ~context_impl();
-
- // The underlying scheduler.
- detail::scheduler& scheduler_;
-
- // The threads in the system thread pool.
- detail::thread_group threads_;
- };
- };
-
- #if !defined(GENERATING_DOCUMENTATION)
- template <> struct is_executor<system_executor> : true_type {};
- #endif // !defined(GENERATING_DOCUMENTATION)
-
- } // namespace asio
-
- #include "asio/detail/pop_options.hpp"
-
- #include "asio/impl/system_executor.hpp"
- #if defined(ASIO_HEADER_ONLY)
- # include "asio/impl/system_executor.ipp"
- #endif // defined(ASIO_HEADER_ONLY)
-
- #endif // ASIO_SYSTEM_EXECUTOR_HPP
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