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[lhc/web/wiklou.git] / includes / GlobalFunctions.php

diff --git a/includes/GlobalFunctions.php b/includes/GlobalFunctions.php
index 2c26fef..11388e8 100644 (file)
--- a/includes/GlobalFunctions.php
+++ b/includes/GlobalFunctions.php
@@ -3765,11 +3765,19 @@ function wfGetNull() {
 }
 
 /**
- * Modern version of wfWaitForSlaves(). Instead of looking at replication lag
- * and waiting for it to go down, this waits for the slaves to catch up to the
- * master position. Use this when updating very large numbers of rows, as
- * in maintenance scripts, to avoid causing too much lag.  Of course, this is
- * a no-op if there are no slaves.
+ * Waits for the slaves to catch up to the master position
+ *
+ * Use this when updating very large numbers of rows, as in maintenance scripts,
+ * to avoid causing too much lag. Of course, this is a no-op if there are no slaves.
+ *
+ * By default this waits on the main DB cluster of the current wiki.
+ * If $cluster is set to "*" it will wait on all DB clusters, including
+ * external ones. If the lag being waiting on is caused by the code that
+ * does this check, it makes since to use $ifWritesSince, particularly if
+ * cluster is "*", to avoid excess overhead.
+ *
+ * Never call this function after a big DB write that is still in a transaction.
+ * This only makes sense after the possible lag inducing changes were committed.
  *
  * @param float|null $ifWritesSince Only wait if writes were done since this UNIX timestamp
  * @param string|bool $wiki Wiki identifier accepted by wfGetLB
@@ -3787,31 +3795,47 @@ function wfWaitForSlaves(
                $timeout = ( PHP_SAPI === 'cli' ) ? 86400 : 10;
        }
 
-       if ( $cluster !== false ) {
-               $lb = wfGetLBFactory()->getExternalLB( $cluster );
+       // Figure out which clusters need to be checked
+       $lbs = array();
+       if ( $cluster === '*' ) {
+               wfGetLBFactory()->forEachLB( function( LoadBalancer $lb ) use ( &$lbs ) {
+                       $lbs[] = $lb;
+               } );
+       } elseif ( $cluster !== false ) {
+               $lbs[] = wfGetLBFactory()->getExternalLB( $cluster );
        } else {
-               $lb = wfGetLB( $wiki );
+               $lbs[] = wfGetLB( $wiki );
+       }
+
+       // Get all the master positions of applicable DBs right now.
+       // This can be faster since waiting on one cluster reduces the
+       // time needed to wait on the next clusters.
+       $masterPositions = array_fill( 0, count( $lbs ), false );
+       foreach ( $lbs as $i => $lb ) {
+               // bug 27975 - Don't try to wait for slaves if there are none
+               // Prevents permission error when getting master position
+               if ( $lb->getServerCount() > 1 ) {
+                       if ( $ifWritesSince && !$lb->hasMasterConnection() ) {
+                               continue; // assume no writes done
+                       }
+                       $dbw = $lb->getConnection( DB_MASTER, array(), $wiki );
+                       if ( $ifWritesSince && $dbw->lastDoneWrites() < $ifWritesSince ) {
+                               continue; // no writes since the last wait
+                       }
+                       $masterPositions[$i] = $dbw->getMasterPos();
+               }
        }
 
-       // bug 27975 - Don't try to wait for slaves if there are none
-       // Prevents permission error when getting master position
-       if ( $lb->getServerCount() > 1 ) {
-               if ( $ifWritesSince && !$lb->hasMasterConnection() ) {
-                       return true; // assume no writes done
-               }
-               $dbw = $lb->getConnection( DB_MASTER, array(), $wiki );
-               if ( $ifWritesSince && $dbw->lastDoneWrites() < $ifWritesSince ) {
-                       return true; // no writes since the last wait
-               }
-               $pos = $dbw->getMasterPos();
-               // The DBMS may not support getMasterPos() or the whole
-               // load balancer might be fake (e.g. $wgAllDBsAreLocalhost).
-               if ( $pos !== false ) {
-                       return $lb->waitForAll( $pos, $timeout );
+       $ok = true;
+       foreach ( $lbs as $i => $lb ) {
+               if ( $masterPositions[$i] ) {
+                       // The DBMS may not support getMasterPos() or the whole
+                       // load balancer might be fake (e.g. $wgAllDBsAreLocalhost).
+                       $ok = $lb->waitForAll( $masterPositions[$i], $timeout ) && $ok;
                }
        }
 
-       return true;
+       return $ok;
 }
 
 /**