1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
2 * vim:expandtab:shiftwidth=8:tabstop=8:
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 only,
10 * as published by the Free Software Foundation.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License version 2 for more details (a copy is included
16 * in the LICENSE file that accompanied this code).
18 * You should have received a copy of the GNU General Public License
19 * version 2 along with this program; If not, see
20 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
29 * Copyright 2008 Sun Microsystems, Inc. All rights reserved
30 * Use is subject to license terms.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
37 #ifndef __CLASS_HASH_H
38 #define __CLASS_HASH_H
40 #include <lustre_lib.h>
42 struct lustre_hash_ops;
44 typedef struct lustre_hash_bucket {
45 struct hlist_head lhb_head; /* entries list */
46 atomic_t lhb_count; /* current entries */
47 rwlock_t lhb_rwlock; /* lustre_hash_bucket */
48 } lustre_hash_bucket_t;
50 #define LUSTRE_MAX_HASH_NAME 16
52 typedef struct lustre_hash {
53 int lh_cur_size; /* current hash size */
54 int lh_min_size; /* min hash size */
55 int lh_max_size; /* max hash size */
56 int lh_min_theta; /* resize min threshold */
57 int lh_max_theta; /* resize max threshold */
58 int lh_flags; /* hash flags */
59 atomic_t lh_count; /* current entries */
60 atomic_t lh_rehash_count;/* resize count */
61 struct lustre_hash_bucket *lh_buckets; /* hash buckets */
62 struct lustre_hash_ops *lh_ops; /* hash operations */
63 rwlock_t lh_rwlock; /* lustre_hash */
64 char lh_name[LUSTRE_MAX_HASH_NAME];
67 typedef struct lustre_hash_ops {
68 unsigned (*lh_hash)(lustre_hash_t *lh, void *key, unsigned mask);
69 void * (*lh_key)(struct hlist_node *hnode);
70 int (*lh_compare)(void *key, struct hlist_node *hnode);
71 void * (*lh_get)(struct hlist_node *hnode);
72 void * (*lh_put)(struct hlist_node *hnode);
73 void (*lh_exit)(struct hlist_node *hnode);
76 #define LH_DEBUG 0x0001 /* Enable expensive debug checks */
77 #define LH_REHASH 0x0002 /* Enable dynamic hash resizing */
79 #define LHO(lh) (lh)->lh_ops
80 #define LHP(lh, op) (lh)->lh_ops->lh_ ## op
82 static inline unsigned
83 lh_hash(lustre_hash_t *lh, void *key, unsigned mask)
89 return LHP(lh, hash)(lh, key, mask);
95 lh_key(lustre_hash_t *lh, struct hlist_node *hnode)
102 return LHP(lh, key)(hnode);
108 * Returns 1 on a match,
109 * XXX: This would be better if it returned, -1, 0, or 1 for
110 * <, =, > respectivly. It could then be used to implement
111 * a LH_SORT feature flags which could keep each lustre hash
112 * bucket in order. This would increase insertion times
113 * but could reduce lookup times for deep chains. Ideally,
114 * the rehash should keep chain depth short but if that
115 * ends up not being the case this would be a nice feature.
118 lh_compare(lustre_hash_t *lh, void *key, struct hlist_node *hnode)
124 if (LHP(lh, compare))
125 return LHP(lh, compare)(key, hnode);
131 lh_get(lustre_hash_t *lh, struct hlist_node *hnode)
138 return LHP(lh, get)(hnode);
144 lh_put(lustre_hash_t *lh, struct hlist_node *hnode)
151 return LHP(lh, put)(hnode);
157 lh_exit(lustre_hash_t *lh, struct hlist_node *hnode)
164 return LHP(lh, exit)(hnode);
168 * Validate hnode references the correct key.
171 __lustre_hash_key_validate(lustre_hash_t *lh, void *key,
172 struct hlist_node *hnode)
174 if (unlikely(lh->lh_flags & LH_DEBUG))
175 LASSERT(lh_compare(lh, key, hnode));
179 * Validate hnode is in the correct bucket.
182 __lustre_hash_bucket_validate(lustre_hash_t *lh, lustre_hash_bucket_t *lhb,
183 struct hlist_node *hnode)
187 if (unlikely(lh->lh_flags & LH_DEBUG)) {
188 i = lh_hash(lh, lh_key(lh, hnode), lh->lh_cur_size - 1);
189 LASSERT(&lh->lh_buckets[i] == lhb);
193 static inline struct hlist_node *
194 __lustre_hash_bucket_lookup(lustre_hash_t *lh,
195 lustre_hash_bucket_t *lhb, void *key)
197 struct hlist_node *hnode;
199 hlist_for_each(hnode, &lhb->lhb_head)
200 if (lh_compare(lh, key, hnode))
207 __lustre_hash_bucket_add(lustre_hash_t *lh,
208 lustre_hash_bucket_t *lhb,
209 struct hlist_node *hnode)
211 hlist_add_head(hnode, &(lhb->lhb_head));
212 atomic_inc(&lhb->lhb_count);
213 atomic_inc(&lh->lh_count);
215 return lh_get(lh, hnode);
219 __lustre_hash_bucket_del(lustre_hash_t *lh,
220 lustre_hash_bucket_t *lhb,
221 struct hlist_node *hnode)
223 hlist_del_init(hnode);
224 LASSERT(atomic_read(&lhb->lhb_count) > 0);
225 atomic_dec(&lhb->lhb_count);
226 LASSERT(atomic_read(&lh->lh_count) > 0);
227 atomic_dec(&lh->lh_count);
229 return lh_put(lh, hnode);
233 * Hash init/cleanup functions.
235 lustre_hash_t *lustre_hash_init(char *name, unsigned int cur_size,
236 unsigned int max_size,
237 lustre_hash_ops_t *ops, int flags);
238 void lustre_hash_exit(lustre_hash_t *lh);
241 * Hash addition functions.
243 void lustre_hash_add(lustre_hash_t *lh, void *key,
244 struct hlist_node *hnode);
245 int lustre_hash_add_unique(lustre_hash_t *lh, void *key,
246 struct hlist_node *hnode);
247 void *lustre_hash_findadd_unique(lustre_hash_t *lh, void *key,
248 struct hlist_node *hnode);
251 * Hash deletion functions.
253 void *lustre_hash_del(lustre_hash_t *lh, void *key, struct hlist_node *hnode);
254 void *lustre_hash_del_key(lustre_hash_t *lh, void *key);
257 * Hash lookup/for_each functions.
259 void *lustre_hash_lookup(lustre_hash_t *lh, void *key);
260 typedef void (*lh_for_each_cb)(void *obj, void *data);
261 void lustre_hash_for_each(lustre_hash_t *lh, lh_for_each_cb, void *data);
262 void lustre_hash_for_each_safe(lustre_hash_t *lh, lh_for_each_cb, void *data);
263 void lustre_hash_for_each_empty(lustre_hash_t *lh, lh_for_each_cb, void *data);
264 void lustre_hash_for_each_key(lustre_hash_t *lh, void *key,
265 lh_for_each_cb, void *data);
268 * Rehash - Theta is calculated to be the average chained
269 * hash depth assuming a perfectly uniform hash funcion.
271 int lustre_hash_rehash(lustre_hash_t *lh, int size);
272 void lustre_hash_rehash_key(lustre_hash_t *lh, void *old_key,
273 void *new_key, struct hlist_node *hnode);
277 __lustre_hash_theta(lustre_hash_t *lh)
279 return ((atomic_read(&lh->lh_count) * 1000) / lh->lh_cur_size);
283 __lustre_hash_set_theta(lustre_hash_t *lh, int min, int max)
286 lh->lh_min_theta = min;
287 lh->lh_max_theta = max;
291 * Generic debug formatting routines mainly for proc handler.
293 int lustre_hash_debug_header(char *str, int size);
294 int lustre_hash_debug_str(lustre_hash_t *lh, char *str, int size);
297 * 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1
299 #define CFS_GOLDEN_RATIO_PRIME_32 0x9e370001UL
301 * 2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1
303 #define CFS_GOLDEN_RATIO_PRIME_64 0x9e37fffffffc0001ULL
306 * Generic djb2 hash algorithm for character arrays.
308 static inline unsigned
309 lh_djb2_hash(void *key, size_t size, unsigned mask)
311 unsigned i, hash = 5381;
313 LASSERT(key != NULL);
315 for (i = 0; i < size; i++)
316 hash = hash * 33 + ((char *)key)[i];
318 return (hash & mask);
322 * Generic u32 hash algorithm.
324 static inline unsigned
325 lh_u32_hash(__u32 key, unsigned mask)
327 return ((key * CFS_GOLDEN_RATIO_PRIME_32) & mask);
331 * Generic u64 hash algorithm.
333 static inline unsigned
334 lh_u64_hash(__u64 key, unsigned mask)
336 return ((unsigned)(key * CFS_GOLDEN_RATIO_PRIME_64) & mask);
339 #define lh_for_each_bucket(lh, lhb, pos) \
341 pos < lh->lh_cur_size && \
342 ({ lhb = &lh->lh_buckets[i]; 1; }); \
345 #endif /* __CLASS_HASH_H */