Repository: grpc/grpc-go
File: credentials/alts/internal/handshaker/service/service.go (Go)

Code before:
	mu sync.Mutex
	// hsConn represents a mapping from a hypervisor handshaker service address
	// to a corresponding connection to a hypervisor handshaker service
	// instance.
	hsConnMap = make(map[string]*grpc.ClientConn)
)

// Dial dials the handshake service in the hypervisor. If a connection has
// already been established, this function returns it. Otherwise, a new
// connection is created.
func Dial(hsAddress string) (*grpc.ClientConn, error) {
	mu.Lock()
	defer mu.Unlock()

	hsConn, ok := hsConnMap[hsAddress]
	if !ok {
		// Create a new connection to the handshaker service. Note that
		// this connection stays open until the application is closed.
		// Disable the service config to avoid unnecessary TXT record lookups that
		// cause timeouts with some versions of systemd-resolved.
		var err error
		opts := []grpc.DialOption{
			grpc.WithTransportCredentials(insecure.NewCredentials()),
			grpc.WithDisableServiceConfig(),
			grpc.WithKeepaliveParams(keepalive.ClientParameters{
				Timeout:             5 * time.Second,
				Time:                time.Hour,
				PermitWithoutStream: true,
			}),
		}
		hsConn, err = grpc.NewClient(hsAddress, opts...)
		if err != nil {
			return nil, err
		}
		hsConnMap[hsAddress] = hsConn
	}
	return hsConn, nil
}

// CloseForTesting closes all open connections to the handshaker service.
//
// For testing purposes only.
func CloseForTesting() error {
	for _, hsConn := range hsConnMap {
		if hsConn == nil {
			continue
		}
		if err := hsConn.Close(); err != nil {
			return err
		}
	}

Review comment (suggestion):
I can't see any other defaults (internally) setting the timeout lower than 10 seconds, so might set this to 10 seconds just to match other defaults.

I'm debating about `Time` to 1 hour. 10 minutes would also be conservative but small enough to be frequently exercised in tests...

cc @ejona86 FYI

Code after:
	// mu guards hsConnMap and hsDialer.
	mu sync.Mutex
	// hsConn represents a mapping from a hypervisor handshaker service address
	// to a corresponding connection to a hypervisor handshaker service
	// instance.
	hsConnMap = make(map[string]*grpc.ClientConn)
)

// Dial dials the handshake service in the hypervisor. If a connection has
// already been established, this function returns it. Otherwise, a new
// connection is created.
func Dial(hsAddress string) (*grpc.ClientConn, error) {
	mu.Lock()
	defer mu.Unlock()

	hsConn, ok := hsConnMap[hsAddress]
	if !ok {
		// Create a new connection to the handshaker service. Note that
		// this connection stays open until the application is closed.
		// Disable the service config to avoid unnecessary TXT record lookups that
		// cause timeouts with some versions of systemd-resolved.
		var err error
		opts := []grpc.DialOption{
			grpc.WithTransportCredentials(insecure.NewCredentials()),
			grpc.WithDisableServiceConfig(),
		}
		if envconfig.ALTSHandshakerKeepaliveParams {
			opts = append(opts, grpc.WithKeepaliveParams(keepalive.ClientParameters{
				Timeout: 10 * time.Second,
				Time:    10 * time.Minute,
			}))
		}
		hsConn, err = grpc.NewClient(hsAddress, opts...)
		if err != nil {
			return nil, err
		}
		hsConnMap[hsAddress] = hsConn
	}
	return hsConn, nil
}

// CloseForTesting closes all open connections to the handshaker service.
//
// For testing purposes only.
func CloseForTesting() error {
	for _, hsConn := range hsConnMap {
		if hsConn == nil {
			continue
		}
		if err := hsConn.Close(); err != nil {
			return err