cd $GOPATH/src/google.golang.org/grpc/examples/route_guide
定义服务
从前面的介绍中我们已经介绍如何使用 protocol buffers来定义服务以及返回值类型。
// Interface exported by the server.
service RouteGuide {
// 一元RPC
// A simple RPC.
//
// Obtains the feature at a given position.
//
// A feature with an empty name is returned if there's no feature at the given
// position.
rpc GetFeature(Point) returns (Feature) {}
// 服务端流式RPC
// A server-to-client streaming RPC.
//
// Obtains the Features available within the given Rectangle. Results are
// streamed rather than returned at once (e.g. in a response message with a
// repeated field), as the rectangle may cover a large area and contain a
// huge number of features.
rpc ListFeatures(Rectangle) returns (stream Feature) {}
// 客户端流式RPC
// A client-to-server streaming RPC.
//
// Accepts a stream of Points on a route being traversed, returning a
// RouteSummary when traversal is completed.
rpc RecordRoute(stream Point) returns (RouteSummary) {}
// 双向流式RPC
// A Bidirectional streaming RPC.
//
// Accepts a stream of RouteNotes sent while a route is being traversed,
// while receiving other RouteNotes (e.g. from other users).
rpc RouteChat(stream RouteNote) returns (stream RouteNote) {}
}
同时在 .proto 文件中还定义了用于请求和响应的message 类型。
// Points are represented as latitude-longitude pairs in the E7 representation
// (degrees multiplied by 10**7 and rounded to the nearest integer).
// Latitudes should be in the range +/- 90 degrees and longitude should be in
// the range +/- 180 degrees (inclusive).
message Point {
int32 latitude = 1;
int32 longitude = 2;
}
// A latitude-longitude rectangle, represented as two diagonally opposite
// points "lo" and "hi".
message Rectangle {
// One corner of the rectangle.
Point lo = 1;
// The other corner of the rectangle.
Point hi = 2;
}
// A feature names something at a given point.
//
// If a feature could not be named, the name is empty.
message Feature {
// The name of the feature.
string name = 1;
// The point where the feature is detected.
Point location = 2;
}
// A RouteNote is a message sent while at a given point.
message RouteNote {
// The location from which the message is sent.
Point location = 1;
// The message to be sent.
string message = 2;
}
// A RouteSummary is received in response to a RecordRoute rpc.
//
// It contains the number of individual points received, the number of
// detected features, and the total distance covered as the cumulative sum of
// the distance between each point.
message RouteSummary {
// The number of points received.
int32 point_count = 1;
// The number of known features passed while traversing the route.
int32 feature_count = 2;
// The distance covered in metres.
int32 distance = 3;
// The duration of the traversal in seconds.
int32 elapsed_time = 4;
}
// GetFeature returns the feature at the given point.func (s *routeGuideServer) GetFeature(ctx context.Context, point *pb.Point) (*pb.Feature, error) {for _, feature :=range s.savedFeatures {if proto.Equal(feature.Location, point) {return feature, nil } }// No feature was found, return an unnamed featurereturn&pb.Feature{Location: point}, nil}
// RecordRoute records a route composited of a sequence of points.//// It gets a stream of points, and responds with statistics about the "trip":// number of points, number of known features visited, total distance traveled, and// total time spent.func (s *routeGuideServer) RecordRoute(stream pb.RouteGuide_RecordRouteServer) error {var pointCount, featureCount, distance int32var lastPoint *pb.Point startTime := time.Now()for { point, err := stream.Recv()if err == io.EOF { endTime := time.Now()return stream.SendAndClose(&pb.RouteSummary{ PointCount: pointCount, FeatureCount: featureCount, Distance: distance, ElapsedTime: int32(endTime.Sub(startTime).Seconds()), }) }if err !=nil {return err } pointCount++for _, feature :=range s.savedFeatures {if proto.Equal(feature.Location, point) { featureCount++ } }if lastPoint !=nil { distance +=calcDistance(lastPoint, point) } lastPoint = point }}
// RouteChat receives a stream of message/location pairs, and responds with a stream of all// previous messages at each of those locations.func (s *routeGuideServer) RouteChat(stream pb.RouteGuide_RouteChatServer) error {for { in, err := stream.Recv()if err == io.EOF {returnnil }if err !=nil {return err } key :=serialize(in.Location) s.mu.Lock() s.routeNotes[key] =append(s.routeNotes[key], in)// Note: this copy prevents blocking other clients while serving this one.// We don't need to do a deep copy, because elements in the slice are// insert-only and never modified. rn :=make([]*pb.RouteNote, len(s.routeNotes[key]))copy(rn, s.routeNotes[key]) s.mu.Unlock()for _, note :=range rn {if err := stream.Send(note); err !=nil {return err } } }}