NAME

NAME
Algorithm::Backoff - Various backoff strategies for retry

VERSION
This document describes version 0.009 of Algorithm::Backoff (from Perl
distribution Algorithm-Backoff), released on 2019-06-20.

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, timestamp is
# optional but must 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.

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 time. 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
time. 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>.

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.

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 - Somehow I didn't find this module before writing
Algorithm::Backoff. Otherwise I probably would not have created
Algorithm::Backoff. But Algorithm::Backoff offers an alternative
interface, some additional parameters (like delay on success and jitter
factor), a lighter footprint (no Moo), and a couple more strategies.

AUTHOR
perlancar <[email protected]>

COPYRIGHT AND LICENSE
This software is copyright (c) 2019 by [email protected].

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