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 explicite 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" );
                        return false;
                }

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

                if ( $wgUser->getOption( 'nocache' ) ) {
                        wfDebug( "$fname: USER DISABLED CACHE\n", false );
                        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: " . $modsince . "\n", false );
                        wfDebug( "$fname: --  we might send Last-Modified : $lastmod\n", false );

                        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", false );

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