X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Fcommon%2Fhashtable%2Fhashtable.c;h=ac765808f9e804b80db20998b3892ba72d130085;hb=ca806b0b247f89c62ac628a7779ae84049a8c2d7;hp=b08a57e5cc0a07f53582a3181443d395c8b97765;hpb=3c4599b9a5c12ceff19368c6cd51e01d81824726;p=lttng-tools.git

diff --git a/src/common/hashtable/hashtable.c b/src/common/hashtable/hashtable.c
index b08a57e5c..ac765808f 100644
--- a/src/common/hashtable/hashtable.c
+++ b/src/common/hashtable/hashtable.c
@@ -1,22 +1,11 @@
 /*
- * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2 only,
- * as published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
-#include <assert.h>
+#define _LGPL_SOURCE
 #include <string.h>
 #include <urcu.h>
 #include <urcu/compiler.h>
@@ -27,11 +16,21 @@
 #include "hashtable.h"
 #include "utils.h"
 
+/* seed_lock protects both seed_init and lttng_ht_seed. */
+static pthread_mutex_t seed_lock = PTHREAD_MUTEX_INITIALIZER;
+static bool seed_init;
 unsigned long lttng_ht_seed;
 
 static unsigned long min_hash_alloc_size = 1;
 static unsigned long max_hash_buckets_size = 0;
 
+/*
+ * Getter/lookup functions need to be called with RCU read-side lock
+ * held. However, modification functions (add, add_unique, replace, del)
+ * take the RCU lock internally, so it does not matter whether the
+ * caller hold the RCU lock or not.
+ */
+
 /*
  * Match function for string node.
  */
@@ -76,6 +75,24 @@ static int match_two_u64(struct cds_lfht_node *node, const void *key)
 	return hash_match_key_two_u64((void *) &match_node->key, (void *) key);
 }
 
+static inline
+const char *lttng_ht_type_str(enum lttng_ht_type type)
+{
+	switch (type) {
+	case LTTNG_HT_TYPE_STRING:
+		return "STRING";
+	case LTTNG_HT_TYPE_ULONG:
+		return "ULONG";
+	case LTTNG_HT_TYPE_U64:
+		return "U64";
+	case LTTNG_HT_TYPE_TWO_U64:
+		return "TWO_U64";
+	default:
+		ERR("Unknown lttng hashtable type %d", type);
+		abort();
+	}
+}
+
 /*
  * Return an allocated lttng hashtable.
  */
@@ -87,6 +104,13 @@ struct lttng_ht *lttng_ht_new(unsigned long size, int type)
 	if (!size)
 		size = DEFAULT_HT_SIZE;
 
+	pthread_mutex_lock(&seed_lock);
+	if (!seed_init) {
+		lttng_ht_seed = (unsigned long) time(NULL);
+		seed_init = true;
+	}
+	pthread_mutex_unlock(&seed_lock);
+
 	ht = zmalloc(sizeof(*ht));
 	if (ht == NULL) {
 		PERROR("zmalloc lttng_ht");
@@ -99,7 +123,7 @@ struct lttng_ht *lttng_ht_new(unsigned long size, int type)
 	 * There is already an assert in the RCU hashtable code so if the ht is
 	 * NULL here there is a *huge* problem.
 	 */
-	assert(ht->ht);
+	LTTNG_ASSERT(ht->ht);
 
 	switch (type) {
 	case LTTNG_HT_TYPE_STRING:
@@ -124,7 +148,8 @@ struct lttng_ht *lttng_ht_new(unsigned long size, int type)
 		goto error;
 	}
 
-	DBG3("Created hashtable size %lu at %p of type %d", size, ht->ht, type);
+	DBG3("Created hashtable size %lu at %p of type %s", size, ht->ht,
+			lttng_ht_type_str(type));
 
 	return ht;
 
@@ -140,7 +165,7 @@ void lttng_ht_destroy(struct lttng_ht *ht)
 	int ret;
 
 	ret = cds_lfht_destroy(ht->ht, NULL);
-	assert(!ret);
+	LTTNG_ASSERT(!ret);
 	free(ht);
 }
 
@@ -149,7 +174,7 @@ void lttng_ht_destroy(struct lttng_ht *ht)
  */
 void lttng_ht_node_init_str(struct lttng_ht_node_str *node, char *key)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 
 	node->key = key;
 	cds_lfht_node_init(&node->node);
@@ -161,7 +186,7 @@ void lttng_ht_node_init_str(struct lttng_ht_node_str *node, char *key)
 void lttng_ht_node_init_ulong(struct lttng_ht_node_ulong *node,
 		unsigned long key)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 
 	node->key = key;
 	cds_lfht_node_init(&node->node);
@@ -173,7 +198,7 @@ void lttng_ht_node_init_ulong(struct lttng_ht_node_ulong *node,
 void lttng_ht_node_init_u64(struct lttng_ht_node_u64 *node,
 		uint64_t key)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 
 	node->key = key;
 	cds_lfht_node_init(&node->node);
@@ -185,7 +210,7 @@ void lttng_ht_node_init_u64(struct lttng_ht_node_u64 *node,
 void lttng_ht_node_init_two_u64(struct lttng_ht_node_two_u64 *node,
 		uint64_t key1, uint64_t key2)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 
 	node->key.key1 = key1;
 	node->key.key2 = key2;
@@ -197,7 +222,7 @@ void lttng_ht_node_init_two_u64(struct lttng_ht_node_two_u64 *node,
  */
 void lttng_ht_node_free_str(struct lttng_ht_node_str *node)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 	free(node);
 }
 
@@ -206,7 +231,7 @@ void lttng_ht_node_free_str(struct lttng_ht_node_str *node)
  */
 void lttng_ht_node_free_ulong(struct lttng_ht_node_ulong *node)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 	free(node);
 }
 
@@ -215,7 +240,7 @@ void lttng_ht_node_free_ulong(struct lttng_ht_node_ulong *node)
  */
 void lttng_ht_node_free_u64(struct lttng_ht_node_u64 *node)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 	free(node);
 }
 
@@ -224,18 +249,18 @@ void lttng_ht_node_free_u64(struct lttng_ht_node_u64 *node)
  */
 void lttng_ht_node_free_two_u64(struct lttng_ht_node_two_u64 *node)
 {
-	assert(node);
+	LTTNG_ASSERT(node);
 	free(node);
 }
 
 /*
  * Lookup function in hashtable.
  */
-void lttng_ht_lookup(struct lttng_ht *ht, void *key,
+void lttng_ht_lookup(struct lttng_ht *ht, const void *key,
 		struct lttng_ht_iter *iter)
 {
-	assert(ht);
-	assert(ht->ht);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
 
 	cds_lfht_lookup(ht->ht, ht->hash_fct(key, lttng_ht_seed),
 			ht->match_fct, key, &iter->iter);
@@ -248,13 +273,16 @@ void lttng_ht_add_unique_str(struct lttng_ht *ht,
 		struct lttng_ht_node_str *node)
 {
 	struct cds_lfht_node *node_ptr;
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	node_ptr = cds_lfht_add_unique(ht->ht, ht->hash_fct(node->key, lttng_ht_seed),
 			ht->match_fct, node->key, &node->node);
-	assert(node_ptr == &node->node);
+	rcu_read_unlock();
+	LTTNG_ASSERT(node_ptr == &node->node);
 }
 
 /*
@@ -263,12 +291,15 @@ void lttng_ht_add_unique_str(struct lttng_ht *ht,
 void lttng_ht_add_str(struct lttng_ht *ht,
 		struct lttng_ht_node_str *node)
 {
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	cds_lfht_add(ht->ht, ht->hash_fct(node->key, lttng_ht_seed),
 			&node->node);
+	rcu_read_unlock();
 }
 
 /*
@@ -276,26 +307,31 @@ void lttng_ht_add_str(struct lttng_ht *ht,
  */
 void lttng_ht_add_ulong(struct lttng_ht *ht, struct lttng_ht_node_ulong *node)
 {
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	cds_lfht_add(ht->ht, ht->hash_fct((void *) node->key, lttng_ht_seed),
 			&node->node);
+	rcu_read_unlock();
 }
 
 /*
  * Add uint64_t node to hashtable.
-
  */
 void lttng_ht_add_u64(struct lttng_ht *ht, struct lttng_ht_node_u64 *node)
 {
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	cds_lfht_add(ht->ht, ht->hash_fct(&node->key, lttng_ht_seed),
 			&node->node);
+	rcu_read_unlock();
 }
 
 /*
@@ -305,14 +341,17 @@ void lttng_ht_add_unique_ulong(struct lttng_ht *ht,
 		struct lttng_ht_node_ulong *node)
 {
 	struct cds_lfht_node *node_ptr;
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	node_ptr = cds_lfht_add_unique(ht->ht,
 			ht->hash_fct((void *) node->key, lttng_ht_seed), ht->match_fct,
 			(void *) node->key, &node->node);
-	assert(node_ptr == &node->node);
+	rcu_read_unlock();
+	LTTNG_ASSERT(node_ptr == &node->node);
 }
 
 /*
@@ -322,14 +361,17 @@ void lttng_ht_add_unique_u64(struct lttng_ht *ht,
 		struct lttng_ht_node_u64 *node)
 {
 	struct cds_lfht_node *node_ptr;
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	node_ptr = cds_lfht_add_unique(ht->ht,
 			ht->hash_fct(&node->key, lttng_ht_seed), ht->match_fct,
 			&node->key, &node->node);
-	assert(node_ptr == &node->node);
+	rcu_read_unlock();
+	LTTNG_ASSERT(node_ptr == &node->node);
 }
 
 /*
@@ -339,14 +381,17 @@ void lttng_ht_add_unique_two_u64(struct lttng_ht *ht,
 		struct lttng_ht_node_two_u64 *node)
 {
 	struct cds_lfht_node *node_ptr;
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	node_ptr = cds_lfht_add_unique(ht->ht,
 			ht->hash_fct((void *) &node->key, lttng_ht_seed), ht->match_fct,
 			(void *) &node->key, &node->node);
-	assert(node_ptr == &node->node);
+	rcu_read_unlock();
+	LTTNG_ASSERT(node_ptr == &node->node);
 }
 
 /*
@@ -356,19 +401,22 @@ struct lttng_ht_node_ulong *lttng_ht_add_replace_ulong(struct lttng_ht *ht,
 		struct lttng_ht_node_ulong *node)
 {
 	struct cds_lfht_node *node_ptr;
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	node_ptr = cds_lfht_add_replace(ht->ht,
 			ht->hash_fct((void *) node->key, lttng_ht_seed), ht->match_fct,
 			(void *) node->key, &node->node);
+	rcu_read_unlock();
 	if (!node_ptr) {
 		return NULL;
 	} else {
 		return caa_container_of(node_ptr, struct lttng_ht_node_ulong, node);
 	}
-	assert(node_ptr == &node->node);
+	LTTNG_ASSERT(node_ptr == &node->node);
 }
 
 /*
@@ -378,19 +426,22 @@ struct lttng_ht_node_u64 *lttng_ht_add_replace_u64(struct lttng_ht *ht,
 		struct lttng_ht_node_u64 *node)
 {
 	struct cds_lfht_node *node_ptr;
-	assert(ht);
-	assert(ht->ht);
-	assert(node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(node);
 
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
 	node_ptr = cds_lfht_add_replace(ht->ht,
 			ht->hash_fct(&node->key, lttng_ht_seed), ht->match_fct,
 			&node->key, &node->node);
+	rcu_read_unlock();
 	if (!node_ptr) {
 		return NULL;
 	} else {
 		return caa_container_of(node_ptr, struct lttng_ht_node_u64, node);
 	}
-	assert(node_ptr == &node->node);
+	LTTNG_ASSERT(node_ptr == &node->node);
 }
 
 /*
@@ -398,11 +449,17 @@ struct lttng_ht_node_u64 *lttng_ht_add_replace_u64(struct lttng_ht *ht,
  */
 int lttng_ht_del(struct lttng_ht *ht, struct lttng_ht_iter *iter)
 {
-	assert(ht);
-	assert(ht->ht);
-	assert(iter);
+	int ret;
 
-	return cds_lfht_del(ht->ht, iter->iter.node);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(iter);
+
+	/* RCU read lock protects from ABA. */
+	rcu_read_lock();
+	ret = cds_lfht_del(ht->ht, iter->iter.node);
+	rcu_read_unlock();
+	return ret;
 }
 
 /*
@@ -410,9 +467,9 @@ int lttng_ht_del(struct lttng_ht *ht, struct lttng_ht_iter *iter)
  */
 void lttng_ht_get_first(struct lttng_ht *ht, struct lttng_ht_iter *iter)
 {
-	assert(ht);
-	assert(ht->ht);
-	assert(iter);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(iter);
 
 	cds_lfht_first(ht->ht, &iter->iter);
 }
@@ -422,9 +479,9 @@ void lttng_ht_get_first(struct lttng_ht *ht, struct lttng_ht_iter *iter)
  */
 void lttng_ht_get_next(struct lttng_ht *ht, struct lttng_ht_iter *iter)
 {
-	assert(ht);
-	assert(ht->ht);
-	assert(iter);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
+	LTTNG_ASSERT(iter);
 
 	cds_lfht_next(ht->ht, &iter->iter);
 }
@@ -437,10 +494,13 @@ unsigned long lttng_ht_get_count(struct lttng_ht *ht)
 	long scb, sca;
 	unsigned long count;
 
-	assert(ht);
-	assert(ht->ht);
+	LTTNG_ASSERT(ht);
+	LTTNG_ASSERT(ht->ht);
 
+	/* RCU read lock protects from ABA and allows RCU traversal. */
+	rcu_read_lock();
 	cds_lfht_count_nodes(ht->ht, &scb, &count, &sca);
+	rcu_read_unlock();
 
 	return count;
 }
@@ -453,7 +513,7 @@ struct lttng_ht_node_str *lttng_ht_iter_get_node_str(
 {
 	struct cds_lfht_node *node;
 
-	assert(iter);
+	LTTNG_ASSERT(iter);
 	node = cds_lfht_iter_get_node(&iter->iter);
 	if (!node) {
 		return NULL;
@@ -469,7 +529,7 @@ struct lttng_ht_node_ulong *lttng_ht_iter_get_node_ulong(
 {
 	struct cds_lfht_node *node;
 
-	assert(iter);
+	LTTNG_ASSERT(iter);
 	node = cds_lfht_iter_get_node(&iter->iter);
 	if (!node) {
 		return NULL;
@@ -485,7 +545,7 @@ struct lttng_ht_node_u64 *lttng_ht_iter_get_node_u64(
 {
 	struct cds_lfht_node *node;
 
-	assert(iter);
+	LTTNG_ASSERT(iter);
 	node = cds_lfht_iter_get_node(&iter->iter);
 	if (!node) {
 		return NULL;
@@ -501,19 +561,10 @@ struct lttng_ht_node_two_u64 *lttng_ht_iter_get_node_two_u64(
 {
 	struct cds_lfht_node *node;
 
-	assert(iter);
+	LTTNG_ASSERT(iter);
 	node = cds_lfht_iter_get_node(&iter->iter);
 	if (!node) {
 		return NULL;
 	}
 	return caa_container_of(node, struct lttng_ht_node_two_u64, node);
 }
-
-/*
- * lib constructor
- */
-static void __attribute__((constructor)) _init(void)
-{
-	/* Init hash table seed */
-	lttng_ht_seed = (unsigned long) time(NULL);
-}