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   block_on_overflow.hpp
Chris@16:  * \author Andrey Semashev
Chris@16:  * \date   04.01.2012
Chris@16:  *
Chris@16:  * The header contains implementation of \c block_on_overflow strategy for handling
Chris@16:  * queue overflows in bounded queues for the asynchronous sink frontend.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_LOG_SINKS_BLOCK_ON_OVERFLOW_HPP_INCLUDED_
Chris@16: #define BOOST_LOG_SINKS_BLOCK_ON_OVERFLOW_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/intrusive/options.hpp>
Chris@16: #include <boost/intrusive/list.hpp>
Chris@16: #include <boost/intrusive/list_hook.hpp>
Chris@16: #include <boost/thread/condition_variable.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 Blocking strategy for handling log record queue overflows
Chris@16:  *
Chris@16:  * This strategy will cause enqueueing threads to block when the
Chris@16:  * log record queue overflows. The blocked threads will be woken as
Chris@16:  * soon as there appears free space in the queue, in the same order
Chris@16:  * they attempted to enqueue records.
Chris@16:  */
Chris@16: class block_on_overflow
Chris@16: {
Chris@16: #ifndef BOOST_LOG_DOXYGEN_PASS
Chris@16: private:
Chris@16:     typedef intrusive::list_base_hook<
Chris@16:         intrusive::link_mode< intrusive::auto_unlink >
Chris@16:     > thread_context_hook_t;
Chris@16: 
Chris@16:     struct thread_context :
Chris@16:         public thread_context_hook_t
Chris@16:     {
Chris@16:         condition_variable cond;
Chris@16:         bool result;
Chris@16: 
Chris@16:         thread_context() : result(true) {}
Chris@16:     };
Chris@16: 
Chris@16:     typedef intrusive::list<
Chris@16:         thread_context,
Chris@16:         intrusive::base_hook< thread_context_hook_t >,
Chris@16:         intrusive::constant_time_size< false >
Chris@16:     > thread_contexts;
Chris@16: 
Chris@16: private:
Chris@16:     //! Blocked threads
Chris@16:     thread_contexts m_thread_contexts;
Chris@16: 
Chris@16: public:
Chris@16:     /*!
Chris@16:      * Default constructor.
Chris@16:      */
Chris@101:     BOOST_DEFAULTED_FUNCTION(block_on_overflow(), {})
Chris@16: 
Chris@16:     /*!
Chris@16:      * This method is called by the queue when overflow is detected.
Chris@16:      *
Chris@16:      * \param lock An internal lock that protects the queue
Chris@16:      *
Chris@16:      * \retval true Attempt to enqueue the record again.
Chris@16:      * \retval false Discard the record.
Chris@16:      */
Chris@16:     template< typename LockT >
Chris@16:     bool on_overflow(record_view const&, LockT& lock)
Chris@16:     {
Chris@16:         thread_context context;
Chris@16:         m_thread_contexts.push_back(context);
Chris@16:         do
Chris@16:         {
Chris@16:             context.cond.wait(lock);
Chris@16:         }
Chris@16:         while (context.is_linked());
Chris@16: 
Chris@16:         return context.result;
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * This method is called by the queue when there appears a free space.
Chris@16:      * The internal lock protecting the queue is locked when calling this method.
Chris@16:      */
Chris@16:     void on_queue_space_available()
Chris@16:     {
Chris@16:         if (!m_thread_contexts.empty())
Chris@16:         {
Chris@16:             m_thread_contexts.front().cond.notify_one();
Chris@16:             m_thread_contexts.pop_front();
Chris@16:         }
Chris@16:     }
Chris@16: 
Chris@16:     /*!
Chris@16:      * This method is called by the queue to interrupt any possible waits in \c on_overflow.
Chris@16:      * The internal lock protecting the queue is locked when calling this method.
Chris@16:      */
Chris@16:     void interrupt()
Chris@16:     {
Chris@16:         while (!m_thread_contexts.empty())
Chris@16:         {
Chris@16:             thread_context& context = m_thread_contexts.front();
Chris@16:             context.result = false;
Chris@16:             context.cond.notify_one();
Chris@16:             m_thread_contexts.pop_front();
Chris@16:         }
Chris@16:     }
Chris@101: 
Chris@101:     //  Copying prohibited
Chris@101:     BOOST_DELETED_FUNCTION(block_on_overflow(block_on_overflow const&))
Chris@101:     BOOST_DELETED_FUNCTION(block_on_overflow& operator= (block_on_overflow const&))
Chris@16: #endif // BOOST_LOG_DOXYGEN_PASS
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_BLOCK_ON_OVERFLOW_HPP_INCLUDED_