/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ /* ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * 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 Mozilla JavaScript code. * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1999-2001 * the Initial Developer. All Rights Reserved. * * Contributor(s): * Brendan Eich (Original Author) * Chris Waterson * L. David Baron , Mozilla Corporation * * Alternatively, the contents of this file may be used under the terms of * either of the GNU General Public License Version 2 or later (the "GPL"), * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ /* * Double hashing implementation. * GENERATED BY js/src/plify_jsdhash.sed -- DO NOT EDIT!!! */ #include #include #include #include "prbit.h" #include "pldhash.h" #include "nsDebug.h" /* for PR_ASSERT */ #ifdef PL_DHASHMETER # if defined MOZILLA_CLIENT && defined DEBUG_XXXbrendan # include "nsTraceMalloc.h" # endif # define METER(x) x #else # define METER(x) /* nothing */ #endif /* * The following DEBUG-only code is used to assert that calls to one of * table->ops or to an enumerator do not cause re-entry into a call that * can mutate the table. The recursion level is stored in additional * space allocated at the end of the entry store to avoid changing * PLDHashTable, which could cause issues when mixing DEBUG and * non-DEBUG components. */ #ifdef DEBUG #define RECURSION_LEVEL(table_) (*(PRUint32*)(table_->entryStore + \ PL_DHASH_TABLE_SIZE(table_) * \ table_->entrySize)) #define ENTRY_STORE_EXTRA sizeof(PRUint32) #define INCREMENT_RECURSION_LEVEL(table_) (++RECURSION_LEVEL(table_)) #define DECREMENT_RECURSION_LEVEL(table_) (--RECURSION_LEVEL(table_)) #else #define ENTRY_STORE_EXTRA 0 #define INCREMENT_RECURSION_LEVEL(table_) ((void)1) #define DECREMENT_RECURSION_LEVEL(table_) ((void)0) #endif /* defined(DEBUG) */ void * PL_DHashAllocTable(PLDHashTable *table, PRUint32 nbytes) { return malloc(nbytes); } void PL_DHashFreeTable(PLDHashTable *table, void *ptr) { free(ptr); } PLDHashNumber PL_DHashStringKey(PLDHashTable *table, const void *key) { PLDHashNumber h; const unsigned char *s; h = 0; for (s = key; *s != '\0'; s++) h = PR_ROTATE_LEFT32(h, 4) ^ *s; return h; } PLDHashNumber PL_DHashVoidPtrKeyStub(PLDHashTable *table, const void *key) { return (PLDHashNumber)(unsigned long)key >> 2; } PRBool PL_DHashMatchEntryStub(PLDHashTable *table, const PLDHashEntryHdr *entry, const void *key) { const PLDHashEntryStub *stub = (const PLDHashEntryStub *)entry; return stub->key == key; } PRBool PL_DHashMatchStringKey(PLDHashTable *table, const PLDHashEntryHdr *entry, const void *key) { const PLDHashEntryStub *stub = (const PLDHashEntryStub *)entry; /* XXX tolerate null keys on account of sloppy Mozilla callers. */ return stub->key == key || (stub->key && key && strcmp(stub->key, key) == 0); } void PL_DHashMoveEntryStub(PLDHashTable *table, const PLDHashEntryHdr *from, PLDHashEntryHdr *to) { memcpy(to, from, table->entrySize); } void PL_DHashClearEntryStub(PLDHashTable *table, PLDHashEntryHdr *entry) { memset(entry, 0, table->entrySize); } void PL_DHashFreeStringKey(PLDHashTable *table, PLDHashEntryHdr *entry) { const PLDHashEntryStub *stub = (const PLDHashEntryStub *)entry; free((void *) stub->key); memset(entry, 0, table->entrySize); } void PL_DHashFinalizeStub(PLDHashTable *table) { } static const PLDHashTableOps stub_ops = { PL_DHashAllocTable, PL_DHashFreeTable, PL_DHashVoidPtrKeyStub, PL_DHashMatchEntryStub, PL_DHashMoveEntryStub, PL_DHashClearEntryStub, PL_DHashFinalizeStub, NULL }; const PLDHashTableOps * PL_DHashGetStubOps(void) { return &stub_ops; } PLDHashTable * PL_NewDHashTable(const PLDHashTableOps *ops, void *data, PRUint32 entrySize, PRUint32 capacity) { PLDHashTable *table; table = (PLDHashTable *) malloc(sizeof *table); if (!table) return NULL; if (!PL_DHashTableInit(table, ops, data, entrySize, capacity)) { free(table); return NULL; } return table; } void PL_DHashTableDestroy(PLDHashTable *table) { PL_DHashTableFinish(table); free(table); } PRBool PL_DHashTableInit(PLDHashTable *table, const PLDHashTableOps *ops, void *data, PRUint32 entrySize, PRUint32 capacity) { int log2; PRUint32 nbytes; #ifdef DEBUG if (entrySize > 10 * sizeof(void *)) { printf_stderr( "pldhash: for the table at address %p, the given entrySize" " of %lu %s favors chaining over double hashing.\n", (void *)table, (unsigned long) entrySize, (entrySize > 16 * sizeof(void*)) ? "definitely" : "probably"); } #endif table->ops = ops; table->data = data; if (capacity < PL_DHASH_MIN_SIZE) capacity = PL_DHASH_MIN_SIZE; PR_CEILING_LOG2(log2, capacity); capacity = PR_BIT(log2); if (capacity >= PL_DHASH_SIZE_LIMIT) return PR_FALSE; table->hashShift = PL_DHASH_BITS - log2; table->maxAlphaFrac = (uint8)(0x100 * PL_DHASH_DEFAULT_MAX_ALPHA); table->minAlphaFrac = (uint8)(0x100 * PL_DHASH_DEFAULT_MIN_ALPHA); table->entrySize = entrySize; table->entryCount = table->removedCount = 0; table->generation = 0; nbytes = capacity * entrySize; table->entryStore = ops->allocTable(table, nbytes + ENTRY_STORE_EXTRA); if (!table->entryStore) return PR_FALSE; memset(table->entryStore, 0, nbytes); METER(memset(&table->stats, 0, sizeof table->stats)); #ifdef DEBUG RECURSION_LEVEL(table) = 0; #endif return PR_TRUE; } /* * Compute max and min load numbers (entry counts) from table params. */ #define MAX_LOAD(table, size) (((table)->maxAlphaFrac * (size)) >> 8) #define MIN_LOAD(table, size) (((table)->minAlphaFrac * (size)) >> 8) void PL_DHashTableSetAlphaBounds(PLDHashTable *table, float maxAlpha, float minAlpha) { PRUint32 size; /* * Reject obviously insane bounds, rather than trying to guess what the * buggy caller intended. */ NS_ASSERTION(0.5 <= maxAlpha && maxAlpha < 1 && 0 <= minAlpha, "0.5 <= maxAlpha && maxAlpha < 1 && 0 <= minAlpha"); if (maxAlpha < 0.5 || 1 <= maxAlpha || minAlpha < 0) return; /* * Ensure that at least one entry will always be free. If maxAlpha at * minimum size leaves no entries free, reduce maxAlpha based on minimum * size and the precision limit of maxAlphaFrac's fixed point format. */ NS_ASSERTION(PL_DHASH_MIN_SIZE - (maxAlpha * PL_DHASH_MIN_SIZE) >= 1, "PL_DHASH_MIN_SIZE - (maxAlpha * PL_DHASH_MIN_SIZE) >= 1"); if (PL_DHASH_MIN_SIZE - (maxAlpha * PL_DHASH_MIN_SIZE) < 1) { maxAlpha = (float) (PL_DHASH_MIN_SIZE - PR_MAX(PL_DHASH_MIN_SIZE / 256, 1)) / PL_DHASH_MIN_SIZE; } /* * Ensure that minAlpha is strictly less than half maxAlpha. Take care * not to truncate an entry's worth of alpha when storing in minAlphaFrac * (8-bit fixed point format). */ NS_ASSERTION(minAlpha < maxAlpha / 2, "minAlpha < maxAlpha / 2"); if (minAlpha >= maxAlpha / 2) { size = PL_DHASH_TABLE_SIZE(table); minAlpha = (size * maxAlpha - PR_MAX(size / 256, 1)) / (2 * size); } table->maxAlphaFrac = (uint8)(maxAlpha * 256); table->minAlphaFrac = (uint8)(minAlpha * 256); } /* * Double hashing needs the second hash code to be relatively prime to table * size, so we simply make hash2 odd. */ #define HASH1(hash0, shift) ((hash0) >> (shift)) #define HASH2(hash0,log2,shift) ((((hash0) << (log2)) >> (shift)) | 1) /* * Reserve keyHash 0 for free entries and 1 for removed-entry sentinels. Note * that a removed-entry sentinel need be stored only if the removed entry had * a colliding entry added after it. Therefore we can use 1 as the collision * flag in addition to the removed-entry sentinel value. Multiplicative hash * uses the high order bits of keyHash, so this least-significant reservation * should not hurt the hash function's effectiveness much. * * If you change any of these magic numbers, also update PL_DHASH_ENTRY_IS_LIVE * in pldhash.h. It used to be private to pldhash.c, but then became public to * assist iterator writers who inspect table->entryStore directly. */ #define COLLISION_FLAG ((PLDHashNumber) 1) #define MARK_ENTRY_FREE(entry) ((entry)->keyHash = 0) #define MARK_ENTRY_REMOVED(entry) ((entry)->keyHash = 1) #define ENTRY_IS_REMOVED(entry) ((entry)->keyHash == 1) #define ENTRY_IS_LIVE(entry) PL_DHASH_ENTRY_IS_LIVE(entry) #define ENSURE_LIVE_KEYHASH(hash0) if (hash0 < 2) hash0 -= 2; else (void)0 /* Match an entry's keyHash against an unstored one computed from a key. */ #define MATCH_ENTRY_KEYHASH(entry,hash0) \ (((entry)->keyHash & ~COLLISION_FLAG) == (hash0)) /* Compute the address of the indexed entry in table. */ #define ADDRESS_ENTRY(table, index) \ ((PLDHashEntryHdr *)((table)->entryStore + (index) * (table)->entrySize)) void PL_DHashTableFinish(PLDHashTable *table) { char *entryAddr, *entryLimit; PRUint32 entrySize; PLDHashEntryHdr *entry; #ifdef DEBUG_XXXbrendan static FILE *dumpfp = NULL; if (!dumpfp) dumpfp = fopen("/tmp/pldhash.bigdump", "w"); if (dumpfp) { #ifdef MOZILLA_CLIENT NS_TraceStack(1, dumpfp); #endif PL_DHashTableDumpMeter(table, NULL, dumpfp); fputc('\n', dumpfp); } #endif INCREMENT_RECURSION_LEVEL(table); /* Call finalize before clearing entries, so it can enumerate them. */ table->ops->finalize(table); /* Clear any remaining live entries. */ entryAddr = table->entryStore; entrySize = table->entrySize; entryLimit = entryAddr + PL_DHASH_TABLE_SIZE(table) * entrySize; while (entryAddr < entryLimit) { entry = (PLDHashEntryHdr *)entryAddr; if (ENTRY_IS_LIVE(entry)) { METER(table->stats.removeEnums++); table->ops->clearEntry(table, entry); } entryAddr += entrySize; } DECREMENT_RECURSION_LEVEL(table); NS_ASSERTION(RECURSION_LEVEL(table) == 0, "RECURSION_LEVEL(table) == 0"); /* Free entry storage last. */ table->ops->freeTable(table, table->entryStore); } static PLDHashEntryHdr * PL_DHASH_FASTCALL SearchTable(PLDHashTable *table, const void *key, PLDHashNumber keyHash, PLDHashOperator op) { PLDHashNumber hash1, hash2; int hashShift, sizeLog2; PLDHashEntryHdr *entry, *firstRemoved; PLDHashMatchEntry matchEntry; PRUint32 sizeMask; METER(table->stats.searches++); NS_ASSERTION(!(keyHash & COLLISION_FLAG), "!(keyHash & COLLISION_FLAG)"); /* Compute the primary hash address. */ hashShift = table->hashShift; hash1 = HASH1(keyHash, hashShift); entry = ADDRESS_ENTRY(table, hash1); /* Miss: return space for a new entry. */ if (PL_DHASH_ENTRY_IS_FREE(entry)) { METER(table->stats.misses++); return entry; } /* Hit: return entry. */ matchEntry = table->ops->matchEntry; if (MATCH_ENTRY_KEYHASH(entry, keyHash) && matchEntry(table, entry, key)) { METER(table->stats.hits++); return entry; } /* Collision: double hash. */ sizeLog2 = PL_DHASH_BITS - table->hashShift; hash2 = HASH2(keyHash, sizeLog2, hashShift); sizeMask = PR_BITMASK(sizeLog2); /* Save the first removed entry pointer so PL_DHASH_ADD can recycle it. */ firstRemoved = NULL; for (;;) { if (NS_UNLIKELY(ENTRY_IS_REMOVED(entry))) { if (!firstRemoved) firstRemoved = entry; } else { if (op == PL_DHASH_ADD) entry->keyHash |= COLLISION_FLAG; } METER(table->stats.steps++); hash1 -= hash2; hash1 &= sizeMask; entry = ADDRESS_ENTRY(table, hash1); if (PL_DHASH_ENTRY_IS_FREE(entry)) { METER(table->stats.misses++); return (firstRemoved && op == PL_DHASH_ADD) ? firstRemoved : entry; } if (MATCH_ENTRY_KEYHASH(entry, keyHash) && matchEntry(table, entry, key)) { METER(table->stats.hits++); return entry; } } /* NOTREACHED */ return NULL; } /* * This is a copy of SearchTable, used by ChangeTable, hardcoded to * 1. assume |op == PL_DHASH_ADD|, * 2. assume that |key| will never match an existing entry, and * 3. assume that no entries have been removed from the current table * structure. * Avoiding the need for |key| means we can avoid needing a way to map * entries to keys, which means callers can use complex key types more * easily. */ static PLDHashEntryHdr * PL_DHASH_FASTCALL FindFreeEntry(PLDHashTable *table, PLDHashNumber keyHash) { PLDHashNumber hash1, hash2; int hashShift, sizeLog2; PLDHashEntryHdr *entry; PRUint32 sizeMask; METER(table->stats.searches++); NS_ASSERTION(!(keyHash & COLLISION_FLAG), "!(keyHash & COLLISION_FLAG)"); /* Compute the primary hash address. */ hashShift = table->hashShift; hash1 = HASH1(keyHash, hashShift); entry = ADDRESS_ENTRY(table, hash1); /* Miss: return space for a new entry. */ if (PL_DHASH_ENTRY_IS_FREE(entry)) { METER(table->stats.misses++); return entry; } /* Collision: double hash. */ sizeLog2 = PL_DHASH_BITS - table->hashShift; hash2 = HASH2(keyHash, sizeLog2, hashShift); sizeMask = PR_BITMASK(sizeLog2); for (;;) { NS_ASSERTION(!ENTRY_IS_REMOVED(entry), "!ENTRY_IS_REMOVED(entry)"); entry->keyHash |= COLLISION_FLAG; METER(table->stats.steps++); hash1 -= hash2; hash1 &= sizeMask; entry = ADDRESS_ENTRY(table, hash1); if (PL_DHASH_ENTRY_IS_FREE(entry)) { METER(table->stats.misses++); return entry; } } /* NOTREACHED */ return NULL; } static PRBool ChangeTable(PLDHashTable *table, int deltaLog2) { int oldLog2, newLog2; PRUint32 oldCapacity, newCapacity; char *newEntryStore, *oldEntryStore, *oldEntryAddr; PRUint32 entrySize, i, nbytes; PLDHashEntryHdr *oldEntry, *newEntry; PLDHashMoveEntry moveEntry; #ifdef DEBUG PRUint32 recursionLevel; #endif /* Look, but don't touch, until we succeed in getting new entry store. */ oldLog2 = PL_DHASH_BITS - table->hashShift; newLog2 = oldLog2 + deltaLog2; oldCapacity = PR_BIT(oldLog2); newCapacity = PR_BIT(newLog2); if (newCapacity >= PL_DHASH_SIZE_LIMIT) return PR_FALSE; entrySize = table->entrySize; nbytes = newCapacity * entrySize; newEntryStore = table->ops->allocTable(table, nbytes + ENTRY_STORE_EXTRA); if (!newEntryStore) return PR_FALSE; /* We can't fail from here on, so update table parameters. */ #ifdef DEBUG recursionLevel = RECURSION_LEVEL(table); #endif table->hashShift = PL_DHASH_BITS - newLog2; table->removedCount = 0; table->generation++; /* Assign the new entry store to table. */ memset(newEntryStore, 0, nbytes); oldEntryAddr = oldEntryStore = table->entryStore; table->entryStore = newEntryStore; moveEntry = table->ops->moveEntry; #ifdef DEBUG RECURSION_LEVEL(table) = recursionLevel; #endif /* Copy only live entries, leaving removed ones behind. */ for (i = 0; i < oldCapacity; i++) { oldEntry = (PLDHashEntryHdr *)oldEntryAddr; if (ENTRY_IS_LIVE(oldEntry)) { oldEntry->keyHash &= ~COLLISION_FLAG; newEntry = FindFreeEntry(table, oldEntry->keyHash); NS_ASSERTION(PL_DHASH_ENTRY_IS_FREE(newEntry), "PL_DHASH_ENTRY_IS_FREE(newEntry)"); moveEntry(table, oldEntry, newEntry); newEntry->keyHash = oldEntry->keyHash; } oldEntryAddr += entrySize; } table->ops->freeTable(table, oldEntryStore); return PR_TRUE; } PLDHashEntryHdr * PL_DHASH_FASTCALL PL_DHashTableOperate(PLDHashTable *table, const void *key, PLDHashOperator op) { PLDHashNumber keyHash; PLDHashEntryHdr *entry; PRUint32 size; int deltaLog2; NS_ASSERTION(op == PL_DHASH_LOOKUP || RECURSION_LEVEL(table) == 0, "op == PL_DHASH_LOOKUP || RECURSION_LEVEL(table) == 0"); INCREMENT_RECURSION_LEVEL(table); keyHash = table->ops->hashKey(table, key); keyHash *= PL_DHASH_GOLDEN_RATIO; /* Avoid 0 and 1 hash codes, they indicate free and removed entries. */ ENSURE_LIVE_KEYHASH(keyHash); keyHash &= ~COLLISION_FLAG; switch (op) { case PL_DHASH_LOOKUP: METER(table->stats.lookups++); entry = SearchTable(table, key, keyHash, op); break; case PL_DHASH_ADD: /* * If alpha is >= .75, grow or compress the table. If key is already * in the table, we may grow once more than necessary, but only if we * are on the edge of being overloaded. */ size = PL_DHASH_TABLE_SIZE(table); if (table->entryCount + table->removedCount >= MAX_LOAD(table, size)) { /* Compress if a quarter or more of all entries are removed. */ if (table->removedCount >= size >> 2) { METER(table->stats.compresses++); deltaLog2 = 0; } else { METER(table->stats.grows++); deltaLog2 = 1; } /* * Grow or compress table, returning null if ChangeTable fails and * falling through might claim the last free entry. */ if (!ChangeTable(table, deltaLog2) && table->entryCount + table->removedCount == size - 1) { METER(table->stats.addFailures++); entry = NULL; break; } } /* * Look for entry after possibly growing, so we don't have to add it, * then skip it while growing the table and re-add it after. */ entry = SearchTable(table, key, keyHash, op); if (!ENTRY_IS_LIVE(entry)) { /* Initialize the entry, indicating that it's no longer free. */ METER(table->stats.addMisses++); if (ENTRY_IS_REMOVED(entry)) { METER(table->stats.addOverRemoved++); table->removedCount--; keyHash |= COLLISION_FLAG; } if (table->ops->initEntry && !table->ops->initEntry(table, entry, key)) { /* We haven't claimed entry yet; fail with null return. */ memset(entry + 1, 0, table->entrySize - sizeof *entry); entry = NULL; break; } entry->keyHash = keyHash; table->entryCount++; } METER(else table->stats.addHits++); break; case PL_DHASH_REMOVE: entry = SearchTable(table, key, keyHash, op); if (ENTRY_IS_LIVE(entry)) { /* Clear this entry and mark it as "removed". */ METER(table->stats.removeHits++); PL_DHashTableRawRemove(table, entry); /* Shrink if alpha is <= .25 and table isn't too small already. */ size = PL_DHASH_TABLE_SIZE(table); if (size > PL_DHASH_MIN_SIZE && table->entryCount <= MIN_LOAD(table, size)) { METER(table->stats.shrinks++); (void) ChangeTable(table, -1); } } METER(else table->stats.removeMisses++); entry = NULL; break; default: NS_NOTREACHED("0"); entry = NULL; } DECREMENT_RECURSION_LEVEL(table); return entry; } void PL_DHashTableRawRemove(PLDHashTable *table, PLDHashEntryHdr *entry) { PLDHashNumber keyHash; /* load first in case clearEntry goofs it */ NS_ASSERTION(PL_DHASH_ENTRY_IS_LIVE(entry), "PL_DHASH_ENTRY_IS_LIVE(entry)"); keyHash = entry->keyHash; table->ops->clearEntry(table, entry); if (keyHash & COLLISION_FLAG) { MARK_ENTRY_REMOVED(entry); table->removedCount++; } else { METER(table->stats.removeFrees++); MARK_ENTRY_FREE(entry); } table->entryCount--; } PRUint32 PL_DHashTableEnumerate(PLDHashTable *table, PLDHashEnumerator etor, void *arg) { char *entryAddr, *entryLimit; PRUint32 i, capacity, entrySize, ceiling; PRBool didRemove; PLDHashEntryHdr *entry; PLDHashOperator op; INCREMENT_RECURSION_LEVEL(table); entryAddr = table->entryStore; entrySize = table->entrySize; capacity = PL_DHASH_TABLE_SIZE(table); entryLimit = entryAddr + capacity * entrySize; i = 0; didRemove = PR_FALSE; while (entryAddr < entryLimit) { entry = (PLDHashEntryHdr *)entryAddr; if (ENTRY_IS_LIVE(entry)) { op = etor(table, entry, i++, arg); if (op & PL_DHASH_REMOVE) { METER(table->stats.removeEnums++); PL_DHashTableRawRemove(table, entry); didRemove = PR_TRUE; } if (op & PL_DHASH_STOP) break; } entryAddr += entrySize; } NS_ASSERTION(!didRemove || RECURSION_LEVEL(table) == 1, "!didRemove || RECURSION_LEVEL(table) == 1"); /* * Shrink or compress if a quarter or more of all entries are removed, or * if the table is underloaded according to the configured minimum alpha, * and is not minimal-size already. Do this only if we removed above, so * non-removing enumerations can count on stable table->entryStore until * the next non-lookup-Operate or removing-Enumerate. */ if (didRemove && (table->removedCount >= capacity >> 2 || (capacity > PL_DHASH_MIN_SIZE && table->entryCount <= MIN_LOAD(table, capacity)))) { METER(table->stats.enumShrinks++); capacity = table->entryCount; capacity += capacity >> 1; if (capacity < PL_DHASH_MIN_SIZE) capacity = PL_DHASH_MIN_SIZE; PR_CEILING_LOG2(ceiling, capacity); ceiling -= PL_DHASH_BITS - table->hashShift; (void) ChangeTable(table, ceiling); } DECREMENT_RECURSION_LEVEL(table); return i; } #ifdef PL_DHASHMETER #include void PL_DHashTableDumpMeter(PLDHashTable *table, PLDHashEnumerator dump, FILE *fp) { char *entryAddr; PRUint32 entrySize, entryCount; int hashShift, sizeLog2; PRUint32 i, tableSize, sizeMask, chainLen, maxChainLen, chainCount; PLDHashNumber hash1, hash2, saveHash1, maxChainHash1, maxChainHash2; double sqsum, mean, variance, sigma; PLDHashEntryHdr *entry, *probe; entryAddr = table->entryStore; entrySize = table->entrySize; hashShift = table->hashShift; sizeLog2 = PL_DHASH_BITS - hashShift; tableSize = PL_DHASH_TABLE_SIZE(table); sizeMask = PR_BITMASK(sizeLog2); chainCount = maxChainLen = 0; hash2 = 0; sqsum = 0; for (i = 0; i < tableSize; i++) { entry = (PLDHashEntryHdr *)entryAddr; entryAddr += entrySize; if (!ENTRY_IS_LIVE(entry)) continue; hash1 = HASH1(entry->keyHash & ~COLLISION_FLAG, hashShift); saveHash1 = hash1; probe = ADDRESS_ENTRY(table, hash1); chainLen = 1; if (probe == entry) { /* Start of a (possibly unit-length) chain. */ chainCount++; } else { hash2 = HASH2(entry->keyHash & ~COLLISION_FLAG, sizeLog2, hashShift); do { chainLen++; hash1 -= hash2; hash1 &= sizeMask; probe = ADDRESS_ENTRY(table, hash1); } while (probe != entry); } sqsum += chainLen * chainLen; if (chainLen > maxChainLen) { maxChainLen = chainLen; maxChainHash1 = saveHash1; maxChainHash2 = hash2; } } entryCount = table->entryCount; if (entryCount && chainCount) { mean = (double)entryCount / chainCount; variance = chainCount * sqsum - entryCount * entryCount; if (variance < 0 || chainCount == 1) variance = 0; else variance /= chainCount * (chainCount - 1); sigma = sqrt(variance); } else { mean = sigma = 0; } fprintf(fp, "Double hashing statistics:\n"); fprintf(fp, " table size (in entries): %u\n", tableSize); fprintf(fp, " number of entries: %u\n", table->entryCount); fprintf(fp, " number of removed entries: %u\n", table->removedCount); fprintf(fp, " number of searches: %u\n", table->stats.searches); fprintf(fp, " number of hits: %u\n", table->stats.hits); fprintf(fp, " number of misses: %u\n", table->stats.misses); fprintf(fp, " mean steps per search: %g\n", table->stats.searches ? (double)table->stats.steps / table->stats.searches : 0.); fprintf(fp, " mean hash chain length: %g\n", mean); fprintf(fp, " standard deviation: %g\n", sigma); fprintf(fp, " maximum hash chain length: %u\n", maxChainLen); fprintf(fp, " number of lookups: %u\n", table->stats.lookups); fprintf(fp, " adds that made a new entry: %u\n", table->stats.addMisses); fprintf(fp, "adds that recycled removeds: %u\n", table->stats.addOverRemoved); fprintf(fp, " adds that found an entry: %u\n", table->stats.addHits); fprintf(fp, " add failures: %u\n", table->stats.addFailures); fprintf(fp, " useful removes: %u\n", table->stats.removeHits); fprintf(fp, " useless removes: %u\n", table->stats.removeMisses); fprintf(fp, "removes that freed an entry: %u\n", table->stats.removeFrees); fprintf(fp, " removes while enumerating: %u\n", table->stats.removeEnums); fprintf(fp, " number of grows: %u\n", table->stats.grows); fprintf(fp, " number of shrinks: %u\n", table->stats.shrinks); fprintf(fp, " number of compresses: %u\n", table->stats.compresses); fprintf(fp, "number of enumerate shrinks: %u\n", table->stats.enumShrinks); if (dump && maxChainLen && hash2) { fputs("Maximum hash chain:\n", fp); hash1 = maxChainHash1; hash2 = maxChainHash2; entry = ADDRESS_ENTRY(table, hash1); i = 0; do { if (dump(table, entry, i++, fp) != PL_DHASH_NEXT) break; hash1 -= hash2; hash1 &= sizeMask; entry = ADDRESS_ENTRY(table, hash1); } while (PL_DHASH_ENTRY_IS_BUSY(entry)); } } #endif /* PL_DHASHMETER */