Refactor global migration context

go/base/context.go

@@ -212,13 +212,7 @@ type ContextConfig struct {
 	}
 }
 
-var context *MigrationContext
+func NewMigrationContext() *MigrationContext {
-
-func init() {
-	context = newMigrationContext()
-}
-
-func newMigrationContext() *MigrationContext {
 	return &MigrationContext{
 		defaultNumRetries:                   60,
 		ChunkSize:                           1000,
@@ -239,11 +233,6 @@ func newMigrationContext() *MigrationContext {
 	}
 }
 
-// GetMigrationContext
-func GetMigrationContext() *MigrationContext {
-	return context
-}
-
 func getSafeTableName(baseName string, suffix string) string {
 	name := fmt.Sprintf("_%s_%s", baseName, suffix)
 	if len(name) <= mysql.MaxTableNameLength {

go/base/context_test.go

@@ -19,27 +19,27 @@ func init() {
 
 func TestGetTableNames(t *testing.T) {
 	{
-		context = newMigrationContext()
+		context := NewMigrationContext()
 		context.OriginalTableName = "some_table"
 		test.S(t).ExpectEquals(context.GetOldTableName(), "_some_table_del")
 		test.S(t).ExpectEquals(context.GetGhostTableName(), "_some_table_gho")
 		test.S(t).ExpectEquals(context.GetChangelogTableName(), "_some_table_ghc")
 	}
 	{
-		context = newMigrationContext()
+		context := NewMigrationContext()
 		context.OriginalTableName = "a123456789012345678901234567890123456789012345678901234567890"
 		test.S(t).ExpectEquals(context.GetOldTableName(), "_a1234567890123456789012345678901234567890123456789012345678_del")
 		test.S(t).ExpectEquals(context.GetGhostTableName(), "_a1234567890123456789012345678901234567890123456789012345678_gho")
 		test.S(t).ExpectEquals(context.GetChangelogTableName(), "_a1234567890123456789012345678901234567890123456789012345678_ghc")
 	}
 	{
-		context = newMigrationContext()
+		context := NewMigrationContext()
 		context.OriginalTableName = "a123456789012345678901234567890123456789012345678901234567890123"
 		oldTableName := context.GetOldTableName()
 		test.S(t).ExpectEquals(oldTableName, "_a1234567890123456789012345678901234567890123456789012345678_del")
 	}
 	{
-		context = newMigrationContext()
+		context := NewMigrationContext()
 		context.OriginalTableName = "a123456789012345678901234567890123456789012345678901234567890123"
 		context.TimestampOldTable = true
 		longForm := "Jan 2, 2006 at 3:04pm (MST)"
@@ -48,7 +48,7 @@ func TestGetTableNames(t *testing.T) {
 		test.S(t).ExpectEquals(oldTableName, "_a1234567890123456789012345678901234567890123_20130203195400_del")
 	}
 	{
-		context = newMigrationContext()
+		context := NewMigrationContext()
 		context.OriginalTableName = "foo_bar_baz"
 		context.ForceTmpTableName = "tmp"
 		test.S(t).ExpectEquals(context.GetOldTableName(), "_tmp_del")

go/binlog/gomysql_reader.go

@@ -29,14 +29,14 @@ type GoMySQLReader struct {
 	MigrationContext         *base.MigrationContext
 }
 
-func NewGoMySQLReader(connectionConfig *mysql.ConnectionConfig) (binlogReader *GoMySQLReader, err error) {
+func NewGoMySQLReader(migrationContext *base.MigrationContext, connectionConfig *mysql.ConnectionConfig) (binlogReader *GoMySQLReader, err error) {
 	binlogReader = &GoMySQLReader{
 		connectionConfig:        connectionConfig,
 		currentCoordinates:      mysql.BinlogCoordinates{},
 		currentCoordinatesMutex: &sync.Mutex{},
 		binlogSyncer:            nil,
 		binlogStreamer:          nil,
-		MigrationContext:        base.GetMigrationContext(),
+		MigrationContext:        migrationContext,
 	}
 
 	serverId := uint32(binlogReader.MigrationContext.ReplicaServerId)

go/cmd/gh-ost/main.go

@@ -43,7 +43,7 @@ func acceptSignals(migrationContext *base.MigrationContext) {
 
 // main is the application's entry point. It will either spawn a CLI or HTTP interfaces.
 func main() {
-	migrationContext := base.GetMigrationContext()
+	migrationContext := base.NewMigrationContext()
 
 	flag.StringVar(&migrationContext.InspectorConnectionConfig.Key.Hostname, "host", "127.0.0.1", "MySQL hostname (preferably a replica, not the master)")
 	flag.StringVar(&migrationContext.AssumeMasterHostname, "assume-master-host", "", "(optional) explicitly tell gh-ost the identity of the master. Format: some.host.com[:port] This is useful in master-master setups where you wish to pick an explicit master, or in a tungsten-replicator where gh-ost is unabel to determine the master")
@@ -241,7 +241,7 @@ func main() {
 	log.Infof("starting gh-ost %+v", AppVersion)
 	acceptSignals(migrationContext)
 
-	migrator := logic.NewMigrator()
+	migrator := logic.NewMigrator(migrationContext)
 	err := migrator.Migrate()
 	if err != nil {
 		migrator.ExecOnFailureHook()

go/logic/applier.go

@@ -36,10 +36,10 @@ type Applier struct {
 	migrationContext *base.MigrationContext
 }
 
-func NewApplier() *Applier {
+func NewApplier(migrationContext *base.MigrationContext) *Applier {
 	return &Applier{
-		connectionConfig: base.GetMigrationContext().ApplierConnectionConfig,
+		connectionConfig: migrationContext.ApplierConnectionConfig,
-		migrationContext: base.GetMigrationContext(),
+		migrationContext: migrationContext,
 	}
 }
 

go/logic/hooks.go

@@ -37,9 +37,9 @@ type HooksExecutor struct {
 	migrationContext *base.MigrationContext
 }
 
-func NewHooksExecutor() *HooksExecutor {
+func NewHooksExecutor(migrationContext *base.MigrationContext) *HooksExecutor {
 	return &HooksExecutor{
-		migrationContext: base.GetMigrationContext(),
+		migrationContext: migrationContext,
 	}
 }
 

go/logic/inspect.go

@@ -31,10 +31,10 @@ type Inspector struct {
 	migrationContext *base.MigrationContext
 }
 
-func NewInspector() *Inspector {
+func NewInspector(migrationContext *base.MigrationContext) *Inspector {
 	return &Inspector{
-		connectionConfig: base.GetMigrationContext().InspectorConnectionConfig,
+		connectionConfig: migrationContext.InspectorConnectionConfig,
-		migrationContext: base.GetMigrationContext(),
+		migrationContext: migrationContext,
 	}
 }
 

go/logic/migrator.go

@@ -87,9 +87,9 @@ type Migrator struct {
 	handledChangelogStates map[string]bool
 }
 
-func NewMigrator() *Migrator {
+func NewMigrator(context *base.MigrationContext) *Migrator {
 	migrator := &Migrator{
-		migrationContext:           base.GetMigrationContext(),
+		migrationContext:           context,
 		parser:                     sql.NewParser(),
 		ghostTableMigrated:         make(chan bool),
 		firstThrottlingCollected:   make(chan bool, 3),
@@ -120,7 +120,7 @@ func (this *Migrator) acceptSignals() {
 
 // initiateHooksExecutor
 func (this *Migrator) initiateHooksExecutor() (err error) {
-	this.hooksExecutor = NewHooksExecutor()
+	this.hooksExecutor = NewHooksExecutor(this.migrationContext)
 	if err := this.hooksExecutor.initHooks(); err != nil {
 		return err
 	}
@@ -655,7 +655,7 @@ func (this *Migrator) initiateServer() (err error) {
 	var f printStatusFunc = func(rule PrintStatusRule, writer io.Writer) {
 		this.printStatus(rule, writer)
 	}
-	this.server = NewServer(this.hooksExecutor, f)
+	this.server = NewServer(this.migrationContext, this.hooksExecutor, f)
 	if err := this.server.BindSocketFile(); err != nil {
 		return err
 	}
@@ -675,7 +675,7 @@ func (this *Migrator) initiateServer() (err error) {
 // - heartbeat
 // When `--allow-on-master` is supplied, the inspector is actually the master.
 func (this *Migrator) initiateInspector() (err error) {
-	this.inspector = NewInspector()
+	this.inspector = NewInspector(this.migrationContext)
 	if err := this.inspector.InitDBConnections(); err != nil {
 		return err
 	}
@@ -934,7 +934,7 @@ func (this *Migrator) printStatus(rule PrintStatusRule, writers ...io.Writer) {
 
 // initiateStreaming begins treaming of binary log events and registers listeners for such events
 func (this *Migrator) initiateStreaming() error {
-	this.eventsStreamer = NewEventsStreamer()
+	this.eventsStreamer = NewEventsStreamer(this.migrationContext)
 	if err := this.eventsStreamer.InitDBConnections(); err != nil {
 		return err
 	}
@@ -982,7 +982,7 @@ func (this *Migrator) addDMLEventsListener() error {
 
 // initiateThrottler kicks in the throttling collection and the throttling checks.
 func (this *Migrator) initiateThrottler() error {
-	this.throttler = NewThrottler(this.applier, this.inspector)
+	this.throttler = NewThrottler(this.migrationContext, this.applier, this.inspector)
 
 	go this.throttler.initiateThrottlerCollection(this.firstThrottlingCollected)
 	log.Infof("Waiting for first throttle metrics to be collected")
@@ -996,7 +996,7 @@ func (this *Migrator) initiateThrottler() error {
 }
 
 func (this *Migrator) initiateApplier() error {
-	this.applier = NewApplier()
+	this.applier = NewApplier(this.migrationContext)
 	if err := this.applier.InitDBConnections(); err != nil {
 		return err
 	}

go/logic/server.go

@@ -30,9 +30,9 @@ type Server struct {
 	printStatus      printStatusFunc
 }
 
-func NewServer(hooksExecutor *HooksExecutor, printStatus printStatusFunc) *Server {
+func NewServer(migrationContext *base.MigrationContext, hooksExecutor *HooksExecutor, printStatus printStatusFunc) *Server {
 	return &Server{
-		migrationContext: base.GetMigrationContext(),
+		migrationContext: migrationContext,
 		hooksExecutor:    hooksExecutor,
 		printStatus:      printStatus,
 	}

go/logic/streamer.go

@@ -45,10 +45,10 @@ type EventsStreamer struct {
 	binlogReader             *binlog.GoMySQLReader
 }
 
-func NewEventsStreamer() *EventsStreamer {
+func NewEventsStreamer(migrationContext *base.MigrationContext) *EventsStreamer {
 	return &EventsStreamer{
-		connectionConfig: base.GetMigrationContext().InspectorConnectionConfig,
+		connectionConfig: migrationContext.InspectorConnectionConfig,
-		migrationContext: base.GetMigrationContext(),
+		migrationContext: migrationContext,
 		listeners:        [](*BinlogEventListener){},
 		listenersMutex:   &sync.Mutex{},
 		eventsChannel:    make(chan *binlog.BinlogEntry, EventsChannelBufferSize),
@@ -122,7 +122,7 @@ func (this *EventsStreamer) InitDBConnections() (err error) {
 
 // initBinlogReader creates and connects the reader: we hook up to a MySQL server as a replica
 func (this *EventsStreamer) initBinlogReader(binlogCoordinates *mysql.BinlogCoordinates) error {
-	goMySQLReader, err := binlog.NewGoMySQLReader(this.migrationContext.InspectorConnectionConfig)
+	goMySQLReader, err := binlog.NewGoMySQLReader(this.migrationContext, this.migrationContext.InspectorConnectionConfig)
 	if err != nil {
 		return err
 	}

go/logic/throttler.go

@@ -47,9 +47,9 @@ type Throttler struct {
 	inspector        *Inspector
 }
 
-func NewThrottler(applier *Applier, inspector *Inspector) *Throttler {
+func NewThrottler(migrationContext *base.MigrationContext, applier *Applier, inspector *Inspector) *Throttler {
 	return &Throttler{
-		migrationContext: base.GetMigrationContext(),
+		migrationContext: migrationContext,
 		applier:          applier,
 		inspector:        inspector,
 	}