143 lines
3.9 KiB
C++
143 lines
3.9 KiB
C++
/*
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* Copyright Andrey Semashev 2007 - 2013.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*/
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/*!
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* \file unbounded_fifo_queue.hpp
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* \author Andrey Semashev
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* \date 24.07.2011
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*
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* The header contains implementation of unbounded FIFO queueing strategy for
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* the asynchronous sink frontend.
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*/
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#ifndef BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_
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#define BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_
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#include <boost/log/detail/config.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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#if defined(BOOST_LOG_NO_THREADS)
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#error Boost.Log: This header content is only supported in multithreaded environment
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#endif
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#include <boost/log/detail/event.hpp>
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#include <boost/log/detail/threadsafe_queue.hpp>
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#include <boost/log/core/record_view.hpp>
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#include <boost/log/detail/header.hpp>
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namespace boost {
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BOOST_LOG_OPEN_NAMESPACE
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namespace sinks {
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/*!
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* \brief Unbounded FIFO log record queueing strategy
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*
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* The \c unbounded_fifo_queue class is intended to be used with
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* the \c asynchronous_sink frontend as a log record queueing strategy.
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*
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* This strategy implements the simplest logic of log record buffering between
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* threads: the queue has no limits and imposes no ordering over the queued
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* elements aside from the order in which they are enqueued.
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* Because of this the queue provides decent performance and scalability,
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* however if sink backends can't consume log records fast enough the queue
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* may grow uncontrollably. When this is an issue, it is recommended to
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* use one of the bounded strategies.
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*/
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class unbounded_fifo_queue
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{
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private:
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typedef boost::log::aux::threadsafe_queue< record_view > queue_type;
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private:
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//! Thread-safe queue
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queue_type m_queue;
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//! Event object to block on
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boost::log::aux::event m_event;
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//! Interruption flag
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volatile bool m_interruption_requested; // TODO: make it atomic
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protected:
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//! Default constructor
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unbounded_fifo_queue() : m_interruption_requested(false)
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{
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}
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//! Initializing constructor
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template< typename ArgsT >
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explicit unbounded_fifo_queue(ArgsT const&) : m_interruption_requested(false)
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{
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}
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//! Enqueues log record to the queue
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void enqueue(record_view const& rec)
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{
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m_queue.push(rec);
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m_event.set_signalled();
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}
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//! Attempts to enqueue log record to the queue
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bool try_enqueue(record_view const& rec)
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{
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// Assume the call never blocks
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enqueue(rec);
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return true;
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}
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//! Attempts to dequeue a log record ready for processing from the queue, does not block if the queue is empty
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bool try_dequeue_ready(record_view& rec)
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{
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return m_queue.try_pop(rec);
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}
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//! Attempts to dequeue log record from the queue, does not block if the queue is empty
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bool try_dequeue(record_view& rec)
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{
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return m_queue.try_pop(rec);
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}
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//! Dequeues log record from the queue, blocks if the queue is empty
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bool dequeue_ready(record_view& rec)
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{
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// Try the fast way first
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if (m_queue.try_pop(rec))
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return true;
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// Ok, we probably have to wait for new records
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while (true)
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{
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m_event.wait();
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if (m_interruption_requested)
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{
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m_interruption_requested = false;
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return false;
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}
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if (m_queue.try_pop(rec))
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return true;
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}
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}
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//! Wakes a thread possibly blocked in the \c dequeue method
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void interrupt_dequeue()
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{
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m_interruption_requested = true;
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m_event.set_signalled();
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}
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};
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} // namespace sinks
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BOOST_LOG_CLOSE_NAMESPACE // namespace log
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} // namespace boost
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#include <boost/log/detail/footer.hpp>
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#endif // BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_
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