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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 {
//#define DEBUG_ARENA_MALLOC
#ifdef DEBUG_ARENA_MALLOC
static int i = 0;
#endif
#define FREELIST_MAX 30
static Arena *arena_freelist;
static int freelist_count = 0;
#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;
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;
}
/*
** ArenaAllocate() -- allocate space from an arena pool
**
** Description: ArenaAllocate() allocates space from an arena
** pool.
**
** First try to satisfy the request from arenas starting at
** pool->current.
**
** If there is not enough space in the arena pool->current, try
** to claim an arena, on a first fit basis, from the global
** freelist (arena_freelist).
**
** If no arena in arena_freelist is suitable, then try to
** allocate a new arena from the heap.
**
** Returns: pointer to allocated space or NULL
**
*/
void* ArenaAllocate(ArenaPool *pool, unsigned int nb)
{
Arena *a;
char *rp; /* returned pointer */
ASSERT((nb & pool->mask) == 0);
nb = (uword)ARENA_ALIGN(nb); /* force alignment */
/* attempt to allocate from arenas at pool->current */
{
a = pool->current;
do {
if ( a->avail +nb <= a->limit ) {
pool->current = a;
rp = (char *)a->avail;
a->avail += nb;
return rp;
}
} while( NULL != (a = a->next) );
}
/* attempt to allocate from arena_freelist */
{
Arena *p = NULL; /* previous pointer, for unlinking from freelist */
for ( a = arena_freelist; a != NULL ; p = a, a = a->next ) {
if ( a->base +nb <= a->limit ) {
if ( p == NULL )
arena_freelist = a->next;
else
p->next = a->next;
a->avail = a->base;
rp = (char *)a->avail;
a->avail += nb;
/* the newly allocated arena is linked after pool->current
* and becomes pool->current */
a->next = pool->current->next;
pool->current->next = a;
pool->current = a;
if ( 0 == pool->first.next )
pool->first.next = a;
freelist_count--;
return(rp);
}
}
}
/* attempt to allocate from the heap */
{
unsigned int sz = max(pool->arenasize, nb);
sz += sizeof *a + pool->mask; /* header and alignment slop */
#ifdef DEBUG_ARENA_MALLOC
i++;
printf("Malloc: %d\n", i);
#endif
a = (Arena*)fastMalloc(sz);
// fastMalloc will abort() if it fails, so we are guaranteed that a is not 0.
a->limit = (uword)a + sz;
a->base = a->avail = (uword)ARENA_ALIGN(a + 1);
rp = (char *)a->avail;
a->avail += nb;
/* the newly allocated arena is linked after pool->current
* and becomes pool->current */
a->next = pool->current->next;
pool->current->next = a;
pool->current = a;
if ( !pool->first.next )
pool->first.next = a;
return(rp);
}
} /* --- end ArenaAllocate() --- */
/*
* 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, bool reallyFree)
{
Arena **ap, *a;
ap = &head->next;
a = *ap;
if (!a)
return;
#ifdef DEBUG
do {
ASSERT(a->base <= a->avail && a->avail <= a->limit);
a->avail = a->base;
CLEAR_UNUSED(a);
} while ((a = a->next) != 0);
a = *ap;
#endif
if (freelist_count >= FREELIST_MAX)
reallyFree = true;
if (reallyFree) {
do {
*ap = a->next;
CLEAR_ARENA(a);
#ifdef DEBUG_ARENA_MALLOC
if (a) {
i--;
printf("Free: %d\n", i);
}
#endif
fastFree(a); a = 0;
} while ((a = *ap) != 0);
} else {
/* Insert the whole arena chain at the front of the freelist. */
do {
ap = &(*ap)->next;
freelist_count++;
} while (*ap);
*ap = arena_freelist;
arena_freelist = a;
head->next = 0;
}
pool->current = head;
}
void FreeArenaPool(ArenaPool *pool)
{
FreeArenaList(pool, &pool->first, false);
}
void FinishArenaPool(ArenaPool *pool)
{
FreeArenaList(pool, &pool->first, true);
}
}
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