X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash.c;h=600feecfa8f4f8230eede1683cf79cff14a0333f;hp=f4187e7993ca9ea53a6915ede1edb6673388db48;hb=5f74363e048fb82d7ad97a780eadbeb063840787;hpb=cc6b0c208a9707f8a64609a51167290caeace288

diff --git a/rculfhash.c b/rculfhash.c
index f4187e7..600feec 100644
--- 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);
 }