diff options
| -rw-r--r-- | COPYING.md | 2 | ||||
| -rw-r--r-- | lib/sqfs/Makemodule.am | 1 | ||||
| -rw-r--r-- | lib/sqfs/frag_table.c | 116 | ||||
| -rw-r--r-- | lib/util/fast_urem_by_const.h | 75 | ||||
| -rw-r--r-- | lib/util/hash_table.c | 415 | ||||
| -rw-r--r-- | lib/util/hash_table.h | 86 |
6 files changed, 623 insertions, 72 deletions
@@ -14,6 +14,8 @@ with the following exceptions: - `lib/sqfs/comp/zlib` contains files that have been extracted from the the zlib compression library and modified. See `lib/sqfs/comp/zlib/README` for details and `licenses/zlib.txt` for details. + - `lib/util/hash_table.*` and `lib/util/fast_urem_by_const.h` contain a hash + table implementation (MIT license). The rest of squashfs-tools-ng is released under the terms and conditions of the **GNU General Public License version 3 or later**. diff --git a/lib/sqfs/Makemodule.am b/lib/sqfs/Makemodule.am index 942c37c..32b4c25 100644 --- a/lib/sqfs/Makemodule.am +++ b/lib/sqfs/Makemodule.am @@ -36,6 +36,7 @@ libsquashfs_la_LIBADD += $(ZSTD_LIBS) $(PTHREAD_LIBS) # directly "import" stuff from libutil libsquashfs_la_SOURCES += lib/util/str_table.c lib/util/alloc.c libsquashfs_la_SOURCES += lib/util/xxhash.c +libsquashfs_la_SOURCES += lib/util/hash_table.c lib/util/hash_table.h if WINDOWS libsquashfs_la_SOURCES += lib/sqfs/win32/io_file.c diff --git a/lib/sqfs/frag_table.c b/lib/sqfs/frag_table.c index 51164e6..59811bb 100644 --- a/lib/sqfs/frag_table.c +++ b/lib/sqfs/frag_table.c @@ -14,13 +14,12 @@ #include "sqfs/block.h" #include "compat.h" +#include "lib/util/hash_table.h" + #include <stdlib.h> #include <string.h> -#define NUM_BUCKETS (128) - - typedef struct chunk_info_t { struct chunk_info_t *next; sqfs_u32 index; @@ -37,23 +36,32 @@ struct sqfs_frag_table_t { size_t used; sqfs_fragment_t *table; - chunk_info_t chunks[NUM_BUCKETS]; + struct hash_table *ht; }; +static uint32_t chunk_info_hash(const void *key) +{ + const chunk_info_t *chunk = key; + return chunk->hash; +} + +static bool chunk_info_equals(const void *a, const void *b) +{ + const chunk_info_t *a_ = a, *b_ = b; + return a_->size == b_->size && + a_->hash == b_->hash; +} + +static void delete_function(struct hash_entry *entry) +{ + free(entry->data); +} + static void frag_table_destroy(sqfs_object_t *obj) { sqfs_frag_table_t *tbl = (sqfs_frag_table_t *)obj; - chunk_info_t *info; - size_t i; - - for (i = 0; i < NUM_BUCKETS; ++i) { - while (tbl->chunks[i].next != NULL) { - info = tbl->chunks[i].next; - tbl->chunks[i].next = info->next; - free(info); - } - } + hash_table_destroy(tbl->ht, delete_function); free(tbl->table); free(tbl); } @@ -62,38 +70,15 @@ static sqfs_object_t *frag_table_copy(const sqfs_object_t *obj) { const sqfs_frag_table_t *tbl = (const sqfs_frag_table_t *)obj; sqfs_frag_table_t *copy; - const chunk_info_t *it; - chunk_info_t *last; - size_t i; copy = malloc(sizeof(*copy)); if (copy == NULL) return NULL; memcpy(copy, tbl, sizeof(*tbl)); - for (i = 0; i < NUM_BUCKETS; ++i) - copy->chunks[i].next = NULL; - - for (i = 0; i < NUM_BUCKETS; ++i) { - last = &(copy->chunks[i]); - it = tbl->chunks[i].next; - - while (it != NULL) { - last->next = malloc(sizeof(*it)); - if (last->next == NULL) - goto fail; - - memcpy(last->next, it, sizeof(*it)); - last = last->next; - last->next = NULL; - it = it->next; - } - } + copy->ht = hash_table_clone(tbl->ht); return (sqfs_object_t *)copy; -fail: - frag_table_destroy((sqfs_object_t *)copy); - return NULL; } sqfs_frag_table_t *sqfs_frag_table_create(sqfs_u32 flags) @@ -107,6 +92,8 @@ sqfs_frag_table_t *sqfs_frag_table_create(sqfs_u32 flags) if (tbl == NULL) return NULL; + tbl->ht = hash_table_create(chunk_info_hash, chunk_info_equals); + ((sqfs_object_t *)tbl)->copy = frag_table_copy; ((sqfs_object_t *)tbl)->destroy = frag_table_destroy; return tbl; @@ -267,30 +254,16 @@ int sqfs_frag_table_add_tail_end(sqfs_frag_table_t *tbl, sqfs_u32 index, sqfs_u32 offset, sqfs_u32 size, sqfs_u32 hash) { - size_t idx = hash % NUM_BUCKETS; - chunk_info_t *new, *it; - - if (tbl->chunks[idx].size == 0 && tbl->chunks[idx].hash == 0) { - tbl->chunks[idx].index = index; - tbl->chunks[idx].offset = offset; - tbl->chunks[idx].size = size; - tbl->chunks[idx].hash = hash; - } else { - new = calloc(1, sizeof(*new)); - if (new == NULL) - return SQFS_ERROR_ALLOC; + chunk_info_t *new = calloc(1, sizeof(*new)); + if (new == NULL) + return SQFS_ERROR_ALLOC; - new->index = index; - new->offset = offset; - new->size = size; - new->hash = hash; + new->index = index; + new->offset = offset; + new->size = size; + new->hash = hash; - it = &tbl->chunks[idx]; - while (it->next != NULL) - it = it->next; - - it->next = new; - } + hash_table_insert_pre_hashed(tbl->ht, new->hash, new, new); return 0; } @@ -299,19 +272,18 @@ int sqfs_frag_table_find_tail_end(sqfs_frag_table_t *tbl, sqfs_u32 hash, sqfs_u32 size, sqfs_u32 *index, sqfs_u32 *offset) { - size_t idx = hash % NUM_BUCKETS; - chunk_info_t *it; + struct hash_entry *entry; + chunk_info_t *chunk, search; - if (tbl->chunks[idx].size == 0 && tbl->chunks[idx].hash == 0) - return SQFS_ERROR_NO_ENTRY; + search.hash = hash; + search.size = size; - for (it = &tbl->chunks[idx]; it != NULL; it = it->next) { - if (it->hash == hash && it->size == size) { - *index = it->index; - *offset = it->offset; - return 0; - } - } + entry = hash_table_search_pre_hashed(tbl->ht, hash, &search); + if (!entry) + return SQFS_ERROR_NO_ENTRY; - return SQFS_ERROR_NO_ENTRY; + chunk = entry->data; + *index = chunk->index; + *offset = chunk->offset; + return 0; } diff --git a/lib/util/fast_urem_by_const.h b/lib/util/fast_urem_by_const.h new file mode 100644 index 0000000..62b22a6 --- /dev/null +++ b/lib/util/fast_urem_by_const.h @@ -0,0 +1,75 @@ +/* + * Copyright © 2010 Valve Software + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + */ + +#include <assert.h> +#include <stdint.h> + +/* + * Code for fast 32-bit unsigned remainder, based off of "Faster Remainder by + * Direct Computation: Applications to Compilers and Software Libraries," + * available at https://arxiv.org/pdf/1902.01961.pdf. + * + * util_fast_urem32(n, d, REMAINDER_MAGIC(d)) returns the same thing as + * n % d for any unsigned n and d, however it compiles down to only a few + * multiplications, so it should be faster than plain uint32_t modulo if the + * same divisor is used many times. + */ + +#define REMAINDER_MAGIC(divisor) \ + ((uint64_t) ~0ull / (divisor) + 1) + +/* + * Get bits 64-96 of a 32x64-bit multiply. If __int128_t is available, we use + * it, which usually compiles down to one instruction on 64-bit architectures. + * Otherwise on 32-bit architectures we usually get four instructions (one + * 32x32->64 multiply, one 32x32->32 multiply, and one 64-bit add). + */ + +static inline uint32_t +_mul32by64_hi(uint32_t a, uint64_t b) +{ +#ifdef HAVE_UINT128 + return ((__uint128_t) b * a) >> 64; +#else + /* + * Let b = b0 + 2^32 * b1. Then a * b = a * b0 + 2^32 * a * b1. We would + * have to do a 96-bit addition to get the full result, except that only + * one term has non-zero lower 32 bits, which means that to get the high 32 + * bits, we only have to add the high 64 bits of each term. Unfortunately, + * we have to do the 64-bit addition in case the low 32 bits overflow. + */ + uint32_t b0 = (uint32_t) b; + uint32_t b1 = b >> 32; + return ((((uint64_t) a * b0) >> 32) + (uint64_t) a * b1) >> 32; +#endif +} + +static inline uint32_t +util_fast_urem32(uint32_t n, uint32_t d, uint64_t magic) +{ + uint64_t lowbits = magic * n; + uint32_t result = _mul32by64_hi(d, lowbits); + assert(result == n % d); + return result; +} + diff --git a/lib/util/hash_table.c b/lib/util/hash_table.c new file mode 100644 index 0000000..d2cce54 --- /dev/null +++ b/lib/util/hash_table.c @@ -0,0 +1,415 @@ +/* + * Copyright © 2009,2012 Intel Corporation + * Copyright © 1988-2004 Keith Packard and Bart Massey. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + * Except as contained in this notice, the names of the authors + * or their institutions shall not be used in advertising or + * otherwise to promote the sale, use or other dealings in this + * Software without prior written authorization from the + * authors. + * + * Authors: + * Eric Anholt <eric@anholt.net> + * Keith Packard <keithp@keithp.com> + */ + +/** + * Implements an open-addressing, linear-reprobing hash table. + * + * For more information, see: + * + * http://cgit.freedesktop.org/~anholt/hash_table/tree/README + */ + +#include <stdlib.h> +#include <string.h> +#include <assert.h> + +#include "fast_urem_by_const.h" +#include "hash_table.h" + +# define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) + +static const uint32_t deleted_key_value; + +/** + * From Knuth -- a good choice for hash/rehash values is p, p-2 where + * p and p-2 are both prime. These tables are sized to have an extra 10% + * free to avoid exponential performance degradation as the hash table fills + */ +static const struct { + uint32_t max_entries, size, rehash; + uint64_t size_magic, rehash_magic; +} hash_sizes[] = { +#define ENTRY(max_entries, size, rehash) \ + { max_entries, size, rehash, \ + REMAINDER_MAGIC(size), REMAINDER_MAGIC(rehash) } + + ENTRY(2, 5, 3 ), + ENTRY(4, 7, 5 ), + ENTRY(8, 13, 11 ), + ENTRY(16, 19, 17 ), + ENTRY(32, 43, 41 ), + ENTRY(64, 73, 71 ), + ENTRY(128, 151, 149 ), + ENTRY(256, 283, 281 ), + ENTRY(512, 571, 569 ), + ENTRY(1024, 1153, 1151 ), + ENTRY(2048, 2269, 2267 ), + ENTRY(4096, 4519, 4517 ), + ENTRY(8192, 9013, 9011 ), + ENTRY(16384, 18043, 18041 ), + ENTRY(32768, 36109, 36107 ), + ENTRY(65536, 72091, 72089 ), + ENTRY(131072, 144409, 144407 ), + ENTRY(262144, 288361, 288359 ), + ENTRY(524288, 576883, 576881 ), + ENTRY(1048576, 1153459, 1153457 ), + ENTRY(2097152, 2307163, 2307161 ), + ENTRY(4194304, 4613893, 4613891 ), + ENTRY(8388608, 9227641, 9227639 ), + ENTRY(16777216, 18455029, 18455027 ), + ENTRY(33554432, 36911011, 36911009 ), + ENTRY(67108864, 73819861, 73819859 ), + ENTRY(134217728, 147639589, 147639587 ), + ENTRY(268435456, 295279081, 295279079 ), + ENTRY(536870912, 590559793, 590559791 ), + ENTRY(1073741824, 1181116273, 1181116271 ), + ENTRY(2147483648ul, 2362232233ul, 2362232231ul ) +}; + +static inline bool +key_pointer_is_reserved(const struct hash_table *ht, const void *key) +{ + return key == NULL || key == ht->deleted_key; +} + +static int +entry_is_free(const struct hash_entry *entry) +{ + return entry->key == NULL; +} + +static int +entry_is_deleted(const struct hash_table *ht, struct hash_entry *entry) +{ + return entry->key == ht->deleted_key; +} + +static int +entry_is_present(const struct hash_table *ht, struct hash_entry *entry) +{ + return entry->key != NULL && entry->key != ht->deleted_key; +} + +static bool +hash_table_init(struct hash_table *ht, + uint32_t (*key_hash_function)(const void *key), + bool (*key_equals_function)(const void *a, + const void *b)) +{ + ht->size_index = 0; + ht->size = hash_sizes[ht->size_index].size; + ht->rehash = hash_sizes[ht->size_index].rehash; + ht->size_magic = hash_sizes[ht->size_index].size_magic; + ht->rehash_magic = hash_sizes[ht->size_index].rehash_magic; + ht->max_entries = hash_sizes[ht->size_index].max_entries; + ht->key_hash_function = key_hash_function; + ht->key_equals_function = key_equals_function; + ht->table = calloc(sizeof(struct hash_entry), ht->size); + ht->entries = 0; + ht->deleted_entries = 0; + ht->deleted_key = &deleted_key_value; + + return ht->table != NULL; +} + +struct hash_table * +hash_table_create(uint32_t (*key_hash_function)(const void *key), + bool (*key_equals_function)(const void *a, + const void *b)) +{ + struct hash_table *ht; + + ht = malloc(sizeof(struct hash_table)); + if (ht == NULL) + return NULL; + + if (!hash_table_init(ht, key_hash_function, key_equals_function)) { + free(ht); + return NULL; + } + + return ht; +} + +struct hash_table * +hash_table_clone(struct hash_table *src) +{ + struct hash_table *ht; + + ht = malloc(sizeof(struct hash_table)); + if (ht == NULL) + return NULL; + + memcpy(ht, src, sizeof(struct hash_table)); + + ht->table = calloc(sizeof(struct hash_entry), ht->size); + if (ht->table == NULL) { + free(ht); + return NULL; + } + + memcpy(ht->table, src->table, ht->size * sizeof(struct hash_entry)); + + return ht; +} + +/** + * Frees the given hash table. + */ +void +hash_table_destroy(struct hash_table *ht, + void (*delete_function)(struct hash_entry *entry)) +{ + if (!ht) + return; + + if (delete_function) { + hash_table_foreach(ht, entry) { + delete_function(entry); + } + } + free(ht->table); + free(ht); +} + +static struct hash_entry * +hash_table_search(struct hash_table *ht, uint32_t hash, const void *key) +{ + assert(!key_pointer_is_reserved(ht, key)); + + uint32_t size = ht->size; + uint32_t start_hash_address = util_fast_urem32(hash, size, ht->size_magic); + uint32_t double_hash = 1 + util_fast_urem32(hash, ht->rehash, + ht->rehash_magic); + uint32_t hash_address = start_hash_address; + + do { + struct hash_entry *entry = ht->table + hash_address; + + if (entry_is_free(entry)) { + return NULL; + } else if (entry_is_present(ht, entry) && entry->hash == hash) { + if (ht->key_equals_function(key, entry->key)) { + return entry; + } + } + + hash_address += double_hash; + if (hash_address >= size) + hash_address -= size; + } while (hash_address != start_hash_address); + + return NULL; +} + +/** + * Finds a hash table entry with the given key and hash of that key. + * + * Returns NULL if no entry is found. Note that the data pointer may be + * modified by the user. + */ +struct hash_entry * +hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash, + const void *key) +{ + assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key)); + return hash_table_search(ht, hash, key); +} + +static void +hash_table_insert_rehash(struct hash_table *ht, uint32_t hash, + const void *key, void *data) +{ + uint32_t size = ht->size; + uint32_t start_hash_address = util_fast_urem32(hash, size, ht->size_magic); + uint32_t double_hash = 1 + util_fast_urem32(hash, ht->rehash, + ht->rehash_magic); + uint32_t hash_address = start_hash_address; + do { + struct hash_entry *entry = ht->table + hash_address; + + if (entry->key == NULL) { + entry->hash = hash; + entry->key = key; + entry->data = data; + return; + } + + hash_address += double_hash; + if (hash_address >= size) + hash_address -= size; + } while (true); +} + +static void +hash_table_rehash(struct hash_table *ht, unsigned new_size_index) +{ + struct hash_table old_ht; + struct hash_entry *table; + + if (new_size_index >= ARRAY_SIZE(hash_sizes)) + return; + + table = calloc(sizeof(struct hash_entry), hash_sizes[new_size_index].size); + if (table == NULL) + return; + + old_ht = *ht; + + ht->table = table; + ht->size_index = new_size_index; + ht->size = hash_sizes[ht->size_index].size; + ht->rehash = hash_sizes[ht->size_index].rehash; + ht->size_magic = hash_sizes[ht->size_index].size_magic; + ht->rehash_magic = hash_sizes[ht->size_index].rehash_magic; + ht->max_entries = hash_sizes[ht->size_index].max_entries; + ht->entries = 0; + ht->deleted_entries = 0; + + hash_table_foreach(&old_ht, entry) { + hash_table_insert_rehash(ht, entry->hash, entry->key, entry->data); + } + + ht->entries = old_ht.entries; + + free(old_ht.table); +} + +static struct hash_entry * +hash_table_insert(struct hash_table *ht, uint32_t hash, + const void *key, void *data) +{ + struct hash_entry *available_entry = NULL; + + assert(!key_pointer_is_reserved(ht, key)); + + if (ht->entries >= ht->max_entries) { + hash_table_rehash(ht, ht->size_index + 1); + } else if (ht->deleted_entries + ht->entries >= ht->max_entries) { + hash_table_rehash(ht, ht->size_index); + } + + uint32_t size = ht->size; + uint32_t start_hash_address = util_fast_urem32(hash, size, ht->size_magic); + uint32_t double_hash = 1 + util_fast_urem32(hash, ht->rehash, + ht->rehash_magic); + uint32_t hash_address = start_hash_address; + do { + struct hash_entry *entry = ht->table + hash_address; + + if (!entry_is_present(ht, entry)) { + /* Stash the first available entry we find */ + if (available_entry == NULL) + available_entry = entry; + if (entry_is_free(entry)) + break; + } + + /* Implement replacement when another insert happens + * with a matching key. This is a relatively common + * feature of hash tables, with the alternative + * generally being "insert the new value as well, and + * return it first when the key is searched for". + * + * Note that the hash table doesn't have a delete + * callback. If freeing of old data pointers is + * required to avoid memory leaks, perform a search + * before inserting. + */ + if (!entry_is_deleted(ht, entry) && + entry->hash == hash && + ht->key_equals_function(key, entry->key)) { + entry->key = key; + entry->data = data; + return entry; + } + + hash_address += double_hash; + if (hash_address >= size) + hash_address -= size; + } while (hash_address != start_hash_address); + + if (available_entry) { + if (entry_is_deleted(ht, available_entry)) + ht->deleted_entries--; + available_entry->hash = hash; + available_entry->key = key; + available_entry->data = data; + ht->entries++; + return available_entry; + } + + /* We could hit here if a required resize failed. An unchecked-malloc + * application could ignore this result. + */ + return NULL; +} + +/** + * Inserts the key with the given hash into the table. + * + * Note that insertion may rearrange the table on a resize or rehash, + * so previously found hash_entries are no longer valid after this function. + */ +struct hash_entry * +hash_table_insert_pre_hashed(struct hash_table *ht, uint32_t hash, + const void *key, void *data) +{ + assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key)); + return hash_table_insert(ht, hash, key, data); +} + +/** + * This function is an iterator over the hash table. + * + * Pass in NULL for the first entry, as in the start of a for loop. Note that + * an iteration over the table is O(table_size) not O(entries). + */ +struct hash_entry * +hash_table_next_entry(struct hash_table *ht, + struct hash_entry *entry) +{ + if (entry == NULL) + entry = ht->table; + else + entry = entry + 1; + + for (; entry != ht->table + ht->size; entry++) { + if (entry_is_present(ht, entry)) { + return entry; + } + } + + return NULL; +} diff --git a/lib/util/hash_table.h b/lib/util/hash_table.h new file mode 100644 index 0000000..ccbd9c0 --- /dev/null +++ b/lib/util/hash_table.h @@ -0,0 +1,86 @@ +/* + * Copyright © 2009,2012 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + * Authors: + * Eric Anholt <eric@anholt.net> + * + */ + +#ifndef _HASH_TABLE_H +#define _HASH_TABLE_H + +#include <stdlib.h> +#include <inttypes.h> +#include <stdbool.h> + +struct hash_entry { + uint32_t hash; + const void *key; + void *data; +}; + +struct hash_table { + struct hash_entry *table; + uint32_t (*key_hash_function)(const void *key); + bool (*key_equals_function)(const void *a, const void *b); + const void *deleted_key; + uint32_t size; + uint32_t rehash; + uint64_t size_magic; + uint64_t rehash_magic; + uint32_t max_entries; + uint32_t size_index; + uint32_t entries; + uint32_t deleted_entries; +}; + +struct hash_table * +hash_table_create(uint32_t (*key_hash_function)(const void *key), + bool (*key_equals_function)(const void *a, + const void *b)); + +struct hash_table * +hash_table_clone(struct hash_table *src); +void hash_table_destroy(struct hash_table *ht, + void (*delete_function)(struct hash_entry *entry)); + +struct hash_entry * +hash_table_insert_pre_hashed(struct hash_table *ht, uint32_t hash, + const void *key, void *data); +struct hash_entry * +hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash, + const void *key); + +struct hash_entry *hash_table_next_entry(struct hash_table *ht, + struct hash_entry *entry); + +/** + * This foreach function is safe against deletion (which just replaces + * an entry's data with the deleted marker), but not against insertion + * (which may rehash the table, making entry a dangling pointer). + */ +#define hash_table_foreach(ht, entry) \ + for (struct hash_entry *entry = hash_table_next_entry(ht, NULL); \ + entry != NULL; \ + entry = hash_table_next_entry(ht, entry)) + +#endif /* _HASH_TABLE_H */ |