ceph/src/boost/boost/log/sinks/unbounded_ordering_queue.hpp

   1 /*
   2  *          Copyright Andrey Semashev 2007 - 2015.
   3  * Distributed under the Boost Software License, Version 1.0.
   4  *    (See accompanying file LICENSE_1_0.txt or copy at
   5  *          http://www.boost.org/LICENSE_1_0.txt)
   6  */
   7 /*!
   8  * \file   unbounded_ordering_queue.hpp
   9  * \author Andrey Semashev
  10  * \date   24.07.2011
  11  *
  12  * The header contains implementation of unbounded ordering record queueing strategy for
  13  * the asynchronous sink frontend.
  14  */
  15
  16 #ifndef BOOST_LOG_SINKS_UNBOUNDED_ORDERING_QUEUE_HPP_INCLUDED_
  17 #define BOOST_LOG_SINKS_UNBOUNDED_ORDERING_QUEUE_HPP_INCLUDED_
  18
  19 #include <boost/log/detail/config.hpp>
  20
  21 #ifdef BOOST_HAS_PRAGMA_ONCE
  22 #pragma once
  23 #endif
  24
  25 #if defined(BOOST_LOG_NO_THREADS)
  26 #error Boost.Log: This header content is only supported in multithreaded environment
  27 #endif
  28
  29 #include <queue>
  30 #include <vector>
  31 #include <boost/cstdint.hpp>
  32 #include <boost/thread/locks.hpp>
  33 #include <boost/thread/mutex.hpp>
  34 #include <boost/thread/condition_variable.hpp>
  35 #include <boost/thread/thread_time.hpp>
  36 #include <boost/date_time/posix_time/posix_time_types.hpp>
  37 #include <boost/log/detail/timestamp.hpp>
  38 #include <boost/log/detail/enqueued_record.hpp>
  39 #include <boost/log/keywords/order.hpp>
  40 #include <boost/log/keywords/ordering_window.hpp>
  41 #include <boost/log/core/record_view.hpp>
  42 #include <boost/log/detail/header.hpp>
  43
  44 namespace boost {
  45
  46 BOOST_LOG_OPEN_NAMESPACE
  47
  48 namespace sinks {
  49
  50 /*!
  51  * \brief Unbounded ordering log record queueing strategy
  52  *
  53  * The \c unbounded_ordering_queue class is intended to be used with
  54  * the \c asynchronous_sink frontend as a log record queueing strategy.
  55  *
  56  * This strategy provides the following properties to the record queueing mechanism:
  57  *
  58  * \li The queue has no size limits.
  59  * \li The queue has a fixed latency window. This means that each log record put
  60  *     into the queue will normally not be dequeued for a certain period of time.
  61  * \li The queue performs stable record ordering within the latency window.
  62  *     The ordering predicate can be specified in the \c OrderT template parameter.
  63  *
  64  * Since this queue has no size limits, it may grow uncontrollably if sink backends
  65  * dequeue log records not fast enough. When this is an issue, it is recommended to
  66  * use one of the bounded strategies.
  67  */
  68 template< typename OrderT >
  69 class unbounded_ordering_queue
  70 {
  71 private:
  72     typedef boost::mutex mutex_type;
  73     typedef sinks::aux::enqueued_record enqueued_record;
  74
  75     typedef std::priority_queue<
  76         enqueued_record,
  77         std::vector< enqueued_record >,
  78         enqueued_record::order< OrderT >
  79     > queue_type;
  80
  81 private:
  82     //! Ordering window duration, in milliseconds
  83     const uint64_t m_ordering_window;
  84     //! Synchronization mutex
  85     mutex_type m_mutex;
  86     //! Condition for blocking
  87     condition_variable m_cond;
  88     //! Thread-safe queue
  89     queue_type m_queue;
  90     //! Interruption flag
  91     bool m_interruption_requested;
  92
  93 public:
  94     /*!
  95      * Returns ordering window size specified during initialization
  96      */
  97     posix_time::time_duration get_ordering_window() const
  98     {
  99         return posix_time::milliseconds(m_ordering_window);
 100     }
 101
 102     /*!
 103      * Returns default ordering window size.
 104      * The default window size is specific to the operating system thread scheduling mechanism.
 105      */
 106     static posix_time::time_duration get_default_ordering_window()
 107     {
 108         // The main idea behind this parameter is that the ordering window should be large enough
 109         // to allow the frontend to order records from different threads on an attribute
 110         // that contains system time. Thus this value should be:
 111         // * No less than the minimum time resolution quant that Boost.DateTime provides on the current OS.
 112         //   For instance, on Windows it defaults to around 15-16 ms.
 113         // * No less than thread switching quant on the current OS. For now 30 ms is large enough window size to
 114         //   switch threads on any known OS. It can be tuned for other platforms as needed.
 115         return posix_time::milliseconds(30);
 116     }
 117
 118 protected:
 119     //! Initializing constructor
 120     template< typename ArgsT >
 121     explicit unbounded_ordering_queue(ArgsT const& args) :
 122         m_ordering_window(args[keywords::ordering_window || &unbounded_ordering_queue::get_default_ordering_window].total_milliseconds()),
 123         m_queue(args[keywords::order]),
 124         m_interruption_requested(false)
 125     {
 126     }
 127
 128     //! Enqueues log record to the queue
 129     void enqueue(record_view const& rec)
 130     {
 131         lock_guard< mutex_type > lock(m_mutex);
 132         enqueue_unlocked(rec);
 133     }
 134
 135     //! Attempts to enqueue log record to the queue
 136     bool try_enqueue(record_view const& rec)
 137     {
 138         unique_lock< mutex_type > lock(m_mutex, try_to_lock);
 139         if (lock.owns_lock())
 140         {
 141             enqueue_unlocked(rec);
 142             return true;
 143         }
 144         else
 145             return false;
 146     }
 147
 148     //! Attempts to dequeue a log record ready for processing from the queue, does not block if no log records are ready to be processed
 149     bool try_dequeue_ready(record_view& rec)
 150     {
 151         lock_guard< mutex_type > lock(m_mutex);
 152         if (!m_queue.empty())
 153         {
 154             const boost::log::aux::timestamp now = boost::log::aux::get_timestamp();
 155             enqueued_record const& elem = m_queue.top();
 156             if (static_cast< uint64_t >((now - elem.m_timestamp).milliseconds()) >= m_ordering_window)
 157             {
 158                 // We got a new element
 159                 rec = elem.m_record;
 160                 m_queue.pop();
 161                 return true;
 162             }
 163         }
 164
 165         return false;
 166     }
 167
 168     //! Attempts to dequeue log record from the queue, does not block.
 169     bool try_dequeue(record_view& rec)
 170     {
 171         lock_guard< mutex_type > lock(m_mutex);
 172         if (!m_queue.empty())
 173         {
 174             enqueued_record const& elem = m_queue.top();
 175             rec = elem.m_record;
 176             m_queue.pop();
 177             return true;
 178         }
 179
 180         return false;
 181     }
 182
 183     //! Dequeues log record from the queue, blocks if no log records are ready to be processed
 184     bool dequeue_ready(record_view& rec)
 185     {
 186         unique_lock< mutex_type > lock(m_mutex);
 187         while (!m_interruption_requested)
 188         {
 189             if (!m_queue.empty())
 190             {
 191                 const boost::log::aux::timestamp now = boost::log::aux::get_timestamp();
 192                 enqueued_record const& elem = m_queue.top();
 193                 const uint64_t difference = (now - elem.m_timestamp).milliseconds();
 194                 if (difference >= m_ordering_window)
 195                 {
 196                     // We got a new element
 197                     rec = elem.m_record;
 198                     m_queue.pop();
 199                     return true;
 200                 }
 201                 else
 202                 {
 203                     // Wait until the element becomes ready to be processed
 204                     m_cond.timed_wait(lock, posix_time::milliseconds(m_ordering_window - difference));
 205                 }
 206             }
 207             else
 208             {
 209                 // Wait for an element to come
 210                 m_cond.wait(lock);
 211             }
 212         }
 213         m_interruption_requested = false;
 214
 215         return false;
 216     }
 217
 218     //! Wakes a thread possibly blocked in the \c dequeue method
 219     void interrupt_dequeue()
 220     {
 221         lock_guard< mutex_type > lock(m_mutex);
 222         m_interruption_requested = true;
 223         m_cond.notify_one();
 224     }
 225
 226 private:
 227     //! Enqueues a log record
 228     void enqueue_unlocked(record_view const& rec)
 229     {
 230         const bool was_empty = m_queue.empty();
 231         m_queue.push(enqueued_record(rec));
 232         if (was_empty)
 233             m_cond.notify_one();
 234     }
 235 };
 236
 237 } // namespace sinks
 238
 239 BOOST_LOG_CLOSE_NAMESPACE // namespace log
 240
 241 } // namespace boost
 242
 243 #include <boost/log/detail/footer.hpp>
 244
 245 #endif // BOOST_LOG_SINKS_UNBOUNDED_ORDERING_QUEUE_HPP_INCLUDED_