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          * @param $url String: url of origin page
  28          * @return ChannelFeed subclass or false on failure
  29          */
  30         public function getFeedObject( $title, $description, $url ) {
  31                 global $wgSitename, $wgLanguageCode, $wgFeedClasses;
  32
  33                 if ( !isset( $wgFeedClasses[$this->format] ) ) {
  34                         return false;
  35                 }
  36
  37                 $feedTitle = "$wgSitename  - {$title} [$wgLanguageCode]";
  38                 return new $wgFeedClasses[$this->format](
  39                         $feedTitle, htmlspecialchars( $description ), $url );
  40         }
  41
  42         /**
  43          * Generates feed's content
  44          *
  45          * @param $feed ChannelFeed subclass object (generally the one returned by getFeedObject())
  46          * @param $rows ResultWrapper object with rows in recentchanges table
  47          * @param $lastmod Integer: timestamp of the last item in the recentchanges table (only used for the cache key)
  48          * @param $opts FormOptions as in SpecialRecentChanges::getDefaultOptions()
  49          * @return null or true
  50          */
  51         public function execute( $feed, $rows, $lastmod, $opts ) {
  52                 global $wgLang, $wgRenderHashAppend;
  53
  54                 if ( !FeedUtils::checkFeedOutput( $this->format ) ) {
  55                         return;
  56                 }
  57
  58                 $optionsHash = md5( serialize( $opts->getAllValues() ) ) . $wgRenderHashAppend;
  59                 $timekey = wfMemcKey( $this->type, $this->format, $wgLang->getCode(), $optionsHash, 'timestamp' );
  60                 $key = wfMemcKey( $this->type, $this->format, $wgLang->getCode(), $optionsHash );
  61
  62                 FeedUtils::checkPurge( $timekey, $key );
  63
  64                 /*
  65                 * Bumping around loading up diffs can be pretty slow, so where
  66                 * possible we want to cache the feed output so the next visitor
  67                 * gets it quick too.
  68                 */
  69                 $cachedFeed = $this->loadFromCache( $lastmod, $timekey, $key );
  70                 if( is_string( $cachedFeed ) ) {
  71                         wfDebug( "RC: Outputting cached feed\n" );
  72                         $feed->httpHeaders();
  73                         echo $cachedFeed;
  74                 } else {
  75                         wfDebug( "RC: rendering new feed and caching it\n" );
  76                         ob_start();
  77                         self::generateFeed( $rows, $feed );
  78                         $cachedFeed = ob_get_contents();
  79                         ob_end_flush();
  80                         $this->saveToCache( $cachedFeed, $timekey, $key );
  81                 }
  82                 return true;
  83         }
  84
  85         /**
  86          * Save to feed result to $messageMemc
  87          *
  88          * @param $feed String: feed's content
  89          * @param $timekey String: memcached key of the last modification
  90          * @param $key String: memcached key of the content
  91          */
  92         public function saveToCache( $feed, $timekey, $key ) {
  93                 global $messageMemc;
  94                 $expire = 3600 * 24; # One day
  95                 $messageMemc->set( $key, $feed, $expire );
  96                 $messageMemc->set( $timekey, wfTimestamp( TS_MW ), $expire );
  97         }
  98
  99         /**
 100          * Try to load the feed result from $messageMemc
 101          *
 102          * @param $lastmod Integer: timestamp of the last item in the recentchanges table
 103          * @param $timekey String: memcached key of the last modification
 104          * @param $key String: memcached key of the content
 105          * @return feed's content on cache hit or false on cache miss
 106          */
 107         public function loadFromCache( $lastmod, $timekey, $key ) {
 108                 global $wgFeedCacheTimeout, $wgOut, $messageMemc;
 109
 110                 $feedLastmod = $messageMemc->get( $timekey );
 111
 112                 if( ( $wgFeedCacheTimeout > 0 ) && $feedLastmod ) {
 113                         /*
 114                         * If the cached feed was rendered very recently, we may
 115                         * go ahead and use it even if there have been edits made
 116                         * since it was rendered. This keeps a swarm of requests
 117                         * from being too bad on a super-frequently edited wiki.
 118                         */
 119
 120                         $feedAge = time() - wfTimestamp( TS_UNIX, $feedLastmod );
 121                         $feedLastmodUnix = wfTimestamp( TS_UNIX, $feedLastmod );
 122                         $lastmodUnix = wfTimestamp( TS_UNIX, $lastmod );
 123
 124                         if( $feedAge < $wgFeedCacheTimeout || $feedLastmodUnix > $lastmodUnix) {
 125                                 wfDebug( "RC: loading feed from cache ($key; $feedLastmod; $lastmod)...\n" );
 126                                 if ( $feedLastmodUnix < $lastmodUnix ) {
 127                                         $wgOut->setLastModified( $feedLastmod ); // bug 21916
 128                                 }
 129                                 return $messageMemc->get( $key );
 130                         } else {
 131                                 wfDebug( "RC: cached feed timestamp check failed ($feedLastmod; $lastmod)\n" );
 132                         }
 133                 }
 134                 return false;
 135         }
 136
 137         /**
 138          * Generate the feed items given a row from the database.
 139          * @param $rows DatabaseBase resource with recentchanges rows
 140          * @param $feed Feed object
 141          */
 142         public static function generateFeed( $rows, &$feed ) {
 143                 wfProfileIn( __METHOD__ );
 144
 145                 $feed->outHeader();
 146
 147                 # Merge adjacent edits by one user
 148                 $sorted = array();
 149                 $n = 0;
 150                 foreach( $rows as $obj ) {
 151                         if( $n > 0 &&
 152                                 $obj->rc_namespace >= 0 &&
 153                                 $obj->rc_cur_id == $sorted[$n-1]->rc_cur_id &&
 154                                 $obj->rc_user_text == $sorted[$n-1]->rc_user_text ) {
 155                                 $sorted[$n-1]->rc_last_oldid = $obj->rc_last_oldid;
 156                         } else {
 157                                 $sorted[$n] = $obj;
 158                                 $n++;
 159                         }
 160                 }
 161
 162                 foreach( $sorted as $obj ) {
 163                         $title = Title::makeTitle( $obj->rc_namespace, $obj->rc_title );
 164                         $talkpage = $title->getTalkPage();
 165                         // Skip items with deleted content (avoids partially complete/inconsistent output)
 166                         if( $obj->rc_deleted ) continue;
 167                         $item = new FeedItem(
 168                                 $title->getPrefixedText(),
 169                                 FeedUtils::formatDiff( $obj ),
 170                                 $obj->rc_this_oldid ? $title->getFullURL( 'diff=' . $obj->rc_this_oldid . '&oldid=prev' ) : $title->getFullURL(),
 171                                 $obj->rc_timestamp,
 172                                 ($obj->rc_deleted & Revision::DELETED_USER) ? wfMsgHtml('rev-deleted-user') : $obj->rc_user_text,
 173                                 $talkpage->getFullURL()
 174                         );
 175                         $feed->outItem( $item );
 176                 }
 177                 $feed->outFooter();
 178                 wfProfileOut( __METHOD__ );
 179         }
 180
 181 }