X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fhash.c;h=f85bd519bf5a1d259de8dfb22fdff73df7c1b2d3;hb=1b85e216d2ceb6d219d509b0471242d5b3dd88eb;hp=1d7a59d113d6bf1c5a000ebf147cdcf888e834d2;hpb=de1b0c616f4497865334c973236206a7d391fd23;p=gnulib.git diff --git a/lib/hash.c b/lib/hash.c index 1d7a59d11..f85bd519b 100644 --- a/lib/hash.c +++ b/lib/hash.c @@ -1,5 +1,8 @@ /* hash - hashing table processing. - Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc. + + Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free + Software Foundation, Inc. + Written by Jim Meyering, 1992. This program is free software; you can redistribute it and/or modify @@ -14,40 +17,23 @@ You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, - Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ /* A generic hash table package. */ /* Define USE_OBSTACK to 1 if you want the allocator to use obstacks instead of malloc. If you change USE_OBSTACK, you have to recompile! */ -#if HAVE_CONFIG_H +#ifdef HAVE_CONFIG_H # include #endif -#if HAVE_STDLIB_H -# include -#endif -#if HAVE_STDBOOL_H -# include -#else -typedef enum {false = 0, true = 1} bool; -#endif -#include -#include -#ifndef HAVE_DECL_FREE -"this configure-time declaration test was not run" -#endif -#if !HAVE_DECL_FREE -void free (); -#endif +#include "hash.h" +#include "xalloc.h" -#ifndef HAVE_DECL_MALLOC -"this configure-time declaration test was not run" -#endif -#if !HAVE_DECL_MALLOC -char *malloc (); -#endif +#include +#include +#include #if USE_OBSTACK # include "obstack.h" @@ -59,7 +45,43 @@ char *malloc (); # endif #endif -#include "hash.h" +#ifndef SIZE_MAX +# define SIZE_MAX ((size_t) -1) +#endif + +struct hash_table + { + /* The array of buckets starts at BUCKET and extends to BUCKET_LIMIT-1, + for a possibility of N_BUCKETS. Among those, N_BUCKETS_USED buckets + are not empty, there are N_ENTRIES active entries in the table. */ + struct hash_entry *bucket; + struct hash_entry const *bucket_limit; + size_t n_buckets; + size_t n_buckets_used; + size_t n_entries; + + /* Tuning arguments, kept in a physicaly separate structure. */ + const Hash_tuning *tuning; + + /* Three functions are given to `hash_initialize', see the documentation + block for this function. In a word, HASHER randomizes a user entry + into a number up from 0 up to some maximum minus 1; COMPARATOR returns + true if two user entries compare equally; and DATA_FREER is the cleanup + function for a user entry. */ + Hash_hasher hasher; + Hash_comparator comparator; + Hash_data_freer data_freer; + + /* A linked list of freed struct hash_entry structs. */ + struct hash_entry *free_entry_list; + +#if USE_OBSTACK + /* Whenever obstacks are used, it is possible to allocate all overflowed + entries into a single stack, so they all can be freed in a single + operation. It is not clear if the speedup is worth the trouble. */ + struct obstack entry_stack; +#endif + }; /* A hash table contains many internal entries, each holding a pointer to some user provided data (also called a user entry). An entry indistinctly @@ -124,7 +146,7 @@ static const Hash_tuning default_tuning = number of buckets (used plus unused), or the maximum number of slots, are the same quantity. */ -unsigned +size_t hash_get_n_buckets (const Hash_table *table) { return table->n_buckets; @@ -132,7 +154,7 @@ hash_get_n_buckets (const Hash_table *table) /* Return the number of slots in use (non-empty buckets). */ -unsigned +size_t hash_get_n_buckets_used (const Hash_table *table) { return table->n_buckets_used; @@ -140,7 +162,7 @@ hash_get_n_buckets_used (const Hash_table *table) /* Return the number of active entries. */ -unsigned +size_t hash_get_n_entries (const Hash_table *table) { return table->n_entries; @@ -148,18 +170,18 @@ hash_get_n_entries (const Hash_table *table) /* Return the length of the longest chain (bucket). */ -unsigned +size_t hash_get_max_bucket_length (const Hash_table *table) { - struct hash_entry *bucket; - unsigned max_bucket_length = 0; + struct hash_entry const *bucket; + size_t max_bucket_length = 0; for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) { if (bucket->data) { - struct hash_entry *cursor = bucket; - unsigned bucket_length = 1; + struct hash_entry const *cursor = bucket; + size_t bucket_length = 1; while (cursor = cursor->next, cursor) bucket_length++; @@ -178,15 +200,15 @@ hash_get_max_bucket_length (const Hash_table *table) bool hash_table_ok (const Hash_table *table) { - struct hash_entry *bucket; - unsigned n_buckets_used = 0; - unsigned n_entries = 0; + struct hash_entry const *bucket; + size_t n_buckets_used = 0; + size_t n_entries = 0; for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) { if (bucket->data) { - struct hash_entry *cursor = bucket; + struct hash_entry const *cursor = bucket; /* Count bucket head. */ n_buckets_used++; @@ -207,16 +229,18 @@ hash_table_ok (const Hash_table *table) void hash_print_statistics (const Hash_table *table, FILE *stream) { - unsigned n_entries = hash_get_n_entries (table); - unsigned n_buckets = hash_get_n_buckets (table); - unsigned n_buckets_used = hash_get_n_buckets_used (table); - unsigned max_bucket_length = hash_get_max_bucket_length (table); - - fprintf (stream, "# entries: %u\n", n_entries); - fprintf (stream, "# buckets: %u\n", n_buckets); - fprintf (stream, "# buckets used: %u (%.2f%%)\n", n_buckets_used, + size_t n_entries = hash_get_n_entries (table); + size_t n_buckets = hash_get_n_buckets (table); + size_t n_buckets_used = hash_get_n_buckets_used (table); + size_t max_bucket_length = hash_get_max_bucket_length (table); + + fprintf (stream, "# entries: %lu\n", (unsigned long int) n_entries); + fprintf (stream, "# buckets: %lu\n", (unsigned long int) n_buckets); + fprintf (stream, "# buckets used: %lu (%.2f%%)\n", + (unsigned long int) n_buckets_used, (100.0 * n_buckets_used) / n_buckets); - fprintf (stream, "max bucket length: %u\n", max_bucket_length); + fprintf (stream, "max bucket length: %lu\n", + (unsigned long int) max_bucket_length); } /* If ENTRY matches an entry already in the hash table, return the @@ -225,11 +249,12 @@ hash_print_statistics (const Hash_table *table, FILE *stream) void * hash_lookup (const Hash_table *table, const void *entry) { - struct hash_entry *bucket + struct hash_entry const *bucket = table->bucket + table->hasher (entry, table->n_buckets); - struct hash_entry *cursor; + struct hash_entry const *cursor; - assert (bucket < table->bucket_limit); + if (! (bucket < table->bucket_limit)) + abort (); if (bucket->data == NULL) return NULL; @@ -253,30 +278,31 @@ hash_lookup (const Hash_table *table, const void *entry) void * hash_get_first (const Hash_table *table) { - struct hash_entry *bucket; + struct hash_entry const *bucket; if (table->n_entries == 0) return NULL; - for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) - if (bucket->data) + for (bucket = table->bucket; ; bucket++) + if (! (bucket < table->bucket_limit)) + abort (); + else if (bucket->data) return bucket->data; - - assert (0); } /* Return the user data for the entry following ENTRY, where ENTRY has been returned by a previous call to either `hash_get_first' or `hash_get_next'. - Return NULL if there is no more entries. */ + Return NULL if there are no more entries. */ void * hash_get_next (const Hash_table *table, const void *entry) { - struct hash_entry *bucket + struct hash_entry const *bucket = table->bucket + table->hasher (entry, table->n_buckets); - struct hash_entry *cursor; + struct hash_entry const *cursor; - assert (bucket < table->bucket_limit); + if (! (bucket < table->bucket_limit)) + abort (); /* Find next entry in the same bucket. */ for (cursor = bucket; cursor; cursor = cursor->next) @@ -284,7 +310,7 @@ hash_get_next (const Hash_table *table, const void *entry) return cursor->next->data; /* Find first entry in any subsequent bucket. */ - for (; bucket < table->bucket_limit; bucket++) + while (++bucket < table->bucket_limit) if (bucket->data) return bucket->data; @@ -296,13 +322,13 @@ hash_get_next (const Hash_table *table, const void *entry) return the number of pointers copied. Do not copy more than BUFFER_SIZE pointers. */ -unsigned +size_t hash_get_entries (const Hash_table *table, void **buffer, - unsigned buffer_size) + size_t buffer_size) { - unsigned counter = 0; - struct hash_entry *bucket; - struct hash_entry *cursor; + size_t counter = 0; + struct hash_entry const *bucket; + struct hash_entry const *cursor; for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) { @@ -328,13 +354,13 @@ hash_get_entries (const Hash_table *table, void **buffer, as received. The walking continue for as long as the PROCESSOR function returns nonzero. When it returns zero, the walking is interrupted. */ -unsigned +size_t hash_do_for_each (const Hash_table *table, Hash_processor processor, void *processor_data) { - unsigned counter = 0; - struct hash_entry *bucket; - struct hash_entry *cursor; + size_t counter = 0; + struct hash_entry const *bucket; + struct hash_entry const *cursor; for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) { @@ -365,21 +391,19 @@ hash_do_for_each (const Hash_table *table, Hash_processor processor, algorithms tend to be domain-specific, so what's good for [diffutils'] io.c may not be good for your application." */ -unsigned -hash_string (const char *string, unsigned n_buckets) +size_t +hash_string (const char *string, size_t n_buckets) { -# ifndef CHAR_BIT -# define CHAR_BIT 8 -# endif # define ROTATE_LEFT(Value, Shift) \ - ((Value) << (Shift) | (Value) >> ((sizeof (unsigned) * CHAR_BIT) - (Shift))) + ((Value) << (Shift) | (Value) >> ((sizeof (size_t) * CHAR_BIT) - (Shift))) # define HASH_ONE_CHAR(Value, Byte) \ ((Byte) + ROTATE_LEFT (Value, 7)) - unsigned value = 0; + size_t value = 0; + unsigned char ch; - for (; *string; string++) - value = HASH_ONE_CHAR (value, *(const unsigned char *) string); + for (; (ch = *string); string++) + value = HASH_ONE_CHAR (value, ch); return value % n_buckets; # undef ROTATE_LEFT @@ -393,14 +417,14 @@ hash_string (const char *string, unsigned n_buckets) very old Cyber `snoop', itself written in typical Greg Mansfield style. (By the way, what happened to this excellent man? Is he still alive?) */ -unsigned -hash_string (const char *string, unsigned n_buckets) +size_t +hash_string (const char *string, size_t n_buckets) { - unsigned value = 0; + size_t value = 0; + unsigned char ch; - while (*string) - value = ((value * 31 + (int) *(const unsigned char *) string++) - % n_buckets); + for (; (ch = *string); string++) + value = (value * 31 + ch) % n_buckets; return value; } @@ -410,10 +434,10 @@ hash_string (const char *string, unsigned n_buckets) number at least equal to 11. */ static bool -is_prime (unsigned long candidate) +is_prime (size_t candidate) { - unsigned long divisor = 3; - unsigned long square = divisor * divisor; + size_t divisor = 3; + size_t square = divisor * divisor; while (square < candidate && (candidate % divisor)) { @@ -422,14 +446,14 @@ is_prime (unsigned long candidate) divisor++; } - return candidate % divisor != 0; + return (candidate % divisor ? true : false); } /* Round a given CANDIDATE number up to the nearest prime, and return that prime. Primes lower than 10 are merely skipped. */ -static unsigned long -next_prime (unsigned long candidate) +static size_t +next_prime (size_t candidate) { /* Skip small primes. */ if (candidate < 10) @@ -461,14 +485,20 @@ check_tuning (Hash_table *table) { const Hash_tuning *tuning = table->tuning; - if (tuning->growth_threshold > 0.0 - && tuning->growth_threshold < 1.0 - && tuning->growth_factor > 1.0 - && tuning->shrink_threshold >= 0.0 - && tuning->shrink_threshold < 1.0 - && tuning->shrink_factor > tuning->shrink_threshold - && tuning->shrink_factor <= 1.0 - && tuning->shrink_threshold < tuning->growth_threshold) + /* Be a bit stricter than mathematics would require, so that + rounding errors in size calculations do not cause allocations to + fail to grow or shrink as they should. The smallest allocation + is 11 (due to next_prime's algorithm), so an epsilon of 0.1 + should be good enough. */ + float epsilon = 0.1f; + + if (epsilon < tuning->growth_threshold + && tuning->growth_threshold < 1 - epsilon + && 1 + epsilon < tuning->growth_factor + && 0 <= tuning->shrink_threshold + && tuning->shrink_threshold + epsilon < tuning->shrink_factor + && tuning->shrink_factor <= 1 + && tuning->shrink_threshold + epsilon < tuning->growth_threshold) return true; table->tuning = &default_tuning; @@ -507,17 +537,16 @@ check_tuning (Hash_table *table) values. */ Hash_table * -hash_initialize (unsigned candidate, const Hash_tuning *tuning, +hash_initialize (size_t candidate, const Hash_tuning *tuning, Hash_hasher hasher, Hash_comparator comparator, Hash_data_freer data_freer) { Hash_table *table; - struct hash_entry *bucket; if (hasher == NULL || comparator == NULL) return NULL; - table = (Hash_table *) malloc (sizeof (Hash_table)); + table = malloc (sizeof *table); if (table == NULL) return NULL; @@ -531,28 +560,25 @@ hash_initialize (unsigned candidate, const Hash_tuning *tuning, if the user provides invalid tuning options, we silently revert to using the defaults, and ignore further request to change the tuning options. */ - free (table); - return NULL; + goto fail; } - table->n_buckets - = next_prime (tuning->is_n_buckets ? candidate - : (unsigned) (candidate / tuning->growth_threshold)); - - table->bucket = (struct hash_entry *) - malloc (table->n_buckets * sizeof (struct hash_entry)); - if (table->bucket == NULL) + if (!tuning->is_n_buckets) { - free (table); - return NULL; + float new_candidate = candidate / tuning->growth_threshold; + if (SIZE_MAX <= new_candidate) + goto fail; + candidate = new_candidate; } - table->bucket_limit = table->bucket + table->n_buckets; - for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) - { - bucket->data = NULL; - bucket->next = NULL; - } + if (xalloc_oversized (candidate, sizeof *table->bucket)) + goto fail; + table->n_buckets = next_prime (candidate); + if (xalloc_oversized (table->n_buckets, sizeof *table->bucket)) + goto fail; + + table->bucket = calloc (table->n_buckets, sizeof *table->bucket); + table->bucket_limit = table->bucket + table->n_buckets; table->n_buckets_used = 0; table->n_entries = 0; @@ -565,6 +591,10 @@ hash_initialize (unsigned candidate, const Hash_tuning *tuning, obstack_init (&table->entry_stack); #endif return table; + + fail: + free (table); + return NULL; } /* Make all buckets empty, placing any chained entries on the free list. @@ -575,19 +605,22 @@ void hash_clear (Hash_table *table) { struct hash_entry *bucket; - struct hash_entry *cursor; for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) { if (bucket->data) { + struct hash_entry *cursor; + struct hash_entry *next; + /* Free the bucket overflow. */ - for (cursor = bucket->next; cursor; cursor = cursor->next) + for (cursor = bucket->next; cursor; cursor = next) { if (table->data_freer) (*table->data_freer) (cursor->data); cursor->data = NULL; + next = cursor->next; /* Relinking is done one entry at a time, as it is to be expected that overflows are either rare or short. */ cursor->next = table->free_entry_list; @@ -681,10 +714,9 @@ allocate_entry (Hash_table *table) else { #if USE_OBSTACK - new = (struct hash_entry *) - obstack_alloc (&table->entry_stack, sizeof (struct hash_entry)); + new = obstack_alloc (&table->entry_stack, sizeof *new); #else - new = (struct hash_entry *) malloc (sizeof (struct hash_entry)); + new = malloc (sizeof *new); #endif } @@ -716,14 +748,16 @@ hash_find_entry (Hash_table *table, const void *entry, = table->bucket + table->hasher (entry, table->n_buckets); struct hash_entry *cursor; - assert (bucket < table->bucket_limit); + if (! (bucket < table->bucket_limit)) + abort (); + *bucket_head = bucket; /* Test for empty bucket. */ if (bucket->data == NULL) return NULL; - /* Check if then entry is found as the bucket head. */ + /* See if the entry is the first in the bucket. */ if ((*table->comparator) (entry, bucket->data)) { void *data = bucket->data; @@ -782,7 +816,7 @@ hash_find_entry (Hash_table *table, const void *entry, exact number of buckets desired. */ bool -hash_rehash (Hash_table *table, unsigned candidate) +hash_rehash (Hash_table *table, size_t candidate) { Hash_table *new_table; struct hash_entry *bucket; @@ -810,7 +844,9 @@ hash_rehash (Hash_table *table, unsigned candidate) = (new_table->bucket + new_table->hasher (data, new_table->n_buckets)); - assert (new_bucket < new_table->bucket_limit); + if (! (new_bucket < new_table->bucket_limit)) + abort (); + next = cursor->next; if (new_bucket->data) @@ -854,6 +890,7 @@ hash_rehash (Hash_table *table, unsigned candidate) table->bucket_limit = new_table->bucket_limit; table->n_buckets = new_table->n_buckets; table->n_buckets_used = new_table->n_buckets_used; + table->free_entry_list = new_table->free_entry_list; /* table->n_entries already holds its value. */ #if USE_OBSTACK table->entry_stack = new_table->entry_stack; @@ -873,7 +910,9 @@ hash_insert (Hash_table *table, const void *entry) void *data; struct hash_entry *bucket; - assert (entry); /* cannot insert a NULL entry */ + /* The caller cannot insert a NULL entry. */ + if (! entry) + abort (); /* If there's a matching entry already in the table, return that. */ if ((data = hash_find_entry (table, entry, &bucket, false)) != NULL) @@ -918,11 +957,14 @@ hash_insert (Hash_table *table, const void *entry) > table->tuning->growth_threshold * table->n_buckets) { const Hash_tuning *tuning = table->tuning; - unsigned candidate - = (unsigned) (tuning->is_n_buckets - ? (table->n_buckets * tuning->growth_factor) - : (table->n_buckets * tuning->growth_factor - * tuning->growth_threshold)); + float candidate = + (tuning->is_n_buckets + ? (table->n_buckets * tuning->growth_factor) + : (table->n_buckets * tuning->growth_factor + * tuning->growth_threshold)); + + if (SIZE_MAX <= candidate) + return NULL; /* If the rehash fails, arrange to return NULL. */ if (!hash_rehash (table, candidate)) @@ -943,7 +985,8 @@ hash_delete (Hash_table *table, const void *entry) void *data; struct hash_entry *bucket; - if (data = hash_find_entry (table, entry, &bucket, true), !data) + data = hash_find_entry (table, entry, &bucket, true); + if (!data) return NULL; table->n_entries--; @@ -964,11 +1007,11 @@ hash_delete (Hash_table *table, const void *entry) < table->tuning->shrink_threshold * table->n_buckets) { const Hash_tuning *tuning = table->tuning; - unsigned candidate - = (unsigned) (tuning->is_n_buckets - ? table->n_buckets * tuning->shrink_factor - : (table->n_buckets * tuning->shrink_factor - * tuning->growth_threshold)); + size_t candidate = + (tuning->is_n_buckets + ? table->n_buckets * tuning->shrink_factor + : (table->n_buckets * tuning->shrink_factor + * tuning->growth_threshold)); hash_rehash (table, candidate); } @@ -985,20 +1028,21 @@ hash_delete (Hash_table *table, const void *entry) void hash_print (const Hash_table *table) { - struct hash_entry *bucket; + struct hash_entry const *bucket; for (bucket = table->bucket; bucket < table->bucket_limit; bucket++) { struct hash_entry *cursor; if (bucket) - printf ("%d:\n", slot); + printf ("%lu:\n", (unsigned long int) (bucket - table->bucket)); for (cursor = bucket; cursor; cursor = cursor->next) { - char *s = (char *) cursor->data; + char const *s = cursor->data; /* FIXME */ - printf (" %s\n", s); + if (s) + printf (" %s\n", s); } } }