public function __construct($bucket, $object, $context, $flags)
{
parent::__construct($bucket, $object, $context);
$this->quiet = ($flags & STREAM_URL_STAT_QUIET) == STREAM_URL_STAT_QUIET;
if (isset($object)) {
// Drop the leading '/' from the object name.
$this->prefix = substr($object, 1);
}
}
public function __construct($bucket_name, $object_prefix, $context)
{
parent::__construct($bucket_name, $object_prefix, $context);
// Ignore the leading slash
if (isset($object_prefix)) {
if (!util\endsWith($object_prefix, '/')) {
$object_prefix .= '/';
}
$this->prefix = substr($object_prefix, 1);
}
}
/**
* Class constructor.
* @param string $bucket_name The name of the bucket.
* @param string $object_name The name of the object.
* @param mixed $context The stream context for this operation.
*/
public function __construct($bucket_name, $object_name, $context)
{
// $object_name should end with a trailing slash.
if (!StringUtil::endsWith($object_name, parent::DELIMITER)) {
$object_name = $object_name . parent::DELIMITER;
}
// $prefix is the $object_name without leading slash.
if (strlen($object_name) > 1) {
$this->prefix = substr($object_name, 1);
}
parent::__construct($bucket_name, $object_name, $context);
}
/**
* Override the makeHttpRequest function so we can implement caching.
* If caching is enabled then we try and retrieve a matching request for the
* object name and range from memcache.
* If we find a result in memcache, and optimistic caching is enabled then
* we return that result immediately without checking if the object has
* changed in GCS. Otherwise, we will issue a 'If-None-Match' request with
* the ETag of the object to ensure it is still current.
*
* Optimisitic caching is best suited when the application is soley updating
* objects in cloud storage, as the cache can be invalidated when the object
* is updated by the application.
*/
protected function makeHttpRequest($url, $method, $headers, $body = null)
{
if (!$this->context_options['enable_cache']) {
return parent::makeHttpRequest($url, $method, $headers, $body);
}
$cache_key = sprintf(parent::MEMCACHE_KEY_FORMAT, $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 $result;
}
/**
* Test if a given bucket is writable. We will cache results in memcache as
* this is an expensive operation. This might lead to incorrect results being
* returned for this call for a short period while the result remains in the
* cache.
*/
private function isBucketWritable($bucket)
{
$cache_key_name = sprintf(parent::WRITABLE_MEMCACHE_KEY_FORMAT, $bucket);
$memcache = new \Memcache();
$result = $memcache->get($cache_key_name);
if ($result) {
return $result['is_writable'];
}
// We determine if the bucket is writable by trying to start a resumable
// upload. GCS will cleanup the abandoned upload after 7 days, and it will
// not be charged to the bucket owner.
$token_header = $this->getOAuthTokenHeader(parent::WRITE_SCOPE);
if ($token_header === false) {
return false;
}
$headers = array_merge(parent::$upload_start_header, $token_header);
$url = parent::createObjectUrl($bucket, parent::WRITABLE_TEMP_FILENAME);
$http_response = $this->makeHttpRequest($url, "POST", $headers);
if ($http_response === false) {
return false;
}
$status_code = $http_response['status_code'];
$is_writable = $status_code == HttpResponse::CREATED;
$memcache->set($cache_key_name, ['is_writable' => $is_writable], null, $this->context_options['writable_cache_expiry_seconds']);
return $is_writable;
}
