ovsdb replication: Provide option to configure probe interval.

When ovsdb-server is in backup mode and connects to the active
ovsdb-server for replication, and if takes more than 5 seconds to
get the dump of the whole database, it will drop the connection
soon after as the default probe interval is 5 seconds. This
results in a snowball effect of reconnections to the active
ovsdb-server.

This patch handles or mitigates this issue by setting the
default probe interval value to 60 seconds and provide the option to
configure this value from the unixctl command.

Other option could be increase the value of 'RECONNECT_DEFAULT_PROBE_INTERVAL'
to a higher value.

Acked-by: Mark Michelson <mmichels@redhat.com>
Signed-off-by: Numan Siddique <numans@ovn.org>
Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: 0-day Robot <robot@bytheb.org>

NEWS

@@ -29,6 +29,11 @@ Post-v2.12.0
    - RSTP:
      * The rstp_statistics column in Port table will only be updated every
        stats-update-interval configured in Open_vSwtich table.
+   - OVSDB:
+     * When ovsdb-server is running in backup mode, the default value of probe
+       interval is increased to 60 seconds for the connection to the
+       replication server. This value is configurable with the unixctl
+       command - ovsdb-server/set-active-ovsdb-server-probe-interval.
 
 v2.12.0 - 03 Sep 2019
 ---------------------

ovsdb/ovsdb-server.1.in

@@ -288,6 +288,11 @@ Switches the server to an active role.  The server stops synchronizing
 its databases with an active server and closes all existing client
 connections, which requires clients to reconnect.
 .
+.IP "\fBovsdb\-server/set\-active\-ovsdb\-server\-probe\-interval \fIprobe interval"
+Sets  the probe interval (in milli seconds) for the connection to
+active \fIserver\fR.
+.
+.
 .IP "\fBovsdb\-server/set\-sync\-exclude\-tables \fIdb\fB:\fItable\fR[\fB,\fIdb\fB:\fItable\fR]..."
 Sets the \fItable\fR within \fIdb\fR that will be excluded from synchronization.
 This overrides the \fB\-\-sync\-exclude-tables\fR command-line option.

ovsdb/ovsdb-server.c

@@ -86,6 +86,7 @@ static unixctl_cb_func ovsdb_server_set_active_ovsdb_server;
 static unixctl_cb_func ovsdb_server_get_active_ovsdb_server;
 static unixctl_cb_func ovsdb_server_connect_active_ovsdb_server;
 static unixctl_cb_func ovsdb_server_disconnect_active_ovsdb_server;
+static unixctl_cb_func ovsdb_server_set_active_ovsdb_server_probe_interval;
 static unixctl_cb_func ovsdb_server_set_sync_exclude_tables;
 static unixctl_cb_func ovsdb_server_get_sync_exclude_tables;
 static unixctl_cb_func ovsdb_server_get_sync_status;
@@ -97,6 +98,7 @@ struct server_config {
     char **sync_from;
     char **sync_exclude;
     bool *is_backup;
+    int *replication_probe_interval;
     struct ovsdb_jsonrpc_server *jsonrpc;
 };
 static unixctl_cb_func ovsdb_server_add_remote;
@@ -144,9 +146,10 @@ static void load_config(FILE *config_file, struct sset *remotes,
 
 static void
 ovsdb_replication_init(const char *sync_from, const char *exclude,
-                       struct shash *all_dbs, const struct uuid *server_uuid)
+                       struct shash *all_dbs, const struct uuid *server_uuid,
+                       int probe_interval)
 {
-    replication_init(sync_from, exclude, server_uuid);
+    replication_init(sync_from, exclude, server_uuid, probe_interval);
     struct shash_node *node;
     SHASH_FOR_EACH (node, all_dbs) {
         struct db *db = node->data;
@@ -304,6 +307,7 @@ main(int argc, char *argv[])
     struct server_config server_config;
     struct shash all_dbs;
     struct shash_node *node, *next;
+    int replication_probe_interval = REPLICATION_DEFAULT_PROBE_INTERVAL;
 
     ovs_cmdl_proctitle_init(argc, argv);
     set_program_name(argv[0]);
@@ -351,6 +355,7 @@ main(int argc, char *argv[])
     server_config.sync_from = &sync_from;
     server_config.sync_exclude = &sync_exclude;
     server_config.is_backup = &is_backup;
+    server_config.replication_probe_interval = &replication_probe_interval;
 
     perf_counters_init();
 
@@ -436,6 +441,9 @@ main(int argc, char *argv[])
     unixctl_command_register("ovsdb-server/disconnect-active-ovsdb-server", "",
                              0, 0, ovsdb_server_disconnect_active_ovsdb_server,
                              &server_config);
+    unixctl_command_register(
+        "ovsdb-server/set-active-ovsdb-server-probe-interval", "", 1, 1,
+        ovsdb_server_set_active_ovsdb_server_probe_interval, &server_config);
     unixctl_command_register("ovsdb-server/set-sync-exclude-tables", "",
                              0, 1, ovsdb_server_set_sync_exclude_tables,
                              &server_config);
@@ -454,7 +462,8 @@ main(int argc, char *argv[])
     if (is_backup) {
         const struct uuid *server_uuid;
         server_uuid = ovsdb_jsonrpc_server_get_uuid(jsonrpc);
-        ovsdb_replication_init(sync_from, sync_exclude, &all_dbs, server_uuid);
+        ovsdb_replication_init(sync_from, sync_exclude, &all_dbs, server_uuid,
+                               replication_probe_interval);
     }
 
     main_loop(&server_config, jsonrpc, &all_dbs, unixctl, &remotes,
@@ -1317,7 +1326,8 @@ ovsdb_server_connect_active_ovsdb_server(struct unixctl_conn *conn,
         const struct uuid *server_uuid;
         server_uuid = ovsdb_jsonrpc_server_get_uuid(config->jsonrpc);
         ovsdb_replication_init(*config->sync_from, *config->sync_exclude,
-                               config->all_dbs, server_uuid);
+                               config->all_dbs, server_uuid,
+                               *config->replication_probe_interval);
         if (!*config->is_backup) {
             *config->is_backup = true;
             save_config(config);
@@ -1340,6 +1350,28 @@ ovsdb_server_disconnect_active_ovsdb_server(struct unixctl_conn *conn,
     unixctl_command_reply(conn, NULL);
 }
 
+static void
+ovsdb_server_set_active_ovsdb_server_probe_interval(struct unixctl_conn *conn,
+                                                   int argc OVS_UNUSED,
+                                                   const char *argv[],
+                                                   void *config_)
+{
+    struct server_config *config = config_;
+
+    int probe_interval;
+    if (str_to_int(argv[1], 10, &probe_interval)) {
+        *config->replication_probe_interval = probe_interval;
+        save_config(config);
+        if (*config->is_backup) {
+            replication_set_probe_interval(probe_interval);
+        }
+        unixctl_command_reply(conn, NULL);
+    } else {
+        unixctl_command_reply(
+            conn, "Invalid probe interval, integer value expected");
+    }
+}
+
 static void
 ovsdb_server_set_sync_exclude_tables(struct unixctl_conn *conn,
                                      int argc OVS_UNUSED,
@@ -1357,7 +1389,8 @@ ovsdb_server_set_sync_exclude_tables(struct unixctl_conn *conn,
             const struct uuid *server_uuid;
             server_uuid = ovsdb_jsonrpc_server_get_uuid(config->jsonrpc);
             ovsdb_replication_init(*config->sync_from, *config->sync_exclude,
-                                   config->all_dbs, server_uuid);
+                                   config->all_dbs, server_uuid,
+                                   *config->replication_probe_interval);
         }
         err = set_blacklist_tables(argv[1], false);
     }
@@ -1568,7 +1601,8 @@ ovsdb_server_add_database(struct unixctl_conn *conn, int argc OVS_UNUSED,
             const struct uuid *server_uuid;
             server_uuid = ovsdb_jsonrpc_server_get_uuid(config->jsonrpc);
             ovsdb_replication_init(*config->sync_from, *config->sync_exclude,
-                                   config->all_dbs, server_uuid);
+                                   config->all_dbs, server_uuid,
+                                   *config->replication_probe_interval);
         }
         unixctl_command_reply(conn, NULL);
     } else {
@@ -1590,7 +1624,8 @@ remove_db(struct server_config *config, struct shash_node *node, char *comment)
         const struct uuid *server_uuid;
         server_uuid = ovsdb_jsonrpc_server_get_uuid(config->jsonrpc);
         ovsdb_replication_init(*config->sync_from, *config->sync_exclude,
-                               config->all_dbs, server_uuid);
+                               config->all_dbs, server_uuid,
+                               *config->replication_probe_interval);
     }
 }
 

ovsdb/replication.c

@@ -125,7 +125,7 @@ static struct replication_db *find_db(const char *db_name);
 
 void
 replication_init(const char *sync_from_, const char *exclude_tables,
-                 const struct uuid *server)
+                 const struct uuid *server, int probe_interval)
 {
     free(sync_from);
     sync_from = xstrdup(sync_from_);
@@ -143,6 +143,8 @@ replication_init(const char *sync_from_, const char *exclude_tables,
     session = jsonrpc_session_open(sync_from, true);
     session_seqno = UINT_MAX;
 
+    jsonrpc_session_set_probe_interval(session, probe_interval);
+
     /* Keep a copy of local server uuid.  */
     server_uuid = *server;
 
@@ -979,6 +981,14 @@ is_replication_possible(struct ovsdb_schema *local_db_schema,
     return true;
 }
 
+void
+replication_set_probe_interval(int probe_interval)
+{
+    if (session) {
+        jsonrpc_session_set_probe_interval(session, probe_interval);
+    }
+}
+
 void
 replication_usage(void)
 {

ovsdb/replication.h

@@ -44,8 +44,10 @@ struct ovsdb;
  *    used mainly by uinxctl commands.
  */
 
+#define REPLICATION_DEFAULT_PROBE_INTERVAL 60000
+
 void replication_init(const char *sync_from, const char *exclude_tables,
-                      const struct uuid *server);
+                      const struct uuid *server, int probe_interval);
 void replication_run(void);
 void replication_wait(void);
 void replication_destroy(void);
@@ -54,6 +56,7 @@ void replication_add_local_db(const char *databse, struct ovsdb *db);
 bool replication_is_alive(void);
 int replication_get_last_error(void);
 char *replication_status(void);
+void replication_set_probe_interval(int);
 
 char *set_blacklist_tables(const char *blacklist, bool dryrun)
     OVS_WARN_UNUSED_RESULT;