pjs/nsprpub/lib/ds/plarena.c

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C

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is the Netscape Portable Runtime (NSPR).
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998-2000 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU General Public License Version 2 or later (the
* "GPL"), in which case the provisions of 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 the GPL and not to
* allow others to use your version of this file under the MPL,
* indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions required by
* the GPL. If you do not delete the provisions above, a recipient
* may use your version of this file under either 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 <stdlib.h>
#include <string.h>
#include "plarena.h"
#include "prmem.h"
#include "prbit.h"
#include "prlog.h"
#include "prmon.h"
#include "prinit.h"
static PLArena *arena_freelist;
#ifdef PL_ARENAMETER
static PLArenaStats *arena_stats_list;
#define COUNT(pool,what) (pool)->stats.what++
#else
#define COUNT(pool,what) /* nothing */
#endif
#define PL_ARENA_DEFAULT_ALIGN sizeof(double)
static PRMonitor *arenaLock;
static PRCallOnceType once;
/*
** InitializeArenas() -- Initialize arena operations.
**
** InitializeArenas() is called exactly once and only once from
** LockArena(). This function creates the arena protection
** monitor: arenaLock.
**
** Note: If the arenaLock cannot be created, InitializeArenas()
** fails quietly, returning only PR_FAILURE. This percolates up
** to the application using the Arena API. He gets no arena
** from PL_ArenaAllocate(). It's up to him to fail gracefully
** or recover.
**
*/
static PRStatus InitializeArenas( void )
{
PR_ASSERT( arenaLock == NULL );
arenaLock = PR_NewMonitor();
if ( arenaLock == NULL )
return PR_FAILURE;
else
return PR_SUCCESS;
} /* end ArenaInitialize() */
static PRStatus LockArena( void )
{
PRStatus rc = PR_CallOnce( &once, InitializeArenas );
if ( PR_FAILURE != rc )
PR_EnterMonitor( arenaLock );
return(rc);
} /* end LockArena() */
static void UnlockArena( void )
{
PR_ExitMonitor( arenaLock );
return;
} /* end UnlockArena() */
PR_IMPLEMENT(void) PL_InitArenaPool(
PLArenaPool *pool, const char *name, PRUint32 size, PRUint32 align)
{
#if defined(XP_MAC)
#pragma unused (name)
#endif
if (align == 0)
align = PL_ARENA_DEFAULT_ALIGN;
pool->mask = PR_BITMASK(PR_CeilingLog2(align));
pool->first.next = NULL;
pool->first.base = pool->first.avail = pool->first.limit =
(PRUword)PL_ARENA_ALIGN(pool, &pool->first + 1);
pool->current = &pool->first;
pool->arenasize = size;
#ifdef PL_ARENAMETER
memset(&pool->stats, 0, sizeof pool->stats);
pool->stats.name = strdup(name);
pool->stats.next = arena_stats_list;
arena_stats_list = &pool->stats;
#endif
}
PR_IMPLEMENT(void *) PL_ArenaAllocate(PLArenaPool *pool, PRUint32 nb)
{
PLArena **ap, *a, *b;
PRUint32 sz;
void *p;
PR_ASSERT((nb & pool->mask) == 0);
#if defined(WIN16)
if (nb >= 60000U)
return 0;
#endif /* WIN16 */
if ( PR_FAILURE == LockArena())
return(0);
ap = &arena_freelist;
for (a = pool->current; a->avail + nb > a->limit; pool->current = a) {
if (a->next) { /* move to next arena */
a = a->next;
continue;
}
while ((b = *ap) != 0) { /* reclaim a free arena */
if (b->limit - b->base == pool->arenasize) {
*ap = b->next;
b->next = 0;
a = a->next = b;
COUNT(pool, nreclaims);
goto claim;
}
ap = &b->next;
}
sz = PR_MAX(pool->arenasize, nb); /* allocate a new arena */
sz += sizeof *a + pool->mask; /* header and alignment slop */
b = (PLArena*)PR_MALLOC(sz);
if (!b)
{
UnlockArena();
return 0;
}
a = a->next = b;
a->next = 0;
a->limit = (PRUword)a + sz;
PL_COUNT_ARENA(pool,++);
COUNT(pool, nmallocs);
claim:
a->base = a->avail = (PRUword)PL_ARENA_ALIGN(pool, a + 1);
}
UnlockArena();
p = (void *)a->avail;
a->avail += nb;
return p;
}
PR_IMPLEMENT(void *) PL_ArenaGrow(
PLArenaPool *pool, void *p, PRUint32 size, PRUint32 incr)
{
void *newp;
PL_ARENA_ALLOCATE(newp, pool, size + incr);
if (newp)
memcpy(newp, p, size);
return newp;
}
/*
* 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(PLArenaPool *pool, PLArena *head, PRBool reallyFree)
{
PLArena **ap, *a;
ap = &head->next;
a = *ap;
if (!a)
return;
#ifdef DEBUG
do {
PR_ASSERT(a->base <= a->avail && a->avail <= a->limit);
a->avail = a->base;
PL_CLEAR_UNUSED(a);
} while ((a = a->next) != 0);
a = *ap;
#endif
if (reallyFree) {
do {
*ap = a->next;
PL_CLEAR_ARENA(a);
PL_COUNT_ARENA(pool,--);
PR_DELETE(a);
} while ((a = *ap) != 0);
} else {
/* Insert the whole arena chain at the front of the freelist. */
do {
ap = &(*ap)->next;
} while (*ap);
LockArena();
*ap = arena_freelist;
arena_freelist = a;
head->next = 0;
UnlockArena();
}
pool->current = head;
}
PR_IMPLEMENT(void) PL_ArenaRelease(PLArenaPool *pool, char *mark)
{
PLArena *a;
for (a = pool->first.next; a; a = a->next) {
if (PR_UPTRDIFF(mark, a->base) < PR_UPTRDIFF(a->avail, a->base)) {
a->avail = (PRUword)PL_ARENA_ALIGN(pool, mark);
FreeArenaList(pool, a, PR_TRUE);
return;
}
}
}
PR_IMPLEMENT(void) PL_FreeArenaPool(PLArenaPool *pool)
{
FreeArenaList(pool, &pool->first, PR_FALSE);
COUNT(pool, ndeallocs);
}
PR_IMPLEMENT(void) PL_FinishArenaPool(PLArenaPool *pool)
{
FreeArenaList(pool, &pool->first, PR_TRUE);
#ifdef PL_ARENAMETER
{
PLArenaStats *stats, **statsp;
if (pool->stats.name)
PR_DELETE(pool->stats.name);
for (statsp = &arena_stats_list; (stats = *statsp) != 0;
statsp = &stats->next) {
if (stats == &pool->stats) {
*statsp = stats->next;
return;
}
}
}
#endif
}
PR_IMPLEMENT(void) PL_CompactArenaPool(PLArenaPool *ap)
{
#if XP_MAC
#pragma unused (ap)
#if 0
PRArena *curr = &(ap->first);
while (curr) {
reallocSmaller(curr, curr->avail - (uprword_t)curr);
curr->limit = curr->avail;
curr = curr->next;
}
#endif
#endif
}
PR_IMPLEMENT(void) PL_ArenaFinish()
{
PLArena *a, *next;
LockArena();
for (a = arena_freelist; a; a = next) {
next = a->next;
PR_DELETE(a);
}
arena_freelist = NULL;
UnlockArena();
}
#ifdef PL_ARENAMETER
PR_IMPLEMENT(void) PL_ArenaCountAllocation(PLArenaPool *pool, PRUint32 nb)
{
pool->stats.nallocs++;
pool->stats.nbytes += nb;
if (nb > pool->stats.maxalloc)
pool->stats.maxalloc = nb;
pool->stats.variance += nb * nb;
}
PR_IMPLEMENT(void) PL_ArenaCountInplaceGrowth(
PLArenaPool *pool, PRUint32 size, PRUint32 incr)
{
pool->stats.ninplace++;
}
PR_IMPLEMENT(void) PL_ArenaCountGrowth(
PLArenaPool *pool, PRUint32 size, PRUint32 incr)
{
pool->stats.ngrows++;
pool->stats.nbytes += incr;
pool->stats.variance -= size * size;
size += incr;
if (size > pool->stats.maxalloc)
pool->stats.maxalloc = size;
pool->stats.variance += size * size;
}
PR_IMPLEMENT(void) PL_ArenaCountRelease(PLArenaPool *pool, char *mark)
{
pool->stats.nreleases++;
}
PR_IMPLEMENT(void) PL_ArenaCountRetract(PLArenaPool *pool, char *mark)
{
pool->stats.nfastrels++;
}
#include <math.h>
#include <stdio.h>
PR_IMPLEMENT(void) PL_DumpArenaStats(FILE *fp)
{
PLArenaStats *stats;
double mean, variance;
for (stats = arena_stats_list; stats; stats = stats->next) {
if (stats->nallocs != 0) {
mean = (double)stats->nbytes / stats->nallocs;
variance = fabs(stats->variance / stats->nallocs - mean * mean);
} else {
mean = variance = 0;
}
fprintf(fp, "\n%s allocation statistics:\n", stats->name);
fprintf(fp, " number of arenas: %u\n", stats->narenas);
fprintf(fp, " number of allocations: %u\n", stats->nallocs);
fprintf(fp, " number of free arena reclaims: %u\n", stats->nreclaims);
fprintf(fp, " number of malloc calls: %u\n", stats->nmallocs);
fprintf(fp, " number of deallocations: %u\n", stats->ndeallocs);
fprintf(fp, " number of allocation growths: %u\n", stats->ngrows);
fprintf(fp, " number of in-place growths: %u\n", stats->ninplace);
fprintf(fp, "number of released allocations: %u\n", stats->nreleases);
fprintf(fp, " number of fast releases: %u\n", stats->nfastrels);
fprintf(fp, " total bytes allocated: %u\n", stats->nbytes);
fprintf(fp, " mean allocation size: %g\n", mean);
fprintf(fp, " standard deviation: %g\n", sqrt(variance));
fprintf(fp, " maximum allocation size: %u\n", stats->maxalloc);
}
}
#endif /* PL_ARENAMETER */