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Diffstat (limited to 'third_party/git/hashmap.h')
-rw-r--r-- | third_party/git/hashmap.h | 547 |
1 files changed, 0 insertions, 547 deletions
diff --git a/third_party/git/hashmap.h b/third_party/git/hashmap.h deleted file mode 100644 index b011b394fefe..000000000000 --- a/third_party/git/hashmap.h +++ /dev/null @@ -1,547 +0,0 @@ -#ifndef HASHMAP_H -#define HASHMAP_H - -#include "hash.h" - -/* - * Generic implementation of hash-based key-value mappings. - * - * An example that maps long to a string: - * For the sake of the example this allows to lookup exact values, too - * (i.e. it is operated as a set, the value is part of the key) - * ------------------------------------- - * - * struct hashmap map; - * struct long2string { - * struct hashmap_entry ent; - * long key; - * char value[FLEX_ARRAY]; // be careful with allocating on stack! - * }; - * - * #define COMPARE_VALUE 1 - * - * static int long2string_cmp(const void *hashmap_cmp_fn_data, - * const struct hashmap_entry *eptr, - * const struct hashmap_entry *entry_or_key, - * const void *keydata) - * { - * const char *string = keydata; - * unsigned flags = *(unsigned *)hashmap_cmp_fn_data; - * const struct long2string *e1, *e2; - * - * e1 = container_of(eptr, const struct long2string, ent); - * e2 = container_of(entry_or_key, const struct long2string, ent); - * - * if (flags & COMPARE_VALUE) - * return e1->key != e2->key || - * strcmp(e1->value, string ? string : e2->value); - * else - * return e1->key != e2->key; - * } - * - * int main(int argc, char **argv) - * { - * long key; - * char value[255], action[32]; - * unsigned flags = 0; - * - * hashmap_init(&map, long2string_cmp, &flags, 0); - * - * while (scanf("%s %ld %s", action, &key, value)) { - * - * if (!strcmp("add", action)) { - * struct long2string *e; - * FLEX_ALLOC_STR(e, value, value); - * hashmap_entry_init(&e->ent, memhash(&key, sizeof(long))); - * e->key = key; - * hashmap_add(&map, &e->ent); - * } - * - * if (!strcmp("print_all_by_key", action)) { - * struct long2string k, *e; - * hashmap_entry_init(&k.ent, memhash(&key, sizeof(long))); - * k.key = key; - * - * flags &= ~COMPARE_VALUE; - * e = hashmap_get_entry(&map, &k, ent, NULL); - * if (e) { - * printf("first: %ld %s\n", e->key, e->value); - * while ((e = hashmap_get_next_entry(&map, e, - * struct long2string, ent))) { - * printf("found more: %ld %s\n", e->key, e->value); - * } - * } - * } - * - * if (!strcmp("has_exact_match", action)) { - * struct long2string *e; - * FLEX_ALLOC_STR(e, value, value); - * hashmap_entry_init(&e->ent, memhash(&key, sizeof(long))); - * e->key = key; - * - * flags |= COMPARE_VALUE; - * printf("%sfound\n", - * hashmap_get(&map, &e->ent, NULL) ? "" : "not "); - * free(e); - * } - * - * if (!strcmp("has_exact_match_no_heap_alloc", action)) { - * struct long2string k; - * hashmap_entry_init(&k.ent, memhash(&key, sizeof(long))); - * k.key = key; - * - * flags |= COMPARE_VALUE; - * printf("%sfound\n", - * hashmap_get(&map, &k.ent, value) ? "" : "not "); - * } - * - * if (!strcmp("end", action)) { - * hashmap_free_entries(&map, struct long2string, ent); - * break; - * } - * } - * - * return 0; - * } - */ - -/* - * Ready-to-use hash functions for strings, using the FNV-1 algorithm (see - * http://www.isthe.com/chongo/tech/comp/fnv). - * `strhash` and `strihash` take 0-terminated strings, while `memhash` and - * `memihash` operate on arbitrary-length memory. - * `strihash` and `memihash` are case insensitive versions. - * `memihash_cont` is a variant of `memihash` that allows a computation to be - * continued with another chunk of data. - */ -unsigned int strhash(const char *buf); -unsigned int strihash(const char *buf); -unsigned int memhash(const void *buf, size_t len); -unsigned int memihash(const void *buf, size_t len); -unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len); - -/* - * Converts a cryptographic hash (e.g. SHA-1) into an int-sized hash code - * for use in hash tables. Cryptographic hashes are supposed to have - * uniform distribution, so in contrast to `memhash()`, this just copies - * the first `sizeof(int)` bytes without shuffling any bits. Note that - * the results will be different on big-endian and little-endian - * platforms, so they should not be stored or transferred over the net. - */ -static inline unsigned int oidhash(const struct object_id *oid) -{ - /* - * Equivalent to 'return *(unsigned int *)oid->hash;', but safe on - * platforms that don't support unaligned reads. - */ - unsigned int hash; - memcpy(&hash, oid->hash, sizeof(hash)); - return hash; -} - -/* - * struct hashmap_entry is an opaque structure representing an entry in the - * hash table. - * Ideally it should be followed by an int-sized member to prevent unused - * memory on 64-bit systems due to alignment. - */ -struct hashmap_entry { - /* - * next points to the next entry in case of collisions (i.e. if - * multiple entries map to the same bucket) - */ - struct hashmap_entry *next; - - /* entry's hash code */ - unsigned int hash; -}; - -/* - * User-supplied function to test two hashmap entries for equality. Shall - * return 0 if the entries are equal. - * - * This function is always called with non-NULL `entry` and `entry_or_key` - * parameters that have the same hash code. - * - * When looking up an entry, the `key` and `keydata` parameters to hashmap_get - * and hashmap_remove are always passed as second `entry_or_key` and third - * argument `keydata`, respectively. Otherwise, `keydata` is NULL. - * - * When it is too expensive to allocate a user entry (either because it is - * large or variable sized, such that it is not on the stack), then the - * relevant data to check for equality should be passed via `keydata`. - * In this case `key` can be a stripped down version of the user key data - * or even just a hashmap_entry having the correct hash. - * - * The `hashmap_cmp_fn_data` entry is the pointer given in the init function. - */ -typedef int (*hashmap_cmp_fn)(const void *hashmap_cmp_fn_data, - const struct hashmap_entry *entry, - const struct hashmap_entry *entry_or_key, - const void *keydata); - -/* - * struct hashmap is the hash table structure. Members can be used as follows, - * but should not be modified directly. - */ -struct hashmap { - struct hashmap_entry **table; - - /* Stores the comparison function specified in `hashmap_init()`. */ - hashmap_cmp_fn cmpfn; - const void *cmpfn_data; - - /* total number of entries (0 means the hashmap is empty) */ - unsigned int private_size; /* use hashmap_get_size() */ - - /* - * tablesize is the allocated size of the hash table. A non-0 value - * indicates that the hashmap is initialized. It may also be useful - * for statistical purposes (i.e. `size / tablesize` is the current - * load factor). - */ - unsigned int tablesize; - - unsigned int grow_at; - unsigned int shrink_at; - - unsigned int do_count_items : 1; -}; - -/* hashmap functions */ - -/* - * Initializes a hashmap structure. - * - * `map` is the hashmap to initialize. - * - * The `equals_function` can be specified to compare two entries for equality. - * If NULL, entries are considered equal if their hash codes are equal. - * - * The `equals_function_data` parameter can be used to provide additional data - * (a callback cookie) that will be passed to `equals_function` each time it - * is called. This allows a single `equals_function` to implement multiple - * comparison functions. - * - * If the total number of entries is known in advance, the `initial_size` - * parameter may be used to preallocate a sufficiently large table and thus - * prevent expensive resizing. If 0, the table is dynamically resized. - */ -void hashmap_init(struct hashmap *map, - hashmap_cmp_fn equals_function, - const void *equals_function_data, - size_t initial_size); - -/* internal function for freeing hashmap */ -void hashmap_free_(struct hashmap *map, ssize_t offset); - -/* - * Frees a hashmap structure and allocated memory, leaves entries undisturbed - */ -#define hashmap_free(map) hashmap_free_(map, -1) - -/* - * Frees @map and all entries. @type is the struct type of the entry - * where @member is the hashmap_entry struct used to associate with @map - */ -#define hashmap_free_entries(map, type, member) \ - hashmap_free_(map, offsetof(type, member)); - -/* hashmap_entry functions */ - -/* - * Initializes a hashmap_entry structure. - * - * `entry` points to the entry to initialize. - * `hash` is the hash code of the entry. - * - * The hashmap_entry structure does not hold references to external resources, - * and it is safe to just discard it once you are done with it (i.e. if - * your structure was allocated with xmalloc(), you can just free(3) it, - * and if it is on stack, you can just let it go out of scope). - */ -static inline void hashmap_entry_init(struct hashmap_entry *e, - unsigned int hash) -{ - e->hash = hash; - e->next = NULL; -} - -/* - * Return the number of items in the map. - */ -static inline unsigned int hashmap_get_size(struct hashmap *map) -{ - if (map->do_count_items) - return map->private_size; - - BUG("hashmap_get_size: size not set"); - return 0; -} - -/* - * Returns the hashmap entry for the specified key, or NULL if not found. - * - * `map` is the hashmap structure. - * - * `key` is a user data structure that starts with hashmap_entry that has at - * least been initialized with the proper hash code (via `hashmap_entry_init`). - * - * `keydata` is a data structure that holds just enough information to check - * for equality to a given entry. - * - * If the key data is variable-sized (e.g. a FLEX_ARRAY string) or quite large, - * it is undesirable to create a full-fledged entry structure on the heap and - * copy all the key data into the structure. - * - * In this case, the `keydata` parameter can be used to pass - * variable-sized key data directly to the comparison function, and the `key` - * parameter can be a stripped-down, fixed size entry structure allocated on the - * stack. - * - * If an entry with matching hash code is found, `key` and `keydata` are passed - * to `hashmap_cmp_fn` to decide whether the entry matches the key. - */ -struct hashmap_entry *hashmap_get(const struct hashmap *map, - const struct hashmap_entry *key, - const void *keydata); - -/* - * Returns the hashmap entry for the specified hash code and key data, - * or NULL if not found. - * - * `map` is the hashmap structure. - * `hash` is the hash code of the entry to look up. - * - * If an entry with matching hash code is found, `keydata` is passed to - * `hashmap_cmp_fn` to decide whether the entry matches the key. The - * `entry_or_key` parameter of `hashmap_cmp_fn` points to a hashmap_entry - * structure that should not be used in the comparison. - */ -static inline struct hashmap_entry *hashmap_get_from_hash( - const struct hashmap *map, - unsigned int hash, - const void *keydata) -{ - struct hashmap_entry key; - hashmap_entry_init(&key, hash); - return hashmap_get(map, &key, keydata); -} - -/* - * Returns the next equal hashmap entry, or NULL if not found. This can be - * used to iterate over duplicate entries (see `hashmap_add`). - * - * `map` is the hashmap structure. - * `entry` is the hashmap_entry to start the search from, obtained via a previous - * call to `hashmap_get` or `hashmap_get_next`. - */ -struct hashmap_entry *hashmap_get_next(const struct hashmap *map, - const struct hashmap_entry *entry); - -/* - * Adds a hashmap entry. This allows to add duplicate entries (i.e. - * separate values with the same key according to hashmap_cmp_fn). - * - * `map` is the hashmap structure. - * `entry` is the entry to add. - */ -void hashmap_add(struct hashmap *map, struct hashmap_entry *entry); - -/* - * Adds or replaces a hashmap entry. If the hashmap contains duplicate - * entries equal to the specified entry, only one of them will be replaced. - * - * `map` is the hashmap structure. - * `entry` is the entry to add or replace. - * Returns the replaced entry, or NULL if not found (i.e. the entry was added). - */ -struct hashmap_entry *hashmap_put(struct hashmap *map, - struct hashmap_entry *entry); - -/* - * Adds or replaces a hashmap entry contained within @keyvar, - * where @keyvar is a pointer to a struct containing a - * "struct hashmap_entry" @member. - * - * Returns the replaced pointer which is of the same type as @keyvar, - * or NULL if not found. - */ -#define hashmap_put_entry(map, keyvar, member) \ - container_of_or_null_offset(hashmap_put(map, &(keyvar)->member), \ - OFFSETOF_VAR(keyvar, member)) - -/* - * Removes a hashmap entry matching the specified key. If the hashmap contains - * duplicate entries equal to the specified key, only one of them will be - * removed. Returns the removed entry, or NULL if not found. - * - * Argument explanation is the same as in `hashmap_get`. - */ -struct hashmap_entry *hashmap_remove(struct hashmap *map, - const struct hashmap_entry *key, - const void *keydata); - -/* - * Removes a hashmap entry contained within @keyvar, - * where @keyvar is a pointer to a struct containing a - * "struct hashmap_entry" @member. - * - * See `hashmap_get` for an explanation of @keydata - * - * Returns the replaced pointer which is of the same type as @keyvar, - * or NULL if not found. - */ -#define hashmap_remove_entry(map, keyvar, member, keydata) \ - container_of_or_null_offset( \ - hashmap_remove(map, &(keyvar)->member, keydata), \ - OFFSETOF_VAR(keyvar, member)) - -/* - * Returns the `bucket` an entry is stored in. - * Useful for multithreaded read access. - */ -int hashmap_bucket(const struct hashmap *map, unsigned int hash); - -/* - * Used to iterate over all entries of a hashmap. Note that it is - * not safe to add or remove entries to the hashmap while - * iterating. - */ -struct hashmap_iter { - struct hashmap *map; - struct hashmap_entry *next; - unsigned int tablepos; -}; - -/* Initializes a `hashmap_iter` structure. */ -void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter); - -/* Returns the next hashmap_entry, or NULL if there are no more entries. */ -struct hashmap_entry *hashmap_iter_next(struct hashmap_iter *iter); - -/* Initializes the iterator and returns the first entry, if any. */ -static inline struct hashmap_entry *hashmap_iter_first(struct hashmap *map, - struct hashmap_iter *iter) -{ - hashmap_iter_init(map, iter); - return hashmap_iter_next(iter); -} - -/* - * returns the first entry in @map using @iter, where the entry is of - * @type (e.g. "struct foo") and @member is the name of the - * "struct hashmap_entry" in @type - */ -#define hashmap_iter_first_entry(map, iter, type, member) \ - container_of_or_null(hashmap_iter_first(map, iter), type, member) - -/* internal macro for hashmap_for_each_entry */ -#define hashmap_iter_next_entry_offset(iter, offset) \ - container_of_or_null_offset(hashmap_iter_next(iter), offset) - -/* internal macro for hashmap_for_each_entry */ -#define hashmap_iter_first_entry_offset(map, iter, offset) \ - container_of_or_null_offset(hashmap_iter_first(map, iter), offset) - -/* - * iterate through @map using @iter, @var is a pointer to a type - * containing a @member which is a "struct hashmap_entry" - */ -#define hashmap_for_each_entry(map, iter, var, member) \ - for (var = NULL, /* for systems without typeof */ \ - var = hashmap_iter_first_entry_offset(map, iter, \ - OFFSETOF_VAR(var, member)); \ - var; \ - var = hashmap_iter_next_entry_offset(iter, \ - OFFSETOF_VAR(var, member))) - -/* - * returns a pointer of type matching @keyvar, or NULL if nothing found. - * @keyvar is a pointer to a struct containing a - * "struct hashmap_entry" @member. - */ -#define hashmap_get_entry(map, keyvar, member, keydata) \ - container_of_or_null_offset( \ - hashmap_get(map, &(keyvar)->member, keydata), \ - OFFSETOF_VAR(keyvar, member)) - -#define hashmap_get_entry_from_hash(map, hash, keydata, type, member) \ - container_of_or_null(hashmap_get_from_hash(map, hash, keydata), \ - type, member) -/* - * returns the next equal pointer to @var, or NULL if not found. - * @var is a pointer of any type containing "struct hashmap_entry" - * @member is the name of the "struct hashmap_entry" field - */ -#define hashmap_get_next_entry(map, var, member) \ - container_of_or_null_offset(hashmap_get_next(map, &(var)->member), \ - OFFSETOF_VAR(var, member)) - -/* - * iterate @map starting from @var, where @var is a pointer of @type - * and @member is the name of the "struct hashmap_entry" field in @type - */ -#define hashmap_for_each_entry_from(map, var, member) \ - for (; \ - var; \ - var = hashmap_get_next_entry(map, var, member)) - -/* - * Disable item counting and automatic rehashing when adding/removing items. - * - * Normally, the hashmap keeps track of the number of items in the map - * and uses it to dynamically resize it. This (both the counting and - * the resizing) can cause problems when the map is being used by - * threaded callers (because the hashmap code does not know about the - * locking strategy used by the threaded callers and therefore, does - * not know how to protect the "private_size" counter). - */ -static inline void hashmap_disable_item_counting(struct hashmap *map) -{ - map->do_count_items = 0; -} - -/* - * Re-enable item counting when adding/removing items. - * If counting is currently disabled, it will force count them. - * It WILL NOT automatically rehash them. - */ -static inline void hashmap_enable_item_counting(struct hashmap *map) -{ - unsigned int n = 0; - struct hashmap_iter iter; - - if (map->do_count_items) - return; - - hashmap_iter_init(map, &iter); - while (hashmap_iter_next(&iter)) - n++; - - map->do_count_items = 1; - map->private_size = n; -} - -/* String interning */ - -/* - * Returns the unique, interned version of the specified string or data, - * similar to the `String.intern` API in Java and .NET, respectively. - * Interned strings remain valid for the entire lifetime of the process. - * - * Can be used as `[x]strdup()` or `xmemdupz` replacement, except that interned - * strings / data must not be modified or freed. - * - * Interned strings are best used for short strings with high probability of - * duplicates. - * - * Uses a hashmap to store the pool of interned strings. - */ -const void *memintern(const void *data, size_t len); -static inline const char *strintern(const char *string) -{ - return memintern(string, strlen(string)); -} - -#endif |