includes/cache/localisation/LCStoreCDB.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  */
  20 use Cdb\Exception;
  21 use Cdb\Reader;
  22 use Cdb\Writer;
  23
  24 /**
  25  * LCStore implementation which stores data as a collection of CDB files in the
  26  * directory given by $wgCacheDirectory. If $wgCacheDirectory is not set, this
  27  * will throw an exception.
  28  *
  29  * Profiling indicates that on Linux, this implementation outperforms MySQL if
  30  * the directory is on a local filesystem and there is ample kernel cache
  31  * space. The performance advantage is greater when the DBA extension is
  32  * available than it is with the PHP port.
  33  *
  34  * See Cdb.php and https://cr.yp.to/cdb.html
  35  */
  36 class LCStoreCDB implements LCStore {
  37
  38         /** @var Reader[] */
  39         private $readers;
  40
  41         /** @var Writer */
  42         private $writer;
  43
  44         /** @var string Current language code */
  45         private $currentLang;
  46
  47         /** @var bool|string Cache directory. False if not set */
  48         private $directory;
  49
  50         function __construct( $conf = [] ) {
  51                 global $wgCacheDirectory;
  52
  53                 $this->directory = $conf['directory'] ?? $wgCacheDirectory;
  54         }
  55
  56         public function get( $code, $key ) {
  57                 if ( !isset( $this->readers[$code] ) ) {
  58                         $fileName = $this->getFileName( $code );
  59
  60                         $this->readers[$code] = false;
  61                         if ( file_exists( $fileName ) ) {
  62                                 try {
  63                                         $this->readers[$code] = Reader::open( $fileName );
  64                                 } catch ( Exception $e ) {
  65                                         wfDebug( __METHOD__ . ": unable to open cdb file for reading\n" );
  66                                 }
  67                         }
  68                 }
  69
  70                 if ( !$this->readers[$code] ) {
  71                         return null;
  72                 } else {
  73                         $value = false;
  74                         try {
  75                                 $value = $this->readers[$code]->get( $key );
  76                         } catch ( Exception $e ) {
  77                                 wfDebug( __METHOD__ . ": \Cdb\Exception caught, error message was "
  78                                         . $e->getMessage() . "\n" );
  79                         }
  80                         if ( $value === false ) {
  81                                 return null;
  82                         }
  83
  84                         return unserialize( $value );
  85                 }
  86         }
  87
  88         public function startWrite( $code ) {
  89                 if ( !file_exists( $this->directory ) && !wfMkdirParents( $this->directory, null, __METHOD__ ) ) {
  90                         throw new MWException( "Unable to create the localisation store " .
  91                                 "directory \"{$this->directory}\"" );
  92                 }
  93
  94                 // Close reader to stop permission errors on write
  95                 if ( !empty( $this->readers[$code] ) ) {
  96                         $this->readers[$code]->close();
  97                 }
  98
  99                 try {
 100                         $this->writer = Writer::open( $this->getFileName( $code ) );
 101                 } catch ( Exception $e ) {
 102                         throw new MWException( $e->getMessage() );
 103                 }
 104                 $this->currentLang = $code;
 105         }
 106
 107         public function finishWrite() {
 108                 // Close the writer
 109                 try {
 110                         $this->writer->close();
 111                 } catch ( Exception $e ) {
 112                         throw new MWException( $e->getMessage() );
 113                 }
 114                 $this->writer = null;
 115                 unset( $this->readers[$this->currentLang] );
 116                 $this->currentLang = null;
 117         }
 118
 119         public function set( $key, $value ) {
 120                 if ( is_null( $this->writer ) ) {
 121                         throw new MWException( __CLASS__ . ': must call startWrite() before calling set()' );
 122                 }
 123                 try {
 124                         $this->writer->set( $key, serialize( $value ) );
 125                 } catch ( Exception $e ) {
 126                         throw new MWException( $e->getMessage() );
 127                 }
 128         }
 129
 130         protected function getFileName( $code ) {
 131                 if ( strval( $code ) === '' || strpos( $code, '/' ) !== false ) {
 132                         throw new MWException( __METHOD__ . ": Invalid language \"$code\"" );
 133                 }
 134
 135                 return "{$this->directory}/l10n_cache-$code.cdb";
 136         }
 137
 138 }