EVOLUTION-MANAGER
Edit File: Runner.php
<?php defined("ABSPATH") or die(""); /* * Copyright 2014 Google Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ if (!class_exists('Duplicator_Pro_Google_Client')) { require_once dirname(__FILE__) . '/../autoload.php'; } /** * A task runner with exponential backoff support. * * @see https://developers.google.com/drive/web/handle-errors#implementing_exponential_backoff */ class Duplicator_Pro_Google_Task_Runner { /** * @var integer $maxDelay The max time (in seconds) to wait before a retry. */ private $maxDelay = 60; /** * @var integer $delay The previous delay from which the next is calculated. */ private $delay = 1; /** * @var integer $factor The base number for the exponential back off. */ private $factor = 2; /** * @var float $jitter A random number between -$jitter and $jitter will be * added to $factor on each iteration to allow for a better distribution of * retries. */ private $jitter = 0.5; /** * @var integer $attempts The number of attempts that have been tried so far. */ private $attempts = 0; /** * @var integer $maxAttempts The max number of attempts allowed. */ private $maxAttempts = 1; /** * @var Duplicator_Pro_Google_Client $client The current API client. */ private $client; /** * @var string $name The name of the current task (used for logging). */ private $name; /** * @var callable $action The task to run and possibly retry. */ private $action; /** * @var array $arguments The task arguments. */ private $arguments; /** * Creates a new task runner with exponential backoff support. * * @param Duplicator_Pro_Google_Client $client The current API client * @param string $name The name of the current task (used for logging) * @param callable $action The task to run and possibly retry * @param array $arguments The task arguments * @throws Duplicator_Pro_Google_Task_Exception when misconfigured */ public function __construct( Duplicator_Pro_Google_Client $client, $name, $action, array $arguments = array() ) { $config = (array) $client->getClassConfig('Duplicator_Pro_Google_Task_Runner'); if (isset($config['initial_delay'])) { if ($config['initial_delay'] < 0) { throw new Duplicator_Pro_Google_Task_Exception( 'Task configuration `initial_delay` must not be negative.' ); } $this->delay = $config['initial_delay']; } if (isset($config['max_delay'])) { if ($config['max_delay'] <= 0) { throw new Duplicator_Pro_Google_Task_Exception( 'Task configuration `max_delay` must be greater than 0.' ); } $this->maxDelay = $config['max_delay']; } if (isset($config['factor'])) { if ($config['factor'] <= 0) { throw new Duplicator_Pro_Google_Task_Exception( 'Task configuration `factor` must be greater than 0.' ); } $this->factor = $config['factor']; } if (isset($config['jitter'])) { if ($config['jitter'] <= 0) { throw new Duplicator_Pro_Google_Task_Exception( 'Task configuration `jitter` must be greater than 0.' ); } $this->jitter = $config['jitter']; } if (isset($config['retries'])) { if ($config['retries'] < 0) { throw new Duplicator_Pro_Google_Task_Exception( 'Task configuration `retries` must not be negative.' ); } $this->maxAttempts += $config['retries']; } if (!is_callable($action)) { throw new Duplicator_Pro_Google_Task_Exception( 'Task argument `$action` must be a valid callable.' ); } $this->name = $name; $this->client = $client; $this->action = $action; $this->arguments = $arguments; } /** * Checks if a retry can be attempted. * * @return boolean */ public function canAttmpt() { return $this->attempts < $this->maxAttempts; } /** * Runs the task and (if applicable) automatically retries when errors occur. * * @return mixed * @throws Duplicator_Pro_Google_Task_Retryable on failure when no retries are available. */ public function run() { while ($this->attempt()) { try { return call_user_func_array($this->action, $this->arguments); } catch (Duplicator_Pro_Google_Task_Retryable $exception) { $allowedRetries = $exception->allowedRetries(); if (!$this->canAttmpt() || !$allowedRetries) { throw $exception; } if ($allowedRetries > 0) { $this->maxAttempts = min( $this->maxAttempts, $this->attempts + $allowedRetries ); } } } } /** * Runs a task once, if possible. This is useful for bypassing the `run()` * loop. * * NOTE: If this is not the first attempt, this function will sleep in * accordance to the backoff configurations before running the task. * * @return boolean */ public function attempt() { if (!$this->canAttmpt()) { return false; } if ($this->attempts > 0) { $this->backOff(); } $this->attempts++; return true; } /** * Sleeps in accordance to the backoff configurations. */ private function backOff() { $delay = $this->getDelay(); $this->client->getLogger()->debug( 'Retrying task with backoff', array( 'request' => $this->name, 'retry' => $this->attempts, 'backoff_seconds' => $delay ) ); usleep($delay * 1000000); } /** * Gets the delay (in seconds) for the current backoff period. * * @return float */ private function getDelay() { $jitter = $this->getJitter(); $factor = $this->attempts > 1 ? $this->factor + $jitter : 1 + abs($jitter); return $this->delay = min($this->maxDelay, $this->delay * $factor); } /** * Gets the current jitter (random number between -$this->jitter and * $this->jitter). * * @return float */ private function getJitter() { return $this->jitter * 2 * mt_rand() / mt_getrandmax() - $this->jitter; } }