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<?php
/**
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
namespace MediaWiki\Storage;
use StatusValue;
/**
* Service for loading and storing data blobs.
*
* @note This was written to act as a drop-in replacement for the corresponding
* static methods in the old Revision class (which was later removed in 1.37).
*
* @since 1.31
*/
interface BlobStore {
/**
* Hint key for use with storeBlob, indicating the general role the block
* takes in the application. For instance, it should be "page-content" if
* the blob represents a Content object.
*/
public const DESIGNATION_HINT = 'designation';
/**
* Hint key for use with storeBlob, indicating the page the blob is associated with.
* This may be used for sharding.
*/
public const PAGE_HINT = 'page_id';
/**
* Hint key for use with storeBlob, indicating the slot the blob is associated with.
* May be relevant for reference counting.
*/
public const ROLE_HINT = 'role_name';
/**
* Hint key for use with storeBlob, indicating the revision the blob is associated with.
* This may be used for differential storage and reference counting.
*/
public const REVISION_HINT = 'rev_id';
/**
* Hint key for use with storeBlob, indicating the parent revision of the revision
* the blob is associated with. This may be used for differential storage.
*/
public const PARENT_HINT = 'rev_parent_id';
/**
* Hint key for use with storeBlob, providing the SHA1 hash of the blob as passed to the
* method. This can be used to avoid re-calculating the hash if it is needed by the BlobStore.
*/
public const SHA1_HINT = 'cont_sha1';
/**
* Hint key for use with storeBlob, indicating the model of the content encoded in the
* given blob. May be used to implement optimized storage for some well known models.
*/
public const MODEL_HINT = 'cont_model';
/**
* Hint key for use with storeBlob, indicating the serialization format used to create
* the blob, as a MIME type. May be used for optimized storage in the underlying database.
*/
public const FORMAT_HINT = 'cont_format';
/**
* Hint key for an image name.
*/
public const IMAGE_HINT = 'img_name';
/**
* Retrieve a blob, given an address.
*
* MCR migration note: this replaced Revision::loadText
*
* @param string $blobAddress The blob address as returned by storeBlob(),
* such as "tt:12345" or "ex:DB://s16/456/9876".
* @param int $queryFlags See IDBAccessObject.
*
* @throws BlobAccessException
* @return string binary blob data
*/
public function getBlob( $blobAddress, $queryFlags = 0 );
/**
* A batched version of BlobStore::getBlob.
*
* @param string[] $blobAddresses An array of blob addresses.
* @param int $queryFlags See IDBAccessObject.
* @throws BlobAccessException
* @return StatusValue A status with a map of blobAddress => binary blob data or null
* if fetching the blob has failed. Fetch failures errors are the
* warnings in the status object.
* @since 1.34
*/
public function getBlobBatch( $blobAddresses, $queryFlags = 0 );
/**
* Stores an arbitrary blob of data and returns an address that can be used with
* getBlob() to retrieve the same blob of data,
*
* @param string $data raw binary data
* @param array $hints An array of hints. Implementations may use the hints to optimize storage.
* All hints are optional, supported hints depend on the implementation. Hint names by
* convention correspond to the names of fields in the database. Callers are encouraged to
* provide the well known hints as defined by the XXX_HINT constants.
*
* @throws BlobAccessException
* @return string an address that can be used with getBlob() to retrieve the data.
*/
public function storeBlob( $data, $hints = [] );
/**
* Check if the blob metadata or backing blob data store is read-only
*
* @return bool
*/
public function isReadOnly();
}
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