includes/libs/filebackend/FileBackendStoreShardListIterator.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  * @ingroup FileBackend
  20  */
  21
  22 /**
  23  * FileBackendStore helper function to handle listings that span container shards.
  24  * Do not use this class from places outside of FileBackendStore.
  25  *
  26  * @ingroup FileBackend
  27  */
  28 abstract class FileBackendStoreShardListIterator extends FilterIterator {
  29         /** @var FileBackendStore */
  30         protected $backend;
  31
  32         /** @var array */
  33         protected $params;
  34
  35         /** @var string Full container name */
  36         protected $container;
  37
  38         /** @var string Resolved relative path */
  39         protected $directory;
  40
  41         /** @var array */
  42         protected $multiShardPaths = []; // (rel path => 1)
  43
  44         /**
  45          * @param FileBackendStore $backend
  46          * @param string $container Full storage container name
  47          * @param string $dir Storage directory relative to container
  48          * @param array $suffixes List of container shard suffixes
  49          * @param array $params
  50          */
  51         public function __construct(
  52                 FileBackendStore $backend, $container, $dir, array $suffixes, array $params
  53         ) {
  54                 $this->backend = $backend;
  55                 $this->container = $container;
  56                 $this->directory = $dir;
  57                 $this->params = $params;
  58
  59                 $iter = new AppendIterator();
  60                 foreach ( $suffixes as $suffix ) {
  61                         $iter->append( $this->listFromShard( $this->container . $suffix ) );
  62                 }
  63
  64                 parent::__construct( $iter );
  65         }
  66
  67         public function accept() {
  68                 $rel = $this->getInnerIterator()->current(); // path relative to given directory
  69                 $path = $this->params['dir'] . "/{$rel}"; // full storage path
  70                 if ( $this->backend->isSingleShardPathInternal( $path ) ) {
  71                         return true; // path is only on one shard; no issue with duplicates
  72                 } elseif ( isset( $this->multiShardPaths[$rel] ) ) {
  73                         // Don't keep listing paths that are on multiple shards
  74                         return false;
  75                 } else {
  76                         $this->multiShardPaths[$rel] = 1;
  77
  78                         return true;
  79                 }
  80         }
  81
  82         public function rewind() {
  83                 parent::rewind();
  84                 $this->multiShardPaths = [];
  85         }
  86
  87         /**
  88          * Get the list for a given container shard
  89          *
  90          * @param string $container Resolved container name
  91          * @return Iterator
  92          */
  93         abstract protected function listFromShard( $container );
  94 }