--- name: "Algorithm::Backoff" section: "3pm" platform: "linux" package: "libalgorithm-backoff-perl" version: "0.010-2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/Algorithm::Backoff" --- # Algorithm::Backoff(3pm) Various backoff strategies for retry ## 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 \. ## SOURCE Source repository is at \. ## 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 \ ## CONTRIBUTORS - • Brendan Byrd \ - • SineSwiper \ ## 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 \. 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 \ 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.