src/servers/app/ReferenceCounting.h

   1 /*
   2  * Copyright 2001-2005, Haiku.
   3  * Distributed under the terms of the MIT License.
   4  *
   5  * Authors:
   6  *              DarkWyrm <bpmagic@columbus.rr.com>
   7  *              Axel Dörfler, axeld@pinc-software.de
   8  */
   9 #ifndef REFERENCE_COUNTING_H
  10 #define REFERENCE_COUNTING_H
  11
  12
  13 #include <SupportDefs.h>
  14
  15
  16 /*!
  17         \class ReferenceCounting ReferenceCounting.h
  18         \brief Base class for reference counting objects
  19
  20         ReferenceCounting objects track dependencies upon a particular object. In this way,
  21         it is possible to ensure that a shared resource is not deleted if something else
  22         needs it. How the dependency tracking is done largely depends on the child class.
  23 */
  24 class ReferenceCounting {
  25         public:
  26                 ReferenceCounting()
  27                         : fReferenceCount(1) {}
  28                 virtual ~ReferenceCounting() {}
  29
  30                 inline void Acquire();
  31                 inline bool Release();
  32
  33         private:
  34                 int32 fReferenceCount;
  35 };
  36
  37
  38 inline void
  39 ReferenceCounting::Acquire()
  40 {
  41         atomic_add(&fReferenceCount, 1);
  42 }
  43
  44 inline bool
  45 ReferenceCounting::Release()
  46 {
  47         if (atomic_add(&fReferenceCount, -1) == 1) {
  48                 delete this;
  49                 return true;
  50         }
  51
  52         return false;
  53 }
  54
  55 #endif  /* REFERENCE_COUNTING_H */