dep/src/zthread/PriorityInheritanceMutex.cxx

   1 /*
   2  * Copyright (c) 2005, Eric Crahen
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a copy
   5  * of this software and associated documentation files (the "Software"), to deal
   6  * in the Software without restriction, including without limitation the rights
   7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8  * copies of the Software, and to permit persons to whom the Software is furnished
   9  * to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in all
  12  * copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  18  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  19  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  20  *
  21  */
  22
  23 #include "zthread/PriorityInheritanceMutex.h"
  24 #include "MutexImpl.h"
  25 #include "ThreadOps.h"
  26
  27
  28 namespace ZThread {
  29
  30   class InheritPriorityBehavior : public NullBehavior {
  31
  32     ThreadImpl* owner;
  33     Priority p;
  34
  35   protected:
  36
  37     // Temporarily raise the effective priority of the owner
  38     inline void waiterArrived(ThreadImpl* impl) {
  39
  40       Priority q = impl->getPriority();
  41       if((int)q > (int)p) {
  42
  43         ThreadOps::setPriority(impl, p);
  44         p = q;
  45
  46       }
  47
  48     }
  49
  50
  51     // Note the owners priority
  52     inline void ownerAcquired(ThreadImpl* impl) {
  53
  54       p = impl->getPriority();
  55       owner = impl;
  56
  57     }
  58
  59     // Restore its original priority
  60     inline void ownerReleased(ThreadImpl* impl) {
  61
  62       if(p > owner->getPriority())
  63         ThreadOps::setPriority(impl, impl->getPriority());
  64
  65     }
  66
  67   };
  68
  69   class PriorityInheritanceMutexImpl :
  70     public MutexImpl<priority_list, InheritPriorityBehavior> { };
  71
  72   PriorityInheritanceMutex::PriorityInheritanceMutex() {
  73
  74     _impl = new PriorityInheritanceMutexImpl();
  75
  76   }
  77
  78   PriorityInheritanceMutex::~PriorityInheritanceMutex() {
  79
  80     if(_impl != 0)
  81       delete _impl;
  82
  83   }
  84
  85   // P
  86   void PriorityInheritanceMutex::acquire() {
  87
  88     _impl->acquire();
  89
  90   }
  91
  92
  93   // P
  94   bool PriorityInheritanceMutex::tryAcquire(unsigned long ms) {
  95
  96     return _impl->tryAcquire(ms);
  97
  98   }
  99
 100   // V
 101   void PriorityInheritanceMutex::release() {
 102
 103     _impl->release();
 104
 105   }
 106
 107
 108 } // namespace ZThread
 109