urcu/rculfhash.h

   1 #ifndef _URCU_RCULFHASH_H
   2 #define _URCU_RCULFHASH_H
   3
   4 /*
   5  * urcu/rculfhash.h
   6  *
   7  * Userspace RCU library - Lock-Free RCU Hash Table
   8  *
   9  * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; either
  14  * version 2.1 of the License, or (at your option) any later version.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <stdint.h>
  27 #include <urcu-call-rcu.h>
  28
  29 #ifdef __cplusplus
  30 extern "C" {
  31 #endif
  32
  33 /*
  34  * struct cds_lfht_node and struct _cds_lfht_node should be aligned on
  35  * 4-bytes boundaries because the two lower bits are used as flags.
  36  */
  37
  38 struct _cds_lfht_node {
  39         struct cds_lfht_node *next;     /* ptr | DUMMY_FLAG | REMOVED_FLAG */
  40         unsigned long reverse_hash;
  41 };
  42
  43 struct cds_lfht_node {
  44         /* cache-hot for iteration */
  45         struct _cds_lfht_node p;          /* needs to be first field */
  46         void *key;
  47         unsigned int key_len;
  48         /* cache-cold for iteration */
  49         struct rcu_head head;
  50 };
  51
  52 struct cds_lfht;
  53
  54 /*
  55  * Caution !
  56  * Ensure reader and writer threads are registered as urcu readers.
  57  */
  58
  59 typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
  60                                         unsigned long seed);
  61 typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
  62                                         void *key2, size_t key2_len);
  63
  64 /*
  65  * cds_lfht_node_init - initialize a hash table node
  66  */
  67 static inline
  68 void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
  69                         size_t key_len)
  70 {
  71         node->key = key;
  72         node->key_len = key_len;
  73 }
  74
  75 /*
  76  * cds_lfht_new - allocate a hash table.
  77  *
  78  * init_size must be power of two.
  79  */
  80 struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
  81                         cds_lfht_compare_fct compare_fct,
  82                         unsigned long hash_seed,
  83                         unsigned long init_size,
  84                         void (*cds_lfht_call_rcu)(struct rcu_head *head,
  85                                 void (*func)(struct rcu_head *head)));
  86
  87 /*
  88  * cds_lfht_destroy - destroy a hash table.
  89  */
  90 int cds_lfht_destroy(struct cds_lfht *ht);
  91
  92 /*
  93  * cds_lfht_count_nodes - count the number of nodes in the hash table.
  94  *
  95  * Call with rcu_read_lock held.
  96  */
  97 void cds_lfht_count_nodes(struct cds_lfht *ht,
  98                         unsigned long *count,
  99                         unsigned long *removed);
 100
 101 /*
 102  * cds_lfht_lookup - lookup a node by key.
 103  *
 104  * Returns NULL if not found.
 105  * Call with rcu_read_lock held.
 106  */
 107 struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
 108
 109 /*
 110  * cds_lfht_next - get the next item with same key (after a lookup).
 111  *
 112  * Returns NULL if no following node exists with same key.
 113  * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
 114  * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
 115  * Call with rcu_read_lock held.
 116  */
 117 struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
 118
 119 /*
 120  * cds_lfht_add - add a node to the hash table.
 121  *
 122  * Call with rcu_read_lock held.
 123  */
 124 void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
 125
 126 /*
 127  * cds_lfht_add_unique - add a node to hash table, if key is not present.
 128  *
 129  * Returns the node added upon success.
 130  * Returns the unique node already present upon failure. If cds_lfht_add_unique fails,
 131  * the node passed as parameter should be freed by the caller.
 132  * Call with rcu_read_lock held.
 133  */
 134 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
 135
 136 /*
 137  * cds_lfht_remove - remove node from hash table.
 138  *
 139  * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
 140  * lookup and removal.
 141  * Call with rcu_read_lock held.
 142  */
 143 int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
 144
 145 /*
 146  * cds_lfht_resize - Force a hash table resize
 147  * @growth: growth order (current size is multiplied by 2^growth)
 148  *
 149  * Currently, only expand operation is supported (growth >= 0).
 150  */
 151 void cds_lfht_resize(struct cds_lfht *ht, int growth);
 152
 153 #ifdef __cplusplus
 154 }
 155 #endif
 156
 157 #endif /* _URCU_RCULFHASH_H */