Disallow mismatched beginMasterChanges/commitMasterChanges

Change-Id: I76a8424e94370dc3776fdac1e974bf61fa69f071

diff --git a/includes/db/loadbalancer/LBFactory.php b/includes/db/loadbalancer/LBFactory.php
index 6b5161b..e40001d 100644 (file)
--- a/includes/db/loadbalancer/LBFactory.php
+++ b/includes/db/loadbalancer/LBFactory.php
@@ -230,6 +230,7 @@ abstract class LBFactory implements DestructibleService {
         *   - commitMasterChanges()
         *   - rollbackMasterChanges()
         *   - commitAll()
+        *
         * This allows for custom transaction rounds from any outer transaction scope.
         *
         * @param string $fname
@@ -240,7 +241,7 @@ abstract class LBFactory implements DestructibleService {
                if ( $this->trxRoundId !== false ) {
                        throw new DBTransactionError(
                                null,
-                               "Transaction round '{$this->trxRoundId}' already started."
+                               "$fname: transaction round '{$this->trxRoundId}' already started."
                        );
                }
                $this->trxRoundId = $fname;
@@ -279,6 +280,12 @@ abstract class LBFactory implements DestructibleService {
         * @throws Exception
         */
        public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) {
+               if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
+                       throw new DBTransactionError(
+                               null,
+                               "$fname: transaction round '{$this->trxRoundId}' still running."
+                       );
+               }
                // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
                $this->forEachLBCallMethod( 'finalizeMasterChanges' );
                $this->trxRoundId = false;
@@ -509,7 +516,7 @@ abstract class LBFactory implements DestructibleService {
         * This will commit and wait unless $ticket indicates it is unsafe to do so
         *
         * @param string $fname Caller name (e.g. __METHOD__)
-        * @param mixed $ticket Result of getOuterTransactionScopeTicket()
+        * @param mixed $ticket Result of getEmptyTransactionTicket()
         * @param array $opts Options to waitForReplication()
         * @throws DBReplicationWaitError
         * @since 1.28
@@ -521,8 +528,21 @@ abstract class LBFactory implements DestructibleService {
                        return;
                }
 
-               $this->commitMasterChanges( $fname );
+               $fnameEffective = $fname;
+               // The transaction owner and any caller with the empty transaction ticket can commit
+               // so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
+               if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
+                       $this->trxLogger->info( "$fname: committing on behalf of {$this->trxRoundId}." );
+                       $fnameEffective = $this->trxRoundId;
+               }
+
+               $this->commitMasterChanges( $fnameEffective );
                $this->waitForReplication( $opts );
+               // If a nested caller committed on behalf of $fname, start another empty $fname
+               // transaction, leaving the caller with the same empty transaction state as before.
+               if ( $fnameEffective !== $fname ) {
+                       $this->beginMasterChanges( $fname );
+               }
        }
 
        /**