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<?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 <guilhermeblanco@hotmail.com>
*/
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 bool
*/
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;
}
}
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