includes/ChangesFeed.php

   1 <?php
   2
   3 /**
   4  * Feed to Special:RecentChanges and Special:RecentChangesLiked
   5  *
   6  * @ingroup Feed
   7  */
   8 class ChangesFeed {
   9         public $format, $type, $titleMsg, $descMsg;
  10
  11         /**
  12          * Constructor
  13          *
  14          * @param $format String: feed's format (either 'rss' or 'atom')
  15          * @param $type String: type of feed (for cache keys)
  16          */
  17         public function __construct( $format, $type ) {
  18                 $this->format = $format;
  19                 $this->type = $type;
  20         }
  21
  22         /**
  23          * Get a ChannelFeed subclass object to use
  24          *
  25          * @param $title String: feed's title
  26          * @param $description String: feed's description
  27          * @return ChannelFeed subclass or false on failure
  28          */
  29         public function getFeedObject( $title, $description ) {
  30                 global $wgSitename, $wgContLanguageCode, $wgFeedClasses, $wgTitle;
  31                 $feedTitle = "$wgSitename  - {$title} [$wgContLanguageCode]";
  32                 if( !isset($wgFeedClasses[$this->format] ) )
  33                         return false;
  34                 return new $wgFeedClasses[$this->format](
  35                         $feedTitle, htmlspecialchars( $description ), $wgTitle->getFullUrl() );
  36         }
  37
  38         /**
  39          * Generates feed's content
  40          *
  41          * @param $feed ChannelFeed subclass object (generally the one returned by getFeedObject())
  42          * @param $rows ResultWrapper object with rows in recentchanges table
  43          * @param $limit Integer: number of rows in $rows (only used for the cache key)
  44          * @param $hideminor Boolean: whether to hide minor edits (only used for the cache key)
  45          * @param $lastmod Integer: timestamp of the last item in the recentchanges table (only used for the cache key)
  46          * @param $target String: target's name; for Special:RecentChangesLinked (only used for the cache key)
  47          * @param $namespace Integer: namespace id (only used for the cache key)
  48          * @return null or true
  49          */
  50         public function execute( $feed, $rows, $limit=0, $hideminor=false, $lastmod=false, $target='', $namespace='' ) {
  51                 global $messageMemc, $wgFeedCacheTimeout;
  52                 global $wgSitename, $wgLang;
  53
  54                 if ( !FeedUtils::checkFeedOutput( $this->format ) ) {
  55                         return;
  56                 }
  57
  58                 $timekey = wfMemcKey( $this->type, $this->format, 'timestamp' );
  59                 $key = wfMemcKey( $this->type, $this->format, $limit, $hideminor, $target, $wgLang->getCode(), $namespace );
  60
  61                 FeedUtils::checkPurge($timekey, $key);
  62
  63                 /*
  64                 * Bumping around loading up diffs can be pretty slow, so where
  65                 * possible we want to cache the feed output so the next visitor
  66                 * gets it quick too.
  67                 */
  68                 $cachedFeed = $this->loadFromCache( $lastmod, $timekey, $key );
  69                 if( is_string( $cachedFeed ) ) {
  70                         wfDebug( "RC: Outputting cached feed\n" );
  71                         $feed->httpHeaders();
  72                         echo $cachedFeed;
  73                 } else {
  74                         wfDebug( "RC: rendering new feed and caching it\n" );
  75                         ob_start();
  76                         self::generateFeed( $rows, $feed );
  77                         $cachedFeed = ob_get_contents();
  78                         ob_end_flush();
  79                         $this->saveToCache( $cachedFeed, $timekey, $key );
  80                 }
  81                 return true;
  82         }
  83
  84         /**
  85          * Save to feed result to $messageMemc
  86          *
  87          * @param $feed String: feed's content
  88          * @param $timekey String: memcached key of the last modification
  89          * @param $key String: memcached key of the content
  90          */
  91         public function saveToCache( $feed, $timekey, $key ) {
  92                 global $messageMemc;
  93                 $expire = 3600 * 24; # One day
  94                 $messageMemc->set( $key, $feed, $expire );
  95                 $messageMemc->set( $timekey, wfTimestamp( TS_MW ), $expire );
  96         }
  97
  98         /**
  99          * Try to load the feed result from $messageMemc
 100          *
 101          * @param $lastmod Integer: timestamp of the last item in the recentchanges table
 102          * @param $timekey String: memcached key of the last modification
 103          * @param $key String: memcached key of the content
 104          * @return feed's content on cache hit or false on cache miss
 105          */
 106         public function loadFromCache( $lastmod, $timekey, $key ) {
 107                 global $wgFeedCacheTimeout, $messageMemc;
 108                 $feedLastmod = $messageMemc->get( $timekey );
 109
 110                 if( ( $wgFeedCacheTimeout > 0 ) && $feedLastmod ) {
 111                         /*
 112                         * If the cached feed was rendered very recently, we may
 113                         * go ahead and use it even if there have been edits made
 114                         * since it was rendered. This keeps a swarm of requests
 115                         * from being too bad on a super-frequently edited wiki.
 116                         */
 117
 118                         $feedAge = time() - wfTimestamp( TS_UNIX, $feedLastmod );
 119                         $feedLastmodUnix = wfTimestamp( TS_UNIX, $feedLastmod );
 120                         $lastmodUnix = wfTimestamp( TS_UNIX, $lastmod );
 121
 122                         if( $feedAge < $wgFeedCacheTimeout || $feedLastmodUnix > $lastmodUnix) {
 123                                 wfDebug( "RC: loading feed from cache ($key; $feedLastmod; $lastmod)...\n" );
 124                                 return $messageMemc->get( $key );
 125                         } else {
 126                                 wfDebug( "RC: cached feed timestamp check failed ($feedLastmod; $lastmod)\n" );
 127                         }
 128                 }
 129                 return false;
 130         }
 131
 132         /**
 133          * Generate the feed items given a row from the database.
 134          * @param $rows DatabaseBase resource with recentchanges rows
 135          * @param $feed Feed object
 136          */
 137         public static function generateFeed( $rows, &$feed ) {
 138                 wfProfileIn( __METHOD__ );
 139
 140                 $feed->outHeader();
 141
 142                 # Merge adjacent edits by one user
 143                 $sorted = array();
 144                 $n = 0;
 145                 foreach( $rows as $obj ) {
 146                         if( $n > 0 &&
 147                                 $obj->rc_namespace >= 0 &&
 148                                 $obj->rc_cur_id == $sorted[$n-1]->rc_cur_id &&
 149                                 $obj->rc_user_text == $sorted[$n-1]->rc_user_text ) {
 150                                 $sorted[$n-1]->rc_last_oldid = $obj->rc_last_oldid;
 151                         } else {
 152                                 $sorted[$n] = $obj;
 153                                 $n++;
 154                         }
 155                 }
 156
 157                 foreach( $sorted as $obj ) {
 158                         $title = Title::makeTitle( $obj->rc_namespace, $obj->rc_title );
 159                         $talkpage = $title->getTalkPage();
 160                         // Skip items with deleted content (avoids partially complete/inconsistent output)
 161                         if( $obj->rc_deleted ) continue;
 162                         $item = new FeedItem(
 163                                 $title->getPrefixedText(),
 164                                 FeedUtils::formatDiff( $obj ),
 165                                 $obj->rc_this_oldid ? $title->getFullURL( 'diff=' . $obj->rc_this_oldid . '&oldid=prev' ) : $title->getFullURL(),
 166                                 $obj->rc_timestamp,
 167                                 ($obj->rc_deleted & Revision::DELETED_USER) ? wfMsgHtml('rev-deleted-user') : $obj->rc_user_text,
 168                                 $talkpage->getFullURL()
 169                         );
 170                         $feed->outItem( $item );
 171                 }
 172                 $feed->outFooter();
 173                 wfProfileOut( __METHOD__ );
 174         }
 175
 176 }