mirror of
https://github.com/freebsd/freebsd-src
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1b65f0bd2b
o allow env var MAKE_OBJDIR_CHECK_WRITABLE=no to skip writable checks in InitObjdir. Explicit .OBJDIR target always allows read-only directory. o Fix building and unit-tests on non-BSD. o More code cleanup and refactoring. o More unit tests
319 lines
9.0 KiB
C
319 lines
9.0 KiB
C
/* $NetBSD: hash.c,v 1.57 2020/11/14 21:29:44 rillig Exp $ */
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/*
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* Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Adam de Boor.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Copyright (c) 1988, 1989 by Adam de Boor
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* Copyright (c) 1989 by Berkeley Softworks
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Adam de Boor.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/* Hash tables with string keys. */
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#include "make.h"
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/* "@(#)hash.c 8.1 (Berkeley) 6/6/93" */
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MAKE_RCSID("$NetBSD: hash.c,v 1.57 2020/11/14 21:29:44 rillig Exp $");
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/*
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* The ratio of # entries to # buckets at which we rebuild the table to
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* make it larger.
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*/
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#define rebuildLimit 3
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/* This hash function matches Gosling's emacs and java.lang.String. */
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static unsigned int
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hash(const char *key, size_t *out_keylen)
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{
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unsigned int h = 0;
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const char *p = key;
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while (*p != '\0')
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h = (h << 5) - h + (unsigned char)*p++;
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if (out_keylen != NULL)
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*out_keylen = (size_t)(p - key);
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return h;
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}
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unsigned int
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Hash_Hash(const char *key)
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{
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return hash(key, NULL);
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}
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static HashEntry *
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HashTable_Find(HashTable *t, unsigned int h, const char *key)
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{
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HashEntry *e;
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unsigned int chainlen = 0;
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#ifdef DEBUG_HASH_LOOKUP
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DEBUG4(HASH, "%s: %p h=%08x key=%s\n", __func__, t, h, key);
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#endif
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for (e = t->buckets[h & t->bucketsMask]; e != NULL; e = e->next) {
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chainlen++;
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if (e->key_hash == h && strcmp(e->key, key) == 0)
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break;
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}
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if (chainlen > t->maxchain)
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t->maxchain = chainlen;
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return e;
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}
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/* Set up the hash table. */
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void
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HashTable_Init(HashTable *t)
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{
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unsigned int n = 16, i;
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HashEntry **buckets = bmake_malloc(sizeof *buckets * n);
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for (i = 0; i < n; i++)
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buckets[i] = NULL;
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t->buckets = buckets;
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t->bucketsSize = n;
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t->numEntries = 0;
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t->bucketsMask = n - 1;
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t->maxchain = 0;
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}
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/* Remove everything from the hash table and frees up the memory. */
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void
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HashTable_Done(HashTable *t)
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{
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HashEntry **buckets = t->buckets;
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size_t i, n = t->bucketsSize;
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for (i = 0; i < n; i++) {
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HashEntry *he = buckets[i];
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while (he != NULL) {
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HashEntry *next = he->next;
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free(he);
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he = next;
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}
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}
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free(t->buckets);
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#ifdef CLEANUP
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t->buckets = NULL;
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#endif
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}
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/* Find the entry corresponding to the key, or return NULL. */
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HashEntry *
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HashTable_FindEntry(HashTable *t, const char *key)
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{
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unsigned int h = hash(key, NULL);
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return HashTable_Find(t, h, key);
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}
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/* Find the value corresponding to the key, or return NULL. */
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void *
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HashTable_FindValue(HashTable *t, const char *key)
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{
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HashEntry *he = HashTable_FindEntry(t, key);
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return he != NULL ? he->value : NULL;
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}
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/* Find the value corresponding to the key and the precomputed hash,
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* or return NULL. */
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void *
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HashTable_FindValueHash(HashTable *t, const char *key, unsigned int h)
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{
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HashEntry *he = HashTable_Find(t, h, key);
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return he != NULL ? he->value : NULL;
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}
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/* Make the hash table larger. Any bucket numbers from the old table become
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* invalid; the hash codes stay valid though. */
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static void
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HashTable_Enlarge(HashTable *t)
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{
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unsigned int oldSize = t->bucketsSize;
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HashEntry **oldBuckets = t->buckets;
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unsigned int newSize = 2 * oldSize;
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unsigned int newMask = newSize - 1;
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HashEntry **newBuckets = bmake_malloc(sizeof *newBuckets * newSize);
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size_t i;
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for (i = 0; i < newSize; i++)
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newBuckets[i] = NULL;
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for (i = 0; i < oldSize; i++) {
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HashEntry *he = oldBuckets[i];
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while (he != NULL) {
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HashEntry *next = he->next;
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he->next = newBuckets[he->key_hash & newMask];
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newBuckets[he->key_hash & newMask] = he;
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he = next;
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}
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}
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free(oldBuckets);
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t->bucketsSize = newSize;
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t->bucketsMask = newMask;
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t->buckets = newBuckets;
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DEBUG5(HASH, "%s: %p size=%d entries=%d maxchain=%d\n",
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__func__, t, t->bucketsSize, t->numEntries, t->maxchain);
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t->maxchain = 0;
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}
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/* Find or create an entry corresponding to the key.
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* Return in out_isNew whether a new entry has been created. */
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HashEntry *
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HashTable_CreateEntry(HashTable *t, const char *key, Boolean *out_isNew)
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{
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size_t keylen;
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unsigned int h = hash(key, &keylen);
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HashEntry *he = HashTable_Find(t, h, key);
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if (he != NULL) {
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if (out_isNew != NULL)
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*out_isNew = FALSE;
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return he;
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}
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if (t->numEntries >= rebuildLimit * t->bucketsSize)
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HashTable_Enlarge(t);
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he = bmake_malloc(sizeof *he + keylen);
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he->value = NULL;
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he->key_hash = h;
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memcpy(he->key, key, keylen + 1);
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he->next = t->buckets[h & t->bucketsMask];
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t->buckets[h & t->bucketsMask] = he;
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t->numEntries++;
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if (out_isNew != NULL)
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*out_isNew = TRUE;
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return he;
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}
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HashEntry *
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HashTable_Set(HashTable *t, const char *key, void *value)
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{
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HashEntry *he = HashTable_CreateEntry(t, key, NULL);
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HashEntry_Set(he, value);
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return he;
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}
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/* Delete the entry from the table and free the associated memory. */
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void
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HashTable_DeleteEntry(HashTable *t, HashEntry *he)
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{
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HashEntry **ref = &t->buckets[he->key_hash & t->bucketsMask];
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HashEntry *p;
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for (; (p = *ref) != NULL; ref = &p->next) {
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if (p == he) {
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*ref = p->next;
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free(p);
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t->numEntries--;
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return;
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}
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}
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abort();
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}
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/* Set things up for iterating over all entries in the hash table. */
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void
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HashIter_Init(HashIter *hi, HashTable *t)
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{
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hi->table = t;
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hi->nextBucket = 0;
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hi->entry = NULL;
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}
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/* Return the next entry in the hash table, or NULL if the end of the table
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* is reached. */
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HashEntry *
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HashIter_Next(HashIter *hi)
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{
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HashTable *t = hi->table;
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HashEntry *he = hi->entry;
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HashEntry **buckets = t->buckets;
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unsigned int bucketsSize = t->bucketsSize;
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if (he != NULL)
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he = he->next; /* skip the most recently returned entry */
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while (he == NULL) { /* find the next nonempty chain */
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if (hi->nextBucket >= bucketsSize)
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return NULL;
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he = buckets[hi->nextBucket++];
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}
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hi->entry = he;
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return he;
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}
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void
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HashTable_DebugStats(HashTable *t, const char *name)
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{
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DEBUG4(HASH, "HashTable %s: size=%u numEntries=%u maxchain=%u\n",
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name, t->bucketsSize, t->numEntries, t->maxchain);
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}
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