includes/Storage/BlobStore.php

   1 <?php
   2 /**
   3  * Service for loading and storing data blobs.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 namespace MediaWiki\Storage;
  24
  25 /**
  26  * Service for loading and storing data blobs.
  27  *
  28  * @note This was written to act as a drop-in replacement for the corresponding
  29  *       static methods in Revision.
  30  *
  31  * @since 1.31
  32  */
  33 interface BlobStore {
  34
  35         /**
  36          * Hint key for use with storeBlob, indicating the general role the block
  37          * takes in the application. For instance, it should be "page-content" if
  38          * the blob represents a Content object.
  39          */
  40         const DESIGNATION_HINT = 'designation';
  41
  42         /**
  43          * Hint key for use with storeBlob, indicating the page the blob is associated with.
  44          * This may be used for sharding.
  45          */
  46         const PAGE_HINT = 'page_id';
  47
  48         /**
  49          * Hint key for use with storeBlob, indicating the slot the blob is associated with.
  50          * May be relevant for reference counting.
  51          */
  52         const ROLE_HINT = 'role_name';
  53
  54         /**
  55          * Hint key for use with storeBlob, indicating the revision the blob is associated with.
  56          * This may be used for differential storage and reference counting.
  57          */
  58         const REVISION_HINT = 'rev_id';
  59
  60         /**
  61          * Hint key for use with storeBlob, indicating the parent revision of the revision
  62          * the blob is associated with. This may be used for differential storage.
  63          */
  64         const PARENT_HINT = 'rev_parent_id';
  65
  66         /**
  67          * Hint key for use with storeBlob, providing the SHA1 hash of the blob as passed to the
  68          * method. This can be used to avoid re-calculating the hash if it is needed by the BlobStore.
  69          */
  70         const SHA1_HINT = 'cont_sha1';
  71
  72         /**
  73          * Hint key for use with storeBlob, indicating the model of the content encoded in the
  74          * given blob. May be used to implement optimized storage for some well known models.
  75          */
  76         const MODEL_HINT = 'cont_model';
  77
  78         /**
  79          * Hint key for use with storeBlob, indicating the serialization format used to create
  80          * the blob, as a MIME type. May be used for optimized storage in the underlying database.
  81          */
  82         const FORMAT_HINT = 'cont_format';
  83
  84         /**
  85          * Retrieve a blob, given an address.
  86          *
  87          * MCR migration note: this replaces Revision::loadText
  88          *
  89          * @param string $blobAddress The blob address as returned by storeBlob(),
  90          *        such as "tt:12345" or "ex:DB://s16/456/9876".
  91          * @param int $queryFlags See IDBAccessObject.
  92          *
  93          * @throws BlobAccessException
  94          * @return string binary blob data
  95          */
  96         public function getBlob( $blobAddress, $queryFlags = 0 );
  97
  98         /**
  99          * Stores an arbitrary blob of data and returns an address that can be used with
 100          * getBlob() to retrieve the same blob of data,
 101          *
 102          * @param string $data raw binary data
 103          * @param array $hints An array of hints. Implementations may use the hints to optimize storage.
 104          * All hints are optional, supported hints depend on the implementation. Hint names by
 105          * convention correspond to the names of fields in the database. Callers are encouraged to
 106          * provide the well known hints as defined by the XXX_HINT constants.
 107          *
 108          * @throws BlobAccessException
 109          * @return string an address that can be used with getBlob() to retrieve the data.
 110          */
 111         public function storeBlob( $data, $hints = [] );
 112
 113 }