Merge branch 'master' into old-table-name-timestamp

Author: Shlomi Noach

go/logic/inspect.go

@@ -348,7 +348,7 @@ func (this *Inspector) validateLogSlaveUpdates() error {
 	}
 
 	if this.migrationContext.IsTungsten {
-		log.Warning("log_slave_updates not found on %s:%d, but --tungsten provided, so I'm proceeding", this.connectionConfig.Key.Hostname, this.connectionConfig.Key.Port)
+		log.Warningf("log_slave_updates not found on %s:%d, but --tungsten provided, so I'm proceeding", this.connectionConfig.Key.Hostname, this.connectionConfig.Key.Port)
 		return nil
 	}
 
@@ -357,7 +357,7 @@ func (this *Inspector) validateLogSlaveUpdates() error {
 	}
 
 	if this.migrationContext.InspectorIsAlsoApplier() {
-		log.Warning("log_slave_updates not found on %s:%d, but executing directly on master, so I'm proceeeding", this.connectionConfig.Key.Hostname, this.connectionConfig.Key.Port)
+		log.Warningf("log_slave_updates not found on %s:%d, but executing directly on master, so I'm proceeeding", this.connectionConfig.Key.Hostname, this.connectionConfig.Key.Port)
 		return nil
 	}
 

go/logic/migrator.go

@@ -1000,11 +1000,13 @@ func (this *Migrator) iterateChunks() error {
 	for {
 		if atomic.LoadInt64(&this.rowCopyCompleteFlag) == 1 {
 			// Done
+			// There's another such check down the line
 			return nil
 		}
 		copyRowsFunc := func() error {
 			if atomic.LoadInt64(&this.rowCopyCompleteFlag) == 1 {
-				// Done
+				// Done.
+				// There's another such check down the line
 				return nil
 			}
 			hasFurtherRange, err := this.applier.CalculateNextIterationRangeEndValues()
@@ -1016,6 +1018,17 @@ func (this *Migrator) iterateChunks() error {
 			}
 			// Copy task:
 			applyCopyRowsFunc := func() error {
+				if atomic.LoadInt64(&this.rowCopyCompleteFlag) == 1 {
+					// No need for more writes.
+					// This is the de-facto place where we avoid writing in the event of completed cut-over.
+					// There could _still_ be a race condition, but that's as close as we can get.
+					// What about the race condition? Well, there's actually no data integrity issue.
+					// when rowCopyCompleteFlag==1 that means **guaranteed** all necessary rows have been copied.
+					// But some are still then collected at the binary log, and these are the ones we're trying to
+					// not apply here. If the race condition wins over us, then we just attempt to apply onto the
+					// _ghost_ table, which no longer exists. So, bothering error messages and all, but no damage.
+					return nil
+				}
 				_, rowsAffected, _, err := this.applier.ApplyIterationInsertQuery()
 				if err != nil {
 					return terminateRowIteration(err)