lib-http: If connect fails, include attempt count and total time in e…

…rror.

This will produce errors such as:
9002 connect(1.2.3.4:801) failed: Connection timed out in 1.001 secs (4 attempts in 4.706 secs)

src/lib-http/http-client-private.h

@@ -220,6 +220,7 @@ struct http_client_queue {
 	   connected IP */
 	unsigned int ips_connect_start_idx;
 
+	struct timeval first_connect_time;
 	unsigned int connect_attempts;
 
 	/* peers we are trying to connect to;

src/lib-http/http-client-queue.c

@@ -282,7 +282,8 @@ void http_client_queue_connection_setup(struct http_client_queue *queue)
 				http_client_peer_addr2str(addr), ssl);
 
 			array_append(&queue->pending_peers, &peer, 1);
-			queue->connect_attempts++;
+			if (queue->connect_attempts++ == 0)
+				queue->first_connect_time = ioloop_timeval;
 		}
 
 		/* start soft connect time-out (but only if we have another IP left) */
@@ -401,6 +402,13 @@ http_client_queue_connection_failure(struct http_client_queue *queue,
 			queue->connect_attempts >= set->max_connect_attempts) {
 			http_client_queue_debug(queue,
 				"Failed to set up any connection; failing all queued requests");
+			if (queue->connect_attempts > 1) {
+				unsigned int total_msecs =
+					timeval_diff_msecs(&ioloop_timeval, &queue->first_connect_time);
+				reason = t_strdup_printf("%s (%u attempts in %u.%03u secs)",
+					reason, queue->connect_attempts,
+					total_msecs/1000, total_msecs%1000);
+			}
 			queue->connect_attempts = 0;
 			http_client_queue_fail(queue,
 				HTTP_CLIENT_REQUEST_ERROR_CONNECT_FAILED, reason);