[RSDK-10924] add IsHoldingSomething to gripper API (#5052)

Author: gvaradarajan

components/gripper/client.go

@@ -74,6 +74,24 @@ func (c *client) Grab(ctx context.Context, extra map[string]interface{}) (bool,
 	return resp.Success, nil
 }
 
+func (c *client) IsHoldingSomething(ctx context.Context, extra map[string]interface{}) (HoldingStatus, error) {
+	ext, err := protoutils.StructToStructPb(extra)
+	if err != nil {
+		return HoldingStatus{}, err
+	}
+	resp, err := c.client.IsHoldingSomething(ctx, &pb.IsHoldingSomethingRequest{
+		Name:  c.name,
+		Extra: ext,
+	})
+	if err != nil {
+		return HoldingStatus{}, err
+	}
+	return HoldingStatus{
+		IsHoldingSomething: resp.IsHoldingSomething,
+		Meta:               resp.Meta.AsMap(),
+	}, nil
+}
+
 func (c *client) Stop(ctx context.Context, extra map[string]interface{}) error {
 	ext, err := protoutils.StructToStructPb(extra)
 	if err != nil {

components/gripper/fake/gripper.go

@@ -109,6 +109,12 @@ func (g *Gripper) Stop(ctx context.Context, extra map[string]interface{}) error
 	return nil
 }
 
+// IsHoldingSomething always returns a status in which the gripper is not holding something and
+// no additional information is supplied.
+func (g *Gripper) IsHoldingSomething(ctx context.Context, extra map[string]interface{}) (gripper.HoldingStatus, error) {
+	return gripper.HoldingStatus{}, nil
+}
+
 // IsMoving is always false for a fake gripper.
 func (g *Gripper) IsMoving(ctx context.Context) (bool, error) {
 	return false, nil

components/gripper/gripper.go

@@ -36,6 +36,13 @@ func Named(name string) resource.Name {
 	return resource.NewName(API, name)
 }
 
+// HoldingStatus represents whether the gripper is currently holding onto
+// an object as well as any additional contextual information (stored in `Meta`).
+type HoldingStatus struct {
+	IsHoldingSomething bool
+	Meta               map[string]interface{}
+}
+
 // A Gripper represents a physical robotic gripper.
 // For more information, see the [gripper component docs].
 //
@@ -74,6 +81,9 @@ type Gripper interface {
 	// returns true if we grabbed something.
 	// This will block until done or a new operation cancels this one.
 	Grab(ctx context.Context, extra map[string]interface{}) (bool, error)
+
+	// IsHoldingSomething returns whether the gripper is currently holding onto an object.
+	IsHoldingSomething(ctx context.Context, extra map[string]interface{}) (HoldingStatus, error)
 }
 
 // FromRobot is a helper for getting the named Gripper from the given Robot.

components/gripper/server.go

@@ -7,9 +7,10 @@ import (
 
 	commonpb "go.viam.com/api/common/v1"
 	pb "go.viam.com/api/component/gripper/v1"
+	"go.viam.com/utils/protoutils"
 
 	"go.viam.com/rdk/operation"
-	"go.viam.com/rdk/protoutils"
+	rprotoutils "go.viam.com/rdk/protoutils"
 	"go.viam.com/rdk/referenceframe"
 	"go.viam.com/rdk/resource"
 	"go.viam.com/rdk/spatialmath"
@@ -77,6 +78,23 @@ func (s *serviceServer) IsMoving(ctx context.Context, req *pb.IsMovingRequest) (
 	return &pb.IsMovingResponse{IsMoving: moving}, nil
 }
 
+// IsHoldingSomething queries if the gripper has managed to grab something.
+func (s *serviceServer) IsHoldingSomething(ctx context.Context, req *pb.IsHoldingSomethingRequest) (*pb.IsHoldingSomethingResponse, error) {
+	gripper, err := s.coll.Resource(req.GetName())
+	if err != nil {
+		return nil, err
+	}
+	holdingStatus, err := gripper.IsHoldingSomething(ctx, req.Extra.AsMap())
+	if err != nil {
+		return nil, err
+	}
+	meta, err := protoutils.StructToStructPb(holdingStatus.Meta)
+	if err != nil {
+		return nil, err
+	}
+	return &pb.IsHoldingSomethingResponse{IsHoldingSomething: holdingStatus.IsHoldingSomething, Meta: meta}, nil
+}
+
 // DoCommand receives arbitrary commands.
 func (s *serviceServer) DoCommand(ctx context.Context,
 	req *commonpb.DoCommandRequest,
@@ -85,7 +103,7 @@ func (s *serviceServer) DoCommand(ctx context.Context,
 	if err != nil {
 		return nil, err
 	}
-	return protoutils.DoFromResourceServer(ctx, gripper, req)
+	return rprotoutils.DoFromResourceServer(ctx, gripper, req)
 }
 
 func (s *serviceServer) GetGeometries(ctx context.Context, req *commonpb.GetGeometriesRequest) (*commonpb.GetGeometriesResponse, error) {

testutils/inject/gripper.go

@@ -12,15 +12,16 @@ import (
 // Gripper is an injected gripper.
 type Gripper struct {
 	gripper.Gripper
-	name           resource.Name
-	DoFunc         func(ctx context.Context, cmd map[string]interface{}) (map[string]interface{}, error)
-	OpenFunc       func(ctx context.Context, extra map[string]interface{}) error
-	GrabFunc       func(ctx context.Context, extra map[string]interface{}) (bool, error)
-	StopFunc       func(ctx context.Context, extra map[string]interface{}) error
-	IsMovingFunc   func(context.Context) (bool, error)
-	CloseFunc      func(ctx context.Context) error
-	GeometriesFunc func(ctx context.Context) ([]spatialmath.Geometry, error)
-	KinematicsFunc func(ctx context.Context) (referenceframe.Model, error)
+	name                   resource.Name
+	DoFunc                 func(ctx context.Context, cmd map[string]interface{}) (map[string]interface{}, error)
+	OpenFunc               func(ctx context.Context, extra map[string]interface{}) error
+	GrabFunc               func(ctx context.Context, extra map[string]interface{}) (bool, error)
+	StopFunc               func(ctx context.Context, extra map[string]interface{}) error
+	IsHoldingSomethingFunc func(ctx context.Context, extra map[string]interface{}) (gripper.HoldingStatus, error)
+	IsMovingFunc           func(context.Context) (bool, error)
+	CloseFunc              func(ctx context.Context) error
+	GeometriesFunc         func(ctx context.Context) ([]spatialmath.Geometry, error)
+	KinematicsFunc         func(ctx context.Context) (referenceframe.Model, error)
 }
 
 // NewGripper returns a new injected gripper.
@@ -49,6 +50,14 @@ func (g *Gripper) Grab(ctx context.Context, extra map[string]interface{}) (bool,
 	return g.GrabFunc(ctx, extra)
 }
 
+// IsHoldingSomething calls the injected IsHoldingSomething or the real version.
+func (g *Gripper) IsHoldingSomething(ctx context.Context, extra map[string]interface{}) (gripper.HoldingStatus, error) {
+	if g.IsHoldingSomethingFunc == nil {
+		return g.Gripper.IsHoldingSomething(ctx, extra)
+	}
+	return g.IsHoldingSomethingFunc(ctx, extra)
+}
+
 // Stop calls the injected Stop or the real version.
 func (g *Gripper) Stop(ctx context.Context, extra map[string]interface{}) error {
 	if g.StopFunc == nil {