blob: f11a74fc662c75b6cc69dc839daaa95417ddbfd0 [file] [log] [blame]
/* hash.c -- hash table maintenance
Copyright (C) 1995, 1999, 2002 Free Software Foundation, Inc.
Written by Greg McGary <gkm@gnu.org> <greg@mcgary.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; see the file COPYING. If not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. */
#include "make.h"
#include "hash.h"
#define CALLOC(t, n) ((t *) calloc (sizeof (t), (n)))
#define MALLOC(t, n) ((t *) xmalloc (sizeof (t) * (n)))
#define REALLOC(o, t, n) ((t *) xrealloc ((o), sizeof (t) * (n)))
#define CLONE(o, t, n) ((t *) memcpy (MALLOC (t, (n)), (o), sizeof (t) * (n)))
static void hash_rehash __P((struct hash_table* ht));
static unsigned long round_up_2 __P((unsigned long rough));
/* Implement double hashing with open addressing. The table size is
always a power of two. The secondary (`increment') hash function
is forced to return an odd-value, in order to be relatively prime
to the table size. This guarantees that the increment can
potentially hit every slot in the table during collision
resolution. */
void *hash_deleted_item = &hash_deleted_item;
/* Force the table size to be a power of two, possibly rounding up the
given size. */
void
hash_init (struct hash_table *ht, unsigned long size,
hash_func_t hash_1, hash_func_t hash_2, hash_cmp_func_t hash_cmp)
{
ht->ht_size = round_up_2 (size);
ht->ht_empty_slots = ht->ht_size;
ht->ht_vec = (void**) CALLOC (struct token *, ht->ht_size);
if (ht->ht_vec == 0)
{
fprintf (stderr, _("can't allocate %ld bytes for hash table: memory exhausted"),
ht->ht_size * sizeof(struct token *));
exit (1);
}
ht->ht_capacity = ht->ht_size - (ht->ht_size / 16); /* 93.75% loading factor */
ht->ht_fill = 0;
ht->ht_collisions = 0;
ht->ht_lookups = 0;
ht->ht_rehashes = 0;
ht->ht_hash_1 = hash_1;
ht->ht_hash_2 = hash_2;
ht->ht_compare = hash_cmp;
}
/* Load an array of items into `ht'. */
void
hash_load (struct hash_table *ht, void *item_table,
unsigned long cardinality, unsigned long size)
{
char *items = (char *) item_table;
while (cardinality--)
{
hash_insert (ht, items);
items += size;
}
}
/* Returns the address of the table slot matching `key'. If `key' is
not found, return the address of an empty slot suitable for
inserting `key'. The caller is responsible for incrementing
ht_fill on insertion. */
void **
hash_find_slot (struct hash_table *ht, const void *key)
{
void **slot;
void **deleted_slot = 0;
unsigned int hash_2 = 0;
unsigned int hash_1 = (*ht->ht_hash_1) (key);
ht->ht_lookups++;
for (;;)
{
hash_1 &= (ht->ht_size - 1);
slot = &ht->ht_vec[hash_1];
if (*slot == 0)
return (deleted_slot ? deleted_slot : slot);
if (*slot == hash_deleted_item)
{
if (deleted_slot == 0)
deleted_slot = slot;
}
else
{
if (key == *slot)
return slot;
if ((*ht->ht_compare) (key, *slot) == 0)
return slot;
ht->ht_collisions++;
}
if (!hash_2)
hash_2 = (*ht->ht_hash_2) (key) | 1;
hash_1 += hash_2;
}
}
void *
hash_find_item (struct hash_table *ht, const void *key)
{
void **slot = hash_find_slot (ht, key);
return ((HASH_VACANT (*slot)) ? 0 : *slot);
}
void *
hash_insert (struct hash_table *ht, const void *item)
{
void **slot = hash_find_slot (ht, item);
const void *old_item = slot ? *slot : 0;
hash_insert_at (ht, item, slot);
return (void *)((HASH_VACANT (old_item)) ? 0 : old_item);
}
void *
hash_insert_at (struct hash_table *ht, const void *item, const void *slot)
{
const void *old_item = *(void **) slot;
if (HASH_VACANT (old_item))
{
ht->ht_fill++;
if (old_item == 0)
ht->ht_empty_slots--;
old_item = item;
}
*(void const **) slot = item;
if (ht->ht_empty_slots < ht->ht_size - ht->ht_capacity)
{
hash_rehash (ht);
return (void *) hash_find_slot (ht, item);
}
else
return (void *) slot;
}
void *
hash_delete (struct hash_table *ht, const void *item)
{
void **slot = hash_find_slot (ht, item);
return hash_delete_at (ht, slot);
}
void *
hash_delete_at (struct hash_table *ht, const void *slot)
{
void *item = *(void **) slot;
if (!HASH_VACANT (item))
{
*(void const **) slot = hash_deleted_item;
ht->ht_fill--;
return item;
}
else
return 0;
}
void
hash_free_items (struct hash_table *ht)
{
void **vec = ht->ht_vec;
void **end = &vec[ht->ht_size];
for (; vec < end; vec++)
{
void *item = *vec;
if (!HASH_VACANT (item))
free (item);
*vec = 0;
}
ht->ht_fill = 0;
ht->ht_empty_slots = ht->ht_size;
}
void
hash_delete_items (struct hash_table *ht)
{
void **vec = ht->ht_vec;
void **end = &vec[ht->ht_size];
for (; vec < end; vec++)
*vec = 0;
ht->ht_fill = 0;
ht->ht_collisions = 0;
ht->ht_lookups = 0;
ht->ht_rehashes = 0;
ht->ht_empty_slots = ht->ht_size;
}
void
hash_free (struct hash_table *ht, int free_items)
{
if (free_items)
hash_free_items (ht);
else
{
ht->ht_fill = 0;
ht->ht_empty_slots = ht->ht_size;
}
free (ht->ht_vec);
ht->ht_vec = 0;
ht->ht_capacity = 0;
}
void
hash_map (struct hash_table *ht, hash_map_func_t map)
{
void **slot;
void **end = &ht->ht_vec[ht->ht_size];
for (slot = ht->ht_vec; slot < end; slot++)
{
if (!HASH_VACANT (*slot))
(*map) (*slot);
}
}
void
hash_map_arg (struct hash_table *ht, hash_map_arg_func_t map, void *arg)
{
void **slot;
void **end = &ht->ht_vec[ht->ht_size];
for (slot = ht->ht_vec; slot < end; slot++)
{
if (!HASH_VACANT (*slot))
(*map) (*slot, arg);
}
}
/* Double the size of the hash table in the event of overflow... */
static void
hash_rehash (struct hash_table *ht)
{
unsigned long old_ht_size = ht->ht_size;
void **old_vec = ht->ht_vec;
void **ovp;
if (ht->ht_fill >= ht->ht_capacity)
{
ht->ht_size *= 2;
ht->ht_capacity = ht->ht_size - (ht->ht_size >> 4);
}
ht->ht_rehashes++;
ht->ht_vec = (void **) CALLOC (struct token *, ht->ht_size);
for (ovp = old_vec; ovp < &old_vec[old_ht_size]; ovp++)
{
if (! HASH_VACANT (*ovp))
{
void **slot = hash_find_slot (ht, *ovp);
*slot = *ovp;
}
}
ht->ht_empty_slots = ht->ht_size - ht->ht_fill;
free (old_vec);
}
void
hash_print_stats (struct hash_table *ht, FILE *out_FILE)
{
/* GKM FIXME: honor NO_FLOAT */
fprintf (out_FILE, _("Load=%ld/%ld=%.0f%%, "), ht->ht_fill, ht->ht_size,
100.0 * (double) ht->ht_fill / (double) ht->ht_size);
fprintf (out_FILE, _("Rehash=%d, "), ht->ht_rehashes);
fprintf (out_FILE, _("Collisions=%ld/%ld=%.0f%%"), ht->ht_collisions, ht->ht_lookups,
(ht->ht_lookups
? (100.0 * (double) ht->ht_collisions / (double) ht->ht_lookups)
: 0));
}
/* Dump all items into a NULL-terminated vector. Use the
user-supplied vector, or malloc one. */
void **
hash_dump (struct hash_table *ht, void **vector_0, qsort_cmp_t compare)
{
void **vector;
void **slot;
void **end = &ht->ht_vec[ht->ht_size];
if (vector_0 == 0)
vector_0 = MALLOC (void *, ht->ht_fill + 1);
vector = vector_0;
for (slot = ht->ht_vec; slot < end; slot++)
if (!HASH_VACANT (*slot))
*vector++ = *slot;
*vector = 0;
if (compare)
qsort (vector_0, ht->ht_fill, sizeof (void *), compare);
return vector_0;
}
/* Round a given number up to the nearest power of 2. */
static unsigned long
round_up_2 (unsigned long n)
{
n |= (n >> 1);
n |= (n >> 2);
n |= (n >> 4);
n |= (n >> 8);
n |= (n >> 16);
#if !defined(HAVE_LIMITS_H) || ULONG_MAX > 4294967295
/* We only need this on systems where unsigned long is >32 bits. */
n |= (n >> 32);
#endif
return n + 1;
}