include/pub_tool_poolalloc.h

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/*--- A simple pool (memory) allocator.       pub_tool_poolalloc.h ---*/
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/*
   This file is part of Valgrind, a dynamic binary instrumentation
   framework.

   Copyright (C) 2011-2013 OpenWorks LLP info@open-works.co.uk,
                           Philippe Waroquiers philippe.waroquiers@skynet.be

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA.

   The GNU General Public License is contained in the file COPYING.
*/

#ifndef __PUB_TOOL_POOLALLOC_H
#define __PUB_TOOL_POOLALLOC_H

#include "pub_tool_basics.h"   // UWord

//--------------------------------------------------------------------
// PURPOSE: Provides efficient allocation and free of elements of
// the same size.
// This pool allocator manages elements alloc/free by allocating
// "pools" of many elements from a lower level allocator (typically
// pub_tool_mallocfree.h).
// Single elements can then be allocated and released from these pools.
// A pool allocator is faster and has less memory overhead than
// calling directly pub_tool_mallocfree.h
// Note: the pools of elements are not freed, even if all the
// single elements have been freed. The only way to free the underlying
// pools of elements is to delete the pool allocator.
//--------------------------------------------------------------------


typedef  struct _PoolAlloc  PoolAlloc;

/* Create new PoolAlloc, using given allocation and free function, and
   for elements of the specified size.  alloc_fn must not return NULL (that
   is, if it returns it must have succeeded.)
   This function never returns NULL. */
extern PoolAlloc* VG_(newPA) ( UWord  elemSzB,
                               UWord  nPerPool,
                               void*  (*alloc)(const HChar*, SizeT),
                               const  HChar* cc,
                               void   (*free_fn)(void*) );


/* Free all memory associated with a PoolAlloc. */
extern void VG_(deletePA) ( PoolAlloc* pa);

/* Allocates an element from pa. The function never returns NULL. */
extern void* VG_(allocEltPA) ( PoolAlloc* pa);

/* Free element of pa. */
extern void VG_(freeEltPA) ( PoolAlloc* pa, void* p);

/* A pool allocator can be shared between multiple data structures.
   For example, multiple OSet* can allocate/free nodes from the same
   pool allocator.
   The Pool Allocator provides support to use a ref counter
   to detect a pool allocator is not needed anymore.
   It is the caller responsibility to call VG_(addRefPA) for
   each new reference to a pool and VG_(releasePA) when such a reference
   disappears.
   VG_(releasePA) will automatically call VG_(deletePA)
   to delete the PA when the ref counter drops to 0. */

// VG_(addRefPA) indicates there is a new reference to pa.
extern void VG_(addRefPA) ( PoolAlloc* pa);

// VG_(releasePA) decrements the pa reference count and deletes the pa if that
// reference count has dropped to zero. Returns the new value of the reference
// count.
extern UWord VG_(releasePA) ( PoolAlloc* pa);

// How many elements are managed by the pool 'pa'. This includes
// the elements allocated by VG_(allocEltPA), the elements freed by
// VG_(freeEltPA) and the elements that are in a block and have not
// yet been allocated.
extern UWord VG_(sizePA) ( PoolAlloc* pa);
#endif   // __PUB_TOOL_POOLALLOC_

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/*--- end                                    pub_tool_poolalloc.h  ---*/
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