RiakCache.php in Zircon Profile 8

Namespace

Doctrine\Common\Cache

File

vendor/doctrine/cache/lib/Doctrine/Common/Cache/RiakCache.php

<?php

/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the MIT license. For more information, see
 * <http://www.doctrine-project.org>.
 */
namespace Doctrine\Common\Cache;

use Riak\Bucket;
use Riak\Connection;
use Riak\Input;
use Riak\Exception;
use Riak\Object;

/**
 * Riak cache provider.
 *
 * @link   www.doctrine-project.org
 * @since  1.1
 * @author Guilherme Blanco <[e-mail]>
 */
class RiakCache extends CacheProvider {
  const EXPIRES_HEADER = 'X-Riak-Meta-Expires';

  /**
   * @var \Riak\Bucket
   */
  private $bucket;

  /**
   * Sets the riak bucket instance to use.
   *
   * @param \Riak\Bucket $bucket
   */
  public function __construct(Bucket $bucket) {
    $this->bucket = $bucket;
  }

  /**
   * {@inheritdoc}
   */
  protected function doFetch($id) {
    try {
      $response = $this->bucket
        ->get($id);

      // No objects found
      if (!$response
        ->hasObject()) {
        return false;
      }

      // Check for attempted siblings
      $object = $response
        ->hasSiblings() ? $this
        ->resolveConflict($id, $response
        ->getVClock(), $response
        ->getObjectList()) : $response
        ->getFirstObject();

      // Check for expired object
      if ($this
        ->isExpired($object)) {
        $this->bucket
          ->delete($object);
        return false;
      }
      return unserialize($object
        ->getContent());
    } catch (Exception\RiakException $e) {

      // Covers:
      // - Riak\ConnectionException
      // - Riak\CommunicationException
      // - Riak\UnexpectedResponseException
      // - Riak\NotFoundException
    }
    return false;
  }

  /**
   * {@inheritdoc}
   */
  protected function doContains($id) {
    try {

      // We only need the HEAD, not the entire object
      $input = new Input\GetInput();
      $input
        ->setReturnHead(true);
      $response = $this->bucket
        ->get($id, $input);

      // No objects found
      if (!$response
        ->hasObject()) {
        return false;
      }
      $object = $response
        ->getFirstObject();

      // Check for expired object
      if ($this
        ->isExpired($object)) {
        $this->bucket
          ->delete($object);
        return false;
      }
      return true;
    } catch (Exception\RiakException $e) {

      // Do nothing
    }
    return false;
  }

  /**
   * {@inheritdoc}
   */
  protected function doSave($id, $data, $lifeTime = 0) {
    try {
      $object = new Object($id);
      $object
        ->setContent(serialize($data));
      if ($lifeTime > 0) {
        $object
          ->addMetadata(self::EXPIRES_HEADER, (string) (time() + $lifeTime));
      }
      $this->bucket
        ->put($object);
      return true;
    } catch (Exception\RiakException $e) {

      // Do nothing
    }
    return false;
  }

  /**
   * {@inheritdoc}
   */
  protected function doDelete($id) {
    try {
      $this->bucket
        ->delete($id);
      return true;
    } catch (Exception\BadArgumentsException $e) {

      // Key did not exist on cluster already
    } catch (Exception\RiakException $e) {

      // Covers:
      // - Riak\Exception\ConnectionException
      // - Riak\Exception\CommunicationException
      // - Riak\Exception\UnexpectedResponseException
    }
    return false;
  }

  /**
   * {@inheritdoc}
   */
  protected function doFlush() {
    try {
      $keyList = $this->bucket
        ->getKeyList();
      foreach ($keyList as $key) {
        $this->bucket
          ->delete($key);
      }
      return true;
    } catch (Exception\RiakException $e) {

      // Do nothing
    }
    return false;
  }

  /**
   * {@inheritdoc}
   */
  protected function doGetStats() {

    // Only exposed through HTTP stats API, not Protocol Buffers API
    return null;
  }

  /**
   * Check if a given Riak Object have expired.
   *
   * @param \Riak\Object $object
   *
   * @return boolean
   */
  private function isExpired(object $object) {
    $metadataMap = $object
      ->getMetadataMap();
    return isset($metadataMap[self::EXPIRES_HEADER]) && $metadataMap[self::EXPIRES_HEADER] < time();
  }

  /**
   * On-read conflict resolution. Applied approach here is last write wins.
   * Specific needs may override this method to apply alternate conflict resolutions.
   *
   * {@internal Riak does not attempt to resolve a write conflict, and store
   * it as sibling of conflicted one. By following this approach, it is up to
   * the next read to resolve the conflict. When this happens, your fetched
   * object will have a list of siblings (read as a list of objects).
   * In our specific case, we do not care about the intermediate ones since
   * they are all the same read from storage, and we do apply a last sibling
   * (last write) wins logic.
   * If by any means our resolution generates another conflict, it'll up to
   * next read to properly solve it.}
   *
   * @param string $id
   * @param string $vClock
   * @param array  $objectList
   *
   * @return \Riak\Object
   */
  protected function resolveConflict($id, $vClock, array $objectList) {

    // Our approach here is last-write wins
    $winner = $objectList[count($objectList)];
    $putInput = new Input\PutInput();
    $putInput
      ->setVClock($vClock);
    $mergedObject = new Object($id);
    $mergedObject
      ->setContent($winner
      ->getContent());
    $this->bucket
      ->put($mergedObject, $putInput);
    return $mergedObject;
  }

}

Classes

Name	Description
RiakCache	Riak cache provider.