NetBSD/usr.bin/make/hash.c

334 lines
9.3 KiB
C

/* $NetBSD: hash.c,v 1.72 2022/02/09 21:09:24 rillig Exp $ */
/*
* Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Adam de Boor.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Copyright (c) 1988, 1989 by Adam de Boor
* Copyright (c) 1989 by Berkeley Softworks
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Adam de Boor.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* Hash tables with string keys. */
#include "make.h"
/* "@(#)hash.c 8.1 (Berkeley) 6/6/93" */
MAKE_RCSID("$NetBSD: hash.c,v 1.72 2022/02/09 21:09:24 rillig Exp $");
/*
* The ratio of # entries to # buckets at which we rebuild the table to
* make it larger.
*/
#define rebuildLimit 3
/* This hash function matches Gosling's Emacs and java.lang.String. */
static unsigned int
Hash_String(const char *key, const char **out_keyEnd)
{
unsigned int h;
const char *p;
h = 0;
for (p = key; *p != '\0'; p++)
h = 31 * h + (unsigned char)*p;
*out_keyEnd = p;
return h;
}
/* This hash function matches Gosling's Emacs and java.lang.String. */
unsigned int
Hash_Substring(Substring key)
{
unsigned int h;
const char *p;
h = 0;
for (p = key.start; p != key.end; p++)
h = 31 * h + (unsigned char)*p;
return h;
}
static HashEntry *
HashTable_Find(HashTable *t, Substring key, unsigned int h)
{
HashEntry *e;
unsigned int chainlen = 0;
size_t keyLen = Substring_Length(key);
#ifdef DEBUG_HASH_LOOKUP
DEBUG4(HASH, "HashTable_Find: %p h=%08x key=%.*s\n",
t, h, (int)keyLen, key.start);
#endif
for (e = t->buckets[h & t->bucketsMask]; e != NULL; e = e->next) {
chainlen++;
if (e->key_hash == h &&
strncmp(e->key, key.start, keyLen) == 0 &&
e->key[keyLen] == '\0')
break;
}
if (chainlen > t->maxchain)
t->maxchain = chainlen;
return e;
}
/* Set up the hash table. */
void
HashTable_Init(HashTable *t)
{
unsigned int n = 16, i;
HashEntry **buckets = bmake_malloc(sizeof *buckets * n);
for (i = 0; i < n; i++)
buckets[i] = NULL;
t->buckets = buckets;
t->bucketsSize = n;
t->numEntries = 0;
t->bucketsMask = n - 1;
t->maxchain = 0;
}
/*
* Remove everything from the hash table and free up the memory for the keys
* of the hash table, but not for the values associated to these keys.
*/
void
HashTable_Done(HashTable *t)
{
HashEntry **buckets = t->buckets;
size_t i, n = t->bucketsSize;
for (i = 0; i < n; i++) {
HashEntry *he = buckets[i];
while (he != NULL) {
HashEntry *next = he->next;
free(he);
he = next;
}
}
free(t->buckets);
#ifdef CLEANUP
t->buckets = NULL;
#endif
}
/* Find the entry corresponding to the key, or return NULL. */
HashEntry *
HashTable_FindEntry(HashTable *t, const char *key)
{
const char *keyEnd;
unsigned int h = Hash_String(key, &keyEnd);
return HashTable_Find(t, Substring_Init(key, keyEnd), h);
}
/* Find the value corresponding to the key, or return NULL. */
void *
HashTable_FindValue(HashTable *t, const char *key)
{
HashEntry *he = HashTable_FindEntry(t, key);
return he != NULL ? he->value : NULL;
}
/*
* Find the value corresponding to the key and the precomputed hash,
* or return NULL.
*/
void *
HashTable_FindValueBySubstringHash(HashTable *t, Substring key, unsigned int h)
{
HashEntry *he = HashTable_Find(t, key, h);
return he != NULL ? he->value : NULL;
}
/*
* Make the hash table larger. Any bucket numbers from the old table become
* invalid; the hash codes stay valid though.
*/
static void
HashTable_Enlarge(HashTable *t)
{
unsigned int oldSize = t->bucketsSize;
HashEntry **oldBuckets = t->buckets;
unsigned int newSize = 2 * oldSize;
unsigned int newMask = newSize - 1;
HashEntry **newBuckets = bmake_malloc(sizeof *newBuckets * newSize);
size_t i;
for (i = 0; i < newSize; i++)
newBuckets[i] = NULL;
for (i = 0; i < oldSize; i++) {
HashEntry *he = oldBuckets[i];
while (he != NULL) {
HashEntry *next = he->next;
he->next = newBuckets[he->key_hash & newMask];
newBuckets[he->key_hash & newMask] = he;
he = next;
}
}
free(oldBuckets);
t->bucketsSize = newSize;
t->bucketsMask = newMask;
t->buckets = newBuckets;
DEBUG4(HASH, "HashTable_Enlarge: %p size=%d entries=%d maxchain=%d\n",
(void *)t, t->bucketsSize, t->numEntries, t->maxchain);
t->maxchain = 0;
}
/*
* Find or create an entry corresponding to the key.
* Return in out_isNew whether a new entry has been created.
*/
HashEntry *
HashTable_CreateEntry(HashTable *t, const char *key, bool *out_isNew)
{
const char *keyEnd;
unsigned int h = Hash_String(key, &keyEnd);
HashEntry *he = HashTable_Find(t, Substring_Init(key, keyEnd), h);
if (he != NULL) {
if (out_isNew != NULL)
*out_isNew = false;
return he;
}
if (t->numEntries >= rebuildLimit * t->bucketsSize)
HashTable_Enlarge(t);
he = bmake_malloc(sizeof *he + (size_t)(keyEnd - key));
he->value = NULL;
he->key_hash = h;
memcpy(he->key, key, (size_t)(keyEnd - key) + 1);
he->next = t->buckets[h & t->bucketsMask];
t->buckets[h & t->bucketsMask] = he;
t->numEntries++;
if (out_isNew != NULL)
*out_isNew = true;
return he;
}
void
HashTable_Set(HashTable *t, const char *key, void *value)
{
HashEntry *he = HashTable_CreateEntry(t, key, NULL);
HashEntry_Set(he, value);
}
/* Delete the entry from the table, don't free the value of the entry. */
void
HashTable_DeleteEntry(HashTable *t, HashEntry *he)
{
HashEntry **ref = &t->buckets[he->key_hash & t->bucketsMask];
HashEntry *p;
for (; (p = *ref) != NULL; ref = &p->next) {
if (p == he) {
*ref = p->next;
free(p);
t->numEntries--;
return;
}
}
abort();
}
/*
* Return the next entry in the hash table, or NULL if the end of the table
* is reached.
*/
HashEntry *
HashIter_Next(HashIter *hi)
{
HashTable *t = hi->table;
HashEntry *he = hi->entry;
HashEntry **buckets = t->buckets;
unsigned int bucketsSize = t->bucketsSize;
if (he != NULL)
he = he->next; /* skip the most recently returned entry */
while (he == NULL) { /* find the next nonempty chain */
if (hi->nextBucket >= bucketsSize)
return NULL;
he = buckets[hi->nextBucket++];
}
hi->entry = he;
return he;
}
void
HashTable_DebugStats(HashTable *t, const char *name)
{
DEBUG4(HASH, "HashTable %s: size=%u numEntries=%u maxchain=%u\n",
name, t->bucketsSize, t->numEntries, t->maxchain);
}