From 3c85298b77a07030bf783723be53883894206467 Mon Sep 17 00:00:00 2001
From: Shlomi Noach <shlomi-noach@github.com>
Date: Tue, 19 Apr 2016 04:25:32 -0700
Subject: [PATCH] - Better, fewer NOOP checks around the code - Keeping track
 of `TotalDMLEventsApplied`

---
 go/base/context.go   |  1 +
 go/logic/applier.go  | 18 +++---------------
 go/logic/migrator.go | 15 +++++++--------
 3 files changed, 11 insertions(+), 23 deletions(-)

diff --git a/go/base/context.go b/go/base/context.go
index e6c5c15..074193f 100644
--- a/go/base/context.go
+++ b/go/base/context.go
@@ -65,6 +65,7 @@ type MigrationContext struct {
 	RenameTablesEndTime       time.Time
 	CurrentLag                int64
 	TotalRowsCopied           int64
+	TotalDMLEventsApplied     int64
 	isThrottled               bool
 	throttleReason            string
 	throttleMutex             *sync.Mutex
diff --git a/go/logic/applier.go b/go/logic/applier.go
index 8d355b8..c7ff916 100644
--- a/go/logic/applier.go
+++ b/go/logic/applier.go
@@ -134,10 +134,6 @@ func (this *Applier) CreateChangelogTable() error {
 
 // dropTable drops a given table on the applied host
 func (this *Applier) dropTable(tableName string) error {
-	if this.migrationContext.Noop {
-		log.Debugf("Noop operation; not really dropping table %s", sql.EscapeName(tableName))
-		return nil
-	}
 	query := fmt.Sprintf(`drop /* gh-osc */ table if exists %s.%s`,
 		sql.EscapeName(this.migrationContext.DatabaseName),
 		sql.EscapeName(tableName),
@@ -399,11 +395,6 @@ func (this *Applier) ApplyIterationInsertQuery() (chunkSize int64, rowsAffected
 
 // LockTables
 func (this *Applier) LockTables() error {
-	if this.migrationContext.Noop {
-		log.Debugf("Noop operation; not really locking tables")
-		return nil
-	}
-
 	// query := fmt.Sprintf(`lock /* gh-osc */ tables %s.%s write, %s.%s write, %s.%s write`,
 	// 	sql.EscapeName(this.migrationContext.DatabaseName),
 	// 	sql.EscapeName(this.migrationContext.OriginalTableName),
@@ -438,11 +429,6 @@ func (this *Applier) UnlockTables() error {
 
 // LockTables
 func (this *Applier) SwapTables() error {
-	if this.migrationContext.Noop {
-		log.Debugf("Noop operation; not really swapping tables")
-		return nil
-	}
-
 	// query := fmt.Sprintf(`rename /* gh-osc */ table %s.%s to %s.%s, %s.%s to %s.%s`,
 	// 	sql.EscapeName(this.migrationContext.DatabaseName),
 	// 	sql.EscapeName(this.migrationContext.OriginalTableName),
@@ -529,7 +515,9 @@ func (this *Applier) ApplyDMLEventQuery(dmlEvent *binlog.BinlogDMLEvent) error {
 	if err != nil {
 		return err
 	}
-	log.Errorf(query)
 	_, err = sqlutils.Exec(this.db, query, args...)
+	if err == nil {
+		atomic.AddInt64(&this.migrationContext.TotalDMLEventsApplied, 1)
+	}
 	return err
 }
diff --git a/go/logic/migrator.go b/go/logic/migrator.go
index 1b5b406..25b910b 100644
--- a/go/logic/migrator.go
+++ b/go/logic/migrator.go
@@ -294,6 +294,10 @@ func (this *Migrator) Migrate() (err error) {
 }
 
 func (this *Migrator) stopWritesAndCompleteMigration() (err error) {
+	if this.migrationContext.Noop {
+		log.Debugf("Noop operation; not really swapping tables")
+		return nil
+	}
 	this.throttle(func() {
 		log.Debugf("throttling before LOCK TABLES")
 	})
@@ -319,11 +323,9 @@ func (this *Migrator) stopWritesAndCompleteMigration() (err error) {
 		if err := this.retryOperation(this.applier.SwapTables); err != nil {
 			return err
 		}
-		// Unlock
 		if err := this.retryOperation(this.applier.UnlockTables); err != nil {
 			return err
 		}
-		// Drop old table
 		if this.migrationContext.OkToDropTable {
 			dropTableFunc := func() error {
 				return this.applier.dropTable(this.migrationContext.GetOldTableName())
@@ -408,8 +410,9 @@ func (this *Migrator) printStatus() {
 	if isThrottled, throttleReason := this.migrationContext.IsThrottled(); isThrottled {
 		eta = fmt.Sprintf("throttled, %s", throttleReason)
 	}
-	status := fmt.Sprintf("Copy: %d/%d %.1f%%; Backlog: %d/%d; Elapsed: %+v(copy), %+v(total); ETA: %s",
+	status := fmt.Sprintf("Copy: %d/%d %.1f%%; Applied: %d; Backlog: %d/%d; Elapsed: %+v(copy), %+v(total); ETA: %s",
 		totalRowsCopied, rowsEstimate, progressPct,
+		atomic.LoadInt64(&this.migrationContext.TotalDMLEventsApplied),
 		len(this.applyEventsQueue), cap(this.applyEventsQueue),
 		base.PrettifyDurationOutput(this.migrationContext.ElapsedRowCopyTime()), base.PrettifyDurationOutput(elapsedTime),
 		eta,
@@ -448,10 +451,6 @@ func (this *Migrator) initiateStreaming() error {
 	if err := this.eventsStreamer.InitDBConnections(); err != nil {
 		return err
 	}
-	if this.migrationContext.Noop {
-		log.Debugf("Noop operation; not really listening on binlog events")
-		return nil
-	}
 	this.eventsStreamer.AddListener(
 		false,
 		this.migrationContext.DatabaseName,
@@ -540,7 +539,7 @@ func (this *Migrator) iterateChunks() error {
 
 func (this *Migrator) executeWriteFuncs() error {
 	if this.migrationContext.Noop {
-		log.Debugf("Noop operation; not really doing writes")
+		log.Debugf("Noop operation; not really executing write funcs")
 		return nil
 	}
 	for {