sparkcentral/backoff

Utility trait with retry (back off) functionality

v1.1.0 2016-11-10 02:17 UTC

Requires

• php: >=5.6

Requires (Dev)

• phpunit/phpunit: 4.*

MIT

• Sparkcentral Engineering

README

Simple utility trait which provides backoff / retry functionality.

Features

• Two different strategies: backoffOnException, backoffOnCondition
• You can provide list of exception classes so that retry will happen only when one of those from the list is thrown.
• You can pass custom function to backoffOnCondition which defines whether to retry operation or not.
• Retries happen with delays which grow linearly (y=x*2), you can pass custom starting delay as well.

For details please refer to documentation for backoffOnException(), backoffOnCondition() methods.

Dependencies

• PHP >= 5.6 (variadics)

Basic example

<?php

use Sparkcentral\Backoff\Backoff;

class ExternalServiceWrapper
{
    use Backoff;

    private $externalApiClient;

    public function __construct(ExternalApiClient $client)
    {
        $this->externalApiClient = $client;
    }

    public function getById($id)
    {
        $result = $this->backoffOnException(
            [$this->externalApiClient, 'get'], // call 'get' method on externalApiClient
            [$id], // pass this argument to 'get'
            5, // try up to 5 times
            [ConnectException::class] // only retry on ConnectExceptions, will re-throw everything else
        );

        return $result->getObject();
    }
}

Similarly you can use backoffOnCondition() in case code you're trying to execute does not throw any exceptions, but (for instance) returns null in case of failure.

<?php

use Sparkcentral\Backoff\Backoff;

class ExternalServiceWrapper
{
    use Backoff;

    private $externalApiClient;

    public function __construct(ExternalApiClient $client)
    {
        $this->externalApiClient = $client;
    }

    public function getById($id)
    {
        $result = $this->backoffOnCondition(
            [$this->externalApiClient, 'get'],
            [$id],
            5,
            function ($result) {
                return !is_null($result);
            }
        );

        return $result->getObject();
    }
}