// // detail/strand_service.hpp // ~~~~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2014 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 BOOST_ASIO_DETAIL_STRAND_SERVICE_HPP #define BOOST_ASIO_DETAIL_STRAND_SERVICE_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include <boost/asio/detail/config.hpp> #include <boost/asio/io_service.hpp> #include <boost/asio/detail/mutex.hpp> #include <boost/asio/detail/op_queue.hpp> #include <boost/asio/detail/operation.hpp> #include <boost/asio/detail/scoped_ptr.hpp> #include <boost/asio/detail/push_options.hpp> namespace boost { namespace asio { namespace detail { // Default service implementation for a strand. class strand_service : public boost::asio::detail::service_base<strand_service> { private: // Helper class to re-post the strand on exit. struct on_do_complete_exit; // Helper class to re-post the strand on exit. struct on_dispatch_exit; public: // The underlying implementation of a strand. class strand_impl : public operation { public: strand_impl(); private: // Only this service will have access to the internal values. friend class strand_service; friend struct on_do_complete_exit; friend struct on_dispatch_exit; // Mutex to protect access to internal data. boost::asio::detail::mutex mutex_; // Indicates whether the strand is currently "locked" by a handler. This // means that there is a handler upcall in progress, or that the strand // itself has been scheduled in order to invoke some pending handlers. bool locked_; // The handlers that are waiting on the strand but should not be run until // after the next time the strand is scheduled. This queue must only be // modified while the mutex is locked. op_queue<operation> waiting_queue_; // The handlers that are ready to be run. Logically speaking, these are the // handlers that hold the strand's lock. The ready queue is only modified // from within the strand and so may be accessed without locking the mutex. op_queue<operation> ready_queue_; }; typedef strand_impl* implementation_type; // Construct a new strand service for the specified io_service. BOOST_ASIO_DECL explicit strand_service(boost::asio::io_service& io_service); // Destroy all user-defined handler objects owned by the service. BOOST_ASIO_DECL void shutdown_service(); // Construct a new strand implementation. BOOST_ASIO_DECL void construct(implementation_type& impl); // Request the io_service to invoke the given handler. template <typename Handler> void dispatch(implementation_type& impl, Handler& handler); // Request the io_service to invoke the given handler and return immediately. template <typename Handler> void post(implementation_type& impl, Handler& handler); // Determine whether the strand is running in the current thread. BOOST_ASIO_DECL bool running_in_this_thread( const implementation_type& impl) const; private: // Helper function to dispatch a handler. Returns true if the handler should // be dispatched immediately. BOOST_ASIO_DECL bool do_dispatch(implementation_type& impl, operation* op); // Helper fiunction to post a handler. BOOST_ASIO_DECL void do_post(implementation_type& impl, operation* op, bool is_continuation); BOOST_ASIO_DECL static void do_complete(io_service_impl* owner, operation* base, const boost::system::error_code& ec, std::size_t bytes_transferred); // The io_service implementation used to post completions. io_service_impl& io_service_; // Mutex to protect access to the array of implementations. boost::asio::detail::mutex mutex_; // Number of implementations shared between all strand objects. #if defined(BOOST_ASIO_STRAND_IMPLEMENTATIONS) enum { num_implementations = BOOST_ASIO_STRAND_IMPLEMENTATIONS }; #else // defined(BOOST_ASIO_STRAND_IMPLEMENTATIONS) enum { num_implementations = 193 }; #endif // defined(BOOST_ASIO_STRAND_IMPLEMENTATIONS) // Pool of implementations. scoped_ptr<strand_impl> implementations_[num_implementations]; // Extra value used when hashing to prevent recycled memory locations from // getting the same strand implementation. std::size_t salt_; }; } // namespace detail } // namespace asio } // namespace boost #include <boost/asio/detail/pop_options.hpp> #include <boost/asio/detail/impl/strand_service.hpp> #if defined(BOOST_ASIO_HEADER_ONLY) # include <boost/asio/detail/impl/strand_service.ipp> #endif // defined(BOOST_ASIO_HEADER_ONLY) #endif // BOOST_ASIO_DETAIL_STRAND_SERVICE_HPP