AjaxResponse.php

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<?php
class AjaxResponse {
    private $mCacheDuration;

    private $mContentType;

    private $mDisabled;

    private $mLastModified;

    private $mResponseCode;

    private $mVary;

    private $mText;

    function __construct( $text = null ) {
        $this->mCacheDuration = null;
        $this->mVary = null;

        $this->mDisabled = false;
        $this->mText = '';
        $this->mResponseCode = '200 OK';
        $this->mLastModified = false;
        $this->mContentType = 'application/x-wiki';

        if ( $text ) {
            $this->addText( $text );
        }
    }

    function setCacheDuration( $duration ) {
        $this->mCacheDuration = $duration;
    }

    function setVary( $vary ) {
        $this->mVary = $vary;
    }

    function setResponseCode( $code ) {
        $this->mResponseCode = $code;
    }

    function setContentType( $type ) {
        $this->mContentType = $type;
    }

    function disable() {
        $this->mDisabled = true;
    }

    function addText( $text ) {
        if ( ! $this->mDisabled && $text ) {
            $this->mText .= $text;
        }
    }

    function printText() {
        if ( ! $this->mDisabled ) {
            print $this->mText;
        }
    }

    function sendHeaders() {
        global $wgUseSquid, $wgUseESI;

        if ( $this->mResponseCode ) {
            $n = preg_replace( '/^ *(\d+)/', '\1', $this->mResponseCode );
            header( "Status: " . $this->mResponseCode, true, (int)$n );
        }

        header ( "Content-Type: " . $this->mContentType );

        if ( $this->mLastModified ) {
            header ( "Last-Modified: " . $this->mLastModified );
        } else {
            header ( "Last-Modified: " . gmdate( "D, d M Y H:i:s" ) . " GMT" );
        }

        if ( $this->mCacheDuration ) {
            # If squid caches are configured, tell them to cache the response,
            # and tell the client to always check with the squid. Otherwise,
            # tell the client to use a cached copy, without a way to purge it.

            if ( $wgUseSquid ) {
                # Expect explicit purge of the proxy cache, but require end user agents
                # to revalidate against the proxy on each visit.
                # Surrogate-Control controls our Squid, Cache-Control downstream caches

                if ( $wgUseESI ) {
                    header( 'Surrogate-Control: max-age=' . $this->mCacheDuration . ', content="ESI/1.0"' );
                    header( 'Cache-Control: s-maxage=0, must-revalidate, max-age=0' );
                } else {
                    header( 'Cache-Control: s-maxage=' . $this->mCacheDuration . ', must-revalidate, max-age=0' );
                }

            } else {
                # Let the client do the caching. Cache is not purged.
                header ( "Expires: " . gmdate( "D, d M Y H:i:s", time() + $this->mCacheDuration ) . " GMT" );
                header ( "Cache-Control: s-maxage={$this->mCacheDuration}," .
                    "public,max-age={$this->mCacheDuration}" );
            }

        } else {
            # always expired, always modified
            header ( "Expires: Mon, 26 Jul 1997 05:00:00 GMT" );    // Date in the past
            header ( "Cache-Control: no-cache, must-revalidate" );  // HTTP/1.1
            header ( "Pragma: no-cache" );                          // HTTP/1.0
        }

        if ( $this->mVary ) {
            header ( "Vary: " . $this->mVary );
        }
    }

    function checkLastModified( $timestamp ) {
        global $wgCachePages, $wgCacheEpoch, $wgUser;
        $fname = 'AjaxResponse::checkLastModified';

        if ( !$timestamp || $timestamp == '19700101000000' ) {
            wfDebug( "$fname: CACHE DISABLED, NO TIMESTAMP\n", 'log' );
            return false;
        }

        if ( !$wgCachePages ) {
            wfDebug( "$fname: CACHE DISABLED\n", 'log' );
            return false;
        }

        $timestamp = wfTimestamp( TS_MW, $timestamp );
        $lastmod = wfTimestamp( TS_RFC2822, max( $timestamp, $wgUser->getTouched(), $wgCacheEpoch ) );

        if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
            # IE sends sizes after the date like this:
            # Wed, 20 Aug 2003 06:51:19 GMT; length=5202
            # this breaks strtotime().
            $modsince = preg_replace( '/;.*$/', '', $_SERVER["HTTP_IF_MODIFIED_SINCE"] );
            $modsinceTime = strtotime( $modsince );
            $ismodsince = wfTimestamp( TS_MW, $modsinceTime ? $modsinceTime : 1 );
            wfDebug( "$fname: -- client send If-Modified-Since: " . $modsince . "\n", 'log' );
            wfDebug( "$fname: --  we might send Last-Modified : $lastmod\n", 'log' );

            if ( ( $ismodsince >= $timestamp )
                && $wgUser->validateCache( $ismodsince ) &&
                $ismodsince >= $wgCacheEpoch
            ) {
                ini_set( 'zlib.output_compression', 0 );
                $this->setResponseCode( "304 Not Modified" );
                $this->disable();
                $this->mLastModified = $lastmod;

                wfDebug( "$fname: CACHED client: $ismodsince ; user: {$wgUser->getTouched()} ; " .
                    "page: $timestamp ; site $wgCacheEpoch\n", 'log' );

                return true;
            } else {
                wfDebug( "$fname: READY  client: $ismodsince ; user: {$wgUser->getTouched()} ; " .
                    "page: $timestamp ; site $wgCacheEpoch\n", 'log' );
                $this->mLastModified = $lastmod;
            }
        } else {
            wfDebug( "$fname: client did not send If-Modified-Since header\n", 'log' );
            $this->mLastModified = $lastmod;
        }
        return false;
    }

    function loadFromMemcached( $mckey, $touched ) {
        global $wgMemc;

        if ( !$touched ) {
            return false;
        }

        $mcvalue = $wgMemc->get( $mckey );
        if ( $mcvalue ) {
            # Check to see if the value has been invalidated
            if ( $touched <= $mcvalue['timestamp'] ) {
                wfDebug( "Got $mckey from cache\n" );
                $this->mText = $mcvalue['value'];

                return true;
            } else {
                wfDebug( "$mckey has expired\n" );
            }
        }

        return false;
    }

    function storeInMemcached( $mckey, $expiry = 86400 ) {
        global $wgMemc;

        $wgMemc->set( $mckey,
            array(
                'timestamp' => wfTimestampNow(),
                'value' => $this->mText
            ), $expiry
        );

        return true;
    }
}