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583 lines
24 KiB
C
583 lines
24 KiB
C
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef pldhash_h___
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#define pldhash_h___
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/*
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* Double hashing, a la Knuth 6.
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*/
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#include "mozilla/fallible.h"
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#include "mozilla/MemoryReporting.h"
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#include "mozilla/Types.h"
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#include "nscore.h"
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#if defined(__GNUC__) && defined(__i386__)
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#define PL_DHASH_FASTCALL __attribute__ ((regparm (3),stdcall))
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#elif defined(XP_WIN)
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#define PL_DHASH_FASTCALL __fastcall
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#else
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#define PL_DHASH_FASTCALL
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#endif
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/*
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* Table capacity limit; do not exceed. The max capacity used to be 1<<23 but
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* that occasionally that wasn't enough. Making it much bigger than 1<<26
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* probably isn't worthwhile -- tables that big are kind of ridiculous. Also,
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* the growth operation will (deliberately) fail if |capacity * entrySize|
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* overflows a uint32_t, and entrySize is always at least 8 bytes.
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*/
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#define PL_DHASH_MAX_CAPACITY ((uint32_t)1 << 26)
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#define PL_DHASH_MIN_CAPACITY 16
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/*
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* Making this half of the max capacity ensures it'll fit. Nobody should need
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* an initial length anywhere nearly this large, anyway.
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*/
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#define PL_DHASH_MAX_INITIAL_LENGTH (PL_DHASH_MAX_CAPACITY / 2)
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/* This gives a default initial capacity of 16. */
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#define PL_DHASH_DEFAULT_INITIAL_LENGTH 8
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/*
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* Multiplicative hash uses an unsigned 32 bit integer and the golden ratio,
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* expressed as a fixed-point 32-bit fraction.
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*/
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#define PL_DHASH_BITS 32
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#define PL_DHASH_GOLDEN_RATIO 0x9E3779B9U
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/* Primitive and forward-struct typedefs. */
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typedef uint32_t PLDHashNumber;
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typedef struct PLDHashEntryHdr PLDHashEntryHdr;
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typedef struct PLDHashEntryStub PLDHashEntryStub;
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typedef struct PLDHashTable PLDHashTable;
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typedef struct PLDHashTableOps PLDHashTableOps;
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/*
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* Table entry header structure.
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*
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* In order to allow in-line allocation of key and value, we do not declare
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* either here. Instead, the API uses const void *key as a formal parameter.
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* The key need not be stored in the entry; it may be part of the value, but
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* need not be stored at all.
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*
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* Callback types are defined below and grouped into the PLDHashTableOps
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* structure, for single static initialization per hash table sub-type.
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*
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* Each hash table sub-type should nest the PLDHashEntryHdr structure at the
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* front of its particular entry type. The keyHash member contains the result
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* of multiplying the hash code returned from the hashKey callback (see below)
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* by PL_DHASH_GOLDEN_RATIO, then constraining the result to avoid the magic 0
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* and 1 values. The stored keyHash value is table size invariant, and it is
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* maintained automatically by PL_DHashTableOperate -- users should never set
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* it, and its only uses should be via the entry macros below.
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*
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* The PL_DHASH_ENTRY_IS_LIVE function tests whether entry is neither free nor
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* removed. An entry may be either busy or free; if busy, it may be live or
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* removed. Consumers of this API should not access members of entries that
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* are not live.
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*
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* However, use PL_DHASH_ENTRY_IS_BUSY for faster liveness testing of entries
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* returned by PL_DHashTableOperate, as PL_DHashTableOperate never returns a
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* non-live, busy (i.e., removed) entry pointer to its caller. See below for
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* more details on PL_DHashTableOperate's calling rules.
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*/
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struct PLDHashEntryHdr
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{
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PLDHashNumber keyHash; /* every entry must begin like this */
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};
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MOZ_ALWAYS_INLINE bool
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PL_DHASH_ENTRY_IS_FREE(PLDHashEntryHdr* aEntry)
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{
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return aEntry->keyHash == 0;
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}
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MOZ_ALWAYS_INLINE bool
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PL_DHASH_ENTRY_IS_BUSY(PLDHashEntryHdr* aEntry)
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{
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return !PL_DHASH_ENTRY_IS_FREE(aEntry);
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}
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MOZ_ALWAYS_INLINE bool
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PL_DHASH_ENTRY_IS_LIVE(PLDHashEntryHdr* aEntry)
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{
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return aEntry->keyHash >= 2;
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}
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/*
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* A PLDHashTable is currently 8 words (without the PL_DHASHMETER overhead)
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* on most architectures, and may be allocated on the stack or within another
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* structure or class (see below for the Init and Finish functions to use).
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*
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* To decide whether to use double hashing vs. chaining, we need to develop a
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* trade-off relation, as follows:
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*
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* Let alpha be the load factor, esize the entry size in words, count the
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* entry count, and pow2 the power-of-two table size in entries.
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*
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* (PLDHashTable overhead) > (PLHashTable overhead)
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* (unused table entry space) > (malloc and .next overhead per entry) +
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* (buckets overhead)
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* (1 - alpha) * esize * pow2 > 2 * count + pow2
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*
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* Notice that alpha is by definition (count / pow2):
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*
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* (1 - alpha) * esize * pow2 > 2 * alpha * pow2 + pow2
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* (1 - alpha) * esize > 2 * alpha + 1
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*
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* esize > (1 + 2 * alpha) / (1 - alpha)
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*
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* This assumes both tables must keep keyHash, key, and value for each entry,
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* where key and value point to separately allocated strings or structures.
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* If key and value can be combined into one pointer, then the trade-off is:
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*
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* esize > (1 + 3 * alpha) / (1 - alpha)
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*
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* If the entry value can be a subtype of PLDHashEntryHdr, rather than a type
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* that must be allocated separately and referenced by an entry.value pointer
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* member, and provided key's allocation can be fused with its entry's, then
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* k (the words wasted per entry with chaining) is 4.
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*
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* To see these curves, feed gnuplot input like so:
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*
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* gnuplot> f(x,k) = (1 + k * x) / (1 - x)
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* gnuplot> plot [0:.75] f(x,2), f(x,3), f(x,4)
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*
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* For k of 2 and a well-loaded table (alpha > .5), esize must be more than 4
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* words for chaining to be more space-efficient than double hashing.
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*
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* Solving for alpha helps us decide when to shrink an underloaded table:
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*
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* esize > (1 + k * alpha) / (1 - alpha)
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* esize - alpha * esize > 1 + k * alpha
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* esize - 1 > (k + esize) * alpha
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* (esize - 1) / (k + esize) > alpha
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*
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* alpha < (esize - 1) / (esize + k)
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*
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* Therefore double hashing should keep alpha >= (esize - 1) / (esize + k),
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* assuming esize is not too large (in which case, chaining should probably be
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* used for any alpha). For esize=2 and k=3, we want alpha >= .2; for esize=3
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* and k=2, we want alpha >= .4. For k=4, esize could be 6, and alpha >= .5
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* would still obtain.
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*
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* The current implementation uses a lower bound of 0.25 for alpha when
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* deciding whether to shrink the table (while still respecting
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* PL_DHASH_MIN_CAPACITY).
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*
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* Note a qualitative difference between chaining and double hashing: under
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* chaining, entry addresses are stable across table shrinks and grows. With
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* double hashing, you can't safely hold an entry pointer and use it after an
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* ADD or REMOVE operation, unless you sample aTable->generation before adding
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* or removing, and compare the sample after, dereferencing the entry pointer
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* only if aTable->generation has not changed.
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*
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* The moral of this story: there is no one-size-fits-all hash table scheme,
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* but for small table entry size, and assuming entry address stability is not
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* required, double hashing wins.
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*/
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struct PLDHashTable
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{
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const PLDHashTableOps* ops; /* virtual operations, see below */
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void* data; /* ops- and instance-specific data */
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int16_t hashShift; /* multiplicative hash shift */
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/*
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* |recursionLevel| is only used in debug builds, but is present in opt
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* builds to avoid binary compatibility problems when mixing DEBUG and
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* non-DEBUG components. (Actually, even if it were removed,
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* sizeof(PLDHashTable) wouldn't change, due to struct padding.)
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*/
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uint16_t recursionLevel; /* used to detect unsafe re-entry */
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uint32_t entrySize; /* number of bytes in an entry */
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uint32_t entryCount; /* number of entries in table */
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uint32_t removedCount; /* removed entry sentinels in table */
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uint32_t generation; /* entry storage generation number */
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char* entryStore; /* entry storage */
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#ifdef PL_DHASHMETER
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struct PLDHashStats
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{
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uint32_t searches; /* total number of table searches */
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uint32_t steps; /* hash chain links traversed */
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uint32_t hits; /* searches that found key */
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uint32_t misses; /* searches that didn't find key */
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uint32_t lookups; /* number of PL_DHASH_LOOKUPs */
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uint32_t addMisses; /* adds that miss, and do work */
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uint32_t addOverRemoved; /* adds that recycled a removed entry */
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uint32_t addHits; /* adds that hit an existing entry */
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uint32_t addFailures; /* out-of-memory during add growth */
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uint32_t removeHits; /* removes that hit, and do work */
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uint32_t removeMisses; /* useless removes that miss */
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uint32_t removeFrees; /* removes that freed entry directly */
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uint32_t removeEnums; /* removes done by Enumerate */
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uint32_t grows; /* table expansions */
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uint32_t shrinks; /* table contractions */
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uint32_t compresses; /* table compressions */
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uint32_t enumShrinks; /* contractions after Enumerate */
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} stats;
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#endif
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};
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/*
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* Size in entries (gross, not net of free and removed sentinels) for table.
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* We store hashShift rather than sizeLog2 to optimize the collision-free case
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* in SearchTable.
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*/
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#define PL_DHASH_TABLE_CAPACITY(table) \
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((uint32_t)1 << (PL_DHASH_BITS - (table)->hashShift))
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/*
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* Table space at entryStore is allocated and freed using these callbacks.
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* The allocator should return null on error only (not if called with aNBytes
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* equal to 0; but note that pldhash.c code will never call with 0 aNBytes).
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*/
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typedef void* (*PLDHashAllocTable)(PLDHashTable* aTable, uint32_t aNBytes);
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typedef void (*PLDHashFreeTable)(PLDHashTable* aTable, void* aPtr);
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/*
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* Compute the hash code for a given key to be looked up, added, or removed
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* from aTable. A hash code may have any PLDHashNumber value.
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*/
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typedef PLDHashNumber (*PLDHashHashKey)(PLDHashTable* aTable,
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const void* aKey);
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/*
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* Compare the key identifying aEntry in aTable with the provided key parameter.
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* Return true if keys match, false otherwise.
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*/
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typedef bool (*PLDHashMatchEntry)(PLDHashTable* aTable,
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const PLDHashEntryHdr* aEntry,
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const void* aKey);
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/*
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* Copy the data starting at aFrom to the new entry storage at aTo. Do not add
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* reference counts for any strong references in the entry, however, as this
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* is a "move" operation: the old entry storage at from will be freed without
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* any reference-decrementing callback shortly.
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*/
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typedef void (*PLDHashMoveEntry)(PLDHashTable* aTable,
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const PLDHashEntryHdr* aFrom,
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PLDHashEntryHdr* aTo);
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/*
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* Clear the entry and drop any strong references it holds. This callback is
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* invoked during a PL_DHASH_REMOVE operation (see below for operation codes),
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* but only if the given key is found in the table.
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*/
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typedef void (*PLDHashClearEntry)(PLDHashTable* aTable,
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PLDHashEntryHdr* aEntry);
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/*
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* Called when a table (whether allocated dynamically by itself, or nested in
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* a larger structure, or allocated on the stack) is finished. This callback
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* allows aTable->ops-specific code to finalize aTable->data.
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*/
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typedef void (*PLDHashFinalize)(PLDHashTable* aTable);
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/*
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* Initialize a new entry, apart from keyHash. This function is called when
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* PL_DHashTableOperate's PL_DHASH_ADD case finds no existing entry for the
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* given key, and must add a new one. At that point, aEntry->keyHash is not
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* set yet, to avoid claiming the last free entry in a severely overloaded
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* table.
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*/
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typedef bool (*PLDHashInitEntry)(PLDHashTable* aTable, PLDHashEntryHdr* aEntry,
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const void* aKey);
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/*
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* Finally, the "vtable" structure for PLDHashTable. The first eight hooks
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* must be provided by implementations; they're called unconditionally by the
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* generic pldhash.c code. Hooks after these may be null.
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*
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* Summary of allocation-related hook usage with C++ placement new emphasis:
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* allocTable Allocate raw bytes with malloc, no ctors run.
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* freeTable Free raw bytes with free, no dtors run.
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* initEntry Call placement new using default key-based ctor.
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* Return true on success, false on error.
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* moveEntry Call placement new using copy ctor, run dtor on old
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* entry storage.
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* clearEntry Run dtor on entry.
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* finalize Stub unless aTable->data was initialized and needs to
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* be finalized.
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*
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* Note the reason why initEntry is optional: the default hooks (stubs) clear
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* entry storage: On successful PL_DHashTableOperate(tbl, key, PL_DHASH_ADD),
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* the returned entry pointer addresses an entry struct whose keyHash member
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* has been set non-zero, but all other entry members are still clear (null).
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* PL_DHASH_ADD callers can test such members to see whether the entry was
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* newly created by the PL_DHASH_ADD call that just succeeded. If placement
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* new or similar initialization is required, define an initEntry hook. Of
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* course, the clearEntry hook must zero or null appropriately.
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*
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* XXX assumes 0 is null for pointer types.
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*/
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struct PLDHashTableOps
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{
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/* Mandatory hooks. All implementations must provide these. */
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PLDHashAllocTable allocTable;
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PLDHashFreeTable freeTable;
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PLDHashHashKey hashKey;
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PLDHashMatchEntry matchEntry;
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PLDHashMoveEntry moveEntry;
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PLDHashClearEntry clearEntry;
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PLDHashFinalize finalize;
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/* Optional hooks start here. If null, these are not called. */
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PLDHashInitEntry initEntry;
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};
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/*
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* Default implementations for the above ops.
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*/
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NS_COM_GLUE void* PL_DHashAllocTable(PLDHashTable* aTable, uint32_t aNBytes);
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NS_COM_GLUE void PL_DHashFreeTable(PLDHashTable* aTable, void* aPtr);
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NS_COM_GLUE PLDHashNumber PL_DHashStringKey(PLDHashTable* aTable,
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const void* aKey);
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/* A minimal entry contains a keyHash header and a void key pointer. */
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struct PLDHashEntryStub
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{
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PLDHashEntryHdr hdr;
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const void* key;
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};
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NS_COM_GLUE PLDHashNumber PL_DHashVoidPtrKeyStub(PLDHashTable* aTable,
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const void* aKey);
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NS_COM_GLUE bool PL_DHashMatchEntryStub(PLDHashTable* aTable,
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const PLDHashEntryHdr* aEntry,
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const void* aKey);
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NS_COM_GLUE bool PL_DHashMatchStringKey(PLDHashTable* aTable,
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const PLDHashEntryHdr* aEntry,
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const void* aKey);
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NS_COM_GLUE void
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PL_DHashMoveEntryStub(PLDHashTable* aTable,
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const PLDHashEntryHdr* aFrom,
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PLDHashEntryHdr* aTo);
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NS_COM_GLUE void PL_DHashClearEntryStub(PLDHashTable* aTable,
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PLDHashEntryHdr* aEntry);
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NS_COM_GLUE void PL_DHashFreeStringKey(PLDHashTable* aTable,
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PLDHashEntryHdr* aEntry);
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NS_COM_GLUE void PL_DHashFinalizeStub(PLDHashTable* aTable);
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/*
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* If you use PLDHashEntryStub or a subclass of it as your entry struct, and
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* if your entries move via memcpy and clear via memset(0), you can use these
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* stub operations.
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*/
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NS_COM_GLUE const PLDHashTableOps* PL_DHashGetStubOps(void);
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/*
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* Dynamically allocate a new PLDHashTable using malloc, initialize it using
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* PL_DHashTableInit, and return its address. Return null on malloc failure.
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* Note that the entry storage at aTable->entryStore will be allocated using
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* the aOps->allocTable callback.
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*/
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NS_COM_GLUE PLDHashTable* PL_NewDHashTable(
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const PLDHashTableOps* aOps, void* aData, uint32_t aEntrySize,
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uint32_t aLength = PL_DHASH_DEFAULT_INITIAL_LENGTH);
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/*
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* Finalize aTable's data, free its entry storage (via aTable->ops->freeTable),
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* and return the memory starting at aTable to the malloc heap.
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*/
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NS_COM_GLUE void PL_DHashTableDestroy(PLDHashTable* aTable);
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/*
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* Initialize aTable with aOps, aData, aEntrySize, and aCapacity. The table's
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* initial capacity will be chosen such that |aLength| elements can be inserted
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* without rehashing. If |aLength| is a power-of-two, this capacity will be
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* |2*length|.
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*
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* This function will crash if it can't allocate enough memory, or if
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* |aEntrySize| and/or |aLength| are too large.
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*/
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NS_COM_GLUE void PL_DHashTableInit(
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PLDHashTable* aTable, const PLDHashTableOps* aOps, void* aData,
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uint32_t aEntrySize, uint32_t aLength = PL_DHASH_DEFAULT_INITIAL_LENGTH);
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/*
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* Initialize aTable. This is the same as PL_DHashTableInit, except that it
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* returns a boolean indicating success, rather than crashing on failure.
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*/
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MOZ_WARN_UNUSED_RESULT NS_COM_GLUE bool PL_DHashTableInit(
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PLDHashTable* aTable, const PLDHashTableOps* aOps, void* aData,
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uint32_t aEntrySize, const mozilla::fallible_t&,
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uint32_t aLength = PL_DHASH_DEFAULT_INITIAL_LENGTH);
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/*
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* Finalize aTable's data, free its entry storage using aTable->ops->freeTable,
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* and leave its members unchanged from their last live values (which leaves
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* pointers dangling). If you want to burn cycles clearing aTable, it's up to
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* your code to call memset.
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*/
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NS_COM_GLUE void PL_DHashTableFinish(PLDHashTable* aTable);
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/*
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* To consolidate keyHash computation and table grow/shrink code, we use a
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* single entry point for lookup, add, and remove operations. The operation
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* codes are declared here, along with codes returned by PLDHashEnumerator
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* functions, which control PL_DHashTableEnumerate's behavior.
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*/
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typedef enum PLDHashOperator
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{
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PL_DHASH_LOOKUP = 0, /* lookup entry */
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PL_DHASH_ADD = 1, /* add entry */
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PL_DHASH_REMOVE = 2, /* remove entry, or enumerator says remove */
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PL_DHASH_NEXT = 0, /* enumerator says continue */
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PL_DHASH_STOP = 1 /* enumerator says stop */
|
|
} PLDHashOperator;
|
|
|
|
/*
|
|
* To lookup a key in table, call:
|
|
*
|
|
* entry = PL_DHashTableOperate(table, key, PL_DHASH_LOOKUP);
|
|
*
|
|
* If PL_DHASH_ENTRY_IS_BUSY(entry) is true, key was found and it identifies
|
|
* entry. If PL_DHASH_ENTRY_IS_FREE(entry) is true, key was not found.
|
|
*
|
|
* To add an entry identified by key to table, call:
|
|
*
|
|
* entry = PL_DHashTableOperate(table, key, PL_DHASH_ADD);
|
|
*
|
|
* If entry is null upon return, then either the table is severely overloaded,
|
|
* and memory can't be allocated for entry storage via aTable->ops->allocTable;
|
|
* Or if aTable->ops->initEntry is non-null, the aTable->ops->initEntry op may
|
|
* have returned false.
|
|
*
|
|
* Otherwise, aEntry->keyHash has been set so that PL_DHASH_ENTRY_IS_BUSY(entry)
|
|
* is true, and it is up to the caller to initialize the key and value parts
|
|
* of the entry sub-type, if they have not been set already (i.e. if entry was
|
|
* not already in the table, and if the optional initEntry hook was not used).
|
|
*
|
|
* To remove an entry identified by key from table, call:
|
|
*
|
|
* (void) PL_DHashTableOperate(table, key, PL_DHASH_REMOVE);
|
|
*
|
|
* If key's entry is found, it is cleared (via table->ops->clearEntry) and
|
|
* the entry is marked so that PL_DHASH_ENTRY_IS_FREE(entry). This operation
|
|
* returns null unconditionally; you should ignore its return value.
|
|
*/
|
|
NS_COM_GLUE PLDHashEntryHdr* PL_DHASH_FASTCALL
|
|
PL_DHashTableOperate(PLDHashTable* aTable, const void* aKey,
|
|
PLDHashOperator aOp);
|
|
|
|
/*
|
|
* Remove an entry already accessed via LOOKUP or ADD.
|
|
*
|
|
* NB: this is a "raw" or low-level routine, intended to be used only where
|
|
* the inefficiency of a full PL_DHashTableOperate (which rehashes in order
|
|
* to find the entry given its key) is not tolerable. This function does not
|
|
* shrink the table if it is underloaded. It does not update stats #ifdef
|
|
* PL_DHASHMETER, either.
|
|
*/
|
|
NS_COM_GLUE void PL_DHashTableRawRemove(PLDHashTable* aTable,
|
|
PLDHashEntryHdr* aEntry);
|
|
|
|
/*
|
|
* Enumerate entries in table using etor:
|
|
*
|
|
* count = PL_DHashTableEnumerate(table, etor, arg);
|
|
*
|
|
* PL_DHashTableEnumerate calls etor like so:
|
|
*
|
|
* op = etor(table, entry, number, arg);
|
|
*
|
|
* where number is a zero-based ordinal assigned to live entries according to
|
|
* their order in aTable->entryStore.
|
|
*
|
|
* The return value, op, is treated as a set of flags. If op is PL_DHASH_NEXT,
|
|
* then continue enumerating. If op contains PL_DHASH_REMOVE, then clear (via
|
|
* aTable->ops->clearEntry) and free entry. Then we check whether op contains
|
|
* PL_DHASH_STOP; if so, stop enumerating and return the number of live entries
|
|
* that were enumerated so far. Return the total number of live entries when
|
|
* enumeration completes normally.
|
|
*
|
|
* If etor calls PL_DHashTableOperate on table with op != PL_DHASH_LOOKUP, it
|
|
* must return PL_DHASH_STOP; otherwise undefined behavior results.
|
|
*
|
|
* If any enumerator returns PL_DHASH_REMOVE, aTable->entryStore may be shrunk
|
|
* or compressed after enumeration, but before PL_DHashTableEnumerate returns.
|
|
* Such an enumerator therefore can't safely set aside entry pointers, but an
|
|
* enumerator that never returns PL_DHASH_REMOVE can set pointers to entries
|
|
* aside, e.g., to avoid copying live entries into an array of the entry type.
|
|
* Copying entry pointers is cheaper, and safe so long as the caller of such a
|
|
* "stable" Enumerate doesn't use the set-aside pointers after any call either
|
|
* to PL_DHashTableOperate, or to an "unstable" form of Enumerate, which might
|
|
* grow or shrink entryStore.
|
|
*
|
|
* If your enumerator wants to remove certain entries, but set aside pointers
|
|
* to other entries that it retains, it can use PL_DHashTableRawRemove on the
|
|
* entries to be removed, returning PL_DHASH_NEXT to skip them. Likewise, if
|
|
* you want to remove entries, but for some reason you do not want entryStore
|
|
* to be shrunk or compressed, you can call PL_DHashTableRawRemove safely on
|
|
* the entry being enumerated, rather than returning PL_DHASH_REMOVE.
|
|
*/
|
|
typedef PLDHashOperator (*PLDHashEnumerator)(PLDHashTable* aTable,
|
|
PLDHashEntryHdr* aHdr,
|
|
uint32_t aNumber, void* aArg);
|
|
|
|
NS_COM_GLUE uint32_t
|
|
PL_DHashTableEnumerate(PLDHashTable* aTable, PLDHashEnumerator aEtor,
|
|
void* aArg);
|
|
|
|
typedef size_t (*PLDHashSizeOfEntryExcludingThisFun)(
|
|
PLDHashEntryHdr* aHdr, mozilla::MallocSizeOf aMallocSizeOf, void* aArg);
|
|
|
|
/**
|
|
* Measure the size of the table's entry storage, and if
|
|
* |aSizeOfEntryExcludingThis| is non-nullptr, measure the size of things
|
|
* pointed to by entries. Doesn't measure |ops| because it's often shared
|
|
* between tables, nor |data| because it's opaque.
|
|
*/
|
|
NS_COM_GLUE size_t PL_DHashTableSizeOfExcludingThis(
|
|
const PLDHashTable* aTable,
|
|
PLDHashSizeOfEntryExcludingThisFun aSizeOfEntryExcludingThis,
|
|
mozilla::MallocSizeOf aMallocSizeOf, void* aArg = nullptr);
|
|
|
|
/**
|
|
* Like PL_DHashTableSizeOfExcludingThis, but includes sizeof(*this).
|
|
*/
|
|
NS_COM_GLUE size_t PL_DHashTableSizeOfIncludingThis(
|
|
const PLDHashTable* aTable,
|
|
PLDHashSizeOfEntryExcludingThisFun aSizeOfEntryExcludingThis,
|
|
mozilla::MallocSizeOf aMallocSizeOf, void* aArg = nullptr);
|
|
|
|
#ifdef DEBUG
|
|
/**
|
|
* Mark a table as immutable for the remainder of its lifetime. This
|
|
* changes the implementation from ASSERTing one set of invariants to
|
|
* ASSERTing a different set.
|
|
*
|
|
* When a table is NOT marked as immutable, the table implementation
|
|
* asserts that the table is not mutated from its own callbacks. It
|
|
* assumes the caller protects the table from being accessed on multiple
|
|
* threads simultaneously.
|
|
*
|
|
* When the table is marked as immutable, the re-entry assertions will
|
|
* no longer trigger erroneously due to multi-threaded access. Instead,
|
|
* mutations will cause assertions.
|
|
*/
|
|
NS_COM_GLUE void PL_DHashMarkTableImmutable(PLDHashTable* aTable);
|
|
#endif
|
|
|
|
#ifdef PL_DHASHMETER
|
|
#include <stdio.h>
|
|
|
|
NS_COM_GLUE void PL_DHashTableDumpMeter(PLDHashTable* aTable,
|
|
PLDHashEnumerator aDump, FILE* aFp);
|
|
#endif
|
|
|
|
#endif /* pldhash_h___ */
|