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Diffstat (limited to 'sys/contrib/openzfs/module/icp/os/modhash.c')
| -rw-r--r-- | sys/contrib/openzfs/module/icp/os/modhash.c | 927 |
1 files changed, 927 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/module/icp/os/modhash.c b/sys/contrib/openzfs/module/icp/os/modhash.c new file mode 100644 index 000000000000..a897871001ce --- /dev/null +++ b/sys/contrib/openzfs/module/icp/os/modhash.c @@ -0,0 +1,927 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ +/* + * Copyright 2008 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +/* + * mod_hash: flexible hash table implementation. + * + * This is a reasonably fast, reasonably flexible hash table implementation + * which features pluggable hash algorithms to support storing arbitrary keys + * and values. It is designed to handle small (< 100,000 items) amounts of + * data. The hash uses chaining to resolve collisions, and does not feature a + * mechanism to grow the hash. Care must be taken to pick nchains to be large + * enough for the application at hand, or lots of time will be wasted searching + * hash chains. + * + * The client of the hash is required to supply a number of items to support + * the various hash functions: + * + * - Destructor functions for the key and value being hashed. + * A destructor is responsible for freeing an object when the hash + * table is no longer storing it. Since keys and values can be of + * arbitrary type, separate destructors for keys & values are used. + * These may be mod_hash_null_keydtor and mod_hash_null_valdtor if no + * destructor is needed for either a key or value. + * + * - A hashing algorithm which returns a uint_t representing a hash index + * The number returned need _not_ be between 0 and nchains. The mod_hash + * code will take care of doing that. The second argument (after the + * key) to the hashing function is a void * that represents + * hash_alg_data-- this is provided so that the hashing algorithm can + * maintain some state across calls, or keep algorithm-specific + * constants associated with the hash table. + * + * A pointer-hashing and a string-hashing algorithm are supplied in + * this file. + * + * - A key comparator (a la qsort). + * This is used when searching the hash chain. The key comparator + * determines if two keys match. It should follow the return value + * semantics of strcmp. + * + * string and pointer comparators are supplied in this file. + * + * mod_hash_create_strhash() and mod_hash_create_ptrhash() provide good + * examples of how to create a customized hash table. + * + * Basic hash operations: + * + * mod_hash_create_strhash(name, nchains, dtor), + * create a hash using strings as keys. + * NOTE: This create a hash which automatically cleans up the string + * values it is given for keys. + * + * mod_hash_create_ptrhash(name, nchains, dtor, key_elem_size): + * create a hash using pointers as keys. + * + * mod_hash_create_extended(name, nchains, kdtor, vdtor, + * hash_alg, hash_alg_data, + * keycmp, sleep) + * create a customized hash table. + * + * mod_hash_destroy_hash(hash): + * destroy the given hash table, calling the key and value destructors + * on each key-value pair stored in the hash. + * + * mod_hash_insert(hash, key, val): + * place a key, value pair into the given hash. + * duplicate keys are rejected. + * + * mod_hash_insert_reserve(hash, key, val, handle): + * place a key, value pair into the given hash, using handle to indicate + * the reserved storage for the pair. (no memory allocation is needed + * during a mod_hash_insert_reserve.) duplicate keys are rejected. + * + * mod_hash_reserve(hash, *handle): + * reserve storage for a key-value pair using the memory allocation + * policy of 'hash', returning the storage handle in 'handle'. + * + * mod_hash_reserve_nosleep(hash, *handle): reserve storage for a key-value + * pair ignoring the memory allocation policy of 'hash' and always without + * sleep, returning the storage handle in 'handle'. + * + * mod_hash_remove(hash, key, *val): + * remove a key-value pair with key 'key' from 'hash', destroying the + * stored key, and returning the value in val. + * + * mod_hash_replace(hash, key, val) + * atomically remove an existing key-value pair from a hash, and replace + * the key and value with the ones supplied. The removed key and value + * (if any) are destroyed. + * + * mod_hash_destroy(hash, key): + * remove a key-value pair with key 'key' from 'hash', destroying both + * stored key and stored value. + * + * mod_hash_find(hash, key, val): + * find a value in the hash table corresponding to the given key. + * + * mod_hash_find_cb(hash, key, val, found_callback) + * find a value in the hash table corresponding to the given key. + * If a value is found, call specified callback passing key and val to it. + * The callback is called with the hash lock held. + * It is intended to be used in situations where the act of locating the + * data must also modify it - such as in reference counting schemes. + * + * mod_hash_walk(hash, callback(key, elem, arg), arg) + * walks all the elements in the hashtable and invokes the callback + * function with the key/value pair for each element. the hashtable + * is locked for readers so the callback function should not attempt + * to do any updates to the hashable. the callback function should + * return MH_WALK_CONTINUE to continue walking the hashtable or + * MH_WALK_TERMINATE to abort the walk of the hashtable. + * + * mod_hash_clear(hash): + * clears the given hash table of entries, calling the key and value + * destructors for every element in the hash. + */ + +#include <sys/zfs_context.h> +#include <sys/bitmap.h> +#include <sys/modhash_impl.h> +#include <sys/sysmacros.h> + +/* + * MH_KEY_DESTROY() + * Invoke the key destructor. + */ +#define MH_KEY_DESTROY(hash, key) ((hash->mh_kdtor)(key)) + +/* + * MH_VAL_DESTROY() + * Invoke the value destructor. + */ +#define MH_VAL_DESTROY(hash, val) ((hash->mh_vdtor)(val)) + +/* + * MH_KEYCMP() + * Call the key comparator for the given hash keys. + */ +#define MH_KEYCMP(hash, key1, key2) ((hash->mh_keycmp)(key1, key2)) + +/* + * Cache for struct mod_hash_entry + */ +kmem_cache_t *mh_e_cache = NULL; +mod_hash_t *mh_head = NULL; +kmutex_t mh_head_lock; + +/* + * mod_hash_null_keydtor() + * mod_hash_null_valdtor() + * no-op key and value destructors. + */ +/*ARGSUSED*/ +void +mod_hash_null_keydtor(mod_hash_key_t key) +{ +} + +/*ARGSUSED*/ +void +mod_hash_null_valdtor(mod_hash_val_t val) +{ +} + +/* + * mod_hash_bystr() + * mod_hash_strkey_cmp() + * mod_hash_strkey_dtor() + * mod_hash_strval_dtor() + * Hash and key comparison routines for hashes with string keys. + * + * mod_hash_create_strhash() + * Create a hash using strings as keys + * + * The string hashing algorithm is from the "Dragon Book" -- + * "Compilers: Principles, Tools & Techniques", by Aho, Sethi, Ullman + */ + +/*ARGSUSED*/ +uint_t +mod_hash_bystr(void *hash_data, mod_hash_key_t key) +{ + uint_t hash = 0; + uint_t g; + char *p, *k = (char *)key; + + ASSERT(k); + for (p = k; *p != '\0'; p++) { + hash = (hash << 4) + *p; + if ((g = (hash & 0xf0000000)) != 0) { + hash ^= (g >> 24); + hash ^= g; + } + } + return (hash); +} + +int +mod_hash_strkey_cmp(mod_hash_key_t key1, mod_hash_key_t key2) +{ + return (strcmp((char *)key1, (char *)key2)); +} + +void +mod_hash_strkey_dtor(mod_hash_key_t key) +{ + char *c = (char *)key; + kmem_free(c, strlen(c) + 1); +} + +void +mod_hash_strval_dtor(mod_hash_val_t val) +{ + char *c = (char *)val; + kmem_free(c, strlen(c) + 1); +} + +mod_hash_t * +mod_hash_create_strhash_nodtr(char *name, size_t nchains, + void (*val_dtor)(mod_hash_val_t)) +{ + return mod_hash_create_extended(name, nchains, mod_hash_null_keydtor, + val_dtor, mod_hash_bystr, NULL, mod_hash_strkey_cmp, KM_SLEEP); +} + +mod_hash_t * +mod_hash_create_strhash(char *name, size_t nchains, + void (*val_dtor)(mod_hash_val_t)) +{ + return mod_hash_create_extended(name, nchains, mod_hash_strkey_dtor, + val_dtor, mod_hash_bystr, NULL, mod_hash_strkey_cmp, KM_SLEEP); +} + +void +mod_hash_destroy_strhash(mod_hash_t *strhash) +{ + ASSERT(strhash); + mod_hash_destroy_hash(strhash); +} + + +/* + * mod_hash_byptr() + * mod_hash_ptrkey_cmp() + * Hash and key comparison routines for hashes with pointer keys. + * + * mod_hash_create_ptrhash() + * mod_hash_destroy_ptrhash() + * Create a hash that uses pointers as keys. This hash algorithm + * picks an appropriate set of middle bits in the address to hash on + * based on the size of the hash table and a hint about the size of + * the items pointed at. + */ +uint_t +mod_hash_byptr(void *hash_data, mod_hash_key_t key) +{ + uintptr_t k = (uintptr_t)key; + k >>= (int)(uintptr_t)hash_data; + + return ((uint_t)k); +} + +int +mod_hash_ptrkey_cmp(mod_hash_key_t key1, mod_hash_key_t key2) +{ + uintptr_t k1 = (uintptr_t)key1; + uintptr_t k2 = (uintptr_t)key2; + if (k1 > k2) + return (-1); + else if (k1 < k2) + return (1); + else + return (0); +} + +mod_hash_t * +mod_hash_create_ptrhash(char *name, size_t nchains, + void (*val_dtor)(mod_hash_val_t), size_t key_elem_size) +{ + size_t rshift; + + /* + * We want to hash on the bits in the middle of the address word + * Bits far to the right in the word have little significance, and + * are likely to all look the same (for example, an array of + * 256-byte structures will have the bottom 8 bits of address + * words the same). So we want to right-shift each address to + * ignore the bottom bits. + * + * The high bits, which are also unused, will get taken out when + * mod_hash takes hashkey % nchains. + */ + rshift = highbit64(key_elem_size); + + return mod_hash_create_extended(name, nchains, mod_hash_null_keydtor, + val_dtor, mod_hash_byptr, (void *)rshift, mod_hash_ptrkey_cmp, + KM_SLEEP); +} + +void +mod_hash_destroy_ptrhash(mod_hash_t *hash) +{ + ASSERT(hash); + mod_hash_destroy_hash(hash); +} + +/* + * mod_hash_byid() + * mod_hash_idkey_cmp() + * Hash and key comparison routines for hashes with 32-bit unsigned keys. + * + * mod_hash_create_idhash() + * mod_hash_destroy_idhash() + * mod_hash_iddata_gen() + * Create a hash that uses numeric keys. + * + * The hash algorithm is documented in "Introduction to Algorithms" + * (Cormen, Leiserson, Rivest); when the hash table is created, it + * attempts to find the next largest prime above the number of hash + * slots. The hash index is then this number times the key modulo + * the hash size, or (key * prime) % nchains. + */ +uint_t +mod_hash_byid(void *hash_data, mod_hash_key_t key) +{ + uint_t kval = (uint_t)(uintptr_t)hash_data; + return ((uint_t)(uintptr_t)key * (uint_t)kval); +} + +int +mod_hash_idkey_cmp(mod_hash_key_t key1, mod_hash_key_t key2) +{ + return ((uint_t)(uintptr_t)key1 - (uint_t)(uintptr_t)key2); +} + +/* + * Generate the next largest prime number greater than nchains; this value + * is intended to be later passed in to mod_hash_create_extended() as the + * hash_data. + */ +uint_t +mod_hash_iddata_gen(size_t nchains) +{ + uint_t kval, i, prime; + + /* + * Pick the first (odd) prime greater than nchains. Make sure kval is + * odd (so start with nchains +1 or +2 as appropriate). + */ + kval = (nchains % 2 == 0) ? nchains + 1 : nchains + 2; + + for (;;) { + prime = 1; + for (i = 3; i * i <= kval; i += 2) { + if (kval % i == 0) + prime = 0; + } + if (prime == 1) + break; + kval += 2; + } + return (kval); +} + +mod_hash_t * +mod_hash_create_idhash(char *name, size_t nchains, + void (*val_dtor)(mod_hash_val_t)) +{ + uint_t kval = mod_hash_iddata_gen(nchains); + + return (mod_hash_create_extended(name, nchains, mod_hash_null_keydtor, + val_dtor, mod_hash_byid, (void *)(uintptr_t)kval, + mod_hash_idkey_cmp, KM_SLEEP)); +} + +void +mod_hash_destroy_idhash(mod_hash_t *hash) +{ + ASSERT(hash); + mod_hash_destroy_hash(hash); +} + +void +mod_hash_fini(void) +{ + mutex_destroy(&mh_head_lock); + + if (mh_e_cache) { + kmem_cache_destroy(mh_e_cache); + mh_e_cache = NULL; + } +} + +/* + * mod_hash_init() + * sets up globals, etc for mod_hash_* + */ +void +mod_hash_init(void) +{ + ASSERT(mh_e_cache == NULL); + mh_e_cache = kmem_cache_create("mod_hash_entries", + sizeof (struct mod_hash_entry), 0, NULL, NULL, NULL, NULL, + NULL, 0); + + mutex_init(&mh_head_lock, NULL, MUTEX_DEFAULT, NULL); +} + +/* + * mod_hash_create_extended() + * The full-blown hash creation function. + * + * notes: + * nchains - how many hash slots to create. More hash slots will + * result in shorter hash chains, but will consume + * slightly more memory up front. + * sleep - should be KM_SLEEP or KM_NOSLEEP, to indicate whether + * to sleep for memory, or fail in low-memory conditions. + * + * Fails only if KM_NOSLEEP was specified, and no memory was available. + */ +mod_hash_t * +mod_hash_create_extended( + char *hname, /* descriptive name for hash */ + size_t nchains, /* number of hash slots */ + void (*kdtor)(mod_hash_key_t), /* key destructor */ + void (*vdtor)(mod_hash_val_t), /* value destructor */ + uint_t (*hash_alg)(void *, mod_hash_key_t), /* hash algorithm */ + void *hash_alg_data, /* pass-thru arg for hash_alg */ + int (*keycmp)(mod_hash_key_t, mod_hash_key_t), /* key comparator */ + int sleep) /* whether to sleep for mem */ +{ + mod_hash_t *mod_hash; + size_t size; + ASSERT(hname && keycmp && hash_alg && vdtor && kdtor); + + if ((mod_hash = kmem_zalloc(MH_SIZE(nchains), sleep)) == NULL) + return (NULL); + + size = strlen(hname) + 1; + mod_hash->mh_name = kmem_alloc(size, sleep); + if (mod_hash->mh_name == NULL) { + kmem_free(mod_hash, MH_SIZE(nchains)); + return (NULL); + } + (void) strlcpy(mod_hash->mh_name, hname, size); + + rw_init(&mod_hash->mh_contents, NULL, RW_DEFAULT, NULL); + mod_hash->mh_sleep = sleep; + mod_hash->mh_nchains = nchains; + mod_hash->mh_kdtor = kdtor; + mod_hash->mh_vdtor = vdtor; + mod_hash->mh_hashalg = hash_alg; + mod_hash->mh_hashalg_data = hash_alg_data; + mod_hash->mh_keycmp = keycmp; + + /* + * Link the hash up on the list of hashes + */ + mutex_enter(&mh_head_lock); + mod_hash->mh_next = mh_head; + mh_head = mod_hash; + mutex_exit(&mh_head_lock); + + return (mod_hash); +} + +/* + * mod_hash_destroy_hash() + * destroy a hash table, destroying all of its stored keys and values + * as well. + */ +void +mod_hash_destroy_hash(mod_hash_t *hash) +{ + mod_hash_t *mhp, *mhpp; + + mutex_enter(&mh_head_lock); + /* + * Remove the hash from the hash list + */ + if (hash == mh_head) { /* removing 1st list elem */ + mh_head = mh_head->mh_next; + } else { + /* + * mhpp can start out NULL since we know the 1st elem isn't the + * droid we're looking for. + */ + mhpp = NULL; + for (mhp = mh_head; mhp != NULL; mhp = mhp->mh_next) { + if (mhp == hash) { + mhpp->mh_next = mhp->mh_next; + break; + } + mhpp = mhp; + } + } + mutex_exit(&mh_head_lock); + + /* + * Clean out keys and values. + */ + mod_hash_clear(hash); + + rw_destroy(&hash->mh_contents); + kmem_free(hash->mh_name, strlen(hash->mh_name) + 1); + kmem_free(hash, MH_SIZE(hash->mh_nchains)); +} + +/* + * i_mod_hash() + * Call the hashing algorithm for this hash table, with the given key. + */ +uint_t +i_mod_hash(mod_hash_t *hash, mod_hash_key_t key) +{ + uint_t h; + /* + * Prevent div by 0 problems; + * Also a nice shortcut when using a hash as a list + */ + if (hash->mh_nchains == 1) + return (0); + + h = (hash->mh_hashalg)(hash->mh_hashalg_data, key); + return (h % (hash->mh_nchains - 1)); +} + +/* + * i_mod_hash_insert_nosync() + * mod_hash_insert() + * mod_hash_insert_reserve() + * insert 'val' into the hash table, using 'key' as its key. If 'key' is + * already a key in the hash, an error will be returned, and the key-val + * pair will not be inserted. i_mod_hash_insert_nosync() supports a simple + * handle abstraction, allowing hash entry allocation to be separated from + * the hash insertion. this abstraction allows simple use of the mod_hash + * structure in situations where mod_hash_insert() with a KM_SLEEP + * allocation policy would otherwise be unsafe. + */ +int +i_mod_hash_insert_nosync(mod_hash_t *hash, mod_hash_key_t key, + mod_hash_val_t val, mod_hash_hndl_t handle) +{ + uint_t hashidx; + struct mod_hash_entry *entry; + + ASSERT(hash); + + /* + * If we've not been given reserved storage, allocate storage directly, + * using the hash's allocation policy. + */ + if (handle == (mod_hash_hndl_t)0) { + entry = kmem_cache_alloc(mh_e_cache, hash->mh_sleep); + if (entry == NULL) { + hash->mh_stat.mhs_nomem++; + return (MH_ERR_NOMEM); + } + } else { + entry = (struct mod_hash_entry *)handle; + } + + hashidx = i_mod_hash(hash, key); + entry->mhe_key = key; + entry->mhe_val = val; + entry->mhe_next = hash->mh_entries[hashidx]; + + hash->mh_entries[hashidx] = entry; + hash->mh_stat.mhs_nelems++; + + return (0); +} + +int +mod_hash_insert(mod_hash_t *hash, mod_hash_key_t key, mod_hash_val_t val) +{ + int res; + mod_hash_val_t v; + + rw_enter(&hash->mh_contents, RW_WRITER); + + /* + * Disallow duplicate keys in the hash + */ + if (i_mod_hash_find_nosync(hash, key, &v) == 0) { + rw_exit(&hash->mh_contents); + hash->mh_stat.mhs_coll++; + return (MH_ERR_DUPLICATE); + } + + res = i_mod_hash_insert_nosync(hash, key, val, (mod_hash_hndl_t)0); + rw_exit(&hash->mh_contents); + + return (res); +} + +int +mod_hash_insert_reserve(mod_hash_t *hash, mod_hash_key_t key, + mod_hash_val_t val, mod_hash_hndl_t handle) +{ + int res; + mod_hash_val_t v; + + rw_enter(&hash->mh_contents, RW_WRITER); + + /* + * Disallow duplicate keys in the hash + */ + if (i_mod_hash_find_nosync(hash, key, &v) == 0) { + rw_exit(&hash->mh_contents); + hash->mh_stat.mhs_coll++; + return (MH_ERR_DUPLICATE); + } + res = i_mod_hash_insert_nosync(hash, key, val, handle); + rw_exit(&hash->mh_contents); + + return (res); +} + +/* + * mod_hash_reserve() + * mod_hash_reserve_nosleep() + * mod_hash_cancel() + * Make or cancel a mod_hash_entry_t reservation. Reservations are used in + * mod_hash_insert_reserve() above. + */ +int +mod_hash_reserve(mod_hash_t *hash, mod_hash_hndl_t *handlep) +{ + *handlep = kmem_cache_alloc(mh_e_cache, hash->mh_sleep); + if (*handlep == NULL) { + hash->mh_stat.mhs_nomem++; + return (MH_ERR_NOMEM); + } + + return (0); +} + +int +mod_hash_reserve_nosleep(mod_hash_t *hash, mod_hash_hndl_t *handlep) +{ + *handlep = kmem_cache_alloc(mh_e_cache, KM_NOSLEEP); + if (*handlep == NULL) { + hash->mh_stat.mhs_nomem++; + return (MH_ERR_NOMEM); + } + + return (0); + +} + +/*ARGSUSED*/ +void +mod_hash_cancel(mod_hash_t *hash, mod_hash_hndl_t *handlep) +{ + kmem_cache_free(mh_e_cache, *handlep); + *handlep = (mod_hash_hndl_t)0; +} + +/* + * i_mod_hash_remove_nosync() + * mod_hash_remove() + * Remove an element from the hash table. + */ +int +i_mod_hash_remove_nosync(mod_hash_t *hash, mod_hash_key_t key, + mod_hash_val_t *val) +{ + int hashidx; + struct mod_hash_entry *e, *ep; + + hashidx = i_mod_hash(hash, key); + ep = NULL; /* e's parent */ + + for (e = hash->mh_entries[hashidx]; e != NULL; e = e->mhe_next) { + if (MH_KEYCMP(hash, e->mhe_key, key) == 0) + break; + ep = e; + } + + if (e == NULL) { /* not found */ + return (MH_ERR_NOTFOUND); + } + + if (ep == NULL) /* special case 1st element in bucket */ + hash->mh_entries[hashidx] = e->mhe_next; + else + ep->mhe_next = e->mhe_next; + + /* + * Clean up resources used by the node's key. + */ + MH_KEY_DESTROY(hash, e->mhe_key); + + *val = e->mhe_val; + kmem_cache_free(mh_e_cache, e); + hash->mh_stat.mhs_nelems--; + + return (0); +} + +int +mod_hash_remove(mod_hash_t *hash, mod_hash_key_t key, mod_hash_val_t *val) +{ + int res; + + rw_enter(&hash->mh_contents, RW_WRITER); + res = i_mod_hash_remove_nosync(hash, key, val); + rw_exit(&hash->mh_contents); + + return (res); +} + +/* + * mod_hash_replace() + * atomically remove an existing key-value pair from a hash, and replace + * the key and value with the ones supplied. The removed key and value + * (if any) are destroyed. + */ +int +mod_hash_replace(mod_hash_t *hash, mod_hash_key_t key, mod_hash_val_t val) +{ + int res; + mod_hash_val_t v; + + rw_enter(&hash->mh_contents, RW_WRITER); + + if (i_mod_hash_remove_nosync(hash, key, &v) == 0) { + /* + * mod_hash_remove() takes care of freeing up the key resources. + */ + MH_VAL_DESTROY(hash, v); + } + res = i_mod_hash_insert_nosync(hash, key, val, (mod_hash_hndl_t)0); + + rw_exit(&hash->mh_contents); + + return (res); +} + +/* + * mod_hash_destroy() + * Remove an element from the hash table matching 'key', and destroy it. + */ +int +mod_hash_destroy(mod_hash_t *hash, mod_hash_key_t key) +{ + mod_hash_val_t val; + int rv; + + rw_enter(&hash->mh_contents, RW_WRITER); + + if ((rv = i_mod_hash_remove_nosync(hash, key, &val)) == 0) { + /* + * mod_hash_remove() takes care of freeing up the key resources. + */ + MH_VAL_DESTROY(hash, val); + } + + rw_exit(&hash->mh_contents); + return (rv); +} + +/* + * i_mod_hash_find_nosync() + * mod_hash_find() + * Find a value in the hash table corresponding to the given key. + */ +int +i_mod_hash_find_nosync(mod_hash_t *hash, mod_hash_key_t key, + mod_hash_val_t *val) +{ + uint_t hashidx; + struct mod_hash_entry *e; + + hashidx = i_mod_hash(hash, key); + + for (e = hash->mh_entries[hashidx]; e != NULL; e = e->mhe_next) { + if (MH_KEYCMP(hash, e->mhe_key, key) == 0) { + *val = e->mhe_val; + hash->mh_stat.mhs_hit++; + return (0); + } + } + hash->mh_stat.mhs_miss++; + return (MH_ERR_NOTFOUND); +} + +int +mod_hash_find(mod_hash_t *hash, mod_hash_key_t key, mod_hash_val_t *val) +{ + int res; + + rw_enter(&hash->mh_contents, RW_READER); + res = i_mod_hash_find_nosync(hash, key, val); + rw_exit(&hash->mh_contents); + + return (res); +} + +int +mod_hash_find_cb(mod_hash_t *hash, mod_hash_key_t key, mod_hash_val_t *val, + void (*find_cb)(mod_hash_key_t, mod_hash_val_t)) +{ + int res; + + rw_enter(&hash->mh_contents, RW_READER); + res = i_mod_hash_find_nosync(hash, key, val); + if (res == 0) { + find_cb(key, *val); + } + rw_exit(&hash->mh_contents); + + return (res); +} + +int +mod_hash_find_cb_rval(mod_hash_t *hash, mod_hash_key_t key, mod_hash_val_t *val, + int (*find_cb)(mod_hash_key_t, mod_hash_val_t), int *cb_rval) +{ + int res; + + rw_enter(&hash->mh_contents, RW_READER); + res = i_mod_hash_find_nosync(hash, key, val); + if (res == 0) { + *cb_rval = find_cb(key, *val); + } + rw_exit(&hash->mh_contents); + + return (res); +} + +void +i_mod_hash_walk_nosync(mod_hash_t *hash, + uint_t (*callback)(mod_hash_key_t, mod_hash_val_t *, void *), void *arg) +{ + struct mod_hash_entry *e; + uint_t hashidx; + int res = MH_WALK_CONTINUE; + + for (hashidx = 0; + (hashidx < (hash->mh_nchains - 1)) && (res == MH_WALK_CONTINUE); + hashidx++) { + e = hash->mh_entries[hashidx]; + while ((e != NULL) && (res == MH_WALK_CONTINUE)) { + res = callback(e->mhe_key, e->mhe_val, arg); + e = e->mhe_next; + } + } +} + +/* + * mod_hash_walk() + * Walks all the elements in the hashtable and invokes the callback + * function with the key/value pair for each element. The hashtable + * is locked for readers so the callback function should not attempt + * to do any updates to the hashable. The callback function should + * return MH_WALK_CONTINUE to continue walking the hashtable or + * MH_WALK_TERMINATE to abort the walk of the hashtable. + */ +void +mod_hash_walk(mod_hash_t *hash, + uint_t (*callback)(mod_hash_key_t, mod_hash_val_t *, void *), void *arg) +{ + rw_enter(&hash->mh_contents, RW_READER); + i_mod_hash_walk_nosync(hash, callback, arg); + rw_exit(&hash->mh_contents); +} + + +/* + * i_mod_hash_clear_nosync() + * mod_hash_clear() + * Clears the given hash table by calling the destructor of every hash + * element and freeing up all mod_hash_entry's. + */ +void +i_mod_hash_clear_nosync(mod_hash_t *hash) +{ + int i; + struct mod_hash_entry *e, *old_e; + + for (i = 0; i < hash->mh_nchains; i++) { + e = hash->mh_entries[i]; + while (e != NULL) { + MH_KEY_DESTROY(hash, e->mhe_key); + MH_VAL_DESTROY(hash, e->mhe_val); + old_e = e; + e = e->mhe_next; + kmem_cache_free(mh_e_cache, old_e); + } + hash->mh_entries[i] = NULL; + } + hash->mh_stat.mhs_nelems = 0; +} + +void +mod_hash_clear(mod_hash_t *hash) +{ + ASSERT(hash); + rw_enter(&hash->mh_contents, RW_WRITER); + i_mod_hash_clear_nosync(hash); + rw_exit(&hash->mh_contents); +} |