145 lines
4.5 KiB
C++
145 lines
4.5 KiB
C++
//
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// detail/strand_service.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef ASIO_DETAIL_STRAND_SERVICE_HPP
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#define ASIO_DETAIL_STRAND_SERVICE_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include "asio/detail/config.hpp"
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#include "asio/io_context.hpp"
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#include "asio/detail/mutex.hpp"
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#include "asio/detail/op_queue.hpp"
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#include "asio/detail/operation.hpp"
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#include "asio/detail/scoped_ptr.hpp"
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#include "asio/detail/push_options.hpp"
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namespace asio {
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namespace detail {
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// Default service implementation for a strand.
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class strand_service
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: public asio::detail::service_base<strand_service>
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{
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private:
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// Helper class to re-post the strand on exit.
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struct on_do_complete_exit;
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// Helper class to re-post the strand on exit.
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struct on_dispatch_exit;
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public:
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// The underlying implementation of a strand.
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class strand_impl
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: public operation
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{
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public:
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strand_impl();
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private:
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// Only this service will have access to the internal values.
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friend class strand_service;
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friend struct on_do_complete_exit;
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friend struct on_dispatch_exit;
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// Mutex to protect access to internal data.
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asio::detail::mutex mutex_;
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// Indicates whether the strand is currently "locked" by a handler. This
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// means that there is a handler upcall in progress, or that the strand
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// itself has been scheduled in order to invoke some pending handlers.
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bool locked_;
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// The handlers that are waiting on the strand but should not be run until
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// after the next time the strand is scheduled. This queue must only be
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// modified while the mutex is locked.
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op_queue<operation> waiting_queue_;
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// The handlers that are ready to be run. Logically speaking, these are the
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// handlers that hold the strand's lock. The ready queue is only modified
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// from within the strand and so may be accessed without locking the mutex.
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op_queue<operation> ready_queue_;
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};
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typedef strand_impl* implementation_type;
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// Construct a new strand service for the specified io_context.
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ASIO_DECL explicit strand_service(asio::io_context& io_context);
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// Destroy all user-defined handler objects owned by the service.
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ASIO_DECL void shutdown();
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// Construct a new strand implementation.
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ASIO_DECL void construct(implementation_type& impl);
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// Request the io_context to invoke the given handler.
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template <typename Handler>
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void dispatch(implementation_type& impl, Handler& handler);
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// Request the io_context to invoke the given handler and return immediately.
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template <typename Handler>
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void post(implementation_type& impl, Handler& handler);
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// Determine whether the strand is running in the current thread.
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ASIO_DECL bool running_in_this_thread(
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const implementation_type& impl) const;
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private:
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// Helper function to dispatch a handler.
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ASIO_DECL void do_dispatch(implementation_type& impl, operation* op);
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// Helper function to post a handler.
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ASIO_DECL void do_post(implementation_type& impl,
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operation* op, bool is_continuation);
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ASIO_DECL static void do_complete(void* owner,
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operation* base, const asio::error_code& ec,
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std::size_t bytes_transferred);
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// The io_context used to obtain an I/O executor.
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io_context& io_context_;
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// The io_context implementation used to post completions.
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io_context_impl& io_context_impl_;
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// Mutex to protect access to the array of implementations.
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asio::detail::mutex mutex_;
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// Number of implementations shared between all strand objects.
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#if defined(ASIO_STRAND_IMPLEMENTATIONS)
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enum { num_implementations = ASIO_STRAND_IMPLEMENTATIONS };
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#else // defined(ASIO_STRAND_IMPLEMENTATIONS)
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enum { num_implementations = 193 };
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#endif // defined(ASIO_STRAND_IMPLEMENTATIONS)
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// Pool of implementations.
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scoped_ptr<strand_impl> implementations_[num_implementations];
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// Extra value used when hashing to prevent recycled memory locations from
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// getting the same strand implementation.
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std::size_t salt_;
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};
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} // namespace detail
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#include "asio/detail/impl/strand_service.hpp"
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#if defined(ASIO_HEADER_ONLY)
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# include "asio/detail/impl/strand_service.ipp"
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#endif // defined(ASIO_HEADER_ONLY)
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#endif // ASIO_DETAIL_STRAND_SERVICE_HPP
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