MINOR: stream: Simplify retries counter calculation

The conn_retries counter was set to the max value and decremented at each
connection retry. Thus the counter reflected the number of retries left and
not the real number of retries. All calculations of redispatch or reporting
of number of retries experienced were made using subtracts from the
configured retries, which was complicated and didn't bring any benefit.

Now, this counter is set to 0 and incremented at each retry. We know we've
reached the maximum allowed connection retries by comparing it to the
configured value. In all other cases, we directly use the counter.

This patch should address the feature request #1608.

include/haproxy/stream-t.h

@@ -139,7 +139,7 @@ struct stream {
 	int16_t priority_class;         /* priority class of the stream for the pending queue */
 	int32_t priority_offset;        /* priority offset of the stream for the pending queue */
 
-	int conn_retries;               /* number of connect retries left */
+	int conn_retries;               /* number of connect retries performed */
 
 	struct list list;               /* position in the thread's streams list */
 	struct mt_list by_srv;          /* position in server stream list */

include/haproxy/stream.h

@@ -331,11 +331,9 @@ static inline void stream_choose_redispatch(struct stream *s)
 	    (s->be->options & PR_O_REDISP) && !(s->flags & SF_FORCE_PRST) &&
 	    ((__objt_server(s->target)->cur_state < SRV_ST_RUNNING) ||
 	     (((s->be->redispatch_after > 0) &&
-	       ((s->be->conn_retries - s->conn_retries) %
-	        s->be->redispatch_after == 0)) ||
+	       (s->conn_retries % s->be->redispatch_after == 0)) ||
 	      ((s->be->redispatch_after < 0) &&
-	       ((s->be->conn_retries - s->conn_retries) %
-	        (s->be->conn_retries + 1 + s->be->redispatch_after) == 0))) ||
+	       (s->conn_retries % (s->be->conn_retries + 1 + s->be->redispatch_after) == 0))) ||
 	     (!(s->flags & SF_DIRECT) && s->be->srv_act > 1 &&
 	      ((s->be->lbprm.algo & BE_LB_KIND) == BE_LB_KIND_RR)))) {
 		sess_change_server(s, NULL);

src/backend.c

@@ -1720,8 +1720,7 @@ static int connect_server(struct stream *s)
 	     * it's our first try
 	     */
 	    ((cli_conn->flags & CO_FL_EARLY_DATA) ||
-	     ((s->be->retry_type & PR_RE_EARLY_ERROR) &&
-	      s->conn_retries == s->be->conn_retries)) &&
+	     ((s->be->retry_type & PR_RE_EARLY_ERROR) && !s->conn_retries)) &&
 	    !channel_is_empty(cs_oc(s->csb)) &&
 	    srv_conn->flags & CO_FL_SSL_WAIT_HS)
 		srv_conn->flags &= ~(CO_FL_SSL_WAIT_HS | CO_FL_WAIT_L6_CONN);
@@ -2222,6 +2221,8 @@ void back_handle_st_cer(struct stream *s)
 	cs->si->exp    = TICK_ETERNITY;
 	cs->si->flags &= ~SI_FL_EXP;
 
+	s->conn_retries++;
+
 	/* we probably have to release last stream from the server */
 	if (objt_server(s->target)) {
 		struct connection *conn = cs_conn(cs);
@@ -2251,14 +2252,13 @@ void back_handle_st_cer(struct stream *s)
 			 * provided by the client and we don't want to let the
 			 * client provoke retries.
 			 */
-			s->conn_retries = 0;
+			s->conn_retries = s->be->conn_retries;
 			DBG_TRACE_DEVEL("Bad SSL cert, disable connection retries", STRM_EV_STRM_PROC|STRM_EV_SI_ST|STRM_EV_STRM_ERR, s);
 		}
 	}
 
 	/* ensure that we have enough retries left */
-	s->conn_retries--;
-	if (s->conn_retries < 0 || !(s->be->retry_type & PR_RE_CONN_FAILED)) {
+	if (s->conn_retries >= s->be->conn_retries || !(s->be->retry_type & PR_RE_CONN_FAILED)) {
 		if (!cs->si->err_type) {
 			cs->si->err_type = SI_ET_CONN_ERR;
 		}

src/http_ana.c

@@ -1226,8 +1226,8 @@ static __inline int do_l7_retry(struct stream *s, struct stream_interface *si)
 	struct channel *req, *res;
 	int co_data;
 
-	s->conn_retries--;
-	if (s->conn_retries < 0)
+	s->conn_retries++;
+	if (s->conn_retries >= s->be->conn_retries)
 		return -1;
 
 	if (objt_server(s->target)) {

src/log.c

@@ -2616,10 +2616,7 @@ int sess_build_logline(struct session *sess, struct stream *s, char *dst, size_t
 			case LOG_FMT_RETRIES:  // %rq
 				if (s_flags & SF_REDISP)
 					LOGCHAR('+');
-				ret = ltoa_o(((s && s->conn_retries > 0)
-					      ? (be->conn_retries - s->conn_retries)
-					      : ((s && cs_si(s->csb)->state != SI_ST_INI) ? be->conn_retries : 0)),
-					     tmplog, dst + maxsize - tmplog);
+				ret = ltoa_o((s  ? s->conn_retries : 0), tmplog, dst + maxsize - tmplog);
 				if (ret == NULL)
 					goto out;
 				tmplog = ret;

src/stream.c

@@ -2161,7 +2161,7 @@ struct task *process_stream(struct task *t, void *context, unsigned int state)
 				 * perform a connection request.
 				 */
 				si_b->state = SI_ST_REQ; /* new connection requested */
-				s->conn_retries = s->be->conn_retries;
+				s->conn_retries = 0;
 				if ((s->be->retry_type &~ PR_RE_CONN_FAILED) &&
 				    (s->be->mode == PR_MODE_HTTP) &&
 				    !(s->txn->flags & TX_D_L7_RETRY))