| // |
| // detail/impl/strand_service.hpp |
| // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| // |
| // Copyright (c) 2003-2010 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_IMPL_STRAND_SERVICE_HPP |
| #define BOOST_ASIO_DETAIL_IMPL_STRAND_SERVICE_HPP |
| |
| #if defined(_MSC_VER) && (_MSC_VER >= 1200) |
| # pragma once |
| #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
| |
| #include <boost/asio/detail/call_stack.hpp> |
| #include <boost/asio/detail/completion_handler.hpp> |
| #include <boost/asio/detail/fenced_block.hpp> |
| #include <boost/asio/detail/handler_alloc_helpers.hpp> |
| #include <boost/asio/detail/handler_invoke_helpers.hpp> |
| |
| #include <boost/asio/detail/push_options.hpp> |
| |
| namespace boost { |
| namespace asio { |
| namespace detail { |
| |
| inline strand_service::strand_impl::strand_impl() |
| : operation(&strand_service::do_complete), |
| count_(0) |
| { |
| } |
| |
| struct strand_service::on_dispatch_exit |
| { |
| io_service_impl* io_service_; |
| strand_impl* impl_; |
| |
| ~on_dispatch_exit() |
| { |
| impl_->mutex_.lock(); |
| bool more_handlers = (--impl_->count_ > 0); |
| impl_->mutex_.unlock(); |
| |
| if (more_handlers) |
| io_service_->post_immediate_completion(impl_); |
| } |
| }; |
| |
| inline void strand_service::destroy(strand_service::implementation_type& impl) |
| { |
| impl = 0; |
| } |
| |
| template <typename Handler> |
| void strand_service::dispatch(strand_service::implementation_type& impl, |
| Handler handler) |
| { |
| // If we are already in the strand then the handler can run immediately. |
| if (call_stack<strand_impl>::contains(impl)) |
| { |
| boost::asio::detail::fenced_block b; |
| boost_asio_handler_invoke_helpers::invoke(handler, handler); |
| return; |
| } |
| |
| // Allocate and construct an operation to wrap the handler. |
| typedef completion_handler<Handler> op; |
| typename op::ptr p = { boost::addressof(handler), |
| boost_asio_handler_alloc_helpers::allocate( |
| sizeof(op), handler), 0 }; |
| p.p = new (p.v) op(handler); |
| |
| // If we are running inside the io_service, and no other handler is queued |
| // or running, then the handler can run immediately. |
| bool can_dispatch = call_stack<io_service_impl>::contains(&io_service_); |
| impl->mutex_.lock(); |
| bool first = (++impl->count_ == 1); |
| if (can_dispatch && first) |
| { |
| // Immediate invocation is allowed. |
| impl->mutex_.unlock(); |
| |
| // Memory must be releaesed before any upcall is made. |
| p.reset(); |
| |
| // Indicate that this strand is executing on the current thread. |
| call_stack<strand_impl>::context ctx(impl); |
| |
| // Ensure the next handler, if any, is scheduled on block exit. |
| on_dispatch_exit on_exit = { &io_service_, impl }; |
| (void)on_exit; |
| |
| boost::asio::detail::fenced_block b; |
| boost_asio_handler_invoke_helpers::invoke(handler, handler); |
| return; |
| } |
| |
| // Immediate invocation is not allowed, so enqueue for later. |
| impl->queue_.push(p.p); |
| impl->mutex_.unlock(); |
| p.v = p.p = 0; |
| |
| // The first handler to be enqueued is responsible for scheduling the |
| // strand. |
| if (first) |
| io_service_.post_immediate_completion(impl); |
| } |
| |
| // Request the io_service to invoke the given handler and return immediately. |
| template <typename Handler> |
| void strand_service::post(strand_service::implementation_type& impl, |
| Handler handler) |
| { |
| // Allocate and construct an operation to wrap the handler. |
| typedef completion_handler<Handler> op; |
| typename op::ptr p = { boost::addressof(handler), |
| boost_asio_handler_alloc_helpers::allocate( |
| sizeof(op), handler), 0 }; |
| p.p = new (p.v) op(handler); |
| |
| // Add the handler to the queue. |
| impl->mutex_.lock(); |
| bool first = (++impl->count_ == 1); |
| impl->queue_.push(p.p); |
| impl->mutex_.unlock(); |
| p.v = p.p = 0; |
| |
| // The first handler to be enqueue is responsible for scheduling the strand. |
| if (first) |
| io_service_.post_immediate_completion(impl); |
| } |
| |
| } // namespace detail |
| } // namespace asio |
| } // namespace boost |
| |
| #include <boost/asio/detail/pop_options.hpp> |
| |
| #endif // BOOST_ASIO_DETAIL_IMPL_STRAND_SERVICE_HPP |