Hiding public constructors that take a gRPC connection. (bazelbuild#83)

Prepares for addition of a second connection to the CAS service in
DialParams (bazelbuild#78). Also adding better named overloads for constructors in
order to migrate users to these names.

go/client/client.go

@@ -213,20 +213,20 @@ func DialRaw(ctx context.Context, params DialParams) (*grpc.ClientConn, error) {
 
 // Dial dials a remote execution service and returns a client suitable for higher-level
 // functionality.
+// TODO(olaola): rename to separate creating a gRPC connection from creating a Client:
+//   Dial -> NewClient
+//   DialFromFlags -> NewClientFromFlags
+//   DialRaw -> Dial
+// TODO(olaola): remove this overload when everyone uses NewClient.
 func Dial(ctx context.Context, instanceName string, params DialParams, opts ...Opt) (*Client, error) {
-	conn, err := DialRaw(ctx, params)
-	if err != nil {
-		return nil, err
-	}
-	return NewClient(conn, instanceName, opts...)
-}
-
-// NewClient creates a client from an existing gRPC connection.
-func NewClient(conn *grpc.ClientConn, instanceName string, opts ...Opt) (*Client, error) {
 	if instanceName == "" {
 		return nil, fmt.Errorf("instance needs to be specified")
 	}
 	log.Infof("Connecting to remote execution instance %s", instanceName)
+	conn, err := DialRaw(ctx, params)
+	if err != nil {
+		return nil, err
+	}
 	client := &Client{
 		InstanceName:   instanceName,
 		actionCache:    regrpc.NewActionCacheClient(conn),
@@ -249,6 +249,12 @@ func NewClient(conn *grpc.ClientConn, instanceName string, opts ...Opt) (*Client
 	return client, nil
 }
 
+// NewClient connects to a remote execution service and returns a Client suitable
+// for higher-level functionality.
+func NewClient(ctx context.Context, instanceName string, params DialParams, opts ...Opt) (*Client, error) {
+	return Dial(ctx, instanceName, params, opts...)
+}
+
 // RPCTimeout is a Opt that sets the per-RPC deadline.
 // NOTE that the deadline is only applied to non-streaming calls.
 // The default timeout value is 1 minute.

go/flags/flags.go

@@ -37,6 +37,7 @@ var (
 
 // DialFromFlags dials a remote execution service and returns a client suitable for higher-level
 // functionality. It uses the flags from above to configure the connection to remote execution.
+// TODO(olaola): remove this overload when everyone uses NewClientFromFlags.
 func DialFromFlags(ctx context.Context, opts ...client.Opt) (*client.Client, error) {
 	return client.Dial(ctx, *Instance, client.DialParams{
 		Service:               *Service,
@@ -45,3 +46,10 @@ func DialFromFlags(ctx context.Context, opts ...client.Opt) (*client.Client, err
 		UseComputeEngine:      *UseGCECredentials,
 	}, opts...)
 }
+
+// NewClientFromFlags connects to a remote execution service and returns a client
+// suitable for higher-level functionality. It uses the flags from above to configure
+// the connection to remote execution.
+func NewClientFromFlags(ctx context.Context, opts ...client.Opt) (*client.Client, error) {
+	return DialFromFlags(ctx, opts...)
+}