From 65bc8f2af875028fbccc88be77af5f396330d1a2 Mon Sep 17 00:00:00 2001
From: Brian Wellington <source@isc.org>
Date: Fri, 9 Feb 2001 01:26:51 +0000
Subject: [PATCH] When assigning a bucket lock to an rbt node, use the hash of
 the full name, rather than the hash of the partial name stored in the node. 
 This more evenly distributes nodes across locks.

This change only takes effect when DNS_RBT_USEHASH is defined, and also changes
the rbt so that the hashtable is created when the first node is created in the
tree, not after 64 nodes are added.
---
 lib/dns/rbt.c   | 15 ++++++---------
 lib/dns/rbtdb.c | 16 +++++++++++++++-
 2 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/lib/dns/rbt.c b/lib/dns/rbt.c
index cfde89e67e..e3b410ee90 100644
--- a/lib/dns/rbt.c
+++ b/lib/dns/rbt.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: rbt.c,v 1.100 2001/02/05 20:07:20 bwelling Exp $ */
+/* $Id: rbt.c,v 1.101 2001/02/09 01:26:49 bwelling Exp $ */
 
 /* Principal Authors: DCL */
 
@@ -50,7 +50,7 @@
 
 #ifdef RBT_MEM_TEST
 #undef RBT_HASH_SIZE
-#define RBT_HASH_SIZE 1	/* To give the reallocation code a workout. */
+#define RBT_HASH_SIZE 2	/* To give the reallocation code a workout. */
 #endif
 
 struct dns_rbt {
@@ -1621,7 +1621,7 @@ static isc_result_t
 inithash(dns_rbt_t *rbt) {
 	unsigned int bytes;
 
-	rbt->hashsize = RBT_HASH_SIZE * 2;
+	rbt->hashsize = RBT_HASH_SIZE;
 	bytes = rbt->hashsize * sizeof(dns_rbtnode_t *);
 	rbt->hashtable = isc_mem_get(rbt->mctx, bytes);
 
@@ -1675,12 +1675,9 @@ static inline isc_result_t
 hash_node(dns_rbt_t *rbt, dns_rbtnode_t *node) {
 	isc_result_t result = ISC_R_SUCCESS;
 
-	if (rbt->hashtable == NULL) {
-		if (rbt->nodecount == RBT_HASH_SIZE)
-			result = inithash(rbt);
-		return (result);
-
-	} else if (rbt->nodecount >= rbt->hashsize)
+	if (rbt->hashtable == NULL)
+		result = inithash(rbt);
+	else if (rbt->nodecount >= rbt->hashsize)
 		result = rehash(rbt);
 
 	if (result == ISC_R_SUCCESS)
diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index 58501e0f3d..53e3ea322f 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: rbtdb.c,v 1.146 2001/01/30 02:50:45 bwelling Exp $ */
+/* $Id: rbtdb.c,v 1.147 2001/02/09 01:26:51 bwelling Exp $ */
 
 /*
  * Principal Author: Bob Halley
@@ -984,8 +984,12 @@ findnode(dns_db_t *db, dns_name_t *name, isc_boolean_t create,
 		result = dns_rbt_addnode(rbtdb->tree, name, &node);
 		if (result == ISC_R_SUCCESS) {
 			dns_rbt_namefromnode(node, &nodename);
+#ifdef DNS_RBT_USEHASH
+			node->locknum = node->hashval % rbtdb->node_lock_count;
+#else
 			node->locknum = dns_name_hash(&nodename, ISC_TRUE) %
 				rbtdb->node_lock_count;
+#endif
 		} else if (result != ISC_R_EXISTS) {
 			RWUNLOCK(&rbtdb->tree_lock, locktype);
 			return (result);
@@ -3709,8 +3713,12 @@ loading_addrdataset(void *arg, dns_name_t *name, dns_rdataset_t *rdataset) {
 	if (result != ISC_R_EXISTS) {
 		dns_name_init(&foundname, NULL);
 		dns_rbt_namefromnode(node, &foundname);
+#ifdef DNS_RBT_USEHASH
+		node->locknum = node->hashval % rbtdb->node_lock_count;
+#else
 		node->locknum = dns_name_hash(&foundname, ISC_TRUE) %
 			rbtdb->node_lock_count;
+#endif
 	}
 
 	result = dns_rdataslab_fromrdataset(rdataset, rbtdb->common.mctx,
@@ -4080,9 +4088,15 @@ dns_rbtdb_create
 		 */
 		dns_name_init(&name, NULL);
 		dns_rbt_namefromnode(rbtdb->origin_node, &name);
+#ifdef DNS_RBT_USEHASH
+		rbtdb->origin_node->locknum =
+			rbtdb->origin_node->hashval %
+			rbtdb->node_lock_count;
+#else
 		rbtdb->origin_node->locknum =
 			dns_name_hash(&name, ISC_TRUE) %
 			rbtdb->node_lock_count;
+#endif
 	}
 
 	/*