--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nspr/lib/ds/plhash.c	Mon Jul 28 10:47:06 2014 +0200
@@ -0,0 +1,483 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * PL hash table package.
+ */
+#include "plhash.h"
+#include "prbit.h"
+#include "prlog.h"
+#include "prmem.h"
+#include "prtypes.h"
+#include <stdlib.h>
+#include <string.h>
+
+/* Compute the number of buckets in ht */
+#define NBUCKETS(ht)    (1 << (PL_HASH_BITS - (ht)->shift))
+
+/* The smallest table has 16 buckets */
+#define MINBUCKETSLOG2  4
+#define MINBUCKETS      (1 << MINBUCKETSLOG2)
+
+/* Compute the maximum entries given n buckets that we will tolerate, ~90% */
+#define OVERLOADED(n)   ((n) - ((n) >> 3))
+
+/* Compute the number of entries below which we shrink the table by half */
+#define UNDERLOADED(n)  (((n) > MINBUCKETS) ? ((n) >> 2) : 0)
+
+/*
+** Stubs for default hash allocator ops.
+*/
+static void * PR_CALLBACK
+DefaultAllocTable(void *pool, PRSize size)
+{
+    return PR_MALLOC(size);
+}
+
+static void PR_CALLBACK
+DefaultFreeTable(void *pool, void *item)
+{
+    PR_Free(item);
+}
+
+static PLHashEntry * PR_CALLBACK
+DefaultAllocEntry(void *pool, const void *key)
+{
+    return PR_NEW(PLHashEntry);
+}
+
+static void PR_CALLBACK
+DefaultFreeEntry(void *pool, PLHashEntry *he, PRUintn flag)
+{
+    if (flag == HT_FREE_ENTRY)
+        PR_Free(he);
+}
+
+static PLHashAllocOps defaultHashAllocOps = {
+    DefaultAllocTable, DefaultFreeTable,
+    DefaultAllocEntry, DefaultFreeEntry
+};
+
+PR_IMPLEMENT(PLHashTable *)
+PL_NewHashTable(PRUint32 n, PLHashFunction keyHash,
+                PLHashComparator keyCompare, PLHashComparator valueCompare,
+                const PLHashAllocOps *allocOps, void *allocPriv)
+{
+    PLHashTable *ht;
+    PRSize nb;
+
+    if (n <= MINBUCKETS) {
+        n = MINBUCKETSLOG2;
+    } else {
+        n = PR_CeilingLog2(n);
+        if ((PRInt32)n < 0)
+            return 0;
+    }
+
+    if (!allocOps) allocOps = &defaultHashAllocOps;
+
+    ht = (PLHashTable*)((*allocOps->allocTable)(allocPriv, sizeof *ht));
+    if (!ht)
+	return 0;
+    memset(ht, 0, sizeof *ht);
+    ht->shift = PL_HASH_BITS - n;
+    n = 1 << n;
+    nb = n * sizeof(PLHashEntry *);
+    ht->buckets = (PLHashEntry**)((*allocOps->allocTable)(allocPriv, nb));
+    if (!ht->buckets) {
+        (*allocOps->freeTable)(allocPriv, ht);
+        return 0;
+    }
+    memset(ht->buckets, 0, nb);
+
+    ht->keyHash = keyHash;
+    ht->keyCompare = keyCompare;
+    ht->valueCompare = valueCompare;
+    ht->allocOps = allocOps;
+    ht->allocPriv = allocPriv;
+    return ht;
+}
+
+PR_IMPLEMENT(void)
+PL_HashTableDestroy(PLHashTable *ht)
+{
+    PRUint32 i, n;
+    PLHashEntry *he, *next;
+    const PLHashAllocOps *allocOps = ht->allocOps;
+    void *allocPriv = ht->allocPriv;
+
+    n = NBUCKETS(ht);
+    for (i = 0; i < n; i++) {
+        for (he = ht->buckets[i]; he; he = next) {
+            next = he->next;
+            (*allocOps->freeEntry)(allocPriv, he, HT_FREE_ENTRY);
+        }
+    }
+#ifdef DEBUG
+    memset(ht->buckets, 0xDB, n * sizeof ht->buckets[0]);
+#endif
+    (*allocOps->freeTable)(allocPriv, ht->buckets);
+#ifdef DEBUG
+    memset(ht, 0xDB, sizeof *ht);
+#endif
+    (*allocOps->freeTable)(allocPriv, ht);
+}
+
+/*
+** Multiplicative hash, from Knuth 6.4.
+*/
+#define GOLDEN_RATIO    0x9E3779B9U  /* 2/(1+sqrt(5))*(2^32) */
+
+PR_IMPLEMENT(PLHashEntry **)
+PL_HashTableRawLookup(PLHashTable *ht, PLHashNumber keyHash, const void *key)
+{
+    PLHashEntry *he, **hep, **hep0;
+    PLHashNumber h;
+
+#ifdef HASHMETER
+    ht->nlookups++;
+#endif
+    h = keyHash * GOLDEN_RATIO;
+    h >>= ht->shift;
+    hep = hep0 = &ht->buckets[h];
+    while ((he = *hep) != 0) {
+        if (he->keyHash == keyHash && (*ht->keyCompare)(key, he->key)) {
+            /* Move to front of chain if not already there */
+            if (hep != hep0) {
+                *hep = he->next;
+                he->next = *hep0;
+                *hep0 = he;
+            }
+            return hep0;
+        }
+        hep = &he->next;
+#ifdef HASHMETER
+        ht->nsteps++;
+#endif
+    }
+    return hep;
+}
+
+/*
+** Same as PL_HashTableRawLookup but doesn't reorder the hash entries.
+*/
+PR_IMPLEMENT(PLHashEntry **)
+PL_HashTableRawLookupConst(PLHashTable *ht, PLHashNumber keyHash,
+                           const void *key)
+{
+    PLHashEntry *he, **hep;
+    PLHashNumber h;
+
+#ifdef HASHMETER
+    ht->nlookups++;
+#endif
+    h = keyHash * GOLDEN_RATIO;
+    h >>= ht->shift;
+    hep = &ht->buckets[h];
+    while ((he = *hep) != 0) {
+        if (he->keyHash == keyHash && (*ht->keyCompare)(key, he->key)) {
+            break;
+        }
+        hep = &he->next;
+#ifdef HASHMETER
+        ht->nsteps++;
+#endif
+    }
+    return hep;
+}
+
+PR_IMPLEMENT(PLHashEntry *)
+PL_HashTableRawAdd(PLHashTable *ht, PLHashEntry **hep,
+                   PLHashNumber keyHash, const void *key, void *value)
+{
+    PRUint32 i, n;
+    PLHashEntry *he, *next, **oldbuckets;
+    PRSize nb;
+
+    /* Grow the table if it is overloaded */
+    n = NBUCKETS(ht);
+    if (ht->nentries >= OVERLOADED(n)) {
+        oldbuckets = ht->buckets;
+        nb = 2 * n * sizeof(PLHashEntry *);
+        ht->buckets = (PLHashEntry**)
+            ((*ht->allocOps->allocTable)(ht->allocPriv, nb));
+        if (!ht->buckets) {
+            ht->buckets = oldbuckets;
+            return 0;
+        }
+        memset(ht->buckets, 0, nb);
+#ifdef HASHMETER
+        ht->ngrows++;
+#endif
+        ht->shift--;
+
+        for (i = 0; i < n; i++) {
+            for (he = oldbuckets[i]; he; he = next) {
+                next = he->next;
+                hep = PL_HashTableRawLookup(ht, he->keyHash, he->key);
+                PR_ASSERT(*hep == 0);
+                he->next = 0;
+                *hep = he;
+            }
+        }
+#ifdef DEBUG
+        memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
+#endif
+        (*ht->allocOps->freeTable)(ht->allocPriv, oldbuckets);
+        hep = PL_HashTableRawLookup(ht, keyHash, key);
+    }
+
+    /* Make a new key value entry */
+    he = (*ht->allocOps->allocEntry)(ht->allocPriv, key);
+    if (!he)
+	return 0;
+    he->keyHash = keyHash;
+    he->key = key;
+    he->value = value;
+    he->next = *hep;
+    *hep = he;
+    ht->nentries++;
+    return he;
+}
+
+PR_IMPLEMENT(PLHashEntry *)
+PL_HashTableAdd(PLHashTable *ht, const void *key, void *value)
+{
+    PLHashNumber keyHash;
+    PLHashEntry *he, **hep;
+
+    keyHash = (*ht->keyHash)(key);
+    hep = PL_HashTableRawLookup(ht, keyHash, key);
+    if ((he = *hep) != 0) {
+        /* Hit; see if values match */
+        if ((*ht->valueCompare)(he->value, value)) {
+            /* key,value pair is already present in table */
+            return he;
+        }
+        if (he->value)
+            (*ht->allocOps->freeEntry)(ht->allocPriv, he, HT_FREE_VALUE);
+        he->value = value;
+        return he;
+    }
+    return PL_HashTableRawAdd(ht, hep, keyHash, key, value);
+}
+
+PR_IMPLEMENT(void)
+PL_HashTableRawRemove(PLHashTable *ht, PLHashEntry **hep, PLHashEntry *he)
+{
+    PRUint32 i, n;
+    PLHashEntry *next, **oldbuckets;
+    PRSize nb;
+
+    *hep = he->next;
+    (*ht->allocOps->freeEntry)(ht->allocPriv, he, HT_FREE_ENTRY);
+
+    /* Shrink table if it's underloaded */
+    n = NBUCKETS(ht);
+    if (--ht->nentries < UNDERLOADED(n)) {
+        oldbuckets = ht->buckets;
+        nb = n * sizeof(PLHashEntry*) / 2;
+        ht->buckets = (PLHashEntry**)(
+            (*ht->allocOps->allocTable)(ht->allocPriv, nb));
+        if (!ht->buckets) {
+            ht->buckets = oldbuckets;
+            return;
+        }
+        memset(ht->buckets, 0, nb);
+#ifdef HASHMETER
+        ht->nshrinks++;
+#endif
+        ht->shift++;
+
+        for (i = 0; i < n; i++) {
+            for (he = oldbuckets[i]; he; he = next) {
+                next = he->next;
+                hep = PL_HashTableRawLookup(ht, he->keyHash, he->key);
+                PR_ASSERT(*hep == 0);
+                he->next = 0;
+                *hep = he;
+            }
+        }
+#ifdef DEBUG
+        memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
+#endif
+        (*ht->allocOps->freeTable)(ht->allocPriv, oldbuckets);
+    }
+}
+
+PR_IMPLEMENT(PRBool)
+PL_HashTableRemove(PLHashTable *ht, const void *key)
+{
+    PLHashNumber keyHash;
+    PLHashEntry *he, **hep;
+
+    keyHash = (*ht->keyHash)(key);
+    hep = PL_HashTableRawLookup(ht, keyHash, key);
+    if ((he = *hep) == 0)
+        return PR_FALSE;
+
+    /* Hit; remove element */
+    PL_HashTableRawRemove(ht, hep, he);
+    return PR_TRUE;
+}
+
+PR_IMPLEMENT(void *)
+PL_HashTableLookup(PLHashTable *ht, const void *key)
+{
+    PLHashNumber keyHash;
+    PLHashEntry *he, **hep;
+
+    keyHash = (*ht->keyHash)(key);
+    hep = PL_HashTableRawLookup(ht, keyHash, key);
+    if ((he = *hep) != 0) {
+        return he->value;
+    }
+    return 0;
+}
+
+/*
+** Same as PL_HashTableLookup but doesn't reorder the hash entries.
+*/
+PR_IMPLEMENT(void *)
+PL_HashTableLookupConst(PLHashTable *ht, const void *key)
+{
+    PLHashNumber keyHash;
+    PLHashEntry *he, **hep;
+
+    keyHash = (*ht->keyHash)(key);
+    hep = PL_HashTableRawLookupConst(ht, keyHash, key);
+    if ((he = *hep) != 0) {
+        return he->value;
+    }
+    return 0;
+}
+
+/*
+** Iterate over the entries in the hash table calling func for each
+** entry found. Stop if "f" says to (return value & PR_ENUMERATE_STOP).
+** Return a count of the number of elements scanned.
+*/
+PR_IMPLEMENT(int)
+PL_HashTableEnumerateEntries(PLHashTable *ht, PLHashEnumerator f, void *arg)
+{
+    PLHashEntry *he, **hep;
+    PRUint32 i, nbuckets;
+    int rv, n = 0;
+    PLHashEntry *todo = 0;
+
+    nbuckets = NBUCKETS(ht);
+    for (i = 0; i < nbuckets; i++) {
+        hep = &ht->buckets[i];
+        while ((he = *hep) != 0) {
+            rv = (*f)(he, n, arg);
+            n++;
+            if (rv & (HT_ENUMERATE_REMOVE | HT_ENUMERATE_UNHASH)) {
+                *hep = he->next;
+                if (rv & HT_ENUMERATE_REMOVE) {
+                    he->next = todo;
+                    todo = he;
+                }
+            } else {
+                hep = &he->next;
+            }
+            if (rv & HT_ENUMERATE_STOP) {
+                goto out;
+            }
+        }
+    }
+
+out:
+    hep = &todo;
+    while ((he = *hep) != 0) {
+        PL_HashTableRawRemove(ht, hep, he);
+    }
+    return n;
+}
+
+#ifdef HASHMETER
+#include <math.h>
+#include <stdio.h>
+
+PR_IMPLEMENT(void)
+PL_HashTableDumpMeter(PLHashTable *ht, PLHashEnumerator dump, FILE *fp)
+{
+    double mean, variance;
+    PRUint32 nchains, nbuckets;
+    PRUint32 i, n, maxChain, maxChainLen;
+    PLHashEntry *he;
+
+    variance = 0;
+    nchains = 0;
+    maxChainLen = 0;
+    nbuckets = NBUCKETS(ht);
+    for (i = 0; i < nbuckets; i++) {
+        he = ht->buckets[i];
+        if (!he)
+            continue;
+        nchains++;
+        for (n = 0; he; he = he->next)
+            n++;
+        variance += n * n;
+        if (n > maxChainLen) {
+            maxChainLen = n;
+            maxChain = i;
+        }
+    }
+    mean = (double)ht->nentries / nchains;
+    variance = fabs(variance / nchains - mean * mean);
+
+    fprintf(fp, "\nHash table statistics:\n");
+    fprintf(fp, "     number of lookups: %u\n", ht->nlookups);
+    fprintf(fp, "     number of entries: %u\n", ht->nentries);
+    fprintf(fp, "       number of grows: %u\n", ht->ngrows);
+    fprintf(fp, "     number of shrinks: %u\n", ht->nshrinks);
+    fprintf(fp, "   mean steps per hash: %g\n", (double)ht->nsteps
+                                                / ht->nlookups);
+    fprintf(fp, "mean hash chain length: %g\n", mean);
+    fprintf(fp, "    standard deviation: %g\n", sqrt(variance));
+    fprintf(fp, " max hash chain length: %u\n", maxChainLen);
+    fprintf(fp, "        max hash chain: [%u]\n", maxChain);
+
+    for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
+        if ((*dump)(he, i, fp) != HT_ENUMERATE_NEXT)
+            break;
+}
+#endif /* HASHMETER */
+
+PR_IMPLEMENT(int)
+PL_HashTableDump(PLHashTable *ht, PLHashEnumerator dump, FILE *fp)
+{
+    int count;
+
+    count = PL_HashTableEnumerateEntries(ht, dump, fp);
+#ifdef HASHMETER
+    PL_HashTableDumpMeter(ht, dump, fp);
+#endif
+    return count;
+}
+
+PR_IMPLEMENT(PLHashNumber)
+PL_HashString(const void *key)
+{
+    PLHashNumber h;
+    const PRUint8 *s;
+
+    h = 0;
+    for (s = (const PRUint8*)key; *s; s++)
+        h = PR_ROTATE_LEFT32(h, 4) ^ *s;
+    return h;
+}
+
+PR_IMPLEMENT(int)
+PL_CompareStrings(const void *v1, const void *v2)
+{
+    return strcmp((const char*)v1, (const char*)v2) == 0;
+}
+
+PR_IMPLEMENT(int)
+PL_CompareValues(const void *v1, const void *v2)
+{
+    return v1 == v2;
+}