[Go]: Support device annotations when constructing graphs.

PiperOrigin-RevId: 204225504

tensorflow/go/graph.go

@@ -177,7 +177,14 @@ type OpSpec struct {
 	// being added.
 	ControlDependencies []*Operation
 
-	// Other possible fields: Device, ColocateWith.
+	// The device on which the operation should be executed.
+	// If omitted, an appropriate device will automatically be selected.
+	//
+	// For example, if set of "/device:GPU:0", then the operation will
+	// execute on GPU #0.
+	Device string
+
+	// Other possible fields: ColocateWith.
 }
 
 // AddOperation adds an operation to g.
@@ -225,6 +232,11 @@ func (g *Graph) AddOperation(args OpSpec) (*Operation, error) {
 			return nil, fmt.Errorf("%v (memory will be leaked)", err)
 		}
 	}
+	if len(args.Device) > 0 {
+		cdevice := C.CString(args.Device)
+		C.TF_SetDevice(cdesc, cdevice)
+		C.free(unsafe.Pointer(cdevice))
+	}
 	c := C.TF_FinishOperation(cdesc, status.c)
 	if err := status.Err(); err != nil {
 		return nil, err

tensorflow/go/op/scope.go

@@ -37,6 +37,7 @@ type Scope struct {
 	namemap             map[string]int
 	namespace           string
 	controlDependencies []*tf.Operation
+	device              string
 	err                 *scopeErr
 }
 
@@ -82,6 +83,7 @@ func (s *Scope) AddOperation(args tf.OpSpec) *tf.Operation {
 		args.Name = s.namespace + "/" + args.Name
 	}
 	args.ControlDependencies = append(args.ControlDependencies, s.controlDependencies...)
+	args.Device = s.device
 	op, err := s.graph.AddOperation(args)
 	if err != nil {
 		s.UpdateErr(args.Type, err)
@@ -98,10 +100,12 @@ func (s *Scope) SubScope(namespace string) *Scope {
 		namespace = s.namespace + "/" + namespace
 	}
 	return &Scope{
-		graph:     s.graph,
+		graph:               s.graph,
-		namemap:   make(map[string]int),
+		namemap:             make(map[string]int),
-		namespace: namespace,
+		namespace:           namespace,
-		err:       s.err,
+		controlDependencies: s.controlDependencies,
+		device:              s.device,
+		err:                 s.err,
 	}
 }
 
@@ -123,6 +127,25 @@ func (s *Scope) WithControlDependencies(ops ...*tf.Operation) *Scope {
 		namemap:             s.namemap,
 		namespace:           s.namespace,
 		controlDependencies: deps,
+		device:              s.device,
+		err:                 s.err,
+	}
+}
+
+// WithDevice returns a new Scope which will cause all operations added to the
+// graph to execute on devices that match the provided device specification.
+//
+// For example, WithDevice("/device:GPU:0") will cause operations added to
+// the graph to execute on GPU #0.
+//
+// An empty string removes any device restrictions.
+func (s *Scope) WithDevice(device string) *Scope {
+	return &Scope{
+		graph:               s.graph,
+		namemap:             s.namemap,
+		namespace:           s.namespace,
+		controlDependencies: s.controlDependencies,
+		device:              device,
 		err:                 s.err,
 	}
 }

tensorflow/go/op/scope_test.go

@@ -112,6 +112,21 @@ func TestControlDependencies(t *testing.T) {
 	}
 }
 
+func TestDevice(t *testing.T) {
+	s := NewScope()
+	matrix := Const(s, [][]float32{{3.0}})
+	s = s.WithDevice("/device:GPU:0")
+	square := MatMul(s.SubScope("square"), matrix, matrix)
+	s = s.WithDevice("")
+	cube := MatMul(s.SubScope("cube"), square, matrix)
+	if got, want := square.Op.Device(), "/device:GPU:0"; got != want {
+		t.Errorf("Got %q, want %q", got, want)
+	}
+	if got, want := cube.Op.Device(), ""; got != want {
+		t.Errorf("Got %q, want %q", got, want)
+	}
+}
+
 func TestScopeFinalize(t *testing.T) {
 	var (
 		root = NewScope()

tensorflow/go/operation.go

@@ -45,6 +45,12 @@ func (op *Operation) NumOutputs() int {
 	return int(C.TF_OperationNumOutputs(op.c))
 }
 
+// Device returns a specification of the device on which this operation
+// will be executed, or the empty string if there is no such specification.
+func (op *Operation) Device() string {
+	return C.GoString(C.TF_OperationDevice(op.c))
+}
+
 // OutputListSize returns the size of the list of Outputs that is produced by a
 // named output of op.
 //

tensorflow/go/operation_test.go

@@ -228,6 +228,29 @@ func TestOperationConsumers(t *testing.T) {
 	}
 }
 
+func TestOperationDevice(t *testing.T) {
+	graph := NewGraph()
+	v, err := NewTensor(float32(1.0))
+	if err != nil {
+		t.Fatal(err)
+	}
+	op, err := graph.AddOperation(OpSpec{
+		Type: "Const",
+		Name: "Const",
+		Attrs: map[string]interface{}{
+			"dtype": v.DataType(),
+			"value": v,
+		},
+		Device: "/device:GPU:0",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, want := op.Device(), "/device:GPU:0"; got != want {
+		t.Errorf("Got %q, want %q", got, want)
+	}
+}
+
 func forceGC() {
 	var mem runtime.MemStats
 	runtime.ReadMemStats(&mem)