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