/* Value of the end pointer. Should not interact with flags. */
#define END_VALUE NULL
+/*
+ * ht_items_count: Split-counters counting the number of node addition
+ * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag
+ * is set at hash table creation.
+ *
+ * These are free-running counters, never reset to zero. They count the
+ * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER)
+ * operations to update the global counter. We choose a power-of-2 value
+ * for the trigger to deal with 32 or 64-bit overflow of the counter.
+ */
struct ht_items_count {
unsigned long add, del;
} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+/*
+ * rcu_level: Contains the per order-index-level dummy node table. The
+ * size of each dummy node table is half the number of hashes contained
+ * in this order (except for order 0). The minimum allocation size
+ * parameter allows combining the dummy node arrays of the lowermost
+ * levels to improve cache locality for small index orders.
+ */
struct rcu_level {
/* Note: manually update allocation length when adding a field */
struct _cds_lfht_node nodes[0];
};
+/*
+ * rcu_table: Contains the size and desired new size if a resize
+ * operation is in progress, as well as the statically-sized array of
+ * rcu_level pointers.
+ */
struct rcu_table {
unsigned long size; /* always a power of 2, shared (RCU) */
unsigned long resize_target;
struct rcu_level *tbl[MAX_TABLE_ORDER];
};
+/*
+ * cds_lfht: Top-level data structure representing a lock-free hash
+ * table. Defined in the implementation file to make it be an opaque
+ * cookie to users.
+ */
struct cds_lfht {
struct rcu_table t;
cds_lfht_hash_fct hash_fct;
struct ht_items_count *split_count; /* split item count */
};
+/*
+ * rcu_resize_work: Contains arguments passed to RCU worker thread
+ * responsible for performing lazy resize.
+ */
struct rcu_resize_work {
struct rcu_head head;
struct cds_lfht *ht;
};
+/*
+ * partition_resize_work: Contains arguments passed to worker threads
+ * executing the hash table resize on partitions of the hash table
+ * assigned to each processor's worker thread.
+ */
struct partition_resize_work {
pthread_t thread_id;
struct cds_lfht *ht;
break;
}
next = rcu_dereference(node->p.next);
+ assert(node == clear_flag(node));
if (likely(!is_removed(next))
&& !is_dummy(next)
- && clear_flag(node)->p.reverse_hash == reverse_hash
+ && node->p.reverse_hash == reverse_hash
&& likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
break;
}
* 4-bytes boundaries because the two lower bits are used as flags.
*/
+/*
+ * _cds_lfht_node: Contains the internal pointers and reverse-hash
+ * value required for lookup and traversal of the hash table.
+ */
struct _cds_lfht_node {
struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
unsigned long reverse_hash;
} __attribute__((aligned(4)));
/*
+ * cds_lfht_node: Contains the full key and length required to check for
+ * an actual match, and also contains an rcu_head structure that is used
+ * by RCU to track a node through a given RCU grace period. There is an
+ * instance of _cds_lfht_node enclosed as a field within each
+ * _cds_lfht_node structure.
+ *
* struct cds_lfht_node can be embedded into a structure (as a field).
* caa_container_of() can be used to get the structure from the struct
* cds_lfht_node after a lookup.
struct rcu_head head;
};
+/* cds_lfht_iter: Used to track state while traversing a hash chain. */
struct cds_lfht_iter {
struct cds_lfht_node *node, *next;
};
* @ht: the hash table to destroy.
* @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
* The caller will typically want to free this pointer if dynamically
- * allocated.
+ * allocated. The attr point can be NULL if the caller does not
+ * need to be informed of the value passed to cds_lfht_new().
*
* Return 0 on success, negative error value on error.
* Threads calling this API need to be registered RCU read-side threads.
/*
* cds_lfht_count_nodes - count the number of nodes in the hash table.
- *
+ * @ht: the hash table.
+ * @split_count_before: Sample the node count split-counter before traversal.
+ * @count: Traverse the hash table, count the number of nodes observed.
+ * @removed: Number of logically removed nodes observed during traversal.
+ * @split_count_after: Sample the node count split-counter after traversal.
* Call with rcu_read_lock held.
* Threads calling this API need to be registered RCU read-side threads.
*/
void cds_lfht_count_nodes(struct cds_lfht *ht,
- long *approx_before,
+ long *split_count_before,
unsigned long *count,
unsigned long *removed,
- long *approx_after);
+ long *split_count_after);
/*
* cds_lfht_lookup - lookup a node by key.
projects / userspace-rcu.git / commitdiff
