includes/libs/filebackend/SwiftFileBackendList.php

   1 <?php
   2 /**
   3  * OpenStack Swift based file backend.
   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 FileBackend
  22  * @author Russ Nelson
  23  */
  24
  25 /**
  26  * SwiftFileBackend helper class to page through listings.
  27  * Swift also has a listing limit of 10,000 objects for sanity.
  28  * Do not use this class from places outside SwiftFileBackend.
  29  *
  30  * @ingroup FileBackend
  31  */
  32 abstract class SwiftFileBackendList implements Iterator {
  33         /** @var array List of path or (path,stat array) entries */
  34         protected $bufferIter = [];
  35
  36         /** @var string List items *after* this path */
  37         protected $bufferAfter = null;
  38
  39         /** @var int */
  40         protected $pos = 0;
  41
  42         /** @var array */
  43         protected $params = [];
  44
  45         /** @var SwiftFileBackend */
  46         protected $backend;
  47
  48         /** @var string Container name */
  49         protected $container;
  50
  51         /** @var string Storage directory */
  52         protected $dir;
  53
  54         /** @var int */
  55         protected $suffixStart;
  56
  57         const PAGE_SIZE = 9000; // file listing buffer size
  58
  59         /**
  60          * @param SwiftFileBackend $backend
  61          * @param string $fullCont Resolved container name
  62          * @param string $dir Resolved directory relative to container
  63          * @param array $params
  64          */
  65         public function __construct( SwiftFileBackend $backend, $fullCont, $dir, array $params ) {
  66                 $this->backend = $backend;
  67                 $this->container = $fullCont;
  68                 $this->dir = $dir;
  69                 if ( substr( $this->dir, -1 ) === '/' ) {
  70                         $this->dir = substr( $this->dir, 0, -1 ); // remove trailing slash
  71                 }
  72                 if ( $this->dir == '' ) { // whole container
  73                         $this->suffixStart = 0;
  74                 } else { // dir within container
  75                         $this->suffixStart = strlen( $this->dir ) + 1; // size of "path/to/dir/"
  76                 }
  77                 $this->params = $params;
  78         }
  79
  80         /**
  81          * @see Iterator::key()
  82          * @return int
  83          */
  84         public function key() {
  85                 return $this->pos;
  86         }
  87
  88         /**
  89          * @see Iterator::next()
  90          */
  91         public function next() {
  92                 // Advance to the next file in the page
  93                 next( $this->bufferIter );
  94                 ++$this->pos;
  95                 // Check if there are no files left in this page and
  96                 // advance to the next page if this page was not empty.
  97                 if ( !$this->valid() && count( $this->bufferIter ) ) {
  98                         $this->bufferIter = $this->pageFromList(
  99                                 $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE, $this->params
 100                         ); // updates $this->bufferAfter
 101                 }
 102         }
 103
 104         /**
 105          * @see Iterator::rewind()
 106          */
 107         public function rewind() {
 108                 $this->pos = 0;
 109                 $this->bufferAfter = null;
 110                 $this->bufferIter = $this->pageFromList(
 111                         $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE, $this->params
 112                 ); // updates $this->bufferAfter
 113         }
 114
 115         /**
 116          * @see Iterator::valid()
 117          * @return bool
 118          */
 119         public function valid() {
 120                 if ( $this->bufferIter === null ) {
 121                         return false; // some failure?
 122                 } else {
 123                         return ( current( $this->bufferIter ) !== false ); // no paths can have this value
 124                 }
 125         }
 126
 127         /**
 128          * Get the given list portion (page)
 129          *
 130          * @param string $container Resolved container name
 131          * @param string $dir Resolved path relative to container
 132          * @param string &$after
 133          * @param int $limit
 134          * @param array $params
 135          * @return Traversable|array
 136          */
 137         abstract protected function pageFromList( $container, $dir, &$after, $limit, array $params );
 138 }