Line data    Source code

       1             : 
       2             : /* Copyright (c) 2010-2017, 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_SPINLOCK_H
      19             : #define LUNCHBOX_SPINLOCK_H
      20             : 
      21             : #include <lunchbox/atomic.h> // member
      22             : #include <lunchbox/thread.h> // used in inline method
      23             : 
      24             : #include <memory>
      25             : 
      26             : namespace lunchbox
      27             : {
      28             : /**
      29             :  * A fast lock for uncontended memory access.
      30             :  *
      31             :  * If Thread::yield() does not work, priority inversion is possible. If used as
      32             :  * a read-write lock, readers or writers will starve on high contention.
      33             :  *
      34             :  * @sa ScopedMutex
      35             :  *
      36             :  * Example: @include tests/perf/lock.cpp
      37             :  */
      38             : class SpinLock : public boost::noncopyable
      39             : {
      40             : public:
      41             :     /** Construct a new lock. @version 1.0 */
      42             :     LUNCHBOX_API SpinLock();
      43             : 
      44             :     /** Destruct the lock. @version 1.0 */
      45             :     LUNCHBOX_API ~SpinLock();
      46             : 
      47             :     /** Acquire the lock exclusively. @version 1.0 */
      48             :     LUNCHBOX_API void set();
      49        8053 :     void lock() { set(); }
      50             :     /** Release an exclusive lock. @version 1.0 */
      51             :     LUNCHBOX_API void unset();
      52        8056 :     void unlock() { unset(); }
      53             :     /**
      54             :      * Attempt to acquire the lock exclusively.
      55             :      *
      56             :      * @return true if the lock was set, false if it was not set.
      57             :      * @version 1.0
      58             :      */
      59             :     LUNCHBOX_API bool trySet();
      60             : 
      61             :     /** Acquire the lock shared with other readers. @version 1.1.2 */
      62             :     LUNCHBOX_API void setRead();
      63           0 :     void lock_shared() { setRead(); }
      64             :     /** Release a shared read lock. @version 1.1.2 */
      65             :     LUNCHBOX_API void unsetRead();
      66           0 :     void unlock_shared() { unsetRead(); }
      67             :     /**
      68             :      * Attempt to acquire the lock shared with other readers.
      69             :      *
      70             :      * @return true if the lock was set, false if it was not set.
      71             :      * @version 1.1.2
      72             :      */
      73             :     LUNCHBOX_API bool trySetRead();
      74             : 
      75             :     /**
      76             :      * Test if the lock is set.
      77             :      *
      78             :      * @return true if the lock is set, false if it is not set.
      79             :      * @version 1.0
      80             :      */
      81             :     LUNCHBOX_API bool isSet();
      82             : 
      83             :     /**
      84             :      * Test if the lock is set exclusively.
      85             :      *
      86             :      * @return true if the lock is set, false if it is not set.
      87             :      * @version 1.1.2
      88             :      */
      89             :     LUNCHBOX_API bool isSetWrite();
      90             : 
      91             :     /**
      92             :      * Test if the lock is set shared.
      93             :      *
      94             :      * @return true if the lock is set, false if it is not set.
      95             :      * @version 1.1.2
      96             :      */
      97             :     LUNCHBOX_API bool isSetRead();
      98             : 
      99             : private:
     100             :     class Impl;
     101             :     std::unique_ptr<Impl> _impl;
     102             : 
     103             :     SpinLock(const SpinLock&) = delete;
     104             :     SpinLock(SpinLock&&) = delete;
     105             :     SpinLock& operator=(const SpinLock&) = delete;
     106             :     SpinLock& operator=(SpinLock&&) = delete;
     107             : };
     108             : }
     109             : #endif // LUNCHBOX_SPINLOCK_H