Merge branch 'master' into urcu/ht-shrink

[urcu.git] / rculfhash.c

diff --git a/rculfhash.c b/rculfhash.c
index f4187e7993ca9ea53a6915ede1edb6673388db48..600feecfa8f4f8230eede1683cf79cff14a0333f 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -534,7 +534,7 @@ int get_count_order_ulong(unsigned long x)
 #endif
 
 static
-void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth);
+void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth);
 
 static
 void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
@@ -604,7 +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;
@@ -623,11 +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);
@@ -650,11 +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);
@@ -695,7 +695,7 @@ void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len)
                dbg_printf("WARNING: large chain length: %u.\n",
                           chain_len);
        if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD)
-               cds_lfht_resize_lazy(ht, size,
+               cds_lfht_resize_lazy_grow(ht, size,
                        get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1)));
 }
 
@@ -742,7 +742,8 @@ int is_end(struct cds_lfht_node *node)
 }
 
 static
-unsigned long _uatomic_max(unsigned long *ptr, unsigned long v)
+unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr,
+               unsigned long v)
 {
        unsigned long old1, old2;
 
@@ -752,7 +753,7 @@ unsigned long _uatomic_max(unsigned long *ptr, unsigned long v)
                if (old2 >= v)
                        return old2;
        } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2);
-       return v;
+       return old2;
 }
 
 static
@@ -806,12 +807,12 @@ 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;
@@ -915,9 +916,9 @@ 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 */
@@ -925,7 +926,7 @@ 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 */
@@ -1015,7 +1016,7 @@ 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));
@@ -1408,20 +1409,20 @@ 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);
                assert(node == clear_flag(node));
-               if (likely(!is_removed(next))
+               if (caa_likely(!is_removed(next))
                    && !is_dummy(next)
                    && node->p.reverse_hash == reverse_hash
-                   && 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);
@@ -1446,18 +1447,18 @@ 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);
@@ -1473,12 +1474,12 @@ 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;
                }
@@ -1753,11 +1754,9 @@ void _do_cds_lfht_resize(struct cds_lfht *ht)
 }
 
 static
-unsigned long resize_target_update(struct cds_lfht *ht, unsigned long size,
-                                  int growth_order)
+unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size)
 {
-       return _uatomic_max(&ht->t.resize_target,
-                           size << growth_order);
+       return _uatomic_xchg_monotonic_increase(&ht->t.resize_target, new_size);
 }
 
 static
@@ -1797,15 +1796,13 @@ void do_resize_cb(struct rcu_head *head)
 }
 
 static
-void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth)
+void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht)
 {
        struct rcu_resize_work *work;
-       unsigned long target_size;
 
-       target_size = resize_target_update(ht, size, growth);
        /* Store resize_target before read resize_initiated */
        cmm_smp_mb();
-       if (!CMM_LOAD_SHARED(ht->t.resize_initiated) && size < target_size) {
+       if (!CMM_LOAD_SHARED(ht->t.resize_initiated)) {
                uatomic_inc(&ht->in_progress_resize);
                cmm_smp_mb();   /* increment resize count before load destroy */
                if (CMM_LOAD_SHARED(ht->in_progress_destroy)) {
@@ -1819,27 +1816,47 @@ void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth)
        }
 }
 
+static
+void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth)
+{
+       unsigned long target_size = size << growth;
+
+       if (resize_target_grow(ht, target_size) >= target_size)
+               return;
+
+       __cds_lfht_resize_lazy_launch(ht);
+}
+
+/*
+ * We favor grow operations over shrink. A shrink operation never occurs
+ * if a grow operation is queued for lazy execution. A grow operation
+ * cancels any pending shrink lazy execution.
+ */
 static
 void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
                                unsigned long count)
 {
-       struct rcu_resize_work *work;
-
        if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
                return;
-       resize_target_update_count(ht, count);
-       /* Store resize_target before read resize_initiated */
-       cmm_smp_mb();
-       if (!CMM_LOAD_SHARED(ht->t.resize_initiated)) {
-               uatomic_inc(&ht->in_progress_resize);
-               cmm_smp_mb();   /* increment resize count before load destroy */
-               if (CMM_LOAD_SHARED(ht->in_progress_destroy)) {
-                       uatomic_dec(&ht->in_progress_resize);
+       count = max(count, ht->min_alloc_size);
+       if (count == size)
+               return;         /* Already the right size, no resize needed */
+       if (count > size) {     /* lazy grow */
+               if (resize_target_grow(ht, count) >= count)
                        return;
+       } else {                /* lazy shrink */
+               for (;;) {
+                       unsigned long s;
+
+                       s = uatomic_cmpxchg(&ht->t.resize_target, size, count);
+                       if (s == size)
+                               break;  /* no resize needed */
+                       if (s > size)
+                               return; /* growing is/(was just) in progress */
+                       if (s <= count)
+                               return; /* some other thread do shrink */
+                       size = s;
                }
-               work = malloc(sizeof(*work));
-               work->ht = ht;
-               ht->cds_lfht_call_rcu(&work->head, do_resize_cb);
-               CMM_STORE_SHARED(ht->t.resize_initiated, 1);
        }
+       __cds_lfht_resize_lazy_launch(ht);
 }