includes/externalstore/ExternalStoreMedium.php

   1 <?php
   2 /**
   3  * External storage in some particular medium.
   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  * @ingroup ExternalStorage
  22  */
  23
  24 use Psr\Log\LoggerAwareInterface;
  25 use Psr\Log\LoggerInterface;
  26 use Psr\Log\NullLogger;
  27
  28 /**
  29  * Key/value blob storage for a particular storage medium type (e.g. RDBMs, files)
  30  *
  31  * There can be multiple "locations" for a storage medium type (e.g. DB clusters, filesystems).
  32  * Blobs are stored under URLs of the form "<protocol>://<location>/<path>". Each type of storage
  33  * medium has an associated protocol.
  34  *
  35  * @ingroup ExternalStorage
  36  * @since 1.21
  37  */
  38 abstract class ExternalStoreMedium implements LoggerAwareInterface {
  39         /** @var array Usage context options for this instance */
  40         protected $params = [];
  41         /** @var string Default database domain to store content under */
  42         protected $dbDomain;
  43         /** @var bool Whether this was factoried with an explicit DB domain */
  44         protected $isDbDomainExplicit;
  45         /** @var string[] Writable locations */
  46         protected $writableLocations = [];
  47
  48         /** @var LoggerInterface */
  49         protected $logger;
  50
  51         /**
  52          * @param array $params Usage context options for this instance:
  53          *   - domain: the DB domain ID of the wiki the content is for [required]
  54          *   - writableLocations: locations that are writable [required]
  55          *   - logger: LoggerInterface instance [optional]
  56          *   - isDomainImplicit: whether this was factoried without an explicit DB domain [optional]
  57          */
  58         public function __construct( array $params ) {
  59                 $this->params = $params;
  60                 if ( isset( $params['domain'] ) ) {
  61                         $this->dbDomain = $params['domain'];
  62                         $this->isDbDomainExplicit = empty( $params['isDomainImplicit'] );
  63                 } else {
  64                         throw new InvalidArgumentException( 'Missing DB "domain" parameter.' );
  65                 }
  66
  67                 $this->logger = $params['logger'] ?? new NullLogger();
  68                 $this->writableLocations = $params['writableLocations'] ?? [];
  69         }
  70
  71         public function setLogger( LoggerInterface $logger ) {
  72                 $this->logger = $logger;
  73         }
  74
  75         /**
  76          * Fetch data from given external store URL
  77          *
  78          * @param string $url An external store URL
  79          * @return string|bool The text stored or false on error
  80          * @throws MWException
  81          */
  82         abstract public function fetchFromURL( $url );
  83
  84         /**
  85          * Fetch data from given external store URLs.
  86          *
  87          * @param array $urls A list of external store URLs
  88          * @return string[] Map of (url => text) for the URLs where data was actually found
  89          */
  90         public function batchFetchFromURLs( array $urls ) {
  91                 $retval = [];
  92                 foreach ( $urls as $url ) {
  93                         $data = $this->fetchFromURL( $url );
  94                         // Dont return when false to allow for simpler implementations
  95                         if ( $data !== false ) {
  96                                 $retval[$url] = $data;
  97                         }
  98                 }
  99
 100                 return $retval;
 101         }
 102
 103         /**
 104          * Insert a data item into a given location
 105          *
 106          * @param string $location The location name
 107          * @param string $data The data item
 108          * @return string|bool The URL of the stored data item, or false on error
 109          * @throws MWException
 110          */
 111         abstract public function store( $location, $data );
 112
 113         /**
 114          * Check if a given location is read-only
 115          *
 116          * @param string $location The location name
 117          * @return bool Whether this location is read-only
 118          * @since 1.31
 119          */
 120         public function isReadOnly( $location ) {
 121                 return !in_array( $location, $this->writableLocations, true );
 122         }
 123 }