Chris@16: /*
Chris@101:  *          Copyright Andrey Semashev 2007 - 2015.
Chris@16:  * Distributed under the Boost Software License, Version 1.0.
Chris@16:  *    (See accompanying file LICENSE_1_0.txt or copy at
Chris@16:  *          http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  */
Chris@16: /*!
Chris@16:  * \file   unbounded_fifo_queue.hpp
Chris@16:  * \author Andrey Semashev
Chris@16:  * \date   24.07.2011
Chris@16:  *
Chris@16:  * The header contains implementation of unbounded FIFO queueing strategy for
Chris@16:  * the asynchronous sink frontend.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_
Chris@16: #define BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_
Chris@16: 
Chris@16: #include <boost/log/detail/config.hpp>
Chris@16: 
Chris@16: #ifdef BOOST_HAS_PRAGMA_ONCE
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #if defined(BOOST_LOG_NO_THREADS)
Chris@16: #error Boost.Log: This header content is only supported in multithreaded environment
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/log/detail/event.hpp>
Chris@16: #include <boost/log/detail/threadsafe_queue.hpp>
Chris@16: #include <boost/log/core/record_view.hpp>
Chris@16: #include <boost/log/detail/header.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: BOOST_LOG_OPEN_NAMESPACE
Chris@16: 
Chris@16: namespace sinks {
Chris@16: 
Chris@16: /*!
Chris@16:  * \brief Unbounded FIFO log record queueing strategy
Chris@16:  *
Chris@16:  * The \c unbounded_fifo_queue class is intended to be used with
Chris@16:  * the \c asynchronous_sink frontend as a log record queueing strategy.
Chris@16:  *
Chris@16:  * This strategy implements the simplest logic of log record buffering between
Chris@16:  * threads: the queue has no limits and imposes no ordering over the queued
Chris@16:  * elements aside from the order in which they are enqueued.
Chris@16:  * Because of this the queue provides decent performance and scalability,
Chris@16:  * however if sink backends can't consume log records fast enough the queue
Chris@16:  * may grow uncontrollably. When this is an issue, it is recommended to
Chris@16:  * use one of the bounded strategies.
Chris@16:  */
Chris@16: class unbounded_fifo_queue
Chris@16: {
Chris@16: private:
Chris@16:     typedef boost::log::aux::threadsafe_queue< record_view > queue_type;
Chris@16: 
Chris@16: private:
Chris@16:     //! Thread-safe queue
Chris@16:     queue_type m_queue;
Chris@16:     //! Event object to block on
Chris@16:     boost::log::aux::event m_event;
Chris@16:     //! Interruption flag
Chris@16:     volatile bool m_interruption_requested; // TODO: make it atomic
Chris@16: 
Chris@16: protected:
Chris@16:     //! Default constructor
Chris@16:     unbounded_fifo_queue() : m_interruption_requested(false)
Chris@16:     {
Chris@16:     }
Chris@16:     //! Initializing constructor
Chris@16:     template< typename ArgsT >
Chris@16:     explicit unbounded_fifo_queue(ArgsT const&) : m_interruption_requested(false)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     //! Enqueues log record to the queue
Chris@16:     void enqueue(record_view const& rec)
Chris@16:     {
Chris@16:         m_queue.push(rec);
Chris@16:         m_event.set_signalled();
Chris@16:     }
Chris@16: 
Chris@16:     //! Attempts to enqueue log record to the queue
Chris@16:     bool try_enqueue(record_view const& rec)
Chris@16:     {
Chris@16:         // Assume the call never blocks
Chris@16:         enqueue(rec);
Chris@16:         return true;
Chris@16:     }
Chris@16: 
Chris@16:     //! Attempts to dequeue a log record ready for processing from the queue, does not block if the queue is empty
Chris@16:     bool try_dequeue_ready(record_view& rec)
Chris@16:     {
Chris@16:         return m_queue.try_pop(rec);
Chris@16:     }
Chris@16: 
Chris@16:     //! Attempts to dequeue log record from the queue, does not block if the queue is empty
Chris@16:     bool try_dequeue(record_view& rec)
Chris@16:     {
Chris@16:         return m_queue.try_pop(rec);
Chris@16:     }
Chris@16: 
Chris@16:     //! Dequeues log record from the queue, blocks if the queue is empty
Chris@16:     bool dequeue_ready(record_view& rec)
Chris@16:     {
Chris@16:         // Try the fast way first
Chris@16:         if (m_queue.try_pop(rec))
Chris@16:             return true;
Chris@16: 
Chris@16:         // Ok, we probably have to wait for new records
Chris@16:         while (true)
Chris@16:         {
Chris@16:             m_event.wait();
Chris@16:             if (m_interruption_requested)
Chris@16:             {
Chris@16:                 m_interruption_requested = false;
Chris@16:                 return false;
Chris@16:             }
Chris@16:             if (m_queue.try_pop(rec))
Chris@16:                 return true;
Chris@16:         }
Chris@16:     }
Chris@16: 
Chris@16:     //! Wakes a thread possibly blocked in the \c dequeue method
Chris@16:     void interrupt_dequeue()
Chris@16:     {
Chris@16:         m_interruption_requested = true;
Chris@16:         m_event.set_signalled();
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: } // namespace sinks
Chris@16: 
Chris@16: BOOST_LOG_CLOSE_NAMESPACE // namespace log
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/log/detail/footer.hpp>
Chris@16: 
Chris@16: #endif // BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_