SiteStatsUpdate.php

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<?php
class SiteStatsUpdate implements DeferrableUpdate {
    protected $views = 0;

    protected $edits = 0;

    protected $pages = 0;

    protected $articles = 0;

    protected $users = 0;

    protected $images = 0;

    // @todo deprecate this constructor
    function __construct( $views, $edits, $good, $pages = 0, $users = 0 ) {
        $this->views = $views;
        $this->edits = $edits;
        $this->articles = $good;
        $this->pages = $pages;
        $this->users = $users;
    }

    public static function factory( array $deltas ) {
        $update = new self( 0, 0, 0 );

        $fields = array( 'views', 'edits', 'pages', 'articles', 'users', 'images' );
        foreach ( $fields as $field ) {
            if ( isset( $deltas[$field] ) && $deltas[$field] ) {
                $update->$field = $deltas[$field];
            }
        }

        return $update;
    }

    public function doUpdate() {
        global $wgSiteStatsAsyncFactor;

        $rate = $wgSiteStatsAsyncFactor; // convenience
        // If set to do so, only do actual DB updates 1 every $rate times.
        // The other times, just update "pending delta" values in memcached.
        if ( $rate && ( $rate < 0 || mt_rand( 0, $rate - 1 ) != 0 ) ) {
            $this->doUpdatePendingDeltas();
        } else {
            // Need a separate transaction because this a global lock
            wfGetDB( DB_MASTER )->onTransactionIdle( array( $this, 'tryDBUpdateInternal' ) );
        }
    }

    public function tryDBUpdateInternal() {
        global $wgSiteStatsAsyncFactor;

        $dbw = wfGetDB( DB_MASTER );
        $lockKey = wfMemcKey( 'site_stats' ); // prepend wiki ID
        $pd = array();
        if ( $wgSiteStatsAsyncFactor ) {
            // Lock the table so we don't have double DB/memcached updates
            if ( !$dbw->lockIsFree( $lockKey, __METHOD__ )
                || !$dbw->lock( $lockKey, __METHOD__, 1 ) // 1 sec timeout
            ) {
                $this->doUpdatePendingDeltas();

                return;
            }
            $pd = $this->getPendingDeltas();
            // Piggy-back the async deltas onto those of this stats update....
            $this->views += ( $pd['ss_total_views']['+'] - $pd['ss_total_views']['-'] );
            $this->edits += ( $pd['ss_total_edits']['+'] - $pd['ss_total_edits']['-'] );
            $this->articles += ( $pd['ss_good_articles']['+'] - $pd['ss_good_articles']['-'] );
            $this->pages += ( $pd['ss_total_pages']['+'] - $pd['ss_total_pages']['-'] );
            $this->users += ( $pd['ss_users']['+'] - $pd['ss_users']['-'] );
            $this->images += ( $pd['ss_images']['+'] - $pd['ss_images']['-'] );
        }

        // Build up an SQL query of deltas and apply them...
        $updates = '';
        $this->appendUpdate( $updates, 'ss_total_views', $this->views );
        $this->appendUpdate( $updates, 'ss_total_edits', $this->edits );
        $this->appendUpdate( $updates, 'ss_good_articles', $this->articles );
        $this->appendUpdate( $updates, 'ss_total_pages', $this->pages );
        $this->appendUpdate( $updates, 'ss_users', $this->users );
        $this->appendUpdate( $updates, 'ss_images', $this->images );
        if ( $updates != '' ) {
            $dbw->update( 'site_stats', array( $updates ), array(), __METHOD__ );
        }

        if ( $wgSiteStatsAsyncFactor ) {
            // Decrement the async deltas now that we applied them
            $this->removePendingDeltas( $pd );
            // Commit the updates and unlock the table
            $dbw->unlock( $lockKey, __METHOD__ );
        }
    }

    public static function cacheUpdate( $dbw ) {
        global $wgActiveUserDays;
        $dbr = wfGetDB( DB_SLAVE, array( 'SpecialStatistics', 'vslow' ) );
        # Get non-bot users than did some recent action other than making accounts.
        # If account creation is included, the number gets inflated ~20+ fold on enwiki.
        $activeUsers = $dbr->selectField(
            'recentchanges',
            'COUNT( DISTINCT rc_user_text )',
            array(
                'rc_user != 0',
                'rc_bot' => 0,
                'rc_log_type != ' . $dbr->addQuotes( 'newusers' ) . ' OR rc_log_type IS NULL',
                'rc_timestamp >= ' . $dbr->addQuotes( $dbr->timestamp( wfTimestamp( TS_UNIX )
                    - $wgActiveUserDays * 24 * 3600 ) ),
            ),
            __METHOD__
        );
        $dbw->update(
            'site_stats',
            array( 'ss_active_users' => intval( $activeUsers ) ),
            array( 'ss_row_id' => 1 ),
            __METHOD__
        );

        return $activeUsers;
    }

    protected function doUpdatePendingDeltas() {
        $this->adjustPending( 'ss_total_views', $this->views );
        $this->adjustPending( 'ss_total_edits', $this->edits );
        $this->adjustPending( 'ss_good_articles', $this->articles );
        $this->adjustPending( 'ss_total_pages', $this->pages );
        $this->adjustPending( 'ss_users', $this->users );
        $this->adjustPending( 'ss_images', $this->images );
    }

    protected function appendUpdate( &$sql, $field, $delta ) {
        if ( $delta ) {
            if ( $sql ) {
                $sql .= ',';
            }
            if ( $delta < 0 ) {
                $sql .= "$field=$field-" . abs( $delta );
            } else {
                $sql .= "$field=$field+" . abs( $delta );
            }
        }
    }

    private function getTypeCacheKey( $type, $sign ) {
        return wfMemcKey( 'sitestatsupdate', 'pendingdelta', $type, $sign );
    }

    protected function adjustPending( $type, $delta ) {
        global $wgMemc;

        if ( $delta < 0 ) { // decrement
            $key = $this->getTypeCacheKey( $type, '-' );
        } else { // increment
            $key = $this->getTypeCacheKey( $type, '+' );
        }

        $magnitude = abs( $delta );
        if ( !$wgMemc->incr( $key, $magnitude ) ) { // not there?
            if ( !$wgMemc->add( $key, $magnitude ) ) { // race?
                $wgMemc->incr( $key, $magnitude );
            }
        }
    }

    protected function getPendingDeltas() {
        global $wgMemc;

        $pending = array();
        foreach ( array( 'ss_total_views', 'ss_total_edits',
            'ss_good_articles', 'ss_total_pages', 'ss_users', 'ss_images' ) as $type
        ) {
            // Get pending increments and pending decrements
            $pending[$type]['+'] = (int)$wgMemc->get( $this->getTypeCacheKey( $type, '+' ) );
            $pending[$type]['-'] = (int)$wgMemc->get( $this->getTypeCacheKey( $type, '-' ) );
        }

        return $pending;
    }

    protected function removePendingDeltas( array $pd ) {
        global $wgMemc;

        foreach ( $pd as $type => $deltas ) {
            foreach ( $deltas as $sign => $magnitude ) {
                // Lower the pending counter now that we applied these changes
                $wgMemc->decr( $this->getTypeCacheKey( $type, $sign ), $magnitude );
            }
        }
    }
}