File: application/modules/extensions/aws/Aws/Waiter.php

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File: application/modules/extensions/aws/Aws/Waiter.php
Role: Application script
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<?php
namespace Aws;

use
Aws\Exception\AwsException;
use
GuzzleHttp\Promise;
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.'
           
);
        }
    }

    public function
promise()
    {
        return
Promise\coroutine(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']) ?: [];
        foreach (
$actuals as $actual) {
            if (
$actual == $acceptor['expected']) {
                return
true;
            }
        }

        return
false;
    }

   
/**
     * @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'];
        } elseif (
$result instanceof AwsException && $response = $result->getResponse()) {
            return
$acceptor['expected'] == $response->getStatusCode();
        } else {
            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;
    }
}


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