X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash.c;h=e5c91b9730bb2ffea069dbd1f68e84a41ef811e3;hp=d786a3da743881e5bc0b406d57dd88d5e915401e;hb=b84f92d592010f01851c3fdcd5ac7d3666028146;hpb=5afadd129c36f4778bcc12c8def6f4e3f9604c7b

diff --git a/rculfhash.c b/rculfhash.c
index d786a3d..e5c91b9 100644
--- 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;
@@ -238,13 +260,15 @@ 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;
-	cds_lfht_compare_fct compare_fct;
 	unsigned long min_alloc_order;
 	unsigned long min_alloc_size;
-	unsigned long hash_seed;
 	int flags;
 	/*
 	 * We need to put the work threads offline (QSBR) when taking this
@@ -269,11 +293,20 @@ 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;
@@ -284,6 +317,7 @@ struct partition_resize_work {
 
 static
 void _cds_lfht_add(struct cds_lfht *ht,
+		cds_lfht_match_fct match,
 		unsigned long size,
 		struct cds_lfht_node *node,
 		struct cds_lfht_iter *unique_ret,
@@ -454,7 +488,7 @@ 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);
@@ -498,7 +532,7 @@ 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,
@@ -568,7 +602,7 @@ 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 +621,11 @@ 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 +648,11 @@ 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);
@@ -659,7 +693,7 @@ 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)));
 }
 
@@ -706,7 +740,8 @@ 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;
 
@@ -716,7 +751,7 @@ 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
@@ -770,12 +805,12 @@ 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;
@@ -855,6 +890,7 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
  */
 static
 void _cds_lfht_add(struct cds_lfht *ht,
+		cds_lfht_match_fct match,
 		unsigned long size,
 		struct cds_lfht_node *node,
 		struct cds_lfht_iter *unique_ret,
@@ -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 */
@@ -907,7 +943,7 @@ void _cds_lfht_add(struct cds_lfht *ht,
 				 * (including observe one node by one node
 				 * by forward iterations)
 				 */
-				cds_lfht_next_duplicate(ht, &d_iter);
+				cds_lfht_next_duplicate(ht, match, &d_iter);
 				if (!d_iter.node)
 					goto insert;
 
@@ -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));
@@ -1083,7 +1119,7 @@ void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
 			   i, j, (1UL << (i - 1)) + j);
 		new_node->p.reverse_hash =
 				bit_reverse_ulong((1UL << (i - 1)) + j);
-		_cds_lfht_add(ht, 1UL << (i - 1),
+		_cds_lfht_add(ht, NULL, 1UL << (i - 1),
 				new_node, NULL, 1);
 	}
 	ht->cds_lfht_rcu_read_unlock();
@@ -1300,10 +1336,7 @@ void cds_lfht_create_dummy(struct cds_lfht *ht, unsigned long size)
 	}
 }
 
-struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
-			cds_lfht_compare_fct compare_fct,
-			unsigned long hash_seed,
-			unsigned long init_size,
+struct cds_lfht *_cds_lfht_new(unsigned long init_size,
 			unsigned long min_alloc_size,
 			int flags,
 			void (*cds_lfht_call_rcu)(struct rcu_head *head,
@@ -1330,9 +1363,7 @@ 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->hash_fct = hash_fct;
-	ht->compare_fct = compare_fct;
-	ht->hash_seed = hash_seed;
+	ht->flags = flags;
 	ht->cds_lfht_call_rcu = cds_lfht_call_rcu;
 	ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu;
 	ht->cds_lfht_rcu_read_lock = cds_lfht_rcu_read_lock;
@@ -1345,24 +1376,22 @@ 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;
 }
 
-void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
-		struct cds_lfht_iter *iter)
+void cds_lfht_lookup(struct cds_lfht *ht, cds_lfht_match_fct match,
+		unsigned long hash, void *key, struct cds_lfht_iter *iter)
 {
 	struct cds_lfht_node *node, *next, *dummy_node;
 	struct _cds_lfht_node *lookup;
-	unsigned long hash, reverse_hash, size;
+	unsigned long reverse_hash, size;
 
-	hash = ht->hash_fct(key, key_len, ht->hash_seed);
 	reverse_hash = bit_reverse_ulong(hash);
 
 	size = rcu_dereference(ht->t.size);
@@ -1372,19 +1401,20 @@ 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(match(node, key))) {
 				break;
 		}
 		node = clear_flag(next);
@@ -1394,33 +1424,32 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
 	iter->next = next;
 }
 
-void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter)
+void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match,
+		struct cds_lfht_iter *iter)
 {
 	struct cds_lfht_node *node, *next;
 	unsigned long reverse_hash;
 	void *key;
-	size_t key_len;
 
 	node = iter->node;
 	reverse_hash = node->p.reverse_hash;
 	key = node->key;
-	key_len = node->key_len;
 	next = iter->next;
 	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(match(node->key, key))) {
 				break;
 		}
 		node = clear_flag(next);
@@ -1436,12 +1465,12 @@ 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;
 		}
@@ -1465,46 +1494,45 @@ void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter)
 	cds_lfht_next(ht, iter);
 }
 
-void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node)
+void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
+		struct cds_lfht_node *node)
 {
-	unsigned long hash, size;
+	unsigned long size;
 
-	hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
 	node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
-
 	size = rcu_dereference(ht->t.size);
-	_cds_lfht_add(ht, size, node, NULL, 0);
+	_cds_lfht_add(ht, NULL, size, node, NULL, 0);
 	ht_count_add(ht, size, hash);
 }
 
 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
+				cds_lfht_match_fct match,
+				unsigned long hash,
 				struct cds_lfht_node *node)
 {
-	unsigned long hash, size;
+	unsigned long size;
 	struct cds_lfht_iter iter;
 
-	hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
 	node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
-
 	size = rcu_dereference(ht->t.size);
-	_cds_lfht_add(ht, size, node, &iter, 0);
+	_cds_lfht_add(ht, match, size, node, &iter, 0);
 	if (iter.node == node)
 		ht_count_add(ht, size, hash);
 	return iter.node;
 }
 
 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
+				cds_lfht_match_fct match,
+				unsigned long hash,
 				struct cds_lfht_node *node)
 {
-	unsigned long hash, size;
+	unsigned long size;
 	struct cds_lfht_iter iter;
 
-	hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
 	node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
-
 	size = rcu_dereference(ht->t.size);
 	for (;;) {
-		_cds_lfht_add(ht, size, node, &iter, 0);
+		_cds_lfht_add(ht, match, size, node, &iter, 0);
 		if (iter.node == node) {
 			ht_count_add(ht, size, hash);
 			return NULL;
@@ -1716,11 +1744,9 @@ 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
@@ -1760,15 +1786,13 @@ 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)) {
@@ -1782,27 +1806,47 @@ 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);
 }