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334 lines
9.9 KiB
334 lines
9.9 KiB
/*
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* Copyright (C) 1998-2000 Netscape Communications Corporation.
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*
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* Other contributors:
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* Nick Blievers <nickb@adacel.com.au>
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* Jeff Hostetler <jeff@nerdone.com>
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* Tom Rini <trini@kernel.crashing.org>
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* Raffaele Sena <raff@netwinder.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Alternatively, the contents of this file may be used under the terms
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* of either the Mozilla Public License Version 1.1, found at
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* http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
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* License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
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* (the "GPL"), in which case the provisions of the MPL or the GPL are
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* applicable instead of those above. If you wish to allow use of your
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* version of this file only under the terms of one of those two
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* licenses (the MPL or the GPL) and not to allow others to use your
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* version of this file under the LGPL, indicate your decision by
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* deletingthe provisions above and replace them with the notice and
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* other provisions required by the MPL or the GPL, as the case may be.
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* If you do not delete the provisions above, a recipient may use your
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* version of this file under any of the LGPL, the MPL or the GPL.
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*/
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/*
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* Lifetime-based fast allocation, inspired by much prior art, including
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* "Fast Allocation and Deallocation of Memory Based on Object Lifetimes"
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* David R. Hanson, Software -- Practice and Experience, Vol. 20(1).
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*/
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#include <config.h>
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#include <stdlib.h>
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#include <string.h>
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#include <kglobal.h>
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#include "arena.h"
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#ifdef HAVE_GETPAGESIZE
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#include <unistd.h>
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#define POOL_SIZE kMax(8192u, 2*( unsigned ) getpagesize())
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#else
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#define POOL_SIZE 8192
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#endif
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//#define DEBUG_ARENA_MALLOC
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#ifdef DEBUG_ARENA_MALLOC
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#include <assert.h>
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#include <stdio.h>
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#endif
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namespace khtml {
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#ifdef DEBUG_ARENA_MALLOC
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static int i = 0;
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#endif
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#define FREELIST_MAX 50
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#define LARGE_ALLOCATION_CEIL(pool) (pool)->arenasize * 256
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#define MAX_DISCRETE_ALLOCATION(pool) (pool)->arenasize * 32
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static Arena *arena_freelist = 0;
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static int freelist_count = 0;
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#define ARENA_DEFAULT_ALIGN sizeof(double)
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#define BIT(n) ((unsigned int)1 << (n))
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#define BITMASK(n) (BIT(n) - 1)
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#define CEILING_LOG2(_log2,_n) \
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unsigned int j_ = (unsigned int)(_n); \
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(_log2) = 0; \
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if ((j_) & ((j_)-1)) \
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(_log2) += 1; \
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if ((j_) >> 16) \
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(_log2) += 16, (j_) >>= 16; \
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if ((j_) >> 8) \
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(_log2) += 8, (j_) >>= 8; \
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if ((j_) >> 4) \
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(_log2) += 4, (j_) >>= 4; \
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if ((j_) >> 2) \
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(_log2) += 2, (j_) >>= 2; \
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if ((j_) >> 1) \
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(_log2) += 1;
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int CeilingLog2(unsigned int i) {
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int log2;
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CEILING_LOG2(log2,i);
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return log2;
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}
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void InitArenaPool(ArenaPool *pool, const char* /*name*/,
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unsigned int /*size*/, unsigned int align)
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{
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unsigned int size = POOL_SIZE;
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if (align == 0)
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align = ARENA_DEFAULT_ALIGN;
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pool->mask = BITMASK(CeilingLog2(align));
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pool->first.next = NULL;
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pool->first.base = pool->first.avail = pool->first.limit =
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(uword)ARENA_ALIGN(pool, &pool->first + 1);
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pool->current = &pool->first;
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pool->arenasize = size;
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pool->largealloc = LARGE_ALLOCATION_CEIL(pool);
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pool->cumul = 0;
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}
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/*
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** ArenaAllocate() -- allocate space from an arena pool
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**
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** Description: ArenaAllocate() allocates space from an arena
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** pool.
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**
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** First try to satisfy the request from arenas starting at
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** pool->current.
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**
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** If there is not enough space in the arena pool->current, try
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** to claim an arena, on a first fit basis, from the global
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** freelist (arena_freelist).
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**
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** If no arena in arena_freelist is suitable, then try to
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** allocate a new arena from the heap.
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**
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** Returns: pointer to allocated space or NULL
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**
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*/
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void* ArenaAllocate(ArenaPool *pool, unsigned int nb)
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{
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Arena *a;
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char *rp; /* returned pointer */
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#ifdef DEBUG_ARENA_MALLOC
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assert((nb & pool->mask) == 0);
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#endif
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nb = (uword)ARENA_ALIGN(pool, nb); /* force alignment */
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/* attempt to allocate from arenas at pool->current */
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{
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a = pool->current;
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do {
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if ( a->avail +nb <= a->limit ) {
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pool->current = a;
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rp = (char *)a->avail;
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a->avail += nb;
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VALGRIND_MEMPOOL_ALLOC(a->base, rp, nb);
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return rp;
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}
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} while( NULL != (a = a->next) );
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}
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/* attempt to allocate from arena_freelist */
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{
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Arena *p; /* previous pointer, for unlinking from freelist */
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for ( a = p = arena_freelist; a != NULL ; p = a, a = a->next ) {
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if ( a->base +nb <= a->limit ) {
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if ( p == arena_freelist )
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arena_freelist = a->next;
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else
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p->next = a->next;
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a->avail = a->base;
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rp = (char *)a->avail;
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a->avail += nb;
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VALGRIND_MEMPOOL_ALLOC(a->base, rp, nb);
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/* the newly allocated arena is linked after pool->current
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* and becomes pool->current */
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a->next = pool->current->next;
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pool->current->next = a;
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pool->current = a;
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if ( 0 == pool->first.next )
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pool->first.next = a;
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freelist_count--;
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return(rp);
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}
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}
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}
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/* attempt to allocate from the heap */
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{
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unsigned int sz;
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#ifdef HAVE_MMAP
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if (pool->cumul > pool->largealloc) {
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// High memory pressure. Switch to a fractional allocation strategy
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// so that malloc gets a chance to successfully trim us down when it's over.
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sz = kMin(pool->cumul/25, MAX_DISCRETE_ALLOCATION(pool));
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} else
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#endif
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sz = pool->arenasize > nb ? pool->arenasize : nb;
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sz += sizeof *a + pool->mask; /* header and alignment slop */
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pool->cumul += sz;
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#ifdef DEBUG_ARENA_MALLOC
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i++;
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printf("Malloc: %d\n", i);
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#endif
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a = (Arena*)malloc(sz);
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if (a) {
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a->limit = (uword)a + sz;
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a->base = a->avail = (uword)ARENA_ALIGN(pool, a + 1);
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VALGRIND_CREATE_MEMPOOL(a->base, 0, 0);
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rp = (char *)a->avail;
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a->avail += nb;
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VALGRIND_MEMPOOL_ALLOC(a->base, rp, nb);
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/* the newly allocated arena is linked after pool->current
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* and becomes pool->current */
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a->next = pool->current->next;
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pool->current->next = a;
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pool->current = a;
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if ( !pool->first.next )
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pool->first.next = a;
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return(rp);
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}
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}
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/* we got to here, and there's no memory to allocate */
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return(0);
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} /* --- end ArenaAllocate() --- */
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/*
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* Free tail arenas linked after head, which may not be the true list head.
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* Reset pool->current to point to head in case it pointed at a tail arena.
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*/
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static void FreeArenaList(ArenaPool *pool, Arena *head, bool reallyFree)
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{
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Arena **ap, *a;
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ap = &head->next;
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a = *ap;
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if (!a)
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return;
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#ifdef DEBUG_ARENA_MALLOC
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do {
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assert(a->base <= a->avail && a->avail <= a->limit);
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a->avail = a->base;
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CLEAR_UNUSED(a);
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} while ((a = a->next) != 0);
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a = *ap;
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#endif
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if (freelist_count >= FREELIST_MAX)
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reallyFree = true;
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if (reallyFree) {
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do {
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*ap = a->next;
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VALGRIND_DESTROY_MEMPOOL(a->base);
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CLEAR_ARENA(a);
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#ifdef DEBUG_ARENA_MALLOC
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if (a) {
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i--;
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printf("Free: %d\n", i);
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}
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#endif
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free(a); a = 0;
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} while ((a = *ap) != 0);
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} else {
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/* Insert as much of the arena chain as we can hold at the front of the freelist. */
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do {
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ap = &(*ap)->next;
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freelist_count++;
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} while (*ap && freelist_count < FREELIST_MAX);
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/* Get rid of excess */
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if (*ap) {
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Arena *xa, *n;
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for (xa = *ap; xa; xa = n) {
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VALGRIND_DESTROY_MEMPOOL(xa->base);
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n = xa->next;
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#ifdef DEBUG_ARENA_MALLOC
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i--;
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printf("Free: %d\n", i);
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#endif
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CLEAR_ARENA(xa);
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free(xa);
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}
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}
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*ap = arena_freelist;
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arena_freelist = a;
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head->next = 0;
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}
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pool->current = head;
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}
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void ArenaRelease(ArenaPool *pool, char *mark)
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{
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Arena *a;
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for (a = pool->first.next; a; a = a->next) {
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if (UPTRDIFF(mark, a->base) < UPTRDIFF(a->avail, a->base)) {
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a->avail = (uword)ARENA_ALIGN(pool, mark);
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FreeArenaList(pool, a, false);
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return;
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}
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}
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}
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void FreeArenaPool(ArenaPool *pool)
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{
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FreeArenaList(pool, &pool->first, false);
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}
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void FinishArenaPool(ArenaPool *pool)
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{
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FreeArenaList(pool, &pool->first, true);
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}
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void ArenaFinish()
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{
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Arena *a, *next;
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#ifdef DEBUG_ARENA_MALLOC
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printf("releasing global Arena freelist\n");
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#endif
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for (a = arena_freelist; a; a = next) {
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next = a->next;
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free(a); a = 0;
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}
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freelist_count = 0;
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arena_freelist = NULL;
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}
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} // namespace
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