diff options
Diffstat (limited to 'lib/hash.c')
-rw-r--r-- | lib/hash.c | 214 |
1 files changed, 113 insertions, 101 deletions
diff --git a/lib/hash.c b/lib/hash.c index 3948ce4cf..ad4599e4d 100644 --- a/lib/hash.c +++ b/lib/hash.c @@ -28,8 +28,9 @@ # include <config.h> #endif +#include "hash.h" + #include <limits.h> -#include <stdbool.h> #include <stdio.h> #include <stdlib.h> @@ -43,7 +44,9 @@ # endif #endif -#include "hash.h" +#ifndef SIZE_MAX +# define SIZE_MAX ((size_t) -1) +#endif struct hash_table { @@ -51,10 +54,10 @@ struct hash_table 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 *bucket_limit; - unsigned n_buckets; - unsigned n_buckets_used; - unsigned n_entries; + 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; @@ -142,7 +145,7 @@ 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; @@ -150,7 +153,7 @@ 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; @@ -158,7 +161,7 @@ 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; @@ -166,18 +169,18 @@ 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++; @@ -196,15 +199,15 @@ 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++; @@ -225,16 +228,18 @@ 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 @@ -243,9 +248,9 @@ 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; if (! (bucket < table->bucket_limit)) abort (); @@ -272,7 +277,7 @@ 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; @@ -291,9 +296,9 @@ hash_get_first (const Hash_table *table) 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; if (! (bucket < table->bucket_limit)) abort (); @@ -316,13 +321,13 @@ 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++) { @@ -348,13 +353,13 @@ 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++) { @@ -385,18 +390,18 @@ 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) { # 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; for (; *string; string++) - value = HASH_ONE_CHAR (value, *(const unsigned char *) string); + value = HASH_ONE_CHAR (value, (unsigned char) *string); return value % n_buckets; # undef ROTATE_LEFT @@ -410,14 +415,13 @@ 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; while (*string) - value = ((value * 31 + (int) *(const unsigned char *) string++) - % n_buckets); + value = (value * 31 + (unsigned char) *string++) % n_buckets; return value; } @@ -427,10 +431,10 @@ 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)) { @@ -445,8 +449,8 @@ is_prime (unsigned long candidate) /* 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) @@ -478,14 +482,20 @@ 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; @@ -524,17 +534,16 @@ 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; @@ -548,28 +557,25 @@ 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 (SIZE_MAX / sizeof *table->bucket < candidate) + goto fail; + table->n_buckets = next_prime (candidate); + if (SIZE_MAX / sizeof *table->bucket < table->n_buckets) + 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; @@ -582,6 +588,10 @@ 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. @@ -701,10 +711,9 @@ 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 } @@ -804,7 +813,7 @@ 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; @@ -945,11 +954,14 @@ 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)) @@ -992,11 +1004,11 @@ 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); } @@ -1013,18 +1025,18 @@ 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", bucket - table->bucket); + 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 */ if (s) printf (" %s\n", s); |