Line data    Source code

       1             : 
       2             : /* Copyright (c) 2010-2014, Stefan Eilemann <eile@equalizergraphics.com>
       3             :  *
       4             :  * This library is free software; you can redistribute it and/or modify it under
       5             :  * the terms of the GNU Lesser General Public License version 2.1 as published
       6             :  * by the Free Software Foundation.
       7             :  *
       8             :  * This library is distributed in the hope that it will be useful, but WITHOUT
       9             :  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
      10             :  * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
      11             :  * details.
      12             :  *
      13             :  * You should have received a copy of the GNU Lesser General Public License
      14             :  * along with this library; if not, write to the Free Software Foundation, Inc.,
      15             :  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
      16             :  */
      17             : 
      18             : #ifndef LUNCHBOX_LFQUEUE_H
      19             : #define LUNCHBOX_LFQUEUE_H
      20             : 
      21             : #include <lunchbox/atomic.h> // member
      22             : #include <lunchbox/debug.h>  // used in inline method
      23             : #include <lunchbox/thread.h> // thread-safety checks
      24             : 
      25             : #include <vector>
      26             : 
      27             : namespace lunchbox
      28             : {
      29             : /**
      30             :  * A thread-safe, lock-free queue with non-blocking access.
      31             :  *
      32             :  * Typically used for caches and non-blocking communication between two threads.
      33             :  *
      34             :  * Current implementation constraints:
      35             :  * * One reader thread
      36             :  * * One writer thread
      37             :  * * Fixed maximum size (writes may fail)
      38             :  * * Not copyable
      39             :  *
      40             :  * Example: @include tests/lfQueue.cpp
      41             :  */
      42             : template <typename T>
      43             : class LFQueue : public boost::noncopyable
      44             : {
      45             : public:
      46             :     /** Construct a new queue. @version 1.0 */
      47           1 :     explicit LFQueue(const int32_t size)
      48           1 :         : _data(size + 1)
      49             :         , _readPos(0)
      50           2 :         , _writePos(0)
      51             :     {
      52           1 :     }
      53             : 
      54             :     /** Destruct this queue. @version 1.0 */
      55           1 :     ~LFQueue() {}
      56             :     /** @return true if the queue is empty, false otherwise. @version 1.0 */
      57             :     bool isEmpty() const { return _readPos == _writePos; }
      58             :     /** Reset (empty) the queue. @version 1.0 */
      59             :     void clear();
      60             : 
      61             :     /**
      62             :      * Resize and reset the queue.
      63             :      *
      64             :      * This method is not thread-safe. The queue has to be empty.
      65             :      * @version 1.0
      66             :      */
      67             :     void resize(const int32_t size);
      68             : 
      69             :     /**
      70             :      * Retrieve and pop the front element from the queue.
      71             :      *
      72             :      * @param result the front value or unmodified
      73             :      * @return true if an element was placed in result, false if the queue
      74             :      *         is empty.
      75             :      * @version 1.0
      76             :      */
      77             :     bool pop(T& result);
      78             : 
      79             :     /**
      80             :      * Retrieve the front element from the queue.
      81             :      *
      82             :      * @param result the front value or unmodified
      83             :      * @return true if an element was placed in result, false if the queue
      84             :      *         is empty.
      85             :      * @version 1.0
      86             :      */
      87             :     bool getFront(T& result);
      88             : 
      89             :     /**
      90             :      * Push a new element to the back of the queue.
      91             :      *
      92             :      * @param element the element to add.
      93             :      * @return true if the element was placed, false if the queue is full
      94             :      * @version 1.0
      95             :      */
      96             :     bool push(const T& element);
      97             : 
      98             :     /**
      99             :      * @return the maximum number of elements held by the queue.
     100             :      * @version 1.0
     101             :      */
     102             :     size_t getCapacity() const { return _data.size() - 1; }
     103             : private:
     104             :     std::vector<T> _data;
     105             :     a_int32_t _readPos;
     106             :     a_int32_t _writePos;
     107             : 
     108           2 :     LB_TS_VAR(_reader);
     109           2 :     LB_TS_VAR(_writer);
     110             : };
     111             : }
     112             : 
     113             : #include "lfQueue.ipp" // template implementation
     114             : 
     115             : #endif // LUNCHBOX_LFQUEUE_H