comparison DEPENDENCIES/generic/include/boost/log/sinks/bounded_fifo_queue.hpp @ 16:2665513ce2d3

Add boost headers

+/*
+ *          Copyright Andrey Semashev 2007 - 2013.
+ * 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)
+ */
+/*!
+ * \file   bounded_fifo_queue.hpp
+ * \author Andrey Semashev
+ * \date   04.01.2012
+ *
+ * The header contains implementation of bounded FIFO queueing strategy for
+ * the asynchronous sink frontend.
+ */
+
+#ifndef BOOST_LOG_SINKS_BOUNDED_FIFO_QUEUE_HPP_INCLUDED_
+#define BOOST_LOG_SINKS_BOUNDED_FIFO_QUEUE_HPP_INCLUDED_
+
+#include <boost/log/detail/config.hpp>
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
+#endif
+
+#if defined(BOOST_LOG_NO_THREADS)
+#error Boost.Log: This header content is only supported in multithreaded environment
+#endif
+
+#include <cstddef>
+#include <queue>
+#include <boost/thread/locks.hpp>
+#include <boost/thread/mutex.hpp>
+#include <boost/thread/condition_variable.hpp>
+#include <boost/log/core/record_view.hpp>
+#include <boost/log/detail/header.hpp>
+
+namespace boost {
+
+BOOST_LOG_OPEN_NAMESPACE
+
+namespace sinks {
+
+/*!
+ * \brief Bounded FIFO log record queueing strategy
+ *
+ * The \c bounded_fifo_queue class is intended to be used with
+ * the \c asynchronous_sink frontend as a log record queueing strategy.
+ *
+ * This strategy describes log record queueing logic.
+ * The queue has a limited capacity, upon reaching which the enqueue operation will
+ * invoke the overflow handling strategy specified in the \c OverflowStrategyT
+ * template parameter to handle the situation. The library provides overflow handling
+ * strategies for most common cases: \c drop_on_overflow will silently discard the log record,
+ * and \c block_on_overflow will put the enqueueing thread to wait until there is space
+ * in the queue.
+ *
+ * The log record queue imposes no ordering over the queued
+ * elements aside from the order in which they are enqueued.
+ */
+template< std::size_t MaxQueueSizeV, typename OverflowStrategyT >
+class bounded_fifo_queue :
+    private OverflowStrategyT
+{
+private:
+    typedef OverflowStrategyT overflow_strategy;
+    typedef std::queue< record_view > queue_type;
+    typedef boost::mutex mutex_type;
+
+private:
+    //! Synchronization primitive
+    mutex_type m_mutex;
+    //! Condition to block the consuming thread on
+    condition_variable m_cond;
+    //! Log record queue
+    queue_type m_queue;
+    //! Interruption flag
+    bool m_interruption_requested;
+
+protected:
+    //! Default constructor
+    bounded_fifo_queue() : m_interruption_requested(false)
+    {
+    }
+    //! Initializing constructor
+    template< typename ArgsT >
+    explicit bounded_fifo_queue(ArgsT const&) : m_interruption_requested(false)
+    {
+    }
+
+    //! Enqueues log record to the queue
+    void enqueue(record_view const& rec)
+    {
+        unique_lock< mutex_type > lock(m_mutex);
+        std::size_t size = m_queue.size();
+        for (; size >= MaxQueueSizeV; size = m_queue.size())
+        {
+            if (!overflow_strategy::on_overflow(rec, lock))
+                return;
+        }
+
+        m_queue.push(rec);
+        if (size == 0)
+            m_cond.notify_one();
+    }
+
+    //! Attempts to enqueue log record to the queue
+    bool try_enqueue(record_view const& rec)
+    {
+        unique_lock< mutex_type > lock(m_mutex, try_to_lock);
+        if (lock.owns_lock())
+        {
+            const std::size_t size = m_queue.size();
+
+            // Do not invoke the bounding strategy in case of overflow as it may block
+            if (size < MaxQueueSizeV)
+            {
+                m_queue.push(rec);
+                if (size == 0)
+                    m_cond.notify_one();
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    //! Attempts to dequeue a log record ready for processing from the queue, does not block if the queue is empty
+    bool try_dequeue_ready(record_view& rec)
+    {
+        return try_dequeue(rec);
+    }
+
+    //! Attempts to dequeue log record from the queue, does not block if the queue is empty
+    bool try_dequeue(record_view& rec)
+    {
+        lock_guard< mutex_type > lock(m_mutex);
+        const std::size_t size = m_queue.size();
+        if (size > 0)
+        {
+            rec.swap(m_queue.front());
+            m_queue.pop();
+            if (size == MaxQueueSizeV)
+                overflow_strategy::on_queue_space_available();
+            return true;
+        }
+
+        return false;
+    }
+
+    //! Dequeues log record from the queue, blocks if the queue is empty
+    bool dequeue_ready(record_view& rec)
+    {
+        unique_lock< mutex_type > lock(m_mutex);
+
+        while (!m_interruption_requested)
+        {
+            const std::size_t size = m_queue.size();
+            if (size > 0)
+            {
+                rec.swap(m_queue.front());
+                m_queue.pop();
+                if (size == MaxQueueSizeV)
+                    overflow_strategy::on_queue_space_available();
+                return true;
+            }
+            else
+            {
+                m_cond.wait(lock);
+            }
+        }
+        m_interruption_requested = false;
+
+        return false;
+    }
+
+    //! Wakes a thread possibly blocked in the \c dequeue method
+    void interrupt_dequeue()
+    {
+        lock_guard< mutex_type > lock(m_mutex);
+        m_interruption_requested = true;
+        overflow_strategy::interrupt();
+        m_cond.notify_one();
+    }
+};
+
+} // namespace sinks
+
+BOOST_LOG_CLOSE_NAMESPACE // namespace log
+
+} // namespace boost
+
+#include <boost/log/detail/footer.hpp>
+
+#endif // BOOST_LOG_SINKS_BOUNDED_FIFO_QUEUE_HPP_INCLUDED_