r19402: - use the new tdb_lockall_read() to make ldb_search() more efficient,

  by avoiding chain locks on each tdb_fetch() within the search

- use the tdb_get_seqnum() call to avoid re-reading the @BASEINFO
  record when it hasn't changed.

These speed up the LOCAL-DBSPEED test for ldb from 7k ops/sec to a bit
over 11k ops/sec
(This used to be commit 1347ad254eb8cd12ce22a5a2a37bec0a0ac8dbf1)

4 files changed, 15 insertions, 20 deletions

diff --git a/source4/lib/ldb/ldb_tdb/ldb_cache.c b/source4/lib/ldb/ldb_tdb/ldb_cache.c
index 84932ac47f..467f1ac34d 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_cache.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_cache.c
@@ -316,6 +316,12 @@ int ltdb_cache_load(struct ldb_module *module)
 	uint64_t seq;
 	struct ldb_message *baseinfo;
 
+	/* a very fast check to avoid extra database reads */
+	if (ltdb->cache != NULL && 
+	    tdb_get_seqnum(ltdb->tdb) == ltdb->tdb_seqnum) {
+		return 0;
+	}
+
 	if (ltdb->cache == NULL) {
 		ltdb->cache = talloc_zero(ltdb, struct ltdb_cache);
 		if (ltdb->cache == NULL) goto failed;
@@ -349,6 +355,8 @@ int ltdb_cache_load(struct ldb_module *module)
 		}
 	}
 
+	ltdb->tdb_seqnum = tdb_get_seqnum(ltdb->tdb);
+
 	/* if the current internal sequence number is the same as the one
 	   in the database then assume the rest of the cache is OK */
 	seq = ldb_msg_find_attr_as_uint64(baseinfo, LTDB_SEQUENCE_NUMBER, 0);
diff --git a/source4/lib/ldb/ldb_tdb/ldb_search.c b/source4/lib/ldb/ldb_tdb/ldb_search.c
index 85b6a123ca..4b76c437b6 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_search.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_search.c
@@ -248,25 +248,13 @@ int ltdb_search_dn1(struct ldb_module *module, const struct ldb_dn *dn, struct l
 	return 1;
 }
 
-/* the lock key for search locking. Note that this is not a DN, its
-   just an arbitrary key to give to tdb. Also note that as we and
-   using transactions for all write operations and transactions take
-   care of their own locks, we don't need to do any locking anywhere
-   other than in ldb_search() */
-#define LDBLOCK	"INT_LDBLOCK"
-
 /*
   lock the database for read - use by ltdb_search
 */
 static int ltdb_lock_read(struct ldb_module *module)
 {
 	struct ltdb_private *ltdb = module->private_data;
-	TDB_DATA key;
-
-	key.dptr = discard_const(LDBLOCK);
-	key.dsize = strlen(LDBLOCK);
-
-	return tdb_chainlock_read(ltdb->tdb, key);
+	return tdb_lockall_read(ltdb->tdb);
 }
 
 /*
@@ -275,12 +263,7 @@ static int ltdb_lock_read(struct ldb_module *module)
 static int ltdb_unlock_read(struct ldb_module *module)
 {
 	struct ltdb_private *ltdb = module->private_data;
-	TDB_DATA key;
-
-	key.dptr = discard_const(LDBLOCK);
-	key.dsize = strlen(LDBLOCK);
-
-	return tdb_chainunlock_read(ltdb->tdb, key);
+	return tdb_unlockall_read(ltdb->tdb);
 }
 
 /*
diff --git a/source4/lib/ldb/ldb_tdb/ldb_tdb.c b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
index fd1c8780ae..3f9db39097 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_tdb.c
+++ b/source4/lib/ldb/ldb_tdb/ldb_tdb.c
@@ -1021,7 +1021,7 @@ static int ltdb_connect(struct ldb_context *ldb, const char *url,
 		path = url;
 	}
 
-	tdb_flags = TDB_DEFAULT;
+	tdb_flags = TDB_DEFAULT | TDB_SEQNUM;
 
 	/* check for the 'nosync' option */
 	if (flags & LDB_FLG_NOSYNC) {
diff --git a/source4/lib/ldb/ldb_tdb/ldb_tdb.h b/source4/lib/ldb/ldb_tdb/ldb_tdb.h
index c20c3bd5f9..42f3dc2421 100644
--- a/source4/lib/ldb/ldb_tdb/ldb_tdb.h
+++ b/source4/lib/ldb/ldb_tdb/ldb_tdb.h
@@ -21,6 +21,10 @@ struct ltdb_private {
 	   handling. It has plenty of digits of precision */
 	unsigned long long sequence_number;
 
+	/* the low level tdb seqnum - used to avoid loading BASEINFO when
+	   possible */
+	int tdb_seqnum;
+
 	struct ltdb_cache {
 		struct ldb_message *indexlist;
 		struct ldb_message *attributes;