public function __construct($from_bucket, $from_object, $to_bucket, $to_object, $context)
{
parent::__construct($from_bucket, $from_object, $context);
$this->from_bucket = $from_bucket;
$this->from_object = $from_object;
$this->to_bucket = $to_bucket;
$this->to_object = $to_object;
}
/**
* Override the makeHttpRequest function so we can implement caching.
* If caching is enabled then we try and retrieve a matching request for the
* object name and range from memcache.
* If we find a result in memcache, and optimistic caching is enabled then
* we return that result immediately without checking if the object has
* changed in GCS. Otherwise, we will issue a 'If-None-Match' request with
* the ETag of the object to ensure it is still current.
*
* Optimisitic caching is best suited when the application is soley updating
* objects in cloud storage, as the cache can be invalidated when the object
* is updated by the application.
*/
protected function makeHttpRequest($url, $method, $headers, $body = null)
{
if (!$this->context_options['enable_cache']) {
return parent::makeHttpRequest($url, $method, $headers, $body);
}
$cache_key = static::getReadMemcacheKey($url, $headers['Range']);
$cache_obj = $this->memcache_client->get($cache_key);
if (false !== $cache_obj) {
if ($this->context_options['enable_optimistic_cache']) {
return $cache_obj;
} else {
$cache_etag = $this->getHeaderValue('ETag', $cache_obj['headers']);
if (array_key_exists('If-Match', $headers)) {
// We will perform a If-None-Match to validate the cache object, only
// if it has the same ETag value as what we are asking for.
if ($headers['If-Match'] === $cache_etag) {
unset($headers['If-Match']);
} else {
// We are asking for a different object that what is in the cache.
$cache_etag = null;
}
}
}
if (isset($cache_etag)) {
$headers['If-None-Match'] = $cache_etag;
}
}
$result = parent::makeHttpRequest($url, $method, $headers, $body);
if (false === $result) {
return false;
}
$status_code = $result['status_code'];
if (HttpResponse::NOT_MODIFIED === $result['status_code']) {
return $cache_obj;
}
if (in_array($status_code, self::$valid_status_codes)) {
$this->memcache_client->set($cache_key, $result, 0, $this->context_options['read_cache_expiry_seconds']);
}
return $result;
}
public function __construct($bucket, $object, $context)
{
parent::__construct($bucket, $object, $context);
}
