hooks: reporting GH_OST_ETA_SECONDS. ETA as part of migration context

go/base/context.go

@@ -52,6 +52,7 @@ const (
 const (
 	HTTPStatusOK       = 200
 	MaxEventsBatchSize = 1000
+	ETAUnknown         = math.MinInt64
 )
 
 var (
@@ -182,6 +183,7 @@ type MigrationContext struct {
 	lastHeartbeatOnChangelogMutex          *sync.Mutex
 	CurrentLag                             int64
 	currentProgress                        uint64
+	etaNanoseonds                          int64
 	ThrottleHTTPStatusCode                 int64
 	controlReplicasLagResult               mysql.ReplicationLagResult
 	TotalRowsCopied                        int64
@@ -267,6 +269,7 @@ func NewMigrationContext() *MigrationContext {
 		MaxLagMillisecondsThrottleThreshold: 1500,
 		CutOverLockTimeoutSeconds:           3,
 		DMLBatchSize:                        10,
+		etaNanoseonds:                       ETAUnknown,
 		maxLoad:                             NewLoadMap(),
 		criticalLoad:                        NewLoadMap(),
 		throttleMutex:                       &sync.Mutex{},
@@ -474,6 +477,22 @@ func (this *MigrationContext) SetProgressPct(progressPct float64) {
 	atomic.StoreUint64(&this.currentProgress, math.Float64bits(progressPct))
 }
 
+func (this *MigrationContext) GetETADuration() time.Duration {
+	return time.Duration(atomic.LoadInt64(&this.etaNanoseonds))
+}
+
+func (this *MigrationContext) SetETADuration(etaDuration time.Duration) {
+	atomic.StoreInt64(&this.etaNanoseonds, etaDuration.Nanoseconds())
+}
+
+func (this *MigrationContext) GetETASeconds() int64 {
+	nano := atomic.LoadInt64(&this.etaNanoseonds)
+	if nano < 0 {
+		return ETAUnknown
+	}
+	return nano / int64(time.Second)
+}
+
 // math.Float64bits([f=0..100])
 
 // GetTotalRowsCopied returns the accurate number of rows being copied (affected)

go/logic/hooks.go

@@ -66,6 +66,7 @@ func (this *HooksExecutor) applyEnvironmentVariables(extraVariables ...string) [
 	env = append(env, fmt.Sprintf("GH_OST_INSPECTED_LAG=%f", this.migrationContext.GetCurrentLagDuration().Seconds()))
 	env = append(env, fmt.Sprintf("GH_OST_HEARTBEAT_LAG=%f", this.migrationContext.TimeSinceLastHeartbeatOnChangelog().Seconds()))
 	env = append(env, fmt.Sprintf("GH_OST_PROGRESS=%f", this.migrationContext.GetProgressPct()))
+	env = append(env, fmt.Sprintf("GH_OST_ETA_SECONDS=%d", this.migrationContext.GetETASeconds()))
 	env = append(env, fmt.Sprintf("GH_OST_HOOKS_HINT=%s", this.migrationContext.HooksHintMessage))
 	env = append(env, fmt.Sprintf("GH_OST_HOOKS_HINT_OWNER=%s", this.migrationContext.HooksHintOwner))
 	env = append(env, fmt.Sprintf("GH_OST_HOOKS_HINT_TOKEN=%s", this.migrationContext.HooksHintToken))

go/logic/migrator.go

@@ -939,20 +939,29 @@ func (this *Migrator) printStatus(rule PrintStatusRule, writers ...io.Writer) {
 	}
 
 	var etaSeconds float64 = math.MaxFloat64
-	eta := "N/A"
+	var etaDuration = time.Duration(base.ETAUnknown)
 	if progressPct >= 100.0 {
-		eta = "due"
+		etaDuration = 0
 	} else if progressPct >= 0.1 {
 		elapsedRowCopySeconds := this.migrationContext.ElapsedRowCopyTime().Seconds()
 		totalExpectedSeconds := elapsedRowCopySeconds * float64(rowsEstimate) / float64(totalRowsCopied)
 		etaSeconds = totalExpectedSeconds - elapsedRowCopySeconds
 		if etaSeconds >= 0 {
-			etaDuration := time.Duration(etaSeconds) * time.Second
-			eta = base.PrettifyDurationOutput(etaDuration)
+			etaDuration = time.Duration(etaSeconds) * time.Second
 		} else {
-			eta = "due"
+			etaDuration = 0
 		}
 	}
+	this.migrationContext.SetETADuration(etaDuration)
+	var eta string
+	switch etaDuration {
+	case 0:
+		eta = "due"
+	case time.Duration(base.ETAUnknown):
+		eta = "N/A"
+	default:
+		eta = base.PrettifyDurationOutput(etaDuration)
+	}
 
 	state := "migrating"
 	if atomic.LoadInt64(&this.migrationContext.CountingRowsFlag) > 0 && !this.migrationContext.ConcurrentCountTableRows {

go/logic/throttler.go

@@ -188,9 +188,12 @@ func (this *Throttler) collectControlReplicasLag() {
 		dbUri := connectionConfig.GetDBUri("information_schema")
 
 		var heartbeatValue string
-		if db, _, err := mysql.GetDB(this.migrationContext.Uuid, dbUri); err != nil {
+		db, _, err := mysql.GetDB(this.migrationContext.Uuid, dbUri)
+		if err != nil {
 			return lag, err
-		} else if err = db.QueryRow(replicationLagQuery).Scan(&heartbeatValue); err != nil {
+		}
+
+		if err := db.QueryRow(replicationLagQuery).Scan(&heartbeatValue); err != nil {
 			return lag, err
 		}
 

go/mysql/utils.go

@@ -18,8 +18,11 @@ import (
 	"github.com/outbrain/golib/sqlutils"
 )
 
-const MaxTableNameLength = 64
-const MaxReplicationPasswordLength = 32
+const (
+	MaxTableNameLength           = 64
+	MaxReplicationPasswordLength = 32
+	MaxDBPoolConnections         = 3
+)
 
 type ReplicationLagResult struct {
 	Key InstanceKey
@@ -39,23 +42,22 @@ func (this *ReplicationLagResult) HasLag() bool {
 var knownDBs map[string]*gosql.DB = make(map[string]*gosql.DB)
 var knownDBsMutex = &sync.Mutex{}
 
-func GetDB(migrationUuid string, mysql_uri string) (*gosql.DB, bool, error) {
+func GetDB(migrationUuid string, mysql_uri string) (db *gosql.DB, exists bool, err error) {
 	cacheKey := migrationUuid + ":" + mysql_uri
 
 	knownDBsMutex.Lock()
-	defer func() {
-		knownDBsMutex.Unlock()
-	}()
-
-	var exists bool
-	if _, exists = knownDBs[cacheKey]; !exists {
-		if db, err := gosql.Open("mysql", mysql_uri); err == nil {
-			knownDBs[cacheKey] = db
-		} else {
-			return db, exists, err
+	defer knownDBsMutex.Unlock()
+
+	if db, exists = knownDBs[cacheKey]; !exists {
+		db, err = gosql.Open("mysql", mysql_uri)
+		if err != nil {
+			return nil, false, err
 		}
+		db.SetMaxOpenConns(MaxDBPoolConnections)
+		db.SetMaxIdleConns(MaxDBPoolConnections)
+		knownDBs[cacheKey] = db
 	}
-	return knownDBs[cacheKey], exists, nil
+	return db, exists, nil
 }
 
 // GetReplicationLagFromSlaveStatus returns replication lag for a given db; via SHOW SLAVE STATUS