ArenaHeapSTLAllocator.h File Reference

STL-style allocator wrapper for ArenaHeapAllocator. More...

#include "AthAllocators/ArenaHeapAllocator.h"
#include "CxxUtils/concepts.h"
#include "CxxUtils/checker_macros.h"
#include <string>
#include <cstddef>
#include "AthAllocators/ArenaHeapSTLAllocator.icc"

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Classes
class	SG::ArenaHeapSTLAllocator_initParams< T >
	Initializer for pool allocator parameters. More...
class	SG::ArenaHeapSTLAllocator< T, VETO >
	STL-style allocator wrapper for ArenaHeapAllocator. More...
struct	SG::ArenaHeapSTLAllocator< T, VETO >::rebind< U >
	Standard STL allocator rebinder. More...
class	SG::ArenaNonConstHeapSTLAllocator< T >
	Forward declaration. More...
class	SG::ArenaHeapSTLAllocator< T, T >
	STL-style allocator wrapper for ArenaHeapAllocator. More...
struct	SG::ArenaHeapSTLAllocator< T, T >::rebind< U >
	Standard STL allocator rebinder. More...
class	SG::ArenaNonConstHeapSTLAllocator< T >
	Forward declaration. More...

Namespaces
	SG
	Forward declaration.

Functions
template<class T , class VETO >
void	SG::maybeUnprotect (ArenaHeapSTLAllocator< T, VETO > &a)
	Hook for unprotecting an arena. More...

Detailed Description

STL-style allocator wrapper for ArenaHeapAllocator.

Author

scott snyder

Date

Nov 2011 This class defines a STL-style allocator for types T with the following special properties.

• We use an ArenaHeapAllocator for allocations.
• The memory is owned directly by the allocator object.
• Only one object at a time may be allocated.

So, this allocator is suitable for an STL container which allocates lots of fixed-size objects, such as std::list.

Much of the complexity here is due to the fact that the allocator type that gets passed to the container is an allocator for the container's value_type, but that allocator is not actually used to allocate memory. Instead, an allocator for the internal node type is used. This makes it awkward if you want to have allocators that store state.

Further, to avoid creating a pool for the allocator for the container's value_type (when the container doesn't actually use that for allocation), this template has a second argument. This defaults to the first argument, but is passed through by rebind. If the first and second argument are the same, then we don't create a pool.

The effect of all this is that you can give an allocator type like ArenaHeapSTLAllocator<Mytype> to a STL container. Allocators for Mytype won't use a pool, but an allocator for node<Mytype> will use the pool.

Definition in file ArenaHeapSTLAllocator.h.