feat: add uptime implementation

Signed-off-by: Manan Gupta <manan@planetscale.com>

go/test/endtoend/tabletmanager/main_test.go

@@ -165,6 +165,11 @@ func tmcUnlockTables(ctx context.Context, tabletGrpcPort int) error {
 	return tmClient.UnlockTables(ctx, vtablet)
 }
 
+func tmcUptime(ctx context.Context, tabletGrpcPort int) (uint64, error) {
+	vtablet := getTablet(tabletGrpcPort)
+	return tmClient.Uptime(ctx, vtablet)
+}
+
 func tmcStopReplication(ctx context.Context, tabletGrpcPort int) error {
 	vtablet := getTablet(tabletGrpcPort)
 	return tmClient.StopReplication(ctx, vtablet)

go/test/endtoend/tabletmanager/tablet_test.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"fmt"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -100,3 +101,18 @@ func TestResetReplicationParameters(t *testing.T) {
 	require.NoError(t, err)
 	require.Len(t, res.Rows, 0)
 }
+
+// TestUptime tests the Uptime RPC
+func TestUptime(t *testing.T) {
+	ctx := context.Background()
+	uptimeInitial, err := tmcUptime(ctx, replicaTablet.GrpcPort)
+	require.NoError(t, err)
+	require.Greater(t, uptimeInitial, uint64(0))
+	time.Sleep(1500 * time.Millisecond)
+	uptimeFinal, err := tmcUptime(ctx, replicaTablet.GrpcPort)
+	require.NoError(t, err)
+	require.Greater(t, uptimeFinal, uint64(0))
+	uptimeDiff := uptimeFinal - uptimeInitial
+	require.LessOrEqual(t, uptimeDiff, uint64(2))
+	require.GreaterOrEqual(t, uptimeDiff, uint64(1))
+}

go/vt/mysqlctl/fakemysqldaemon.go

@@ -292,6 +292,11 @@ func (fmd *FakeMysqlDaemon) GetServerUUID(ctx context.Context) (string, error) {
 	return "000000", nil
 }
 
+// Uptime is part of the MysqlDaemon interface.
+func (fmd *FakeMysqlDaemon) Uptime(ctx context.Context) (uint64, error) {
+	return 100, nil
+}
+
 // CurrentPrimaryPositionLocked is thread-safe.
 func (fmd *FakeMysqlDaemon) CurrentPrimaryPositionLocked(pos replication.Position) {
 	fmd.mu.Lock()

go/vt/mysqlctl/mysql_daemon.go

@@ -53,6 +53,9 @@ type MysqlDaemon interface {
 	// GetServerUUID returns the servers UUID
 	GetServerUUID(ctx context.Context) (string, error)
 
+	// Uptime gets the uptime for the server
+	Uptime(ctx context.Context) (uint64, error)
+
 	// replication related methods
 	StartReplication(ctx context.Context, hookExtraEnv map[string]string) error
 	RestartReplication(ctx context.Context, hookExtraEnv map[string]string) error

go/vt/mysqlctl/replication.go

@@ -228,6 +228,18 @@ func (mysqld *Mysqld) GetServerUUID(ctx context.Context) (string, error) {
 	return conn.Conn.GetServerUUID()
 }
 
+// Uptime returns the uptime for the server
+func (mysqld *Mysqld) Uptime(ctx context.Context) (uint64, error) {
+	qr, err := mysqld.FetchSuperQuery(ctx, "SHOW STATUS LIKE 'uptime'")
+	if err != nil {
+		return 0, err
+	}
+	if len(qr.Rows) != 1 {
+		return 0, nil
+	}
+	return qr.Rows[0][1].ToCastUint64()
+}
+
 // IsReadOnly return true if the instance is read only
 func (mysqld *Mysqld) IsReadOnly(ctx context.Context) (bool, error) {
 	qr, err := mysqld.FetchSuperQuery(ctx, "SHOW VARIABLES LIKE 'read_only'")