Proyectos de Subversion Moodle

<?php

namespace Aws;

use Aws\Exception\AwsException;

use GuzzleHttp\Promise\Coroutine;

use GuzzleHttp\Promise\PromisorInterface;

use GuzzleHttp\Promise\RejectedPromise;

/**

 * "Waiters" are associated with an AWS resource (e.g., EC2 instance), and poll

 * that resource and until it is in a particular state.

 * The Waiter object produces a promise that is either a.) resolved once the

 * waiting conditions are met, or b.) rejected if the waiting conditions cannot

 * be met or has exceeded the number of allowed attempts at meeting the

 * conditions. You can use waiters in a blocking or non-blocking way, depending

 * on whether you call wait() on the promise.

 * The configuration for the waiter must include information about the operation

 * and the conditions for wait completion.

 */

class Waiter implements PromisorInterface

{

    /** @var AwsClientInterface Client used to execute each attempt. */

    private $client;

    /** @var string Name of the waiter. */

    private $name;

    /** @var array Params to use with each attempt operation. */

    private $args;

    /** @var array Waiter configuration. */

    private $config;

    /** @var array Default configuration options. */

    private static $defaults = ['initDelay' => 0, 'before' => null];

    /** @var array Required configuration options. */

    private static $required = [

        'acceptors',

        'delay',

        'maxAttempts',

        'operation',

    ];

    /**

     * The array of configuration options include:

     *

     * - acceptors: (array) Array of acceptor options

     * - delay: (int) Number of seconds to delay between attempts

     * - maxAttempts: (int) Maximum number of attempts before failing

     * - operation: (string) Name of the API operation to use for polling

     * - before: (callable) Invoked before attempts. Accepts command and tries.

     *

     * @param AwsClientInterface $client Client used to execute commands.

     * @param string             $name   Waiter name.

     * @param array              $args   Command arguments.

     * @param array              $config Waiter config that overrides defaults.

     *

     * @throws \InvalidArgumentException if the configuration is incomplete.

     */

    public function __construct(

        AwsClientInterface $client,

        $name,

        array $args = [],

        array $config = []

    ) {

        $this->client = $client;

        $this->name = $name;

        $this->args = $args;

        // Prepare and validate config.

        $this->config = $config + self::$defaults;

        foreach (self::$required as $key) {

            if (!isset($this->config[$key])) {

                throw new \InvalidArgumentException(

                    'The provided waiter configuration was incomplete.'

                );

            }

        }

        if ($this->config['before'] && !is_callable($this->config['before'])) {

            throw new \InvalidArgumentException(

                'The provided "before" callback is not callable.'

            );

        }

    }

    /**

     * @return Coroutine

     */

    public function promise()

    {

        return Coroutine::of(function () {

            $name = $this->config['operation'];

            for ($state = 'retry', $attempt = 1; $state === 'retry'; $attempt++) {

                // Execute the operation.

                $args = $this->getArgsForAttempt($attempt);

                $command = $this->client->getCommand($name, $args);

                try {

                    if ($this->config['before']) {

                        $this->config['before']($command, $attempt);

                    }

                    $result = (yield $this->client->executeAsync($command));

                } catch (AwsException $e) {

                    $result = $e;

                }

                // Determine the waiter's state and what to do next.

                $state = $this->determineState($result);

                if ($state === 'success') {

                    yield $command;

                } elseif ($state === 'failed') {

                    $msg = "The {$this->name} waiter entered a failure state.";

                    if ($result instanceof \Exception) {

                        $msg .= ' Reason: ' . $result->getMessage();

                    }

                    yield new RejectedPromise(new \RuntimeException($msg));

                } elseif ($state === 'retry'

                    && $attempt >= $this->config['maxAttempts']

                ) {

                    $state = 'failed';

                    yield new RejectedPromise(new \RuntimeException(

                        "The {$this->name} waiter failed after attempt #{$attempt}."

                    ));

                }

            }

        });

    }

    /**

     * Gets the operation arguments for the attempt, including the delay.

     *

     * @param $attempt Number of the current attempt.

     *

     * @return mixed integer

     */

    private function getArgsForAttempt($attempt)

    {

        $args = $this->args;

        // Determine the delay.

        $delay = ($attempt === 1)

            ? $this->config['initDelay']

            : $this->config['delay'];

        if (is_callable($delay)) {

            $delay = $delay($attempt);

        }

        // Set the delay. (Note: handlers except delay in milliseconds.)

        if (!isset($args['@http'])) {

            $args['@http'] = [];

        }

        $args['@http']['delay'] = $delay * 1000;

        return $args;

    }

    /**

     * Determines the state of the waiter attempt, based on the result of

     * polling the resource. A waiter can have the state of "success", "failed",

     * or "retry".

     *

     * @param mixed $result

     *

     * @return string Will be "success", "failed", or "retry"

     */

    private function determineState($result)

    {

        foreach ($this->config['acceptors'] as $acceptor) {

            $matcher = 'matches' . ucfirst($acceptor['matcher']);

            if ($this->{$matcher}($result, $acceptor)) {

                return $acceptor['state'];

            }

        }

        return $result instanceof \Exception ? 'failed' : 'retry';

    }

    /**

     * @param Result $result   Result or exception.

     * @param array  $acceptor Acceptor configuration being checked.

     *

     * @return bool

     */

    private function matchesPath($result, array $acceptor)

    {

        return !($result instanceof ResultInterface)

            ? false

            : $acceptor['expected'] == $result->search($acceptor['argument']);

    }

    /**

     * @param Result $result   Result or exception.

     * @param array  $acceptor Acceptor configuration being checked.

     *

     * @return bool

     */

    private function matchesPathAll($result, array $acceptor)

    {

        if (!($result instanceof ResultInterface)) {

            return false;

        }

        $actuals = $result->search($acceptor['argument']) ?: [];

        foreach ($actuals as $actual) {

            if ($actual != $acceptor['expected']) {

                return false;

            }

        }

        return true;

    }

    /**

     * @param Result $result   Result or exception.

     * @param array  $acceptor Acceptor configuration being checked.

     *

     * @return bool

     */

    private function matchesPathAny($result, array $acceptor)

    {

        if (!($result instanceof ResultInterface)) {

            return false;

        }

        $actuals = $result->search($acceptor['argument']) ?: [];

        return in_array($acceptor['expected'], $actuals);

    }

    /**

     * @param Result $result   Result or exception.

     * @param array  $acceptor Acceptor configuration being checked.

     *

     * @return bool

     */

    private function matchesStatus($result, array $acceptor)

    {

        if ($result instanceof ResultInterface) {

            return $acceptor['expected'] == $result['@metadata']['statusCode'];

        }

        if ($result instanceof AwsException && $response = $result->getResponse()) {

            return $acceptor['expected'] == $response->getStatusCode();

        }

        return false;

    }

    /**

     * @param Result $result   Result or exception.

     * @param array  $acceptor Acceptor configuration being checked.

     *

     * @return bool

     */

    private function matchesError($result, array $acceptor)

    {

        if ($result instanceof AwsException) {

            return $result->isConnectionError()

                || $result->getAwsErrorCode() == $acceptor['expected'];

        }

        return false;

    }

}