From: Peter Eisentraut <peter@eisentraut.org>
Date: Sun, 29 Sep 2019 09:07:47 +0000 (+0200)
Subject: Improve fast-fail code comments and debug logging
X-Git-Tag: pgbouncer_1_12_0~7
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b42631932b6114bd6b3c185a4d1bf698fae855b4;p=pgbouncer

Improve fast-fail code comments and debug logging

no changes in functionality
---

diff --git a/include/bouncer.h b/include/bouncer.h
index e14cf34..5f8fd27 100644
--- a/include/bouncer.h
+++ b/include/bouncer.h
@@ -250,7 +250,7 @@ struct PgPool {
 
 	usec_t last_lifetime_disconnect;/* last time when server_lifetime was applied */
 
-	/* if last connect failed, there should be delay before next */
+	/* if last connect to server failed, there should be delay before next */
 	usec_t last_connect_time;
 	unsigned last_connect_failed:1;
 	unsigned last_login_failed:1;
diff --git a/src/objects.c b/src/objects.c
index f5f1465..19d89af 100644
--- a/src/objects.c
+++ b/src/objects.c
@@ -575,7 +575,7 @@ void activate_client(PgSocket *client)
 }
 
 /*
- * Don't let clients queue at all, if there is no working server connection.
+ * Don't let clients queue at all if there is no working server connection.
  *
  * It must still allow following cases:
  * - empty pool on startup
@@ -586,22 +586,35 @@ void activate_client(PgSocket *client)
  * - new server connections fail due to server_connect_timeout, or other failure
  *
  * So here we drop client if all server connections have been dropped
- * and new one's fail.
+ * and new ones fail.
+ *
+ * Return true if the client connection should be allowed, false if it
+ * should be rejected.
  */
 bool check_fast_fail(PgSocket *client)
 {
 	int cnt;
 	PgPool *pool = client->pool;
 
-	/* reject if no servers are available and the last login failed */
+	/* If last login succeeded, client can go ahead. */
 	if (!pool->last_login_failed)
 		return true;
+
+	/* If there are servers available, client can go ahead. */
 	cnt = pool_server_count(pool) - statlist_count(&pool->new_server_list);
 	if (cnt)
 		return true;
+
+	/* Else we fail the client. */
 	disconnect_client(client, true, "pgbouncer cannot connect to server");
 
-	/* usual relaunch won't work, as there are no waiting clients */
+	/*
+	 * Try to launch a new connection.  (launch_new_connection()
+	 * will check for server_login_retry etc.)  The usual relaunch
+	 * from janitor.c won't do anything, as there are no waiting
+	 * clients, so we need to do it here to get any new servers
+	 * eventually.
+	 */
 	launch_new_connection(pool);
 
 	return false;
@@ -1129,7 +1142,8 @@ void launch_new_connection(PgPool *pool)
 	if (pool->last_connect_failed) {
 		usec_t now = get_cached_time();
 		if (now - pool->last_connect_time < cf_server_login_retry) {
-			log_debug("launch_new_connection: last failed, wait");
+			log_debug("launch_new_connection: last failed, not launching new connection yet, still waiting %" PRIu64 " s",
+				  (cf_server_login_retry - (now - pool->last_connect_time)) / USEC);
 			return;
 		}
 	}