patinthehat/backoffv2

Backoff algorithms implemented in PHP

v1.1.0 2017-02-16 14:43 UTC

Requires

• php: >=5.5.0

MIT

• Patrick Organ

README

BackoffV2 is a PHP 5.5+ library implementing various backoff algorithms, such as exponential backoff.

This library only returns a backoff delay amount based on the selected algorithms; implementation of the actual delay mechanism (such as sleep()) is left to the user.

Installation

Install BackoffV2 with Composer:

composer require patinthehat/backoffv2

Implementation

"Jitter" is implemented, if you choose to use it. Jitter is a small, variable amount of time that is added to the backoff amount.

Available Jitter algorithms (roughly based on this post) include:

• NoJitter - No jitter
• FullJitter - Standard jitter amount
• EqualJitter - More consistent jitter amounts
• DecorrelatedJitter - Higher jitter amounts

Backoff algorithms include:

• ExponentialBackoff - exponentially increase the backoff amount
• ConstantBackoff - use the same backoff amount, regardless of the attempt count.
• LinearBackoff - linear increase of the backoff amount, i.e. 1, 2, 3, 4, ...

Usage

Using the Backoff class

BackoffV2 implements a main class, Backoff, that acts as a container and manager for the backoff and jitter algorithms you choose. The constructor signature for Backoff is:

public function __construct($maxBackoff, BackoffStrategyInterface $backoff, JitterStrategyInterface $jitter)

Usage is simple:

include 'vendor/autoload.php';
use BackoffV2\Backoff;
use BackoffV2\Backoff\ExponentialBackoff;
use BackoffV2\Jitter\FullJitter;

$b = new Backoff(15, new ExponentialBackoff, new FullJitter);

echo 'backoff = '.$b->getBackoff() . PHP_EOL;
echo 'backoff = '.$b->getBackoff() . PHP_EOL;
echo 'backoff = '.$b->getBackoff() . PHP_EOL;
echo 'backoff = '.$b->getBackoff() . PHP_EOL;
echo 'backoff = '.$b->getBackoff() . ' (attempt ' . $b->getAttempt().')' . PHP_EOL;
$b->reset();

License

BackoffV2 is available under the MIT License.