MEDIUM: backend: remove impossible cases from connect_server()
Now that we start by releasing any possibly existing connection,
the conditions simplify a little bit and some of the complex cases
can be removed. A few comments were also added for non-obvious cases.
diff --git a/src/backend.c b/src/backend.c
index fef6399..917b612 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -1143,6 +1143,7 @@
struct connection *srv_conn = NULL;
struct connection *old_conn = NULL;
struct conn_stream *srv_cs = NULL;
+ struct sess_srv_list *srv_list;
struct server *srv;
int reuse = 0;
int reuse_orphan = 0;
@@ -1156,52 +1157,39 @@
*/
si_release_endpoint(&s->si[1]);
- if (!srv_cs)
- srv_conn = objt_conn(s->si[1].end);
- else
- srv_conn = cs_conn(srv_cs);
-
- if (srv_conn) {
- if (!srv_conn->target || srv_conn->target == s->target) {
- srv_conn->flags &= ~(CO_FL_ERROR | CO_FL_SOCK_RD_SH | CO_FL_SOCK_WR_SH);
- if (srv_cs)
- srv_cs->flags &= ~(CS_FL_ERROR | CS_FL_EOS);
- reuse = 1;
- old_conn = srv_conn;
- } else {
- srv_conn = NULL;
- srv_cs = NULL;
- si_release_endpoint(&s->si[1]);
- }
- }
-
- if (!old_conn) {
- struct sess_srv_list *srv_list;
- list_for_each_entry(srv_list, &s->sess->srv_list, srv_list) {
- if (srv_list->target == s->target) {
- list_for_each_entry(srv_conn, &srv_list->conn_list,
- session_list) {
- if (conn_xprt_ready(srv_conn) &&
- srv_conn->mux && (srv_conn->mux->avail_streams(srv_conn) > 0)) {
- reuse = 1;
- break;
- }
+ /* first, search for a matching connection in the session's idle conns */
+ list_for_each_entry(srv_list, &s->sess->srv_list, srv_list) {
+ if (srv_list->target == s->target) {
+ list_for_each_entry(srv_conn, &srv_list->conn_list, session_list) {
+ if (conn_xprt_ready(srv_conn) &&
+ srv_conn->mux && (srv_conn->mux->avail_streams(srv_conn) > 0)) {
+ reuse = 1;
+ break;
}
- break;
}
+ break;
}
- if (reuse == 0) {
- srv_conn = NULL;
- if (!LIST_ISEMPTY(&s->sess->srv_list)) {
- srv_list = LIST_ELEM(s->sess->srv_list.n,
- struct sess_srv_list *, srv_list);
- if (!LIST_ISEMPTY(&srv_list->conn_list))
- srv_conn = LIST_ELEM(srv_list->conn_list.n,
- struct connection *, session_list);
- }
+ }
+ if (!reuse) {
+ /* no connection was found in our session's list. Pick any
+ * random one that we could trade against another one.
+ */
+ srv_conn = NULL;
+ if (!LIST_ISEMPTY(&s->sess->srv_list)) {
+ srv_list = LIST_ELEM(s->sess->srv_list.n, struct sess_srv_list *, srv_list);
+ if (!LIST_ISEMPTY(&srv_list->conn_list))
+ srv_conn = LIST_ELEM(srv_list->conn_list.n, struct connection *, session_list);
}
+
}
+ /* OK at this point we have this :
+ * - srv_conn points to an existing connection or NULL
+ * - if reuse is set, srv_conn holds a valid connection, otherwise it
+ * points to any of our old connections we may want to trade against
+ * another one
+ */
+
old_conn = srv_conn;
srv = objt_server(s->target);
@@ -1222,6 +1210,9 @@
* ----+-----+-----+ ----+-----+-----+ ----+-----+-----+
* idle| - | 1 | idle| - | 1 | idle| 2 | 1 |
* ----+-----+-----+ ----+-----+-----+ ----+-----+-----+
+ *
+ * Idle conns are necessarily looked up on the same thread so
+ * that there is no concurrency issues.
*/
if (srv->idle_conns && !LIST_ISEMPTY(&srv->idle_conns[tid]) &&
((s->be->options & PR_O_REUSE_MASK) != PR_O_REUSE_NEVR &&
@@ -1256,6 +1247,10 @@
reuse = 1;
}
+
+ /* here reuse might have been set above, indicating srv_conn finally
+ * is OK.
+ */
if (reuse) {
/* Disable connection reuse if a dynamic source is used.
* As long as we don't share connections between servers,
@@ -1271,6 +1266,7 @@
reuse = 0;
}
}
+
if (((!reuse || (srv_conn && !(srv_conn->flags & CO_FL_CONNECTED)))
&& ha_used_fds > global.tune.pool_high_count) && srv->idle_orphan_conns) {
struct connection *tokill_conn;
@@ -1333,7 +1329,7 @@
}
/* We're about to use another connection, let the mux know we're
- * done with this one
+ * done with this one.
*/
if (old_conn != srv_conn && old_conn && reuse && !reuse_orphan) {
struct session *sess = srv_conn->owner;
@@ -1356,10 +1352,7 @@
}
if (reuse) {
- /* We already created a cs earlier when using http_proxy, so
- * only create a new one if we don't have one already.
- */
- if (!srv_cs && srv_conn->mux) {
+ if (srv_conn->mux) {
int avail = srv_conn->mux->avail_streams(srv_conn);
if (avail <= 1) {