Added GetLongevity function so allocator can work with a certain lifetime

policy class used with Loki::SingletonHolder.


git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@293 7ec92016-0320-0410-acc4-a06ded1c099a

include/loki/SmallObj.h

@@ -144,18 +144,33 @@ namespace Loki
         std::size_t objectAlignSize_;
     };
 
+
     /** @class AllocatorSingleton This template class is derived from
-    SmallObjAllocator in order to pass template arguments into it, and still
-    have a default constructor for the singleton.  Each instance is a unique
-    combination of all the template parameters, and hence is singleton only 
-    with respect to those parameters.  The template parameters have default
-    values and the class has typedefs identical to both SmallObject and
-    SmallValueObject so that this class can be used directly instead of going
-    through SmallObject or SmallValueObject.  That design feature allows
-    clients to use the new_handler without having the name of the new_handler
-    function show up in classes derived from SmallObject or SmallValueObject.
-    Thus, the only functions in the allocator which show up in SmallObject or
-    SmallValueObject inheritance heierarchies are the new and delete operators.
+     SmallObjAllocator in order to pass template arguments into it, and still
+     have a default constructor for the singleton.  Each instance is a unique
+     combination of all the template parameters, and hence is singleton only 
+     with respect to those parameters.  The template parameters have default
+     values and the class has typedefs identical to both SmallObject and
+     SmallValueObject so that this class can be used directly instead of going
+     through SmallObject or SmallValueObject.  That design feature allows
+     clients to use the new_handler without having the name of the new_handler
+     function show up in classes derived from SmallObject or SmallValueObject.
+     Thus, the only functions in the allocator which show up in SmallObject or
+     SmallValueObject inheritance heierarchies are the new and delete
+     operators.
+
+     @par Singleton Lifetime Policies and Small-Object Allocator
+     At this time, the only Singleton Lifetime policies recommended for
+     use with the Small-Object Allocator are Loki::SingletonWithLongevity and
+     Loki::NoDestroy.  The Loki::DefaultLifetime and Loki::PhoenixSingleton
+     policies are *not* recommended since they can cause the allocator to be
+     destroyed and release memory for singletons which inherit from either
+     SmallObject or SmallValueObject.  The default is Loki::NoDestroy to
+     insure that memory is never released before the object using that
+     memory is destroyed.  Loki::SingletonWithLongevity can also insure that
+     no memory is released before the owning object is destroyed, and also
+     insure that any memory controlled by a Small-Object Allocator is
+     released.
     */
     template
     <
@@ -227,6 +242,31 @@ namespace Loki
     }
 
 
+    /** This standalone function provides the longevity level for Small-Object
+     Allocators which use the Loki::SingletonWithLongevity policy.  Since no
+     Small-Object Allocator depends on any other Small-Object allocator, this
+     does not need to calculate a dependency level, and so it returns just a
+     constant.  Since all allocators must live longer than the objects which
+     use the allocators, it must return a longevity level higher than any such
+     object.  The SingletonWithLongevity can find this function through
+     argument-dependent lookup.
+     */
+    template
+    <
+        template <class> class TM,
+        std::size_t CS,
+        std::size_t MSOS,
+        std::size_t OAS,
+        template <class> class LP
+    >
+    inline unsigned int GetLongevity(
+        AllocatorSingleton< TM, CS, MSOS, OAS, LP > * )
+    {
+        // Returns highest possible value.
+        return 0xFFFFFFFF;
+    }
+
+
     /** @class SmallObjectBase Base class for small object allocation classes.
      The shared implementation of the new and delete operators are here instead
      of being duplicated in both SmallObject or SmallValueObject.  This class
@@ -443,6 +483,10 @@ namespace Loki
 // Nov. 26, 2004: re-implemented by Rich Sposato.
 //
 // $Log$
+// Revision 1.13  2005/10/07 01:22:09  rich_sposato
+// Added GetLongevity function so allocator can work with a certain lifetime
+// policy class used with Loki::SingletonHolder.
+//
 // Revision 1.12  2005/10/06 00:19:56  rich_sposato
 // Added clarifying comment about destructor.
 //