From: Kurt Zeilenga <kurt@openldap.org>
Date: Tue, 5 Sep 2000 19:11:27 +0000 (+0000)
Subject: Rework connection lock code to avoid unnecessary lock reaquire
X-Git-Tag: LDBM_PRE_GIANT_RWLOCK~2102
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=c8c969a1847e0c0f495bd7ac717ef50032a8992b;p=openldap

Rework connection lock code to avoid unnecessary lock reaquire
---

diff --git a/servers/slapd/connection.c b/servers/slapd/connection.c
index 14e3b40c54..f50eb3d269 100644
--- a/servers/slapd/connection.c
+++ b/servers/slapd/connection.c
@@ -1098,29 +1098,35 @@ connection_resched( Connection *conn )
 	Operation *op;
 
 	if( conn->c_conn_state == SLAP_C_CLOSING ) {
+		int rc;
 		ber_socket_t	sd;
 		ber_sockbuf_ctrl( conn->c_sb, LBER_SB_OPT_GET_FD, &sd );
 
-		Debug( LDAP_DEBUG_TRACE,
-			"connection_resched: reaquiring locks conn=%ld sd=%d\n",
-			conn->c_connid, sd, 0 );
+		/* us trylock to avoid possible deadlock */
+		rc = ldap_pvt_thread_mutex_trylock( &connections_mutex );
 
-		/* reaquire locks in the right order... this may
-		 * allow another thread to close this connection,
-		 * so recheck state
-		 */
-		ldap_pvt_thread_mutex_unlock( &conn->c_mutex );
-		ldap_pvt_thread_mutex_lock( &connections_mutex );
-		ldap_pvt_thread_mutex_lock( &conn->c_mutex );
+		if( rc ) {
+			Debug( LDAP_DEBUG_TRACE,
+				"connection_resched: reaquiring locks conn=%ld sd=%d\n",
+				conn->c_connid, sd, 0 );
+			/*
+			 * reaquire locks in the right order...
+			 * this may allow another thread to close this connection,
+			 * so recheck state below.
+			 */
+			ldap_pvt_thread_mutex_unlock( &conn->c_mutex );
+			ldap_pvt_thread_mutex_lock( &connections_mutex );
+			ldap_pvt_thread_mutex_lock( &conn->c_mutex );
+		}
 
 		if( conn->c_conn_state != SLAP_C_CLOSING ) {
-			Debug( LDAP_DEBUG_TRACE,
-				"connection_resched: closed by other thread conn=%ld sd=%d\n",
+			Debug( LDAP_DEBUG_TRACE, "connection_resched: "
+				"closed by other thread conn=%ld sd=%d\n",
 				conn->c_connid, sd, 0 );
 
 		} else {
-			Debug( LDAP_DEBUG_TRACE,
-				"connection_resched: attempting closing conn=%ld sd=%d\n",
+			Debug( LDAP_DEBUG_TRACE, "connection_resched: "
+				"attempting closing conn=%ld sd=%d\n",
 				conn->c_connid, sd, 0 );
 
 			connection_close( conn );