zypp/base/ReferenceCounted.h

   1 /*---------------------------------------------------------------------\
   2 |                          ____ _   __ __ ___                          |
   3 |                         |__  / \ / / . \ . \                         |
   4 |                           / / \ V /|  _/  _/                         |
   5 |                          / /__ | | | | | |                           |
   6 |                         /_____||_| |_| |_|                           |
   7 |                                                                      |
   8 \---------------------------------------------------------------------*/
   9 /** \file       zypp/base/ReferenceCounted.h
  10  *
  11 */
  12 #ifndef ZYPP_BASE_REFERENCECOUNTED_H
  13 #define ZYPP_BASE_REFERENCECOUNTED_H
  14
  15 #include <iosfwd>
  16
  17 #include "zypp/base/PtrTypes.h"
  18
  19 ///////////////////////////////////////////////////////////////////
  20 namespace zypp
  21 { /////////////////////////////////////////////////////////////////
  22   ///////////////////////////////////////////////////////////////////
  23   namespace base
  24   { /////////////////////////////////////////////////////////////////
  25
  26     ///////////////////////////////////////////////////////////////////
  27     //
  28     //  CLASS NAME : ReferenceCounted
  29     //
  30     /** Base class for reference counted objects.
  31      * \todo Make counter thread safe.
  32     */
  33     class ReferenceCounted
  34     {
  35       /** Stream output via dumpOn. */
  36       friend std::ostream & operator<<( std::ostream & str, const ReferenceCounted & obj );
  37
  38     public:
  39       /** Default ctor.
  40        * Initial reference count is zero.
  41       */
  42       ReferenceCounted();
  43
  44       /** Copy ctor.
  45        * Initial reference count is zero.
  46       */
  47       ReferenceCounted( const ReferenceCounted & rhs );
  48
  49       /** Dtor.
  50        * \throw std::out_of_range if reference count is not zero.
  51       */
  52       virtual ~ReferenceCounted();
  53
  54       /** Assignment.
  55        * Reference count remains untouched.
  56       */
  57       ReferenceCounted & operator=( const ReferenceCounted & )
  58       { return *this; }
  59
  60     public:
  61       /** Return reference counter value. */
  62       unsigned refCount() const
  63       { return _counter; }
  64
  65       /** Add a reference. */
  66       void ref() const
  67       { ref_to( ++_counter ); }
  68
  69       /** Release a reference.
  70        * Deletes the object if reference count gets zero.
  71        * \throw std::out_of_range if reference count is zero.
  72       */
  73       void unref() const
  74       {
  75         if ( !_counter )
  76           unrefException(); // will throw!
  77         if ( --_counter )
  78           unref_to( _counter );
  79         else
  80           delete this;
  81       }
  82
  83       /** Called by zypp::intrusive_ptr to add a reference.
  84        * \see ZYPP_SMART_PTR
  85       */
  86       static void add_ref( const ReferenceCounted * ptr_r )
  87       { if( ptr_r ) ptr_r->ref(); }
  88
  89       /** Called by zypp::intrusive_ptr to add a reference.
  90        * \see ZYPP_SMART_PTR
  91       */
  92       static void release( const ReferenceCounted * ptr_r )
  93       { if( ptr_r ) ptr_r->unref(); }
  94
  95     protected:
  96       /** Overload to realize std::ostream & operator\<\<. */
  97       virtual std::ostream & dumpOn( std::ostream & str ) const;
  98
  99       /** Trigger derived classes after refCount was increased. */
 100       virtual void ref_to( unsigned /* rep_cnt_r */ ) const {}
 101
 102       /** Trigger derived classes after refCount was decreased.
 103        * No trigger is sent, if refCount got zero (i.e. the
 104        * object is deleted).
 105        **/
 106       virtual void unref_to( unsigned /* rep_cnt_r */ ) const {}
 107
 108     private:
 109       /** The reference counter. */
 110       mutable unsigned _counter;
 111
 112       /** Throws Exception on unref. */
 113       void unrefException() const;
 114     };
 115     ///////////////////////////////////////////////////////////////////
 116
 117     /** \relates ReferenceCounted intrusive_ptr hook to add_ref. */
 118     inline void intrusive_ptr_add_ref( const ReferenceCounted * ptr_r )
 119     { ReferenceCounted::add_ref( ptr_r ); }
 120
 121     /** \relates ReferenceCounted intrusive_ptr hook to release. */
 122     inline void intrusive_ptr_release( const ReferenceCounted * ptr_r )
 123     { ReferenceCounted::release( ptr_r ); }
 124
 125     /** \relates ReferenceCounted Stream output. */
 126     inline std::ostream & operator<<( std::ostream & str, const ReferenceCounted & obj )
 127     { return obj.dumpOn( str ); }
 128
 129     /////////////////////////////////////////////////////////////////
 130   } // namespace base
 131   ///////////////////////////////////////////////////////////////////
 132   /////////////////////////////////////////////////////////////////
 133 } // namespace zypp
 134 ///////////////////////////////////////////////////////////////////
 135
 136 #define IMPL_PTR_TYPE(NAME) \
 137 void intrusive_ptr_add_ref( const NAME * ptr_r )               \
 138 { zypp::base::ReferenceCounted::add_ref( ptr_r ); }                  \
 139 void intrusive_ptr_release( const NAME * ptr_r )               \
 140 { zypp::base::ReferenceCounted::release( ptr_r ); }
 141
 142 ///////////////////////////////////////////////////////////////////
 143 #endif // ZYPP_BASE_REFERENCECOUNTED_H