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    $self->{_last_timestamp} = $timestamp;
    $self->{_prev_delay}     = $delay;
    $delay;
}

sub success {
    my ($self, $timestamp) = @_;

    $timestamp //= time();

    $self->{_attempts} = 0;

    $self->_success_or_failure(1, $timestamp);
}

sub failure {
    my ($self, $timestamp) = @_;

    $timestamp //= time();

    return -1 if defined $self->{max_actual_duration} &&
        $self->{max_actual_duration} > 0 &&
        $timestamp - $self->{_start_timestamp} >= $self->{max_actual_duration};

    $self->{_attempts}++;
    return -1 if $self->{max_attempts} &&
        $self->{_attempts} >= $self->{max_attempts};

    $self->_success_or_failure(0, $timestamp);
}

1;
# ABSTRACT: Various backoff strategies for retry

__END__

=pod

=encoding UTF-8

=head1 NAME

Algorithm::Backoff - Various backoff strategies for retry

=head1 VERSION

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

=head1 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

=head1 DESCRIPTION

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

This class (C<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. L<Retry::Backoff>). This allows for things like
printing/returning all the retries and their delay amounts without actually
doing the delay (e.g. in L<show-backoff-delays> script).

=head1 METHODS


=head2 new

Usage:

 new(%args) -> obj

This function is not exported.

Arguments ('*' denotes required arguments):

=over 4

=item * B<jitter_factor> => I<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.

=item * B<max_attempts> => I<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.


=back

Return value:  (obj)


=head2 success

Usage:

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

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

=head2 failure

Usage:

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

Log a failed attempt. If not specified, C<$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 C<max_attempts>
parameter has been exceeded).

=head1 HOMEPAGE

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

=head1 SOURCE

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

=head1 SEE ALSO

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

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

L<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.

=head1 AUTHOR

perlancar <perlancar@cpan.org>

=head1 CONTRIBUTORS

=for stopwords Brendan Byrd SineSwiper

=over 4

=item *

Brendan Byrd <brendan.byrd@grantstreet.com>

=item *

SineSwiper <GitHub@ResonatorSoft.org>

=back

=head1 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 L<Dist::Zilla>,
L<Dist::Zilla::PluginBundle::Author::PERLANCAR>,
L<Pod::Weaver::PluginBundle::Author::PERLANCAR>, and sometimes one or two other