Adding upstream version 7.0.6-dfsg.upstream/7.0.6-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 603 insertions, 0 deletions

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 <brendan@mozilla.org> (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 <stdio.h>
+
+PR_EXTERN(void)
+PL_DHashTableDumpMeter(PLDHashTable *table, PLDHashEnumerator dump, FILE *fp);
+#endif
+
+PR_END_EXTERN_C
+
+#endif /* pldhash_h___ */