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[lhc/web/wiklou.git] / includes / db / ChronologyProtector.php

diff --git a/includes/db/ChronologyProtector.php b/includes/db/ChronologyProtector.php
index cc35999..2539b87 100644 (file)
--- a/includes/db/ChronologyProtector.php
+++ b/includes/db/ChronologyProtector.php
@@ -147,31 +147,20 @@ class ChronologyProtector {
                        implode( ', ', array_keys( $this->shutdownPositions ) ) . "\n"
                );
 
-               $shutdownPositions = $this->shutdownPositions;
-               $ok = $this->store->merge(
-                       $this->key,
-                       function ( $store, $key, $curValue ) use ( $shutdownPositions ) {
-                               /** @var $curPositions DBMasterPos[] */
-                               if ( $curValue === false ) {
-                                       $curPositions = $shutdownPositions;
-                               } else {
-                                       $curPositions = $curValue['positions'];
-                                       // Use the newest positions for each DB master
-                                       foreach ( $shutdownPositions as $db => $pos ) {
-                                               if ( !isset( $curPositions[$db] )
-                                                       || $pos->asOfTime() > $curPositions[$db]->asOfTime()
-                                               ) {
-                                                       $curPositions[$db] = $pos;
-                                               }
-                                       }
-                               }
-
-                               return [ 'positions' => $curPositions ];
-                       },
-                       BagOStuff::TTL_MINUTE,
-                       10,
-                       BagOStuff::WRITE_SYNC // visible in all datacenters
-               );
+               // CP-protected writes should overwhemingly go to the master datacenter, so get DC-local
+               // lock to merge the values. Use a DC-local get() and a synchronous all-DC set(). This
+               // makes it possible for the BagOStuff class to write in parallel to all DCs with one RTT.
+               if ( $this->store->lock( $this->key, 3 ) ) {
+                       $ok = $this->store->set(
+                               $this->key,
+                               self::mergePositions( $this->store->get( $this->key ), $this->shutdownPositions ),
+                               BagOStuff::TTL_MINUTE,
+                               BagOStuff::WRITE_SYNC
+                       );
+                       $this->store->unlock( $this->key );
+               } else {
+                       $ok = false;
+               }
 
                if ( !$ok ) {
                        // Raced out too many times or stash is down
@@ -206,4 +195,28 @@ class ChronologyProtector {
                        wfDebugLog( 'replication', __METHOD__ . ": key is {$this->key} (unread)\n" );
                }
        }
+
+       /**
+        * @param array|bool $curValue
+        * @param DBMasterPos[] $shutdownPositions
+        * @return array
+        */
+       private static function mergePositions( $curValue, array $shutdownPositions ) {
+               /** @var $curPositions DBMasterPos[] */
+               if ( $curValue === false ) {
+                       $curPositions = $shutdownPositions;
+               } else {
+                       $curPositions = $curValue['positions'];
+                       // Use the newest positions for each DB master
+                       foreach ( $shutdownPositions as $db => $pos ) {
+                               if ( !isset( $curPositions[$db] )
+                                       || $pos->asOfTime() > $curPositions[$db]->asOfTime()
+                               ) {
+                                       $curPositions[$db] = $pos;
+                               }
+                       }
+               }
+
+               return [ 'positions' => $curPositions ];
+       }
 }