MINOR: muxes: refactor private connection detach

Following the latest adjustment on session_add_conn() /
session_check_idle_conn(), detach muxes callbacks were rewritten for
private connection handling.

Nothing really fancy here : some more explicit comments and the removal
of a duplicate checks on idle conn status for muxes with true
multipexing support.

src/mux_fcgi.c

@@ -3723,21 +3723,24 @@ static void fcgi_detach(struct sedesc *sd)
 	    (fconn->flags & FCGI_CF_KEEP_CONN)) {
 		if (fconn->conn->flags & CO_FL_PRIVATE) {
 			/* Add the connection in the session serverlist, if not already done */
-			if (!session_add_conn(sess, fconn->conn)) {
+			if (!session_add_conn(sess, fconn->conn))
 				fconn->conn->owner = NULL;
-				if (eb_is_empty(&fconn->streams_by_id)) {
+
-					/* let's kill the connection right away */
+			if (eb_is_empty(&fconn->streams_by_id)) {
+				if (!fconn->conn->owner) {
+					/* Session insertion above has failed and connection is idle, remove it. */
 					fconn->conn->mux->destroy(fconn);
 					TRACE_DEVEL("outgoing connection killed", FCGI_EV_STRM_END|FCGI_EV_FCONN_ERR);
 					return;
 				}
-			}
+
-			if (eb_is_empty(&fconn->streams_by_id)) {
 				/* mark that the tasklet may lose its context to another thread and
 				 * that the handler needs to check it under the idle conns lock.
 				 */
 				HA_ATOMIC_OR(&fconn->wait_event.tasklet->state, TASK_F_USR1);
-				if (session_check_idle_conn(fconn->conn->owner, fconn->conn) != 0) {
+
+				/* Ensure session can keep a new idle connection. */
+				if (session_check_idle_conn(sess, fconn->conn) != 0) {
 					fconn->conn->mux->destroy(fconn);
 					TRACE_DEVEL("outgoing connection killed", FCGI_EV_STRM_END|FCGI_EV_FCONN_ERR);
 					return;

src/mux_h1.c

@@ -1139,16 +1139,20 @@ static int h1s_finish_detach(struct h1s *h1s)
 		if (h1c->conn->flags & CO_FL_PRIVATE) {
 			/* Add the connection in the session server list, if not already done */
 			if (!session_add_conn(sess, h1c->conn)) {
+				/* HTTP/1.1 conn is always idle after detach, can be removed if session insert failed. */
 				h1c->conn->owner = NULL;
 				h1c->conn->mux->destroy(h1c);
 				goto released;
 			}
-			/* Always idle at this step */
+
+			/* HTTP/1.1 conn is always idle after detach. */
 
 			/* mark that the tasklet may lose its context to another thread and
 			 * that the handler needs to check it under the idle conns lock.
 			 */
 			HA_ATOMIC_OR(&h1c->wait_event.tasklet->state, TASK_F_USR1);
+
+			/* Ensure session can keep a new idle connection. */
 			if (session_check_idle_conn(sess, h1c->conn)) {
 				TRACE_DEVEL("outgoing connection rejected", H1_EV_STRM_END|H1_EV_H1C_END, h1c->conn);
 				h1c->conn->mux->destroy(h1c);

src/mux_h2.c

@@ -5533,20 +5533,24 @@ static void h2_detach(struct sedesc *sd)
 
 			if (h2c->conn->flags & CO_FL_PRIVATE) {
 				/* Add the connection in the session server list, if not already done */
-				if (!session_add_conn(sess, h2c->conn)) {
+				if (!session_add_conn(sess, h2c->conn))
 					h2c->conn->owner = NULL;
-					if (eb_is_empty(&h2c->streams_by_id)) {
+
+				if (eb_is_empty(&h2c->streams_by_id)) {
+					if (!h2c->conn->owner) {
+						/* Session insertion above has failed and connection is idle, remove it. */
 						h2c->conn->mux->destroy(h2c);
 						TRACE_DEVEL("leaving on error after killing outgoing connection", H2_EV_STRM_END|H2_EV_H2C_ERR);
 						return;
 					}
-				}
+
-				if (eb_is_empty(&h2c->streams_by_id)) {
 					/* mark that the tasklet may lose its context to another thread and
 					 * that the handler needs to check it under the idle conns lock.
 					 */
 					HA_ATOMIC_OR(&h2c->wait_event.tasklet->state, TASK_F_USR1);
-					if (session_check_idle_conn(h2c->conn->owner, h2c->conn) != 0) {
+
+					/* Ensure session can keep a new idle connection. */
+					if (session_check_idle_conn(sess, h2c->conn) != 0) {
 						h2c->conn->mux->destroy(h2c);
 						TRACE_DEVEL("leaving without reusable idle connection", H2_EV_STRM_END);
 						return;

src/mux_quic.c

@@ -3790,18 +3790,19 @@ static void qmux_strm_detach(struct sedesc *sd)
 			if (!session_add_conn(sess, conn)) {
 				TRACE_ERROR("error during connection insert into session list", QMUX_EV_STRM_END, conn);
 				conn->owner = NULL;
-
-				/* Session insert failure. Close conn if idle,
-				 * else insert will be retry on next detach.
-				 */
-				if (!qcc->nb_sc)
-					goto release;
 			}
 
-			/* If conn is idle, check if session can keep it. Conn is closed if this is not the case. */
+			if (!qcc->nb_sc) {
-			if (!qcc->nb_sc && session_check_idle_conn(sess, conn)) {
+				if (!conn->owner) {
-				TRACE_DEVEL("idle conn rejected by session", QMUX_EV_STRM_END, conn);
+					/* Session insertion above has failed and connection is idle, remove it. */
-				goto release;
+					goto release;
+				}
+
+				/* Ensure session can keep a new idle connection. */
+				if (session_check_idle_conn(sess, conn)) {
+					TRACE_DEVEL("idle conn rejected by session", QMUX_EV_STRM_END, conn);
+					goto release;
+				}
 			}
 		}
 		else {

src/mux_spop.c

@@ -2977,20 +2977,24 @@ static void spop_detach(struct sedesc *sd)
 	if (!(spop_conn->flags & (SPOP_CF_RCVD_SHUT|SPOP_CF_ERR_PENDING|SPOP_CF_ERROR))) {
 		if (spop_conn->conn->flags & CO_FL_PRIVATE) {
 			/* Add the connection in the session server list, if not already done */
-			if (!session_add_conn(sess, spop_conn->conn)) {
+			if (!session_add_conn(sess, spop_conn->conn))
 				spop_conn->conn->owner = NULL;
-				if (eb_is_empty(&spop_conn->streams_by_id)) {
+
+			if (eb_is_empty(&spop_conn->streams_by_id)) {
+				if (!spop_conn->conn->owner) {
+					/* Session insertion above has failed and connection is idle, remove it. */
 					spop_conn->conn->mux->destroy(spop_conn);
 					TRACE_DEVEL("leaving on error after killing outgoing connection", SPOP_EV_STRM_END|SPOP_EV_SPOP_CONN_ERR);
 					return;
 				}
-			}
+
-			if (eb_is_empty(&spop_conn->streams_by_id)) {
 				/* mark that the tasklet may lose its context to another thread and
 				 * that the handler needs to check it under the idle conns lock.
 				 */
 				HA_ATOMIC_OR(&spop_conn->wait_event.tasklet->state, TASK_F_USR1);
-				if (session_check_idle_conn(spop_conn->conn->owner, spop_conn->conn) != 0) {
+
+				/* Ensure session can keep a new idle connection. */
+				if (session_check_idle_conn(sess, spop_conn->conn) != 0) {
 					spop_conn->conn->mux->destroy(spop_conn);
 					TRACE_DEVEL("leaving without reusable idle connection", SPOP_EV_STRM_END);
 					return;