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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
/*
* 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 "prlock.h"
#include "prinit.h"
#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)
PR_IMPLEMENT(void) PL_InitArenaPool(
PLArenaPool *pool, const char *name, PRUint32 size, PRUint32 align)
{
/*
* Look-up table of PR_BITMASK(PR_CeilingLog2(align)) values for
* align = 1 to 32.
*/
static const PRUint8 pmasks[33] = {
0, /* not used */
0, 1, 3, 3, 7, 7, 7, 7,15,15,15,15,15,15,15,15, /* 1 ... 16 */
31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31 /* 17 ... 32 */
};
if (align == 0) {
align = PL_ARENA_DEFAULT_ALIGN;
}
if (align < sizeof(pmasks)/sizeof(pmasks[0])) {
pool->mask = pmasks[align];
}
else {
pool->mask = PR_BITMASK(PR_CeilingLog2(align));
}
pool->first.next = NULL;
/* Set all three addresses in pool->first to the same dummy value.
* These addresses are only compared with each other, but never
* dereferenced. */
pool->first.base = pool->first.avail = pool->first.limit =
(PRUword)PL_ARENA_ALIGN(pool, &pool->first + 1);
pool->current = &pool->first;
/*
* Compute the net size so that each arena's gross size is |size|.
* sizeof(PLArena) + pool->mask is the header and alignment slop
* that PL_ArenaAllocate adds to the net size.
*/
if (size > sizeof(PLArena) + pool->mask) {
pool->arenasize = size - (sizeof(PLArena) + pool->mask);
}
else {
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
}
/*
** PL_ArenaAllocate() -- allocate space from an arena pool
**
** Description: PL_ArenaAllocate() allocates space from an arena
** pool.
**
** First, try to satisfy the request from arenas starting at
** pool->current. Then try to allocate a new arena from the heap.
**
** Returns: pointer to allocated space or NULL
**
** Notes: The original implementation had some difficult to
** solve bugs; the code was difficult to read. Sometimes it's
** just easier to rewrite it. I did that. larryh.
**
** See also: bugzilla: 45343.
**
*/
PR_IMPLEMENT(void *) PL_ArenaAllocate(PLArenaPool *pool, PRUint32 nb)
{
PLArena *a;
char *rp; /* returned pointer */
PRUint32 nbOld;
PR_ASSERT((nb & pool->mask) == 0);
nbOld = nb;
nb = (PRUword)PL_ARENA_ALIGN(pool, nb); /* force alignment */
if (nb < nbOld) {
return NULL;
}
/* attempt to allocate from arenas at pool->current */
{
a = pool->current;
do {
if ( nb <= a->limit - a->avail ) {
pool->current = a;
rp = (char *)a->avail;
a->avail += nb;
return rp;
}
} while( NULL != (a = a->next) );
}
/* attempt to allocate from the heap */
{
PRUint32 sz = PR_MAX(pool->arenasize, nb);
if (PR_UINT32_MAX - sz < sizeof *a + pool->mask) {
a = NULL;
} else {
sz += sizeof *a + pool->mask; /* header and alignment slop */
a = (PLArena*)PR_MALLOC(sz);
}
if ( NULL != a ) {
a->limit = (PRUword)a + sz;
a->base = a->avail = (PRUword)PL_ARENA_ALIGN(pool, a + 1);
PL_MAKE_MEM_NOACCESS((void*)a->avail, a->limit - a->avail);
rp = (char *)a->avail;
a->avail += nb;
PR_ASSERT(a->avail <= a->limit);
/* 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 ( NULL == pool->first.next ) {
pool->first.next = a;
}
PL_COUNT_ARENA(pool,++);
COUNT(pool, nmallocs);
return(rp);
}
}
/* we got to here, and there's no memory to allocate */
return(NULL);
} /* --- end PL_ArenaAllocate() --- */
PR_IMPLEMENT(void *) PL_ArenaGrow(
PLArenaPool *pool, void *p, PRUint32 size, PRUint32 incr)
{
void *newp;
if (PR_UINT32_MAX - size < incr) {
return NULL;
}
PL_ARENA_ALLOCATE(newp, pool, size + incr);
if (newp) {
memcpy(newp, p, size);
}
return newp;
}
PR_IMPLEMENT(void) PL_ClearArenaPool(PLArenaPool *pool, PRInt32 pattern)
{
PLArena *a;
for (a = pool->first.next; a; a = a->next) {
PR_ASSERT(a->base <= a->avail && a->avail <= a->limit);
a->avail = a->base;
PL_CLEAR_UNUSED_PATTERN(a, pattern);
PL_MAKE_MEM_NOACCESS((void*)a->avail, a->limit - a->avail);
}
}
/*
* 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)
{
PLArena *a = head->next;
if (!a) {
return;
}
head->next = NULL;
do {
PLArena *tmp = a;
a = a->next;
PL_CLEAR_ARENA(tmp);
PL_COUNT_ARENA(pool,--);
PR_DELETE(tmp);
} while (a);
pool->current = head;
}
PR_IMPLEMENT(void) PL_ArenaRelease(PLArenaPool *pool, char *mark)
{
PLArena *a;
for (a = &pool->first; 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);
return;
}
}
}
PR_IMPLEMENT(void) PL_FreeArenaPool(PLArenaPool *pool)
{
FreeArenaList(pool, &pool->first);
COUNT(pool, ndeallocs);
}
PR_IMPLEMENT(void) PL_FinishArenaPool(PLArenaPool *pool)
{
FreeArenaList(pool, &pool->first);
#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)
{
}
PR_IMPLEMENT(void) PL_ArenaFinish(void)
{
}
PR_IMPLEMENT(size_t) PL_SizeOfArenaPoolExcludingPool(
const PLArenaPool *pool, PLMallocSizeFn mallocSizeOf)
{
/*
* The first PLArena is within |pool|, so don't measure it. Subsequent
* PLArenas are separate and must be measured.
*/
size_t size = 0;
const PLArena *arena = pool->first.next;
while (arena) {
size += mallocSizeOf(arena);
arena = arena->next;
}
return size;
}
#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 */