Adding --read-only-interval flag, and read-only check on wake-up

bin/pt-heartbeat

@@ -5805,8 +5805,9 @@ sub main {
       my $start_time         = time;
       my $run_time           = $o->get('run-time');
       my $interval           = $o->get('interval') || 5;
+      my $read_only_interval = $o->get('read-only-interval') || $interval;
       while (server_is_readonly($dbh)) {
-         sleep($interval); 
+         sleep($read_only_interval);
          if (
             ($run_time && $run_time < time - $start_time)
             || -f $sentinel
@@ -6223,6 +6224,18 @@ sub main {
          sleep $next_interval - $time;
          PTDEBUG && _d('Woke up at', ts(time));
 
+         if ( $o->get('check-read-only') && $o->get('update') ) {
+           my $read_only_interval = $o->get('read-only-interval') || $interval;
+           while (server_is_readonly($dbh)) {
+              sleep($read_only_interval);
+              if (
+                 -f $sentinel
+              ) {
+                 return 0;
+              }
+           }
+         }
+
          # Connect or reconnect if necessary.
          if ( !$dbh->ping() ) {
             $dbh = $dp->get_dbh($dp->get_cxn_params($dsn), { AutoCommit => 1 });
@@ -6619,7 +6632,7 @@ before its delay.  L<"--recurse"> only works with MySQL.
 =item --check-read-only
 
 Check if the server has read_only enabled; If it does, the tool skips doing
-any inserts.
+any inserts. See also L<"--read-only-interval">
 
 =item --config
 
@@ -6835,6 +6848,13 @@ Print the auto-detected or given L<"--master-server-id">.  If L<"--check">
 or L<"--monitor"> is specified, specifying this option will print the
 auto-detected or given L<"--master-server-id"> at the end of each line.
 
+=item --read-only-interval
+
+type: int
+
+When L<"--check-read-only"> is specified, the interval to sleep while the
+server is found to be read-only. If unspecified, L<"--interval"> is used.
+
 =item --recurse
 
 type: int