/ 
Algorithm-Backoff-0.010
River stage two • 9 direct dependents • 22 total dependents
/ Algorithm::Backoff

NAME

Algorithm::Backoff - Various backoff strategies for retry

VERSION

This document describes version 0.010 of Algorithm::Backoff (from Perl distribution Algorithm-Backoff), released on 2024-02-24.

SYNOPSIS

# 1. pick a strategy and instantiate

use Algorithm::Backoff::Constant;
my $ab = Algorithm::Backoff::Constant->new(
    delay             => 2, # required
    #delay_on_success => 0, # optional, default 0
);

# 2. log success/failure and get a new number of seconds to delay. if you don't
# want to log for the current time, you can pass a timestamp (number of seconds
# passed since some reference value, like a Unix epoch) as the argument, which
# should be monotonically increasing.

my $secs = $ab->failure(); # => 2
my $secs = $ab->success(); # => 0
my $secs = $ab->failure(); # => 2

DESCRIPTION

This distribution provides several classes that implement various backoff strategies for setting delay between retry attempts.

This class (Algorithm::Backoff) is a base class only.

Algorithm::Backoff does not actually provide a function/method to retry a piece of code. It only contains the backoff strategies and splits the actual delaying to another module (e.g. Retry::Backoff). This allows for things like printing/returning all the retries and their delay amounts without actually doing the delay (e.g. in show-backoff-delays script).

METHODS

new

Usage:

new(%args) -> obj

This function is not exported.

Arguments ('*' denotes required arguments):

  • jitter_factor => float

    How much to add randomness.

    If you set this to a value larger than 0, the actual delay will be between a random number between original_delay * (1-jitter_factor) and original_delay * (1+jitter_factor). Jitters are usually added to avoid so-called "thundering herd" problem.

    The jitter will be applied to delay on failure as well as on success.

  • max_attempts => uint (default: 0)

    Maximum number consecutive failures before giving up.

    0 means to retry endlessly without ever giving up. 1 means to give up after a single failure (i.e. no retry attempts). 2 means to retry once after a failure. Note that after a success, the number of attempts is reset (as expected). So if max_attempts is 3, and if you fail twice then succeed, then on the next failure the algorithm will retry again for a maximum of 3 times.

Return value: (obj)

success

Usage:

my $secs = $obj->success([ $timestamp ]);

Log a successful attempt. If not specified, $timestamp defaults to current Unix timestamp. Will return the suggested number of seconds to wait before doing another attempt.

failure

Usage:

my $secs = $obj->failure([ $timestamp ]);

Log a failed attempt. If not specified, $timestamp defaults to current Unix timestamp. Will return the suggested number of seconds to wait before doing another attempt, or -1 if it suggests that one gives up (e.g. if max_attempts parameter has been exceeded).

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/Algorithm-Backoff.

SOURCE

Source repository is at https://github.com/perlancar/perl-Algorithm-Backoff.

SEE ALSO

Retry::Backoff - an application of Algorithm::Backoff to retry a piece of code using various backoff strategies.

App::AlgorithmBackoffUtils - various CLI's related to Algorithm::Backoff.

Action::Retry - A prior art for Algorithm::Backoff. Somehow I didn't find this module before writing Algorithm::Backoff. But Algorithm::Backoff offers an alternative interface (a split of actual sleep/retry vs the algorithm), and some additional parameters (like delay on success and jitter factor), a lighter footprint (no Moo), and a couple more strategies.

AUTHOR

perlancar <perlancar@cpan.org>

CONTRIBUTORS

  • Brendan Byrd <brendan.byrd@grantstreet.com>

  • SineSwiper <GitHub@ResonatorSoft.org>

CONTRIBUTING

To contribute, you can send patches by email/via RT, or send pull requests on GitHub.

Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via:

% prove -l

If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE

This software is copyright (c) 2024, 2019 by perlancar <perlancar@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Algorithm-Backoff

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.