dep/src/zthread/IntrusivePtr.h

   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 #ifndef __ZTINTRUSIVEPTR_H__
  24 #define __ZTINTRUSIVEPTR_H__
  25
  26 #include "zthread/Guard.h"
  27 #include <cstdlib>
  28
  29 namespace ZThread {
  30
  31 /**
  32  * @class IntrusivePtr
  33  * @author Eric Crahen <http://www.code-foo.com>
  34  * @date <2003-07-16T17:54:23-0400>
  35  * @version 2.2.0
  36  *
  37  * This template creates an intrusively reference counted object
  38  * an IntrusivePtr starts out with a 1 count, which is updated as references are
  39  * added and removed. When the reference count drops to 0, the
  40  * IntrusivePtr will delete itself.
  41  */
  42 template <typename T, class LockType>
  43 class IntrusivePtr : NonCopyable {
  44
  45   //! Intrusive reference count
  46   size_t _count;
  47
  48   //! Synchornization object
  49   LockType _lock;
  50
  51 public:
  52
  53   /**
  54    * Create an IntrusivePtr with a count.
  55    */
  56   IntrusivePtr(size_t InitialCount=1) : _count(InitialCount) { }
  57
  58   /**
  59    * Destroy an IntrusivePtr
  60    */
  61   virtual ~IntrusivePtr() {}
  62
  63   /**
  64    * Add a reference to this object, it will take one more
  65    * call to delReference() for it to be deleted.
  66    */
  67   void addReference() {
  68
  69     Guard<LockType, LockedScope> g(_lock);
  70     _count++;
  71
  72   }
  73
  74   /**
  75    * Remove a reference from this object, if the reference count
  76    * drops to 0 as a result, the object deletes itself.
  77    */
  78   void delReference() {
  79
  80     bool result = false;
  81
  82     {
  83
  84       Guard<LockType, LockedScope> g(_lock);
  85       result = (--_count == 0);
  86
  87     }
  88
  89     if(result)
  90       delete this;
  91
  92   }
  93
  94 };
  95
  96
  97 };
  98
  99 #endif