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-rw-r--r--nsprpub/lib/ds/plarena.c348
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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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * 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 */
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