Merge branch 'master' into urcu/ht-shrink

[urcu.git] / rculfhash.c

diff --git a/rculfhash.c b/rculfhash.c
index d786a3da743881e5bc0b406d57dd88d5e915401e..f4187e7993ca9ea53a6915ede1edb6673388db48 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -222,15 +222,37 @@
 /* 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);
@@ -1330,6 +1366,7 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
        init_size = max(init_size, min_alloc_size);
        ht = calloc(1, sizeof(struct cds_lfht));
        assert(ht);
+       ht->flags = flags;
        ht->hash_fct = hash_fct;
        ht->compare_fct = compare_fct;
        ht->hash_seed = hash_seed;
@@ -1345,13 +1382,12 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
        alloc_split_items_count(ht);
        /* this mutex should not nest in read-side C.S. */
        pthread_mutex_init(&ht->resize_mutex, NULL);
-       ht->flags = flags;
        order = get_count_order_ulong(init_size);
        ht->t.resize_target = 1UL << order;
-       cds_lfht_create_dummy(ht, 1UL << order);
-       ht->t.size = 1UL << order;
        ht->min_alloc_size = min_alloc_size;
        ht->min_alloc_order = get_count_order_ulong(min_alloc_size);
+       cds_lfht_create_dummy(ht, 1UL << order);
+       ht->t.size = 1UL << order;
        return ht;
 }
 
@@ -1381,9 +1417,10 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
                        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;
                }