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/*
* Copyright (C) 1998-2000 Netscape Communications Corporation.
* Copyright (C) 2003-6 Apple Computer
*
* Other contributors:
* Nick Blievers <nickb@adacel.com.au>
* Jeff Hostetler <jeff@nerdone.com>
* Tom Rini <trini@kernel.crashing.org>
* Raffaele Sena <raff@netwinder.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Alternatively, the contents of this file may be used under the terms
* of either the Mozilla Public License Version 1.1, found at
* http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
* License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
* (the "GPL"), in which case the provisions of the MPL or the GPL are
* applicable instead of those above. If you wish to allow use of your
* version of this file only under the terms of one of those two
* licenses (the MPL or the GPL) and not to allow others to use your
* version of this file under the LGPL, indicate your decision by
* deletingthe provisions above and replace them with the notice and
* other provisions required by the MPL or the GPL, as the case may be.
* If you do not delete the provisions above, a recipient may use your
* version of this file under any of the LGPL, the MPL or the GPL.
*/
/*
* Lifetime-based fast allocation, inspired by much prior art, including
* "Fast Allocation and Deallocation of Memory Based on Object Lifetimes"
* David R. Hanson, Software -- Practice and Experience, Vol. 20(1).
*/
#include "config.h"
#include "Arena.h"
#include <algorithm>
#include <stdlib.h>
#include <string.h>
#include <wtf/Assertions.h>
#include <wtf/FastMalloc.h>
using namespace std;
namespace WebCore {
#ifdef DEBUG_ARENA_MALLOC
static int i = 0;
#endif
#define ARENA_DEFAULT_ALIGN sizeof(double)
#define BIT(n) ((unsigned int)1 << (n))
#define BITMASK(n) (BIT(n) - 1)
#define CEILING_LOG2(_log2, _n) \
unsigned int j_ = (unsigned int)(_n); \
(_log2) = 0; \
if ((j_) & ((j_)-1)) \
(_log2) += 1; \
if ((j_) >> 16) \
(_log2) += 16, (j_) >>= 16; \
if ((j_) >> 8) \
(_log2) += 8, (j_) >>= 8; \
if ((j_) >> 4) \
(_log2) += 4, (j_) >>= 4; \
if ((j_) >> 2) \
(_log2) += 2, (j_) >>= 2; \
if ((j_) >> 1) \
(_log2) += 1;
#define FREE_PATTERN 0xDA
static int CeilingLog2(unsigned int i) {
int log2;
CEILING_LOG2(log2, i);
return log2;
}
void InitArenaPool(ArenaPool* pool, const char*, unsigned size, unsigned align)
{
if (align == 0)
align = ARENA_DEFAULT_ALIGN;
pool->mask = BITMASK(CeilingLog2(align));
pool->first.next = NULL;
pool->first.base = pool->first.avail = pool->first.limit = (uword)ARENA_ALIGN(&pool->first + 1);
pool->current = &pool->first;
pool->arenasize = size;
}
void* ArenaAllocate(ArenaPool* pool, unsigned int numBytes, unsigned int& bytesAllocated)
{
Arena* arena;
char* returnPointer;
ASSERT((numBytes & pool->mask) == 0);
numBytes = (uword)ARENA_ALIGN(numBytes);
// attempt to allocate from arenas at pool->current
{
arena = pool->current;
do {
if (arena->avail + numBytes <= arena->limit) {
pool->current = arena;
returnPointer = (char *)arena->avail;
arena->avail += numBytes;
return returnPointer;
}
} while (NULL != (arena = arena->next));
}
// attempt to allocate from the heap
{
unsigned int size = max(pool->arenasize, numBytes);
size += sizeof *arena + pool->mask; /* header and alignment slop */
#ifdef DEBUG_ARENA_MALLOC
i++;
printf("Malloc: %d\n", i);
#endif
bytesAllocated = size;
arena = (Arena*)fastMalloc(size);
// fastMalloc will abort() if it fails, so we are guaranteed that a is not 0.
arena->limit = (uword)arena + size;
arena->base = arena->avail = (uword)ARENA_ALIGN(arena + 1);
returnPointer = (char *)arena->avail;
arena->avail += numBytes;
// the newly allocated arena is linked after pool->current and becomes pool->current.
arena->next = pool->current->next;
pool->current->next = arena;
pool->current = arena;
if (!pool->first.next)
pool->first.next = arena;
return(returnPointer);
}
}
// Free tail arenas linked after head, which may not be the true list head.
// Reset pool->current to point to head in case it pointed at a tail arena.
static void FreeArenaList(ArenaPool* pool, Arena* head)
{
Arena** arenaPointer = &head->next;
Arena* arena = *arenaPointer;
if (!arena)
return;
#ifdef DEBUG
do {
ASSERT(arena->base <= arena->avail && arena->avail <= arena->limit);
arena->avail = arena->base;
memset((void*)(arena)->avail, FREE_PATTERN, (arena)->limit - (arena)->avail)
} while ((arena = arena->next) != 0);
arena = *arenaPointer;
#endif
do {
*arenaPointer = arena->next;
#ifdef DEBUG
memset((void*)(arena), FREE_PATTERN, (arena)->limit - (uword)(arena));
#endif
#ifdef DEBUG_ARENA_MALLOC
i--;
printf("Free: %d\n", i);
#endif
fastFree(arena);
arena = 0;
} while ((arena = *arenaPointer) != 0);
pool->current = head;
}
void FinishArenaPool(ArenaPool* pool)
{
FreeArenaList(pool, &pool->first);
}
}
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