freebsd-nq/hash.c
Simon J. Gerraty 6bbc783f48 Import bmake-20200902
Lots of code refactoring, simplification and cleanup.
Lots of new unit-tests providing much higher code coverage.
All courtesy of rillig at netbsd.

Other significant changes:

o new read-only variable .SHELL which provides the path of the shell
  used to run scripts (as defined by  the .SHELL target).

o new debug option -dl: LINT mode, does the equivalent of := for all
  variable assignments so that file and line number are reported for
  variable parse errors.
2020-09-05 16:11:04 +00:00

405 lines
11 KiB
C

/* $NetBSD: hash.c,v 1.29 2020/09/01 21:11:31 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.
*/
#ifndef MAKE_NATIVE
static char rcsid[] = "$NetBSD: hash.c,v 1.29 2020/09/01 21:11:31 rillig Exp $";
#else
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)hash.c 8.1 (Berkeley) 6/6/93";
#else
__RCSID("$NetBSD: hash.c,v 1.29 2020/09/01 21:11:31 rillig Exp $");
#endif
#endif /* not lint */
#endif
/* hash.c --
*
* This module contains routines to manipulate a hash table.
* See hash.h for a definition of the structure of the hash
* table. Hash tables grow automatically as the amount of
* information increases.
*/
#include "make.h"
/*
* Forward references to local procedures that are used before they're
* defined:
*/
static void RebuildTable(Hash_Table *);
/*
* The following defines the ratio of # entries to # buckets
* at which we rebuild the table to make it larger.
*/
#define rebuildLimit 3
/* The hash function(s) */
#ifndef HASH
/* The default: this one matches Gosling's emacs */
#define HASH(h, key, p) do { \
for (h = 0, p = key; *p;) \
h = (h << 5) - h + *p++; \
} while (0)
#endif
/* Sets up the hash table.
*
* Input:
* t Structure to to hold the table.
* numBuckets How many buckets to create for starters. This
* number is rounded up to a power of two. If
* <= 0, a reasonable default is chosen. The
* table will grow in size later as needed.
*/
void
Hash_InitTable(Hash_Table *t, int numBuckets)
{
int i;
struct Hash_Entry **hp;
/*
* Round up the size to a power of two.
*/
if (numBuckets <= 0)
i = 16;
else {
for (i = 2; i < numBuckets; i <<= 1)
continue;
}
t->numEntries = 0;
t->maxchain = 0;
t->bucketsSize = i;
t->bucketsMask = i - 1;
t->buckets = hp = bmake_malloc(sizeof(*hp) * i);
while (--i >= 0)
*hp++ = NULL;
}
/* Removes everything from the hash table and frees up the memory space it
* occupied (except for the space in the Hash_Table structure). */
void
Hash_DeleteTable(Hash_Table *t)
{
struct Hash_Entry **hp, *h, *nexth = NULL;
int i;
for (hp = t->buckets, i = t->bucketsSize; --i >= 0;) {
for (h = *hp++; h != NULL; h = nexth) {
nexth = h->next;
free(h);
}
}
free(t->buckets);
/*
* Set up the hash table to cause memory faults on any future access
* attempts until re-initialization.
*/
t->buckets = NULL;
}
/* Searches the hash table for an entry corresponding to the key.
*
* Input:
* t Hash table to search.
* key A hash key.
*
* Results:
* Returns a pointer to the entry for key, or NULL if the table contains
* no entry for the key.
*/
Hash_Entry *
Hash_FindEntry(Hash_Table *t, const char *key)
{
Hash_Entry *e;
unsigned h;
const char *p;
int chainlen;
if (t == NULL || t->buckets == NULL) {
return NULL;
}
HASH(h, key, p);
p = key;
chainlen = 0;
#ifdef DEBUG_HASH_LOOKUP
if (DEBUG(HASH))
fprintf(debug_file, "%s: %p h=%x key=%s\n", __func__,
t, h, key);
#endif
for (e = t->buckets[h & t->bucketsMask]; e != NULL; e = e->next) {
chainlen++;
if (e->namehash == h && strcmp(e->name, p) == 0)
break;
}
if (chainlen > t->maxchain)
t->maxchain = chainlen;
return e;
}
/* Searches the hash table for an entry corresponding to the key.
* If no entry is found, then one is created.
*
* Input:
* t Hash table to search.
* key A hash key.
* newPtr Filled with TRUE if new entry created,
* FALSE otherwise.
*/
Hash_Entry *
Hash_CreateEntry(Hash_Table *t, const char *key, Boolean *newPtr)
{
Hash_Entry *e;
unsigned h;
const char *p;
int keylen;
int chainlen;
struct Hash_Entry **hp;
/*
* Hash the key. As a side effect, save the length (strlen) of the
* key in case we need to create the entry.
*/
HASH(h, key, p);
keylen = p - key;
p = key;
chainlen = 0;
#ifdef DEBUG_HASH_LOOKUP
if (DEBUG(HASH))
fprintf(debug_file, "%s: %p h=%x key=%s\n", __func__,
t, h, key);
#endif
for (e = t->buckets[h & t->bucketsMask]; e != NULL; e = e->next) {
chainlen++;
if (e->namehash == h && strcmp(e->name, p) == 0) {
if (newPtr != NULL)
*newPtr = FALSE;
break;
}
}
if (chainlen > t->maxchain)
t->maxchain = chainlen;
if (e)
return e;
/*
* The desired entry isn't there. Before allocating a new entry,
* expand the table if necessary (and this changes the resulting
* bucket chain).
*/
if (t->numEntries >= rebuildLimit * t->bucketsSize)
RebuildTable(t);
e = bmake_malloc(sizeof(*e) + keylen);
hp = &t->buckets[h & t->bucketsMask];
e->next = *hp;
*hp = e;
Hash_SetValue(e, NULL);
e->namehash = h;
(void)strcpy(e->name, p);
t->numEntries++;
if (newPtr != NULL)
*newPtr = TRUE;
return e;
}
/* Delete the given hash table entry and free memory associated with it. */
void
Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e)
{
Hash_Entry **hp, *p;
if (e == NULL)
return;
for (hp = &t->buckets[e->namehash & t->bucketsMask];
(p = *hp) != NULL; hp = &p->next) {
if (p == e) {
*hp = p->next;
free(p);
t->numEntries--;
return;
}
}
(void)write(2, "bad call to Hash_DeleteEntry\n", 29);
abort();
}
/* Sets things up for enumerating all entries in the hash table.
*
* Input:
* t Table to be searched.
* searchPtr Area in which to keep state about search.
*
* Results:
* The return value is the address of the first entry in
* the hash table, or NULL if the table is empty.
*/
Hash_Entry *
Hash_EnumFirst(Hash_Table *t, Hash_Search *searchPtr)
{
searchPtr->table = t;
searchPtr->nextBucket = 0;
searchPtr->entry = NULL;
return Hash_EnumNext(searchPtr);
}
/* Returns the next entry in the hash table, or NULL if the end of the table
* is reached.
*
* Input:
* searchPtr Area used to keep state about search.
*/
Hash_Entry *
Hash_EnumNext(Hash_Search *searchPtr)
{
Hash_Entry *e;
Hash_Table *t = searchPtr->table;
/*
* The entry field points to the most recently returned
* entry, or is NULL if we are starting up. If not NULL, we have
* to start at the next one in the chain.
*/
e = searchPtr->entry;
if (e != NULL)
e = e->next;
/*
* If the chain ran out, or if we are starting up, we need to
* find the next nonempty chain.
*/
while (e == NULL) {
if (searchPtr->nextBucket >= t->bucketsSize)
return NULL;
e = t->buckets[searchPtr->nextBucket++];
}
searchPtr->entry = e;
return e;
}
/* Makes a new hash table that is larger than the old one. The entire hash
* table is moved, so any bucket numbers from the old table become invalid. */
static void
RebuildTable(Hash_Table *t)
{
Hash_Entry *e, *next = NULL, **hp, **xp;
int i, mask;
Hash_Entry **oldhp;
int oldsize;
oldhp = t->buckets;
oldsize = i = t->bucketsSize;
i <<= 1;
t->bucketsSize = i;
t->bucketsMask = mask = i - 1;
t->buckets = hp = bmake_malloc(sizeof(*hp) * i);
while (--i >= 0)
*hp++ = NULL;
for (hp = oldhp, i = oldsize; --i >= 0;) {
for (e = *hp++; e != NULL; e = next) {
next = e->next;
xp = &t->buckets[e->namehash & mask];
e->next = *xp;
*xp = e;
}
}
free(oldhp);
if (DEBUG(HASH))
fprintf(debug_file, "%s: %p size=%d entries=%d maxchain=%d\n",
__func__, t, t->bucketsSize, t->numEntries, t->maxchain);
t->maxchain = 0;
}
void
Hash_ForEach(Hash_Table *t, void (*action)(void *, void *), void *data)
{
Hash_Search search;
Hash_Entry *e;
for (e = Hash_EnumFirst(t, &search);
e != NULL;
e = Hash_EnumNext(&search))
action(Hash_GetValue(e), data);
}
void
Hash_DebugStats(Hash_Table *t, const char *name)
{
if (DEBUG(HASH))
fprintf(debug_file, "Hash_Table %s: size=%d numEntries=%d maxchain=%d\n",
name, t->bucketsSize, t->numEntries, t->maxchain);
}