From f215e02bf85f68d3a6106c2a1f4f7f063f819064 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:17:27 +0200 Subject: Adding upstream version 7.0.14-dfsg. Signed-off-by: Daniel Baumann --- src/libs/xpcom18a4/xpcom/ds/pldhash.h | 603 ++++++++++++++++++++++++++++++++++ 1 file changed, 603 insertions(+) create mode 100644 src/libs/xpcom18a4/xpcom/ds/pldhash.h (limited to 'src/libs/xpcom18a4/xpcom/ds/pldhash.h') diff --git a/src/libs/xpcom18a4/xpcom/ds/pldhash.h b/src/libs/xpcom18a4/xpcom/ds/pldhash.h new file mode 100644 index 00000000..8c4347c0 --- /dev/null +++ b/src/libs/xpcom18a4/xpcom/ds/pldhash.h @@ -0,0 +1,603 @@ +/* -*- 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) + * + * 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 ***** */ + +#ifndef pldhash_h___ +#define pldhash_h___ +/* + * Double hashing, a la Knuth 6. + * GENERATED BY js/src/plify_jsdhash.sed -- DO NOT EDIT!!! + */ +#include "prtypes.h" + +#ifdef VBOX_WITH_XPCOM_NAMESPACE_CLEANUP +#define PL_DHashTableInit VBoxNsplPL_DHashTableInit +#define PL_DHashTableFinish VBoxNsplPL_DHashTableFinish +#define PL_DHashTableOperate VBoxNsplPL_DHashTableOperate +#define PL_DHashTableEnumerate VBoxNsplPL_DHashTableEnumerate +#define PL_DHashAllocTable VBoxNsplPL_DHashAllocTable +#define PL_DHashFreeTable VBoxNsplPL_DHashFreeTable +#define PL_DHashMoveEntryStub VBoxNsplPL_DHashMoveEntryStub +#define PL_DHashFinalizeStub VBoxNsplPL_DHashFinalizeStub +#define PL_DHashClearEntryStub VBoxNsplPL_DHashClearEntryStub +#define PL_DHashFreeStringKey VBoxNsplPL_DHashFreeStringKey +#define PL_DHashGetKeyStub VBoxNsplPL_DHashGetKeyStub +#define PL_DHashGetStubOps VBoxNsplPL_DHashGetStubOps +#define PL_DHashMatchEntryStub VBoxNsplPL_DHashMatchEntryStub +#define PL_DHashMatchStringKey VBoxNsplPL_DHashMatchStringKey +#define PL_DHashStringKey VBoxNsplPL_DHashStringKey +#define PL_DHashTableDestroy VBoxNsplPL_DHashTableDestroy +#define PL_DHashTableRawRemove VBoxNsplPL_DHashTableRawRemove +#define PL_DHashTableSetAlphaBounds VBoxNsplPL_DHashTableSetAlphaBounds +#define PL_DHashVoidPtrKeyStub VBoxNsplPL_DHashVoidPtrKeyStub +#define PL_NewDHashTable VBoxNsplPL_NewDHashTable +#endif /* VBOX_WITH_XPCOM_NAMESPACE_CLEANUP */ + +PR_BEGIN_EXTERN_C + +#ifdef DEBUG_XXXbrendan +#define PL_DHASHMETER 1 +#endif + +#if defined(__GNUC__) && defined(__i386__) && (__GNUC__ >= 3) && !defined(XP_OS2) +#define PL_DHASH_FASTCALL __attribute__ ((regparm (3),stdcall)) +#else +#define PL_DHASH_FASTCALL +#endif + +/* Table size limit, do not equal or exceed (see min&maxAlphaFrac, below). */ +#undef PL_DHASH_SIZE_LIMIT +#define PL_DHASH_SIZE_LIMIT PR_BIT(24) + +/* Minimum table size, or gross entry count (net is at most .75 loaded). */ +#ifndef PL_DHASH_MIN_SIZE +#define PL_DHASH_MIN_SIZE 16 +#elif (PL_DHASH_MIN_SIZE & (PL_DHASH_MIN_SIZE - 1)) != 0 +#error "PL_DHASH_MIN_SIZE must be a power of two!" +#endif + +/* + * Multiplicative hash uses an unsigned 32 bit integer and the golden ratio, + * expressed as a fixed-point 32-bit fraction. + */ +#define PL_DHASH_BITS 32 +#define PL_DHASH_GOLDEN_RATIO 0x9E3779B9U + +/* Primitive and forward-struct typedefs. */ +typedef PRUint32 PLDHashNumber; +typedef struct PLDHashEntryHdr PLDHashEntryHdr; +typedef struct PLDHashEntryStub PLDHashEntryStub; +typedef struct PLDHashTable PLDHashTable; +typedef struct PLDHashTableOps PLDHashTableOps; + +/* + * Table entry header structure. + * + * In order to allow in-line allocation of key and value, we do not declare + * either here. Instead, the API uses const void *key as a formal parameter, + * and asks each entry for its key when necessary via a getKey callback, used + * when growing or shrinking the table. Other callback types are defined + * below and grouped into the PLDHashTableOps structure, for single static + * initialization per hash table sub-type. + * + * Each hash table sub-type should nest the PLDHashEntryHdr structure at the + * front of its particular entry type. The keyHash member contains the result + * of multiplying the hash code returned from the hashKey callback (see below) + * by PL_DHASH_GOLDEN_RATIO, then constraining the result to avoid the magic 0 + * and 1 values. The stored keyHash value is table size invariant, and it is + * maintained automatically by PL_DHashTableOperate -- users should never set + * it, and its only uses should be via the entry macros below. + * + * The PL_DHASH_ENTRY_IS_LIVE macro tests whether entry is neither free nor + * removed. An entry may be either busy or free; if busy, it may be live or + * removed. Consumers of this API should not access members of entries that + * are not live. + * + * However, use PL_DHASH_ENTRY_IS_BUSY for faster liveness testing of entries + * returned by PL_DHashTableOperate, as PL_DHashTableOperate never returns a + * non-live, busy (i.e., removed) entry pointer to its caller. See below for + * more details on PL_DHashTableOperate's calling rules. + */ +struct PLDHashEntryHdr { + PLDHashNumber keyHash; /* every entry must begin like this */ +}; + +#define PL_DHASH_ENTRY_IS_FREE(entry) ((entry)->keyHash == 0) +#define PL_DHASH_ENTRY_IS_BUSY(entry) (!PL_DHASH_ENTRY_IS_FREE(entry)) +#define PL_DHASH_ENTRY_IS_LIVE(entry) ((entry)->keyHash >= 2) + +/* + * A PLDHashTable is currently 8 words (without the PL_DHASHMETER overhead) + * on most architectures, and may be allocated on the stack or within another + * structure or class (see below for the Init and Finish functions to use). + * + * To decide whether to use double hashing vs. chaining, we need to develop a + * trade-off relation, as follows: + * + * Let alpha be the load factor, esize the entry size in words, count the + * entry count, and pow2 the power-of-two table size in entries. + * + * (PLDHashTable overhead) > (PLHashTable overhead) + * (unused table entry space) > (malloc and .next overhead per entry) + + * (buckets overhead) + * (1 - alpha) * esize * pow2 > 2 * count + pow2 + * + * Notice that alpha is by definition (count / pow2): + * + * (1 - alpha) * esize * pow2 > 2 * alpha * pow2 + pow2 + * (1 - alpha) * esize > 2 * alpha + 1 + * + * esize > (1 + 2 * alpha) / (1 - alpha) + * + * This assumes both tables must keep keyHash, key, and value for each entry, + * where key and value point to separately allocated strings or structures. + * If key and value can be combined into one pointer, then the trade-off is: + * + * esize > (1 + 3 * alpha) / (1 - alpha) + * + * If the entry value can be a subtype of PLDHashEntryHdr, rather than a type + * that must be allocated separately and referenced by an entry.value pointer + * member, and provided key's allocation can be fused with its entry's, then + * k (the words wasted per entry with chaining) is 4. + * + * To see these curves, feed gnuplot input like so: + * + * gnuplot> f(x,k) = (1 + k * x) / (1 - x) + * gnuplot> plot [0:.75] f(x,2), f(x,3), f(x,4) + * + * For k of 2 and a well-loaded table (alpha > .5), esize must be more than 4 + * words for chaining to be more space-efficient than double hashing. + * + * Solving for alpha helps us decide when to shrink an underloaded table: + * + * esize > (1 + k * alpha) / (1 - alpha) + * esize - alpha * esize > 1 + k * alpha + * esize - 1 > (k + esize) * alpha + * (esize - 1) / (k + esize) > alpha + * + * alpha < (esize - 1) / (esize + k) + * + * Therefore double hashing should keep alpha >= (esize - 1) / (esize + k), + * assuming esize is not too large (in which case, chaining should probably be + * used for any alpha). For esize=2 and k=3, we want alpha >= .2; for esize=3 + * and k=2, we want alpha >= .4. For k=4, esize could be 6, and alpha >= .5 + * would still obtain. See the PL_DHASH_MIN_ALPHA macro further below. + * + * The current implementation uses a configurable lower bound on alpha, which + * defaults to .25, when deciding to shrink the table (while still respecting + * PL_DHASH_MIN_SIZE). + * + * Note a qualitative difference between chaining and double hashing: under + * chaining, entry addresses are stable across table shrinks and grows. With + * double hashing, you can't safely hold an entry pointer and use it after an + * ADD or REMOVE operation, unless you sample table->generation before adding + * or removing, and compare the sample after, dereferencing the entry pointer + * only if table->generation has not changed. + * + * The moral of this story: there is no one-size-fits-all hash table scheme, + * but for small table entry size, and assuming entry address stability is not + * required, double hashing wins. + */ +struct PLDHashTable { + const PLDHashTableOps *ops; /* virtual operations, see below */ + void *data; /* ops- and instance-specific data */ + PRInt16 hashShift; /* multiplicative hash shift */ + uint8 maxAlphaFrac; /* 8-bit fixed point max alpha */ + uint8 minAlphaFrac; /* 8-bit fixed point min alpha */ + PRUint32 entrySize; /* number of bytes in an entry */ + PRUint32 entryCount; /* number of entries in table */ + PRUint32 removedCount; /* removed entry sentinels in table */ + PRUint32 generation; /* entry storage generation number */ + char *entryStore; /* entry storage */ +#ifdef PL_DHASHMETER + struct PLDHashStats { + PRUint32 searches; /* total number of table searches */ + PRUint32 steps; /* hash chain links traversed */ + PRUint32 hits; /* searches that found key */ + PRUint32 misses; /* searches that didn't find key */ + PRUint32 lookups; /* number of PL_DHASH_LOOKUPs */ + PRUint32 addMisses; /* adds that miss, and do work */ + PRUint32 addOverRemoved; /* adds that recycled a removed entry */ + PRUint32 addHits; /* adds that hit an existing entry */ + PRUint32 addFailures; /* out-of-memory during add growth */ + PRUint32 removeHits; /* removes that hit, and do work */ + PRUint32 removeMisses; /* useless removes that miss */ + PRUint32 removeFrees; /* removes that freed entry directly */ + PRUint32 removeEnums; /* removes done by Enumerate */ + PRUint32 grows; /* table expansions */ + PRUint32 shrinks; /* table contractions */ + PRUint32 compresses; /* table compressions */ + PRUint32 enumShrinks; /* contractions after Enumerate */ + } stats; +#endif +}; + +/* + * Size in entries (gross, not net of free and removed sentinels) for table. + * We store hashShift rather than sizeLog2 to optimize the collision-free case + * in SearchTable. + */ +#define PL_DHASH_TABLE_SIZE(table) PR_BIT(PL_DHASH_BITS - (table)->hashShift) + +/* + * Table space at entryStore is allocated and freed using these callbacks. + * The allocator should return null on error only (not if called with nbytes + * equal to 0; but note that pldhash.c code will never call with 0 nbytes). + */ +typedef void * +(* PR_CALLBACK PLDHashAllocTable)(PLDHashTable *table, PRUint32 nbytes); + +typedef void +(* PR_CALLBACK PLDHashFreeTable) (PLDHashTable *table, void *ptr); + +/* + * When a table grows or shrinks, each entry is queried for its key using this + * callback. NB: in that event, entry is not in table any longer; it's in the + * old entryStore vector, which is due to be freed once all entries have been + * moved via moveEntry callbacks. + */ +typedef const void * +(* PR_CALLBACK PLDHashGetKey) (PLDHashTable *table, + PLDHashEntryHdr *entry); + +/* + * Compute the hash code for a given key to be looked up, added, or removed + * from table. A hash code may have any PLDHashNumber value. + */ +typedef PLDHashNumber +(* PR_CALLBACK PLDHashHashKey) (PLDHashTable *table, const void *key); + +/* + * Compare the key identifying entry in table with the provided key parameter. + * Return PR_TRUE if keys match, PR_FALSE otherwise. + */ +typedef PRBool +(* PR_CALLBACK PLDHashMatchEntry)(PLDHashTable *table, + const PLDHashEntryHdr *entry, + const void *key); + +/* + * Copy the data starting at from to the new entry storage at to. Do not add + * reference counts for any strong references in the entry, however, as this + * is a "move" operation: the old entry storage at from will be freed without + * any reference-decrementing callback shortly. + */ +typedef void +(* PR_CALLBACK PLDHashMoveEntry)(PLDHashTable *table, + const PLDHashEntryHdr *from, + PLDHashEntryHdr *to); + +/* + * Clear the entry and drop any strong references it holds. This callback is + * invoked during a PL_DHASH_REMOVE operation (see below for operation codes), + * but only if the given key is found in the table. + */ +typedef void +(* PR_CALLBACK PLDHashClearEntry)(PLDHashTable *table, + PLDHashEntryHdr *entry); + +/* + * Called when a table (whether allocated dynamically by itself, or nested in + * a larger structure, or allocated on the stack) is finished. This callback + * allows table->ops-specific code to finalize table->data. + */ +typedef void +(* PR_CALLBACK PLDHashFinalize) (PLDHashTable *table); + +/* + * Initialize a new entry, apart from keyHash. This function is called when + * PL_DHashTableOperate's PL_DHASH_ADD case finds no existing entry for the + * given key, and must add a new one. At that point, entry->keyHash is not + * set yet, to avoid claiming the last free entry in a severely overloaded + * table. + */ +typedef PRBool +(* PR_CALLBACK PLDHashInitEntry)(PLDHashTable *table, + PLDHashEntryHdr *entry, + const void *key); + +/* + * Finally, the "vtable" structure for PLDHashTable. The first eight hooks + * must be provided by implementations; they're called unconditionally by the + * generic pldhash.c code. Hooks after these may be null. + * + * Summary of allocation-related hook usage with C++ placement new emphasis: + * allocTable Allocate raw bytes with malloc, no ctors run. + * freeTable Free raw bytes with free, no dtors run. + * initEntry Call placement new using default key-based ctor. + * Return PR_TRUE on success, PR_FALSE on error. + * moveEntry Call placement new using copy ctor, run dtor on old + * entry storage. + * clearEntry Run dtor on entry. + * finalize Stub unless table->data was initialized and needs to + * be finalized. + * + * Note the reason why initEntry is optional: the default hooks (stubs) clear + * entry storage: On successful PL_DHashTableOperate(tbl, key, PL_DHASH_ADD), + * the returned entry pointer addresses an entry struct whose keyHash member + * has been set non-zero, but all other entry members are still clear (null). + * PL_DHASH_ADD callers can test such members to see whether the entry was + * newly created by the PL_DHASH_ADD call that just succeeded. If placement + * new or similar initialization is required, define an initEntry hook. Of + * course, the clearEntry hook must zero or null appropriately. + * + * XXX assumes 0 is null for pointer types. + */ +struct PLDHashTableOps { + /* Mandatory hooks. All implementations must provide these. */ + PLDHashAllocTable allocTable; + PLDHashFreeTable freeTable; + PLDHashGetKey getKey; + PLDHashHashKey hashKey; + PLDHashMatchEntry matchEntry; + PLDHashMoveEntry moveEntry; + PLDHashClearEntry clearEntry; + PLDHashFinalize finalize; + + /* Optional hooks start here. If null, these are not called. */ + PLDHashInitEntry initEntry; +}; + +/* + * Default implementations for the above ops. + */ +PR_EXTERN(void *) +PL_DHashAllocTable(PLDHashTable *table, PRUint32 nbytes); + +PR_EXTERN(void) +PL_DHashFreeTable(PLDHashTable *table, void *ptr); + +PR_EXTERN(PLDHashNumber) +PL_DHashStringKey(PLDHashTable *table, const void *key); + +/* A minimal entry contains a keyHash header and a void key pointer. */ +struct PLDHashEntryStub { + PLDHashEntryHdr hdr; + const void *key; +}; + +PR_EXTERN(const void *) +PL_DHashGetKeyStub(PLDHashTable *table, PLDHashEntryHdr *entry); + +PR_EXTERN(PLDHashNumber) +PL_DHashVoidPtrKeyStub(PLDHashTable *table, const void *key); + +PR_EXTERN(PRBool) +PL_DHashMatchEntryStub(PLDHashTable *table, + const PLDHashEntryHdr *entry, + const void *key); + +PR_EXTERN(PRBool) +PL_DHashMatchStringKey(PLDHashTable *table, + const PLDHashEntryHdr *entry, + const void *key); + +PR_EXTERN(void) +PL_DHashMoveEntryStub(PLDHashTable *table, + const PLDHashEntryHdr *from, + PLDHashEntryHdr *to); + +PR_EXTERN(void) +PL_DHashClearEntryStub(PLDHashTable *table, PLDHashEntryHdr *entry); + +PR_EXTERN(void) +PL_DHashFreeStringKey(PLDHashTable *table, PLDHashEntryHdr *entry); + +PR_EXTERN(void) +PL_DHashFinalizeStub(PLDHashTable *table); + +/* + * If you use PLDHashEntryStub or a subclass of it as your entry struct, and + * if your entries move via memcpy and clear via memset(0), you can use these + * stub operations. + */ +PR_EXTERN(const PLDHashTableOps *) +PL_DHashGetStubOps(void); + +/* + * Dynamically allocate a new PLDHashTable using malloc, initialize it using + * PL_DHashTableInit, and return its address. Return null on malloc failure. + * Note that the entry storage at table->entryStore will be allocated using + * the ops->allocTable callback. + */ +PR_EXTERN(PLDHashTable *) +PL_NewDHashTable(const PLDHashTableOps *ops, void *data, PRUint32 entrySize, + PRUint32 capacity); + +/* + * Finalize table's data, free its entry storage (via table->ops->freeTable), + * and return the memory starting at table to the malloc heap. + */ +PR_EXTERN(void) +PL_DHashTableDestroy(PLDHashTable *table); + +/* + * Initialize table with ops, data, entrySize, and capacity. Capacity is a + * guess for the smallest table size at which the table will usually be less + * than 75% loaded (the table will grow or shrink as needed; capacity serves + * only to avoid inevitable early growth from PL_DHASH_MIN_SIZE). + */ +PR_EXTERN(PRBool) +PL_DHashTableInit(PLDHashTable *table, const PLDHashTableOps *ops, void *data, + PRUint32 entrySize, PRUint32 capacity); + +/* + * Set maximum and minimum alpha for table. The defaults are 0.75 and .25. + * maxAlpha must be in [0.5, 0.9375] for the default PL_DHASH_MIN_SIZE; or if + * MinSize=PL_DHASH_MIN_SIZE <= 256, in [0.5, (float)(MinSize-1)/MinSize]; or + * else in [0.5, 255.0/256]. minAlpha must be in [0, maxAlpha / 2), so that + * we don't shrink on the very next remove after growing a table upon adding + * an entry that brings entryCount past maxAlpha * tableSize. + */ +PR_IMPLEMENT(void) +PL_DHashTableSetAlphaBounds(PLDHashTable *table, + float maxAlpha, + float minAlpha); + +/* + * Call this macro with k, the number of pointer-sized words wasted per entry + * under chaining, to compute the minimum alpha at which double hashing still + * beats chaining. + */ +#define PL_DHASH_MIN_ALPHA(table, k) \ + ((float)((table)->entrySize / sizeof(void *) - 1) \ + / ((table)->entrySize / sizeof(void *) + (k))) + +/* + * Finalize table's data, free its entry storage using table->ops->freeTable, + * and leave its members unchanged from their last live values (which leaves + * pointers dangling). If you want to burn cycles clearing table, it's up to + * your code to call memset. + */ +PR_EXTERN(void) +PL_DHashTableFinish(PLDHashTable *table); + +/* + * To consolidate keyHash computation and table grow/shrink code, we use a + * single entry point for lookup, add, and remove operations. The operation + * codes are declared here, along with codes returned by PLDHashEnumerator + * functions, which control PL_DHashTableEnumerate's behavior. + */ +typedef enum PLDHashOperator { + PL_DHASH_LOOKUP = 0, /* lookup entry */ + PL_DHASH_ADD = 1, /* add entry */ + PL_DHASH_REMOVE = 2, /* remove entry, or enumerator says remove */ + PL_DHASH_NEXT = 0, /* enumerator says continue */ + 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 table->ops->allocTable; + * Or if table->ops->initEntry is non-null, the table->ops->initEntry op may + * have returned false. + * + * Otherwise, entry->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. + */ +PR_EXTERN(PLDHashEntryHdr *) PL_DHASH_FASTCALL +PL_DHashTableOperate(PLDHashTable *table, const void *key, PLDHashOperator op); + +/* + * 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. + */ +PR_EXTERN(void) +PL_DHashTableRawRemove(PLDHashTable *table, PLDHashEntryHdr *entry); + +/* + * 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 table->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 + * table->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, table->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 +(* PR_CALLBACK PLDHashEnumerator)(PLDHashTable *table, PLDHashEntryHdr *hdr, + PRUint32 number, void *arg); + +PR_EXTERN(PRUint32) +PL_DHashTableEnumerate(PLDHashTable *table, PLDHashEnumerator etor, void *arg); + +#ifdef PL_DHASHMETER +#include + +PR_EXTERN(void) +PL_DHashTableDumpMeter(PLDHashTable *table, PLDHashEnumerator dump, FILE *fp); +#endif + +PR_END_EXTERN_C + +#endif /* pldhash_h___ */ -- cgit v1.2.3