yriveiro / php-backoff
Simple backoff / retry functionality
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Requires
- php: >=7.0
Requires (Dev)
- php-coveralls/php-coveralls: ~2.1
- phpstan/phpstan: ^0.9.2
- phpunit/phpunit: ~6.5.8
README
NOTE: to use php-backoff with PHP 5.x please use the lastet release of branch 1.x
API
getDefaultOptions():
This method is static and returns an array with the default options:
cap
: Max duration allowed (in microseconds). If backoff duration is greater than cap, cap is returned, default is1000000
microseconds.maxAttempts
: Number of attempts before thrown an Yriveiro\Backoff\BackoffException. Default is0
, no limit.
exponential($attempt):
This method use and exponential function E(attempt) = (2**attempt - 1)
to calculate backoff time.
Parameters
attempt
: incremental value that represents the current retry number.
equalJitter($attempt);
Exponential backoff has one disadvantage. In high concurrence, we can have multiples calls with the same backoff time due the time is highly bound to the current attempt, different calls could be in the same attempt.
To solve this we can add a jitter value to allow some randomization.
equalJitter
uses the function: E(attempt) = min(((2**attempt - 1) / 2), random(0, ((2**attempt - 1) / 2)))
.
Parameters
attempt
: incremental value that represents the current retry number.
fullJitter($attempt);
Full jitter behaves like equalJitter
method, the main difference between them is the way in how the jitter value is calculated.
fullJitter
uses the function: E(attempt) = min(random(0, (2**attempt - 1) / 2))
.
Parameters
attempt
: incremental value that represents the current retry number.
Usage
Zero configuration examples:
With zero configuration, we will never stop to try fetch data. The exit condition is your responsibility.
$attempt = 1; $backoff = new Backoff(); $response = $http->get('http://myservice.com/user/1'); while (!$response) { $time = $backoff->exponential($attempt); $attempt++; usleep($time); $response = $http->get('http://myservice.com/user/1'); }
With configuration examples:
$attempt = 1; $options = Backoff::getDefaultOptions(); $options['maxAttempts'] = 3; $backoff = new Backoff($options); $response = $http->get('http://myservice.com/user/1'); try while (!$response) { $time = $backoff->fullJitter($attempt); $attempt++; usleep($time); $response = $http->get('http://myservice.com/user/1'); } } catch (Yriveiro\Backoff\BackoffException $e) { // Handle the exception }
Installation
The recommended way to install this package is through Composer.
php composer.phar require "yriveiro/php-backoff"
Tests
Tests are performed using the phpunit
library, to run them:
php vendor/bin/phpunit tests
Know issues
None.
How to contribute
Have an idea? Found a bug?, contributions are welcome :)
License
Backoff is licensed under MIT license.