rculfhash: rename likely/unlikely (add caa_ prefix)
[urcu.git] / rculfhash.c
index 4d37fac2f19e9a87c9401c94ae590ab0128d3c60..d1a17669f9fa176660b9552241808f2760f6bdcc 100644 (file)
 /* 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;
@@ -238,6 +260,11 @@ struct rcu_table {
        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;
@@ -269,11 +296,20 @@ struct cds_lfht {
        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;
@@ -454,7 +490,7 @@ unsigned int fls_u32(uint32_t x)
 
 unsigned int fls_ulong(unsigned long x)
 {
-#if (CAA_BITS_PER_lONG == 32)
+#if (CAA_BITS_PER_LONG == 32)
        return fls_u32(x);
 #else
        return fls_u64(x);
@@ -568,7 +604,7 @@ int ht_get_split_count_index(unsigned long hash)
 
        assert(split_count_mask >= 0);
        cpu = sched_getcpu();
-       if (unlikely(cpu < 0))
+       if (caa_unlikely(cpu < 0))
                return hash & split_count_mask;
        else
                return cpu & split_count_mask;
@@ -587,11 +623,11 @@ void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash)
        unsigned long split_count;
        int index;
 
-       if (unlikely(!ht->split_count))
+       if (caa_unlikely(!ht->split_count))
                return;
        index = ht_get_split_count_index(hash);
        split_count = uatomic_add_return(&ht->split_count[index].add, 1);
-       if (unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+       if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
                long count;
 
                dbg_printf("add split count %lu\n", split_count);
@@ -614,11 +650,11 @@ void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash)
        unsigned long split_count;
        int index;
 
-       if (unlikely(!ht->split_count))
+       if (caa_unlikely(!ht->split_count))
                return;
        index = ht_get_split_count_index(hash);
        split_count = uatomic_add_return(&ht->split_count[index].del, 1);
-       if (unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+       if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
                long count;
 
                dbg_printf("del split count %lu\n", split_count);
@@ -770,12 +806,12 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node
                 */
                assert(dummy != node);
                for (;;) {
-                       if (unlikely(is_end(iter)))
+                       if (caa_unlikely(is_end(iter)))
                                return;
-                       if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
+                       if (caa_likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
                                return;
                        next = rcu_dereference(clear_flag(iter)->p.next);
-                       if (likely(is_removed(next)))
+                       if (caa_likely(is_removed(next)))
                                break;
                        iter_prev = clear_flag(iter);
                        iter = next;
@@ -879,9 +915,9 @@ void _cds_lfht_add(struct cds_lfht *ht,
                iter = rcu_dereference(iter_prev->p.next);
                assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
                for (;;) {
-                       if (unlikely(is_end(iter)))
+                       if (caa_unlikely(is_end(iter)))
                                goto insert;
-                       if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
+                       if (caa_likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
                                goto insert;
 
                        /* dummy node is the first node of the identical-hash-value chain */
@@ -889,7 +925,7 @@ void _cds_lfht_add(struct cds_lfht *ht,
                                goto insert;
 
                        next = rcu_dereference(clear_flag(iter)->p.next);
-                       if (unlikely(is_removed(next)))
+                       if (caa_unlikely(is_removed(next)))
                                goto gc_node;
 
                        /* uniquely add */
@@ -979,7 +1015,7 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
                struct cds_lfht_node *new_next;
 
                next = old;
-               if (unlikely(is_removed(next)))
+               if (caa_unlikely(is_removed(next)))
                        return -ENOENT;
                if (dummy_removal)
                        assert(is_dummy(next));
@@ -1372,19 +1408,20 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
        node = rcu_dereference(dummy_node->p.next);
        node = clear_flag(node);
        for (;;) {
-               if (unlikely(is_end(node))) {
+               if (caa_unlikely(is_end(node))) {
                        node = next = NULL;
                        break;
                }
-               if (unlikely(node->p.reverse_hash > reverse_hash)) {
+               if (caa_unlikely(node->p.reverse_hash > reverse_hash)) {
                        node = next = NULL;
                        break;
                }
                next = rcu_dereference(node->p.next);
-               if (likely(!is_removed(next))
+               assert(node == clear_flag(node));
+               if (caa_likely(!is_removed(next))
                    && !is_dummy(next)
-                   && clear_flag(node)->p.reverse_hash == reverse_hash
-                   && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
+                   && node->p.reverse_hash == reverse_hash
+                   && caa_likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
                                break;
                }
                node = clear_flag(next);
@@ -1409,18 +1446,18 @@ void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter)
        node = clear_flag(next);
 
        for (;;) {
-               if (unlikely(is_end(node))) {
+               if (caa_unlikely(is_end(node))) {
                        node = next = NULL;
                        break;
                }
-               if (unlikely(node->p.reverse_hash > reverse_hash)) {
+               if (caa_unlikely(node->p.reverse_hash > reverse_hash)) {
                        node = next = NULL;
                        break;
                }
                next = rcu_dereference(node->p.next);
-               if (likely(!is_removed(next))
+               if (caa_likely(!is_removed(next))
                    && !is_dummy(next)
-                   && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
+                   && caa_likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
                                break;
                }
                node = clear_flag(next);
@@ -1436,12 +1473,12 @@ void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter)
 
        node = clear_flag(iter->next);
        for (;;) {
-               if (unlikely(is_end(node))) {
+               if (caa_unlikely(is_end(node))) {
                        node = next = NULL;
                        break;
                }
                next = rcu_dereference(node->p.next);
-               if (likely(!is_removed(next))
+               if (caa_likely(!is_removed(next))
                    && !is_dummy(next)) {
                                break;
                }
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