AnyEvent::RetryTimer - Retry timers for AnyEvent


       use AnyEvent::RetryTimer;

       my $con =

       my $timer;

       $con->on_disconnect (sub {
          $timer ||=
             AnyEvent::RetryTimer->new (
                on_retry => sub {


          my $secs = $timer->current_interval;

          warn "Lost connection, reconnecting in $secs seconds!";

       $con->on_connect (sub {
          warn "Connected successfully!";

          undef $timer;

    This is a small helper utility to manage timed retries.

    This is a pattern I often stumble across when managing network
    connections. And I'm tired to reimplement it again and again. So I wrote
    this module.

    At the moment it only implements a simple exponential back off retry
    mechanism (with configurable multiplier) using AnyEvent timers. If there
    are other back off strategies you find useful you are free to send a
    feature request or even better a patch!

    my $timer = AnyEvent::RetryTimer->new (%args)
        This is the constructor, it constructs the object.

        At the end of the objects lifetime, when you get rid of the last
        reference to $timer, it will stop and running timeouts and not call
        any of the configured callbacks again.

        %args can contain these keys:

        on_retry => $retry_cb->($timer)
            $retry_cb is the callback that will be called for (re)tries.

            When this constructor is called and no "no_first_try" is given,
            an initial retry interval of the length 0 is started, which
            counts as the first try.

            Later it is also called after a retry interval has passed, which
            was initiated by a call to the "retry" method.

            The first argument is the $timer object itself.

        no_first_try => $bool
            This parameter defines whether the $retry_cb will be called when
            the AnyEvent::RetryTimer object is created or not. If $bool is
            true $retry_cb will not be called.

            The default is false.

        backoff => 'exponential'
            This is the back off algorithm that is used. Currently only
            "exponential" is implemented and is the default.

        max_retries => $max_retry_cnt
            This is the maximum number of retries that are done between the
            first call to "retry" and the finishing call to "success".

            If the number of retries is exceeded by a call to "retry" the
            "on_max_retries" callback is called (see below).

            Please note that a call to "success" will of course reset the
            internal count of calls to "retry".

            Default for this option is 0 (disabled).

        on_max_retries => $max_retry_cb->($timer)
            After "max_retries" the $max_retry_cb callback will be called
            with the $timer as first argument.

            It is usually called when a call to "retry" would exceed

        And then there are keys that are specific to the "backoff" method


            start_interval => $secs
                This is the length of the first interval. Given in seconds.

                Default is 10.

            multiplier => $float
                This is the multiplier for the retry intervals. Each time a
                "retry" is done the previous (if any) interval will be
                multiplied with $float and used for the next interval.

                Default is 1.5.

            max_interval => $max_interval_secs
                As exponential back off intervals can increase quite a lot
                you can give the maximum time to wait in $max_interval_secs.

                Default is "3600 * 4", which is 4 hours.

        This method initiates or continues retries. If already a retry
        interval is installed (eg. by the constructor or another previous
        unfinished call to "retry"), the call will be a nop.

        That means you can call "retry" directly after you created this
        object and will not cause the initial try to be "retried".

        If you are interested in the length of the current interval (after a
        call to this method), you can call the "current_interval" method.

        This signals that the last retry was successful and it will reset
        any state or intervals to the initial settings given to the

        You can reuse the $timer object after a call to "success".

    my $secs = $timer->current_interval
        Returns the length of the current interval to the next call to the

    Robin Redeker, "<>"


    Copyright 2009 Robin Redeker, all rights reserved.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.