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Diffstat (limited to '3rdParty/Boost/src/boost/asio/detail/task_io_service.hpp')
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+//
+// task_io_service.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2008 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_TASK_IO_SERVICE_HPP
+#define BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#if defined(BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE)
+#include <boost/asio/detail/task_io_service_2lock.hpp>
+#else // defined(BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE)
+
+#include <boost/asio/detail/push_options.hpp>
+
+#include <boost/asio/io_service.hpp>
+#include <boost/asio/detail/call_stack.hpp>
+#include <boost/asio/detail/event.hpp>
+#include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/handler_queue.hpp>
+#include <boost/asio/detail/mutex.hpp>
+#include <boost/asio/detail/service_base.hpp>
+#include <boost/asio/detail/task_io_service_fwd.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Task>
+class task_io_service
+ : public boost::asio::detail::service_base<task_io_service<Task> >
+{
+public:
+ // Constructor.
+ task_io_service(boost::asio::io_service& io_service)
+ : boost::asio::detail::service_base<task_io_service<Task> >(io_service),
+ mutex_(),
+ task_(0),
+ task_interrupted_(true),
+ outstanding_work_(0),
+ stopped_(false),
+ shutdown_(false),
+ first_idle_thread_(0)
+ {
+ }
+
+ void init(size_t /*concurrency_hint*/)
+ {
+ }
+
+ // Destroy all user-defined handler objects owned by the service.
+ void shutdown_service()
+ {
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+ shutdown_ = true;
+ lock.unlock();
+
+ // Destroy handler objects.
+ while (!handler_queue_.empty())
+ {
+ handler_queue::handler* h = handler_queue_.front();
+ handler_queue_.pop();
+ if (h != &task_handler_)
+ h->destroy();
+ }
+
+ // Reset to initial state.
+ task_ = 0;
+ }
+
+ // Initialise the task, if required.
+ void init_task()
+ {
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+ if (!shutdown_ && !task_)
+ {
+ task_ = &use_service<Task>(this->get_io_service());
+ handler_queue_.push(&task_handler_);
+ interrupt_one_idle_thread(lock);
+ }
+ }
+
+ // Run the event loop until interrupted or no more work.
+ size_t run(boost::system::error_code& ec)
+ {
+ typename call_stack<task_io_service>::context ctx(this);
+
+ idle_thread_info this_idle_thread;
+ this_idle_thread.next = 0;
+
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+ size_t n = 0;
+ while (do_one(lock, &this_idle_thread, ec))
+ if (n != (std::numeric_limits<size_t>::max)())
+ ++n;
+ return n;
+ }
+
+ // Run until interrupted or one operation is performed.
+ size_t run_one(boost::system::error_code& ec)
+ {
+ typename call_stack<task_io_service>::context ctx(this);
+
+ idle_thread_info this_idle_thread;
+ this_idle_thread.next = 0;
+
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+ return do_one(lock, &this_idle_thread, ec);
+ }
+
+ // Poll for operations without blocking.
+ size_t poll(boost::system::error_code& ec)
+ {
+ typename call_stack<task_io_service>::context ctx(this);
+
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+ size_t n = 0;
+ while (do_one(lock, 0, ec))
+ if (n != (std::numeric_limits<size_t>::max)())
+ ++n;
+ return n;
+ }
+
+ // Poll for one operation without blocking.
+ size_t poll_one(boost::system::error_code& ec)
+ {
+ typename call_stack<task_io_service>::context ctx(this);
+
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+ return do_one(lock, 0, ec);
+ }
+
+ // Interrupt the event processing loop.
+ void stop()
+ {
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+ stop_all_threads(lock);
+ }
+
+ // Reset in preparation for a subsequent run invocation.
+ void reset()
+ {
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+ stopped_ = false;
+ }
+
+ // Notify that some work has started.
+ void work_started()
+ {
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+ ++outstanding_work_;
+ }
+
+ // Notify that some work has finished.
+ void work_finished()
+ {
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+ if (--outstanding_work_ == 0)
+ stop_all_threads(lock);
+ }
+
+ // Request invocation of the given handler.
+ template <typename Handler>
+ void dispatch(Handler handler)
+ {
+ if (call_stack<task_io_service>::contains(this))
+ boost_asio_handler_invoke_helpers::invoke(handler, &handler);
+ else
+ post(handler);
+ }
+
+ // Request invocation of the given handler and return immediately.
+ template <typename Handler>
+ void post(Handler handler)
+ {
+ // Allocate and construct an operation to wrap the handler.
+ handler_queue::scoped_ptr ptr(handler_queue::wrap(handler));
+
+ boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+ // If the service has been shut down we silently discard the handler.
+ if (shutdown_)
+ return;
+
+ // Add the handler to the end of the queue.
+ handler_queue_.push(ptr.get());
+ ptr.release();
+
+ // An undelivered handler is treated as unfinished work.
+ ++outstanding_work_;
+
+ // Wake up a thread to execute the handler.
+ if (!interrupt_one_idle_thread(lock))
+ {
+ if (!task_interrupted_ && task_)
+ {
+ task_interrupted_ = true;
+ task_->interrupt();
+ }
+ }
+ }
+
+private:
+ struct idle_thread_info;
+
+ size_t do_one(boost::asio::detail::mutex::scoped_lock& lock,
+ idle_thread_info* this_idle_thread, boost::system::error_code& ec)
+ {
+ if (outstanding_work_ == 0 && !stopped_)
+ {
+ stop_all_threads(lock);
+ ec = boost::system::error_code();
+ return 0;
+ }
+
+ bool polling = !this_idle_thread;
+ bool task_has_run = false;
+ while (!stopped_)
+ {
+ if (!handler_queue_.empty())
+ {
+ // Prepare to execute first handler from queue.
+ handler_queue::handler* h = handler_queue_.front();
+ handler_queue_.pop();
+
+ if (h == &task_handler_)
+ {
+ bool more_handlers = (!handler_queue_.empty());
+ task_interrupted_ = more_handlers || polling;
+
+ // If the task has already run and we're polling then we're done.
+ if (task_has_run && polling)
+ {
+ task_interrupted_ = true;
+ handler_queue_.push(&task_handler_);
+ ec = boost::system::error_code();
+ return 0;
+ }
+ task_has_run = true;
+
+ lock.unlock();
+ task_cleanup c(lock, *this);
+
+ // Run the task. May throw an exception. Only block if the handler
+ // queue is empty and we have an idle_thread_info object, otherwise
+ // we want to return as soon as possible.
+ task_->run(!more_handlers && !polling);
+ }
+ else
+ {
+ lock.unlock();
+ handler_cleanup c(lock, *this);
+
+ // Invoke the handler. May throw an exception.
+ h->invoke(); // invoke() deletes the handler object
+
+ ec = boost::system::error_code();
+ return 1;
+ }
+ }
+ else if (this_idle_thread)
+ {
+ // Nothing to run right now, so just wait for work to do.
+ this_idle_thread->next = first_idle_thread_;
+ first_idle_thread_ = this_idle_thread;
+ this_idle_thread->wakeup_event.clear(lock);
+ this_idle_thread->wakeup_event.wait(lock);
+ }
+ else
+ {
+ ec = boost::system::error_code();
+ return 0;
+ }
+ }
+
+ ec = boost::system::error_code();
+ return 0;
+ }
+
+ // Stop the task and all idle threads.
+ void stop_all_threads(
+ boost::asio::detail::mutex::scoped_lock& lock)
+ {
+ stopped_ = true;
+ interrupt_all_idle_threads(lock);
+ if (!task_interrupted_ && task_)
+ {
+ task_interrupted_ = true;
+ task_->interrupt();
+ }
+ }
+
+ // Interrupt a single idle thread. Returns true if a thread was interrupted,
+ // false if no running thread could be found to interrupt.
+ bool interrupt_one_idle_thread(
+ boost::asio::detail::mutex::scoped_lock& lock)
+ {
+ if (first_idle_thread_)
+ {
+ idle_thread_info* idle_thread = first_idle_thread_;
+ first_idle_thread_ = idle_thread->next;
+ idle_thread->next = 0;
+ idle_thread->wakeup_event.signal(lock);
+ return true;
+ }
+ return false;
+ }
+
+ // Interrupt all idle threads.
+ void interrupt_all_idle_threads(
+ boost::asio::detail::mutex::scoped_lock& lock)
+ {
+ while (first_idle_thread_)
+ {
+ idle_thread_info* idle_thread = first_idle_thread_;
+ first_idle_thread_ = idle_thread->next;
+ idle_thread->next = 0;
+ idle_thread->wakeup_event.signal(lock);
+ }
+ }
+
+ // Helper class to perform task-related operations on block exit.
+ class task_cleanup;
+ friend class task_cleanup;
+ class task_cleanup
+ {
+ public:
+ task_cleanup(boost::asio::detail::mutex::scoped_lock& lock,
+ task_io_service& task_io_svc)
+ : lock_(lock),
+ task_io_service_(task_io_svc)
+ {
+ }
+
+ ~task_cleanup()
+ {
+ // Reinsert the task at the end of the handler queue.
+ lock_.lock();
+ task_io_service_.task_interrupted_ = true;
+ task_io_service_.handler_queue_.push(&task_io_service_.task_handler_);
+ }
+
+ private:
+ boost::asio::detail::mutex::scoped_lock& lock_;
+ task_io_service& task_io_service_;
+ };
+
+ // Helper class to perform handler-related operations on block exit.
+ class handler_cleanup;
+ friend class handler_cleanup;
+ class handler_cleanup
+ {
+ public:
+ handler_cleanup(boost::asio::detail::mutex::scoped_lock& lock,
+ task_io_service& task_io_svc)
+ : lock_(lock),
+ task_io_service_(task_io_svc)
+ {
+ }
+
+ ~handler_cleanup()
+ {
+ lock_.lock();
+ if (--task_io_service_.outstanding_work_ == 0)
+ task_io_service_.stop_all_threads(lock_);
+ }
+
+ private:
+ boost::asio::detail::mutex::scoped_lock& lock_;
+ task_io_service& task_io_service_;
+ };
+
+ // Mutex to protect access to internal data.
+ boost::asio::detail::mutex mutex_;
+
+ // The task to be run by this service.
+ Task* task_;
+
+ // Handler object to represent the position of the task in the queue.
+ class task_handler
+ : public handler_queue::handler
+ {
+ public:
+ task_handler()
+ : handler_queue::handler(0, 0)
+ {
+ }
+ } task_handler_;
+
+ // Whether the task has been interrupted.
+ bool task_interrupted_;
+
+ // The count of unfinished work.
+ int outstanding_work_;
+
+ // The queue of handlers that are ready to be delivered.
+ handler_queue handler_queue_;
+
+ // Flag to indicate that the dispatcher has been stopped.
+ bool stopped_;
+
+ // Flag to indicate that the dispatcher has been shut down.
+ bool shutdown_;
+
+ // Structure containing information about an idle thread.
+ struct idle_thread_info
+ {
+ event wakeup_event;
+ idle_thread_info* next;
+ };
+
+ // The number of threads that are currently idle.
+ idle_thread_info* first_idle_thread_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/system/error_code.hpp>
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // defined(BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE)
+
+#endif // BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP