rculfhash: Remove unneed branches
[urcu.git] / rculfhash.c
index 18a3cb89c8b273b81757fd763f4b472d8301e6d6..0bcbb1e832a5ab41c4d4357c0dafa4ff87832db7 100644 (file)
@@ -871,12 +871,6 @@ void _cds_lfht_add(struct cds_lfht *ht,
 
        assert(!is_dummy(node));
        assert(!is_removed(node));
-       if (!size) {
-               assert(dummy);
-               assert(!unique_ret);
-               node->p.next = flag_dummy(get_end());
-               return;         /* Initial first add (head) */
-       }
        lookup = lookup_bucket(ht, size, bit_reverse_ulong(node->p.reverse_hash));
        for (;;) {
                uint32_t chain_len = 0;
@@ -894,22 +888,38 @@ void _cds_lfht_add(struct cds_lfht *ht,
                                goto insert;
                        if (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 */
                        if (dummy && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash)
                                goto insert;
+
                        next = rcu_dereference(clear_flag(iter)->p.next);
                        if (unlikely(is_removed(next)))
                                goto gc_node;
+
+                       /* uniquely add */
                        if (unique_ret
                            && !is_dummy(next)
-                           && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash
-                           && !ht->compare_fct(node->key, node->key_len,
-                                               clear_flag(iter)->key,
-                                               clear_flag(iter)->key_len)) {
-                               unique_ret->node = clear_flag(iter);
-                               unique_ret->next = next;
+                           && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash) {
+                               struct cds_lfht_iter d_iter = { .node = node, .next = iter, };
+
+                               /*
+                                * uniquely adding inserts the node as the first
+                                * node of the identical-hash-value node chain.
+                                *
+                                * This semantic ensures no duplicated keys
+                                * should ever be observable in the table
+                                * (including observe one node by one node
+                                * by forward iterations)
+                                */
+                               cds_lfht_next_duplicate(ht, &d_iter);
+                               if (!d_iter.node)
+                                       goto insert;
+
+                               *unique_ret = d_iter;
                                return;
                        }
+
                        /* Only account for identical reverse hash once */
                        if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash
                            && !is_dummy(next))
@@ -1068,16 +1078,17 @@ void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
 {
        unsigned long j;
 
+       assert(i > 0);
        ht->cds_lfht_rcu_read_lock();
        for (j = start; j < start + len; j++) {
                struct cds_lfht_node *new_node =
                        (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
 
                dbg_printf("init populate: i %lu j %lu hash %lu\n",
-                          i, j, !i ? 0 : (1UL << (i - 1)) + j);
+                          i, j, (1UL << (i - 1)) + j);
                new_node->p.reverse_hash =
-                       bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
-               _cds_lfht_add(ht, !i ? 0 : (1UL << (i - 1)),
+                               bit_reverse_ulong((1UL << (i - 1)) + j);
+               _cds_lfht_add(ht, 1UL << (i - 1),
                                new_node, NULL, 1);
        }
        ht->cds_lfht_rcu_read_unlock();
@@ -1105,14 +1116,15 @@ void init_table(struct cds_lfht *ht,
 
        dbg_printf("init table: first_order %lu last_order %lu\n",
                   first_order, last_order);
+       assert(first_order > 0);
        for (i = first_order; i <= last_order; i++) {
                unsigned long len;
 
-               len = !i ? 1 : 1UL << (i - 1);
+               len = 1UL << (i - 1);
                dbg_printf("init order %lu len: %lu\n", i, len);
 
                /* Stop expand if the resize target changes under us */
-               if (CMM_LOAD_SHARED(ht->t.resize_target) < (!i ? 1 : (1UL << i)))
+               if (CMM_LOAD_SHARED(ht->t.resize_target) < (1UL << i))
                        break;
 
                ht->t.tbl[i] = calloc(1, len * sizeof(struct _cds_lfht_node));
@@ -1128,9 +1140,9 @@ void init_table(struct cds_lfht *ht,
                 * Update table size.
                 */
                cmm_smp_wmb();  /* populate data before RCU size */
-               CMM_STORE_SHARED(ht->t.size, !i ? 1 : (1UL << i));
+               CMM_STORE_SHARED(ht->t.size, 1UL << i);
 
-               dbg_printf("init new size: %lu\n", !i ? 1 : (1UL << i));
+               dbg_printf("init new size: %lu\n", 1UL << i);
                if (CMM_LOAD_SHARED(ht->in_progress_destroy))
                        break;
        }
@@ -1167,17 +1179,17 @@ void remove_table_partition(struct cds_lfht *ht, unsigned long i,
 {
        unsigned long j;
 
+       assert(i > 0);
        ht->cds_lfht_rcu_read_lock();
        for (j = start; j < start + len; j++) {
                struct cds_lfht_node *fini_node =
                        (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
 
                dbg_printf("remove entry: i %lu j %lu hash %lu\n",
-                          i, j, !i ? 0 : (1UL << (i - 1)) + j);
+                          i, j, (1UL << (i - 1)) + j);
                fini_node->p.reverse_hash =
-                       bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
-               (void) _cds_lfht_del(ht, !i ? 0 : (1UL << (i - 1)),
-                               fini_node, 1);
+                       bit_reverse_ulong((1UL << (i - 1)) + j);
+               (void) _cds_lfht_del(ht, 1UL << (i - 1), fini_node, 1);
        }
        ht->cds_lfht_rcu_read_unlock();
 }
@@ -1209,7 +1221,7 @@ void fini_table(struct cds_lfht *ht,
        for (i = last_order; i >= first_order; i--) {
                unsigned long len;
 
-               len = !i ? 1 : 1UL << (i - 1);
+               len = 1UL << (i - 1);
                dbg_printf("fini order %lu len: %lu\n", i, len);
 
                /* Stop shrink if the resize target changes under us */
@@ -1250,6 +1262,45 @@ void fini_table(struct cds_lfht *ht,
        }
 }
 
+static
+void cds_lfht_create_dummy(struct cds_lfht *ht, unsigned long size)
+{
+       struct _cds_lfht_node *prev, *node;
+       unsigned long order, len, i, j;
+
+       ht->t.tbl[0] = calloc(1, sizeof(struct _cds_lfht_node));
+       assert(ht->t.tbl[0]);
+
+       dbg_printf("create dummy: order %lu index %lu hash %lu\n", 0, 0, 0);
+       ht->t.tbl[0]->nodes[0].next = flag_dummy(get_end());
+       ht->t.tbl[0]->nodes[0].reverse_hash = 0;
+
+       for (order = 1; order < get_count_order_ulong(size) + 1; order++) {
+               len = 1UL << (order - 1);
+               ht->t.tbl[order] = calloc(1, len * sizeof(struct _cds_lfht_node));
+               assert(ht->t.tbl[order]);
+
+               i = 0;
+               prev = ht->t.tbl[i]->nodes;
+               for (j = 0; j < len; j++) {
+                       if (j & (j - 1)) {      /* Between power of 2 */
+                               prev++;
+                       } else if (j) {         /* At each power of 2 */
+                               i++;
+                               prev = ht->t.tbl[i]->nodes;
+                       }
+
+                       node = &ht->t.tbl[order]->nodes[j];
+                       dbg_printf("create dummy: order %lu index %lu hash %lu\n",
+                                  order, j, j + len);
+                       node->next = prev->next;
+                       assert(is_dummy(node->next));
+                       node->reverse_hash = bit_reverse_ulong(j + len);
+                       prev->next = flag_dummy((struct cds_lfht_node *)node);
+               }
+       }
+}
+
 struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
                        cds_lfht_compare_fct compare_fct,
                        unsigned long hash_seed,
@@ -1289,14 +1340,11 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
        ht->percpu_count = alloc_per_cpu_items_count();
        /* this mutex should not nest in read-side C.S. */
        pthread_mutex_init(&ht->resize_mutex, NULL);
-       order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE));
        ht->flags = flags;
-       ht->cds_lfht_rcu_thread_offline();
-       pthread_mutex_lock(&ht->resize_mutex);
+       order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE));
        ht->t.resize_target = 1UL << order;
-       init_table(ht, 0, order);
-       pthread_mutex_unlock(&ht->resize_mutex);
-       ht->cds_lfht_rcu_thread_online();
+       cds_lfht_create_dummy(ht, 1UL << order);
+       ht->t.size = 1UL << order;
        return ht;
 }
 
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