DeferredUpdates::doUpdates( 'enqueue', DeferredUpdates::PRESEND );
wfDebug( __METHOD__ . ': pre-send deferred updates completed' );
- // Decide when clients block on ChronologyProtector DB position writes
- $urlDomainDistance = (
- $request->wasPosted() &&
- $output->getRedirect() &&
- $lbFactory->hasOrMadeRecentMasterChanges( INF )
- ) ? self::getUrlDomainDistance( $output->getRedirect() ) : false;
+ // Should the client return, their request should observe the new ChronologyProtector
+ // DB positions. This request might be on a foreign wiki domain, so synchronously update
+ // the DB positions in all datacenters to be safe. If this output is not a redirect,
+ // then OutputPage::output() will be relatively slow, meaning that running it in
+ // $postCommitWork should help mask the latency of those updates.
+ $flags = $lbFactory::SHUTDOWN_CHRONPROT_SYNC;
+ $strategy = 'cookie+sync';
$allowHeaders = !( $output->isDisabled() || headers_sent() );
- if ( $urlDomainDistance === 'local' || $urlDomainDistance === 'remote' ) {
- // OutputPage::output() will be fast; $postCommitWork will not be useful for
- // masking the latency of syncing DB positions accross all datacenters synchronously.
- // Instead, make use of the RTT time of the client follow redirects.
- $flags = $lbFactory::SHUTDOWN_CHRONPROT_ASYNC;
- $cpPosTime = microtime( true );
- // Client's next request should see 1+ positions with this DBMasterPos::asOf() time
- if ( $urlDomainDistance === 'local' && $allowHeaders ) {
- // Client will stay on this domain, so set an unobtrusive cookie
- $expires = time() + ChronologyProtector::POSITION_TTL;
- $options = [ 'prefix' => '' ];
- $request->response()->setCookie( 'cpPosTime', $cpPosTime, $expires, $options );
- } else {
- // Cookies may not work across wiki domains, so use a URL parameter
- $safeUrl = $lbFactory->appendPreShutdownTimeAsQuery(
- $output->getRedirect(),
- $cpPosTime
- );
- $output->redirect( $safeUrl );
+ if ( $output->getRedirect() && $lbFactory->hasOrMadeRecentMasterChanges( INF ) ) {
+ // OutputPage::output() will be fast, so $postCommitWork is useless for masking
+ // the latency of synchronously updating the DB positions in all datacenters.
+ // Try to make use of the time the client spends following redirects instead.
+ $domainDistance = self::getUrlDomainDistance( $output->getRedirect() );
+ if ( $domainDistance === 'local' && $allowHeaders ) {
+ $flags = $lbFactory::SHUTDOWN_CHRONPROT_ASYNC;
+ $strategy = 'cookie'; // use same-domain cookie and keep the URL uncluttered
+ } elseif ( $domainDistance === 'remote' ) {
+ $flags = $lbFactory::SHUTDOWN_CHRONPROT_ASYNC;
+ $strategy = 'cookie+url'; // cross-domain cookie might not work
}
- } else {
- // OutputPage::output() is fairly slow; run it in $postCommitWork to mask
- // the latency of syncing DB positions accross all datacenters synchronously
- $flags = $lbFactory::SHUTDOWN_CHRONPROT_SYNC;
- if ( $lbFactory->hasOrMadeRecentMasterChanges( INF ) && $allowHeaders ) {
- $cpPosTime = microtime( true );
- // Set a cookie in case the DB position store cannot sync accross datacenters.
- // This will at least cover the common case of the user staying on the domain.
+ }
+
+ // Record ChronologyProtector positions for DBs affected in this request at this point
+ $cpIndex = null;
+ $lbFactory->shutdown( $flags, $postCommitWork, $cpIndex );
+ wfDebug( __METHOD__ . ': LBFactory shutdown completed' );
+
+ if ( $cpIndex > 0 ) {
+ if ( $allowHeaders ) {
$expires = time() + ChronologyProtector::POSITION_TTL;
$options = [ 'prefix' => '' ];
- $request->response()->setCookie( 'cpPosTime', $cpPosTime, $expires, $options );
+ $request->response()->setCookie( 'cpPosIndex', $cpIndex, $expires, $options );
+ }
+
+ if ( $strategy === 'cookie+url' ) {
+ if ( $output->getRedirect() ) { // sanity
+ $safeUrl = $lbFactory->appendShutdownCPIndexAsQuery(
+ $output->getRedirect(),
+ $cpIndex
+ );
+ $output->redirect( $safeUrl );
+ } else {
+ $e = new LogicException( "No redirect; cannot append cpPosIndex parameter." );
+ MWExceptionHandler::logException( $e );
+ }
}
}
- // Record ChronologyProtector positions for DBs affected in this request at this point
- $lbFactory->shutdown( $flags, $postCommitWork );
- wfDebug( __METHOD__ . ': LBFactory shutdown completed' );
// Set a cookie to tell all CDN edge nodes to "stick" the user to the DC that handles this
// POST request (e.g. the "master" data center). Also have the user briefly bypass CDN so
if ( function_exists( 'register_postsend_function' ) ) {
// https://github.com/facebook/hhvm/issues/1230
register_postsend_function( $callback );
+ /** @noinspection PhpUnusedLocalVariableInspection */
$blocksHttpClient = false;
} else {
if ( function_exists( 'fastcgi_finish_request' ) ) {
fastcgi_finish_request();
+ /** @noinspection PhpUnusedLocalVariableInspection */
$blocksHttpClient = false;
} else {
// Either all DB and deferred updates should happen or none.