4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync/* ***** BEGIN LICENSE BLOCK *****
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Version: MPL 1.1/GPL 2.0/LGPL 2.1
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * The contents of this file are subject to the Mozilla Public License Version
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * 1.1 (the "License"); you may not use this file except in compliance with
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * the License. You may obtain a copy of the License at
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Software distributed under the License is distributed on an "AS IS" basis,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * for the specific language governing rights and limitations under the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * The Original Code is Mozilla JavaScript code.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * The Initial Developer of the Original Code is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Netscape Communications Corporation.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Portions created by the Initial Developer are Copyright (C) 1999-2001
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * the Initial Developer. All Rights Reserved.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Contributor(s):
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Brendan Eich <brendan@mozilla.org> (Original Author)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Alternatively, the contents of this file may be used under the terms of
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * either of the GNU General Public License Version 2 or later (the "GPL"),
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * in which case the provisions of the GPL or the LGPL are applicable instead
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4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * under the terms of either the GPL or the LGPL, and not to allow others to
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4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * decision by deleting the provisions above and replace them with the notice
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * and other provisions required by the GPL or the LGPL. If you do not delete
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * the provisions above, a recipient may use your version of this file under
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4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * ***** END LICENSE BLOCK ***** */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Double hashing, a la Knuth 6.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * GENERATED BY js/src/plify_jsdhash.sed -- DO NOT EDIT!!!
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashTableFinish VBoxNsplPL_DHashTableFinish
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashTableOperate VBoxNsplPL_DHashTableOperate
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashTableEnumerate VBoxNsplPL_DHashTableEnumerate
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashAllocTable VBoxNsplPL_DHashAllocTable
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashMoveEntryStub VBoxNsplPL_DHashMoveEntryStub
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashFinalizeStub VBoxNsplPL_DHashFinalizeStub
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashClearEntryStub VBoxNsplPL_DHashClearEntryStub
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashFreeStringKey VBoxNsplPL_DHashFreeStringKey
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashGetKeyStub VBoxNsplPL_DHashGetKeyStub
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashGetStubOps VBoxNsplPL_DHashGetStubOps
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashMatchEntryStub VBoxNsplPL_DHashMatchEntryStub
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashMatchStringKey VBoxNsplPL_DHashMatchStringKey
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashTableDestroy VBoxNsplPL_DHashTableDestroy
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashTableRawRemove VBoxNsplPL_DHashTableRawRemove
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashTableSetAlphaBounds VBoxNsplPL_DHashTableSetAlphaBounds
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHashVoidPtrKeyStub VBoxNsplPL_DHashVoidPtrKeyStub
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#endif /* VBOX_WITH_XPCOM_NAMESPACE_CLEANUP */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#if defined(__GNUC__) && defined(__i386__) && (__GNUC__ >= 3) && !defined(XP_OS2)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHASH_FASTCALL __attribute__ ((regparm (3),stdcall))
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync/* Table size limit, do not equal or exceed (see min&maxAlphaFrac, below). */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync/* Minimum table size, or gross entry count (net is at most .75 loaded). */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#elif (PL_DHASH_MIN_SIZE & (PL_DHASH_MIN_SIZE - 1)) != 0
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Multiplicative hash uses an unsigned 32 bit integer and the golden ratio,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * expressed as a fixed-point 32-bit fraction.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync/* Primitive and forward-struct typedefs. */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Table entry header structure.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * In order to allow in-line allocation of key and value, we do not declare
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * either here. Instead, the API uses const void *key as a formal parameter,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * and asks each entry for its key when necessary via a getKey callback, used
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * when growing or shrinking the table. Other callback types are defined
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * below and grouped into the PLDHashTableOps structure, for single static
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * initialization per hash table sub-type.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Each hash table sub-type should nest the PLDHashEntryHdr structure at the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * front of its particular entry type. The keyHash member contains the result
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * of multiplying the hash code returned from the hashKey callback (see below)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * by PL_DHASH_GOLDEN_RATIO, then constraining the result to avoid the magic 0
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * and 1 values. The stored keyHash value is table size invariant, and it is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * maintained automatically by PL_DHashTableOperate -- users should never set
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * it, and its only uses should be via the entry macros below.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * The PL_DHASH_ENTRY_IS_LIVE macro tests whether entry is neither free nor
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * removed. An entry may be either busy or free; if busy, it may be live or
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * removed. Consumers of this API should not access members of entries that
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * are not live.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * However, use PL_DHASH_ENTRY_IS_BUSY for faster liveness testing of entries
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * returned by PL_DHashTableOperate, as PL_DHashTableOperate never returns a
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * non-live, busy (i.e., removed) entry pointer to its caller. See below for
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * more details on PL_DHashTableOperate's calling rules.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PLDHashNumber keyHash; /* every entry must begin like this */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHASH_ENTRY_IS_FREE(entry) ((entry)->keyHash == 0)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHASH_ENTRY_IS_BUSY(entry) (!PL_DHASH_ENTRY_IS_FREE(entry))
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHASH_ENTRY_IS_LIVE(entry) ((entry)->keyHash >= 2)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * A PLDHashTable is currently 8 words (without the PL_DHASHMETER overhead)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * on most architectures, and may be allocated on the stack or within another
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * structure or class (see below for the Init and Finish functions to use).
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * To decide whether to use double hashing vs. chaining, we need to develop a
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * trade-off relation, as follows:
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Let alpha be the load factor, esize the entry size in words, count the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * entry count, and pow2 the power-of-two table size in entries.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * (PLDHashTable overhead) > (PLHashTable overhead)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * (unused table entry space) > (malloc and .next overhead per entry) +
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * (buckets overhead)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * (1 - alpha) * esize * pow2 > 2 * count + pow2
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Notice that alpha is by definition (count / pow2):
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * (1 - alpha) * esize * pow2 > 2 * alpha * pow2 + pow2
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * (1 - alpha) * esize > 2 * alpha + 1
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * esize > (1 + 2 * alpha) / (1 - alpha)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * This assumes both tables must keep keyHash, key, and value for each entry,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * where key and value point to separately allocated strings or structures.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * If key and value can be combined into one pointer, then the trade-off is:
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * esize > (1 + 3 * alpha) / (1 - alpha)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * If the entry value can be a subtype of PLDHashEntryHdr, rather than a type
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * that must be allocated separately and referenced by an entry.value pointer
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * member, and provided key's allocation can be fused with its entry's, then
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * k (the words wasted per entry with chaining) is 4.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * To see these curves, feed gnuplot input like so:
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * gnuplot> f(x,k) = (1 + k * x) / (1 - x)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * gnuplot> plot [0:.75] f(x,2), f(x,3), f(x,4)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * For k of 2 and a well-loaded table (alpha > .5), esize must be more than 4
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * words for chaining to be more space-efficient than double hashing.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Solving for alpha helps us decide when to shrink an underloaded table:
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * esize > (1 + k * alpha) / (1 - alpha)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * esize - alpha * esize > 1 + k * alpha
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * esize - 1 > (k + esize) * alpha
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * (esize - 1) / (k + esize) > alpha
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * alpha < (esize - 1) / (esize + k)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Therefore double hashing should keep alpha >= (esize - 1) / (esize + k),
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * assuming esize is not too large (in which case, chaining should probably be
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * used for any alpha). For esize=2 and k=3, we want alpha >= .2; for esize=3
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * and k=2, we want alpha >= .4. For k=4, esize could be 6, and alpha >= .5
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * would still obtain. See the PL_DHASH_MIN_ALPHA macro further below.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * The current implementation uses a configurable lower bound on alpha, which
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * defaults to .25, when deciding to shrink the table (while still respecting
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * PL_DHASH_MIN_SIZE).
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Note a qualitative difference between chaining and double hashing: under
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * chaining, entry addresses are stable across table shrinks and grows. With
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * double hashing, you can't safely hold an entry pointer and use it after an
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * ADD or REMOVE operation, unless you sample table->generation before adding
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * or removing, and compare the sample after, dereferencing the entry pointer
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * only if table->generation has not changed.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * The moral of this story: there is no one-size-fits-all hash table scheme,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * but for small table entry size, and assuming entry address stability is not
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * required, double hashing wins.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync const PLDHashTableOps *ops; /* virtual operations, see below */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync uint8 maxAlphaFrac; /* 8-bit fixed point max alpha */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync uint8 minAlphaFrac; /* 8-bit fixed point min alpha */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 entrySize; /* number of bytes in an entry */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 entryCount; /* number of entries in table */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 removedCount; /* removed entry sentinels in table */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 generation; /* entry storage generation number */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 searches; /* total number of table searches */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 misses; /* searches that didn't find key */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 addMisses; /* adds that miss, and do work */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 addOverRemoved; /* adds that recycled a removed entry */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 addHits; /* adds that hit an existing entry */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 addFailures; /* out-of-memory during add growth */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 removeHits; /* removes that hit, and do work */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 removeMisses; /* useless removes that miss */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 removeFrees; /* removes that freed entry directly */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 removeEnums; /* removes done by Enumerate */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync PRUint32 enumShrinks; /* contractions after Enumerate */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Size in entries (gross, not net of free and removed sentinels) for table.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * We store hashShift rather than sizeLog2 to optimize the collision-free case
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * in SearchTable.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync#define PL_DHASH_TABLE_SIZE(table) PR_BIT(PL_DHASH_BITS - (table)->hashShift)
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Table space at entryStore is allocated and freed using these callbacks.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * The allocator should return null on error only (not if called with nbytes
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * equal to 0; but note that pldhash.c code will never call with 0 nbytes).
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsynctypedef void *
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashAllocTable)(PLDHashTable *table, PRUint32 nbytes);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsynctypedef void
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashFreeTable) (PLDHashTable *table, void *ptr);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * When a table grows or shrinks, each entry is queried for its key using this
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * callback. NB: in that event, entry is not in table any longer; it's in the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * old entryStore vector, which is due to be freed once all entries have been
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * moved via moveEntry callbacks.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsynctypedef const void *
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Compute the hash code for a given key to be looked up, added, or removed
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * from table. A hash code may have any PLDHashNumber value.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashHashKey) (PLDHashTable *table, const void *key);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Compare the key identifying entry in table with the provided key parameter.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Return PR_TRUE if keys match, PR_FALSE otherwise.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashMatchEntry)(PLDHashTable *table,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync const void *key);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Copy the data starting at from to the new entry storage at to. Do not add
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * reference counts for any strong references in the entry, however, as this
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * is a "move" operation: the old entry storage at from will be freed without
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * any reference-decrementing callback shortly.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsynctypedef void
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashMoveEntry)(PLDHashTable *table,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Clear the entry and drop any strong references it holds. This callback is
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * invoked during a PL_DHASH_REMOVE operation (see below for operation codes),
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * but only if the given key is found in the table.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsynctypedef void
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashClearEntry)(PLDHashTable *table,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Called when a table (whether allocated dynamically by itself, or nested in
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * a larger structure, or allocated on the stack) is finished. This callback
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * allows table->ops-specific code to finalize table->data.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsynctypedef void
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashFinalize) (PLDHashTable *table);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Initialize a new entry, apart from keyHash. This function is called when
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * PL_DHashTableOperate's PL_DHASH_ADD case finds no existing entry for the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * given key, and must add a new one. At that point, entry->keyHash is not
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * set yet, to avoid claiming the last free entry in a severely overloaded
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync(* PR_CALLBACK PLDHashInitEntry)(PLDHashTable *table,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync const void *key);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Finally, the "vtable" structure for PLDHashTable. The first eight hooks
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * must be provided by implementations; they're called unconditionally by the
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * generic pldhash.c code. Hooks after these may be null.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Summary of allocation-related hook usage with C++ placement new emphasis:
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * allocTable Allocate raw bytes with malloc, no ctors run.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * freeTable Free raw bytes with free, no dtors run.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * initEntry Call placement new using default key-based ctor.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Return PR_TRUE on success, PR_FALSE on error.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * moveEntry Call placement new using copy ctor, run dtor on old
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * entry storage.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * clearEntry Run dtor on entry.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * finalize Stub unless table->data was initialized and needs to
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * be finalized.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Note the reason why initEntry is optional: the default hooks (stubs) clear
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * entry storage: On successful PL_DHashTableOperate(tbl, key, PL_DHASH_ADD),
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * the returned entry pointer addresses an entry struct whose keyHash member
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * has been set non-zero, but all other entry members are still clear (null).
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * PL_DHASH_ADD callers can test such members to see whether the entry was
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * newly created by the PL_DHASH_ADD call that just succeeded. If placement
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * new or similar initialization is required, define an initEntry hook. Of
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * course, the clearEntry hook must zero or null appropriately.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * XXX assumes 0 is null for pointer types.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync /* Mandatory hooks. All implementations must provide these. */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync /* Optional hooks start here. If null, these are not called. */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Default implementations for the above ops.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_DHashAllocTable(PLDHashTable *table, PRUint32 nbytes);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_DHashStringKey(PLDHashTable *table, const void *key);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync/* A minimal entry contains a keyHash header and a void key pointer. */
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_DHashGetKeyStub(PLDHashTable *table, PLDHashEntryHdr *entry);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_DHashVoidPtrKeyStub(PLDHashTable *table, const void *key);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync const void *key);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync const void *key);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_DHashClearEntryStub(PLDHashTable *table, PLDHashEntryHdr *entry);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_DHashFreeStringKey(PLDHashTable *table, PLDHashEntryHdr *entry);
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * If you use PLDHashEntryStub or a subclass of it as your entry struct, and
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * if your entries move via memcpy and clear via memset(0), you can use these
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * stub operations.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Dynamically allocate a new PLDHashTable using malloc, initialize it using
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * PL_DHashTableInit, and return its address. Return null on malloc failure.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Note that the entry storage at table->entryStore will be allocated using
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * the ops->allocTable callback.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_NewDHashTable(const PLDHashTableOps *ops, void *data, PRUint32 entrySize,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Finalize table's data, free its entry storage (via table->ops->freeTable),
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * and return the memory starting at table to the malloc heap.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Initialize table with ops, data, entrySize, and capacity. Capacity is a
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * guess for the smallest table size at which the table will usually be less
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * than 75% loaded (the table will grow or shrink as needed; capacity serves
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * only to avoid inevitable early growth from PL_DHASH_MIN_SIZE).
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsyncPL_DHashTableInit(PLDHashTable *table, const PLDHashTableOps *ops, void *data,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Set maximum and minimum alpha for table. The defaults are 0.75 and .25.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * maxAlpha must be in [0.5, 0.9375] for the default PL_DHASH_MIN_SIZE; or if
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * MinSize=PL_DHASH_MIN_SIZE <= 256, in [0.5, (float)(MinSize-1)/MinSize]; or
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * else in [0.5, 255.0/256]. minAlpha must be in [0, maxAlpha / 2), so that
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * we don't shrink on the very next remove after growing a table upon adding
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * an entry that brings entryCount past maxAlpha * tableSize.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Call this macro with k, the number of pointer-sized words wasted per entry
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * under chaining, to compute the minimum alpha at which double hashing still
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * beats chaining.
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync ((float)((table)->entrySize / sizeof(void *) - 1) \
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * Finalize table's data, free its entry storage using table->ops->freeTable,
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * and leave its members unchanged from their last live values (which leaves
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * pointers dangling). If you want to burn cycles clearing table, it's up to
4fd606d1f5abe38e1f42c38de1d2e895166bd0f4vboxsync * your code to call memset.
PR_EXTERN(void)
typedef PLDHashOperator
#ifdef PL_DHASHMETER
#include <stdio.h>
PR_EXTERN(void)