avtonom/delay-exponential-backoff-bundle

Exponential backoff to delay for Symfony2 bundle for PHP

v1.1.0 2017-02-14 16:03 UTC

Requires

• php: >=5.3.2
• symfony/dependency-injection: ~2.3|3.*
• yriveiro/php-backoff: ~0.0

MIT

• Anton U

• Symfony2
• bundle
• retry
• job
• backoff
• delay
• Jitter
• exponential backoff

README

Exponential backoff is an algorithm that uses feedback to multiplicatively decrease the rate of some process, in order to gradually find an acceptable rate.

Page bundle: https://github.com/Avtonom/delay-exponential-backoff-bundle

    $ php bin/console exponential-backoff
    $ php bin/console exponential-backoff halfDelay -l 20
    

attempt	microseconds	seconds	minutes	hours
1	150000000	150	2.5	0.04
2	300000000	300	5	0.08
3	600000000	600	10	0.17
4	1200000000	1200	20	0.33
5	2400000000	2400	40	0.67
6	4800000000	4800	80	1.33
7	9600000000	9600	160	2.67
8	19200000000	19200	320	5.33
9	38400000000	38400	640	10.67
10	76800000000	76800	1280	21.33
11	153600000000	153600	2560	42.67

To Install

Run the following in your project root, assuming you have composer set up for your project

composer.phar require avtonom/exponential-backoff-bundle ~1.1

Switching ~1.1 for the most recent tag.

Add the bundle to app/AppKernel.php

$bundles(
    ...
            new Avtonom\ExponentialBackoffBundle\AvtonomExponentialBackoffBundle(),
    ...
);

Configuration options (parameters.yaml):

parameters:
    avtonom_exponential_backoff.cap: 1000000 # [OPTIONAL] - Max duration allowed (in microseconds). If backoff duration is greater than cap, cap is returned
    avtonom_exponential_backoff.max_attempts: 0 # [OPTIONAL] - Number of attemps before thrown an Exception
    

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 is 1000000 microseconds.
• maxAttempts: Number of attempts before thrown an Yriveiro\Backoff\BackoffException. Default is 0, no limit.

halfDelay($attempt):

delay($attempt):

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

    $attempt++;
    usleep($this->('avtonom_exponential_backoff')->equalJitter($attempt));
    

Read information https://habrahabr.ru/post/227225/

Use https://github.com/yriveiro/php-backoff