libcilkrts/include/cilktools/fake_mutex.h

   1 /* fake_mutex.h                  -*-C++-*-
   2  *
   3  *************************************************************************
   4  *
   5  * Copyright (C) 2013-2016, Intel Corporation
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  *   * Redistributions of source code must retain the above copyright
  13  *     notice, this list of conditions and the following disclaimer.
  14  *   * Redistributions in binary form must reproduce the above copyright
  15  *     notice, this list of conditions and the following disclaimer in
  16  *     the documentation and/or other materials provided with the
  17  *     distribution.
  18  *   * Neither the name of Intel Corporation nor the names of its
  19  *     contributors may be used to endorse or promote products derived
  20  *     from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
  29  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
  32  * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33  * POSSIBILITY OF SUCH DAMAGE.
  34  *
  35  * *********************************************************************
  36  *
  37  * PLEASE NOTE: This file is a downstream copy of a file mainitained in
  38  * a repository at cilkplus.org. Changes made to this file that are not
  39  * submitted through the contribution process detailed at
  40  * http://www.cilkplus.org/submit-cilk-contribution will be lost the next
  41  * time that a new version is released. Changes only submitted to the
  42  * GNU compiler collection or posted to the git repository at
  43  * https://bitbucket.org/intelcilkruntime/intel-cilk-runtime.git are
  44  * not tracked.
  45  *
  46  * We welcome your contributions to this open source project. Thank you
  47  * for your assistance in helping us improve Cilk Plus.
  48  *
  49  **************************************************************************
  50  *
  51  * Cilkscreen fake mutexes are provided to indicate to the Cilkscreen race
  52  * detector that a race should be ignored.
  53  *
  54  * NOTE: This class does not provide mutual exclusion.  You should use the
  55  * mutual exclusion constructs provided by TBB or your operating system to
  56  * protect against real data races.
  57  */
  58
  59 #ifndef FAKE_MUTEX_H_INCLUDED
  60 #define FAKE_MUTEX_H_INCLUDED
  61
  62 #include <cilktools/cilkscreen.h>
  63
  64 namespace cilkscreen
  65 {
  66     class fake_mutex
  67     {
  68     public:
  69         fake_mutex() : locked(false)
  70         {
  71         }
  72
  73         ~fake_mutex()
  74         {
  75             __CILKRTS_ASSERT(! locked);
  76         }
  77
  78         // Wait until mutex is available, then enter
  79         void lock()
  80         {
  81             __cilkscreen_acquire_lock(&locked);
  82             __CILKRTS_ASSERT(! locked);
  83             locked = true;
  84         }
  85
  86         // A fake mutex is always available
  87         bool try_lock() { lock(); return true; }
  88
  89         // Releases the mutex
  90         void unlock()
  91         {
  92             __CILKRTS_ASSERT(locked);
  93             locked = false;
  94             __cilkscreen_release_lock(&locked);
  95         }
  96
  97     private:
  98         bool locked;
  99     };
 100
 101 } // namespace cilk
 102
 103 #endif  // FAKE_MUTEX_H_INCLUDED