galang 学习之grpc+ protobuf（二）

上一篇介绍了grpc+ protobuf的一个helloworld，下面介绍一个多接口，并且具有验证功能等辅助一点的例子。这个例子主要是一个坐标使用获取的例子，先看看proto文件定义：

yntax = "proto3";option java_multiple_files = true;option java_package = "io.grpc.examples.routeguide";option java_outer_classname = "RouteGuideProto";package routeguide;// Interface exported by the server.service RouteGuide {  //获取单个Feature方法定义  rpc GetFeature(Point) returns (Feature) {}  // 获取Feature列表方法定义  rpc ListFeatures(Rectangle) returns (stream Feature) {}  // RecordRoute记录point，客户端通过stream发送到服务端  rpc RecordRoute(stream Point) returns (RouteSummary) {}  // 双向stream的例子  rpc RouteChat(stream RouteNote) returns (stream RouteNote) {}}// Points定义包括经度纬度message Point {  int32 latitude = 1;  int32 longitude = 2;}// 长方形定义message Rectangle {  // One corner of the rectangle.  Point lo = 1;  // The other corner of the rectangle.  Point hi = 2;}// 位置定义，包括坐标和名称message Feature {  // The name of the feature.  string name = 1;  // The point where the feature is detected.  Point location = 2;}//RouteNote包含位置和信息message RouteNote {  // The location from which the message is sent.  Point location = 1;  // The message to be sent.  string message = 2;}// RouteSummary 路程总结定义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;}

通过命令

protoc -I routeguide/ routeguide/route_guide.proto --go_out=plugins=grpc:routeguide

生成客户端和服务端调用文件route_guide.pb.go
下面看服务端实现这些接口代码如下：

package mainimport (    "encoding/json"    "flag"    "fmt"    "io"    "io/ioutil"    "math"    "net"    "time"    "strings"    "golang.org/x/net/context"    "google.golang.org/grpc"    "google.golang.org/grpc/credentials"    "google.golang.org/grpc/grpclog"    "github.com/golang/protobuf/proto"    pb "google.golang.org/grpc/examples/route_guide/routeguide"    "path/filepath"    "os"    "log")//支持ca认证服务端需要秘钥key以及私钥var (    tls        = flag.Bool("tls", false, "Connection uses TLS if true, else plain TCP")    certFile   = flag.String("cert_file", "testdata/server1.pem", "The TLS cert file")    keyFile    = flag.String("key_file", "testdata/server1.key", "The TLS key file")    jsonDBFile = flag.String("json_db_file", "/Users/chenxy/go/src/google.golang.org/grpc/examples/route_guide/testdata/route_guide_db.json", "A json file containing a list of features")    port       = flag.Int("port", 10000, "The server port"))type routeGuideServer struct {    savedFeatures []*pb.Feature    routeNotes    map[string][]*pb.RouteNote}// 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 feature    return &pb.Feature{Location: point}, nil}// ListFeatures lists all features contained within the given bounding Rectangle.func (s *routeGuideServer) ListFeatures(rect *pb.Rectangle, stream pb.RouteGuide_ListFeaturesServer) error {    for _, feature := range s.savedFeatures {        if inRange(feature.Location, rect) {            if err := stream.Send(feature); err != nil {                return err            }        }    }    return 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 int32    var 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 {            return nil        }        if err != nil {            return err        }        key := serialize(in.Location)        if _, present := s.routeNotes[key]; !present {            s.routeNotes[key] = []*pb.RouteNote{in}        } else {            s.routeNotes[key] = append(s.routeNotes[key], in)        }        for _, note := range s.routeNotes[key] {            if err := stream.Send(note); err != nil {                return err            }        }    }}// loadFeatures从JSON文件中加载featuresfunc (s *routeGuideServer) loadFeatures(filePath string) {    file, err := ioutil.ReadFile(filePath)    if err != nil {        grpclog.Fatalf("Failed to load default features: %v", err)    }    if err := json.Unmarshal(file, &s.savedFeatures); err != nil {        grpclog.Fatalf("Failed to load default features: %v", err)    }}func toRadians(num float64) float64 {    return num * math.Pi / float64(180)}// calcDistance calculates the distance between two points using the "haversine" formula.// This code was taken from http://www.movable-type.co.uk/scripts/latlong.html.func calcDistance(p1 *pb.Point, p2 *pb.Point) int32 {    const CordFactor float64 = 1e7    const R float64 = float64(6371000) // metres    lat1 := float64(p1.Latitude) / CordFactor    lat2 := float64(p2.Latitude) / CordFactor    lng1 := float64(p1.Longitude) / CordFactor    lng2 := float64(p2.Longitude) / CordFactor    φ1 := toRadians(lat1)    φ2 := toRadians(lat2)    Δφ := toRadians(lat2 - lat1)    Δλ := toRadians(lng2 - lng1)    a := math.Sin(Δφ/2)*math.Sin(Δφ/2) +        math.Cos(φ1)*math.Cos(φ2)*            math.Sin(Δλ/2)*math.Sin(Δλ/2)    c := 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))    distance := R * c    return int32(distance)}func inRange(point *pb.Point, rect *pb.Rectangle) bool {    left := math.Min(float64(rect.Lo.Longitude), float64(rect.Hi.Longitude))    right := math.Max(float64(rect.Lo.Longitude), float64(rect.Hi.Longitude))    top := math.Max(float64(rect.Lo.Latitude), float64(rect.Hi.Latitude))    bottom := math.Min(float64(rect.Lo.Latitude), float64(rect.Hi.Latitude))    if float64(point.Longitude) >= left &&        float64(point.Longitude) <= right &&        float64(point.Latitude) >= bottom &&        float64(point.Latitude) <= top {        return true    }    return false}func serialize(point *pb.Point) string {    return fmt.Sprintf("%d %d", point.Latitude, point.Longitude)}func newServer() *routeGuideServer {    s := new(routeGuideServer)    s.loadFeatures(*jsonDBFile)    s.routeNotes = make(map[string][]*pb.RouteNote)    return s}func main() {    flag.Parse()    lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))    if err != nil {        grpclog.Fatalf("failed to listen: %v", err)    }    var opts []grpc.ServerOption    if *tls {        creds, err := credentials.NewServerTLSFromFile(*certFile, *keyFile)        if err != nil {            grpclog.Fatalf("Failed to generate credentials %v", err)        }        opts = []grpc.ServerOption{grpc.Creds(creds)}    }    grpcServer := grpc.NewServer(opts...)    pb.RegisterRouteGuideServer(grpcServer, newServer())    grpcServer.Serve(lis)}

服务端实现了ListFeatures等这些方法，为了测试服务端需要预先从JSON文件加载Features，格式如下：

[{    "location": {        "latitude": 409146138,        "longitude": -746188906    },    "name": "Berkshire Valley Management Area Trail, Jefferson, NJ, USA"}, {    "location": {        "latitude": 404701380,        "longitude": -744781745    },]

先启动服务端，客户端调用代码如下：

package mainimport (    "flag"    "io"    "math/rand"    "time"    "golang.org/x/net/context"    "google.golang.org/grpc"    "google.golang.org/grpc/credentials"    pb "google.golang.org/grpc/examples/route_guide/routeguide"    "google.golang.org/grpc/grpclog")//指定ca证书var (    tls                = flag.Bool("tls", false, "Connection uses TLS if true, else plain TCP")    caFile             = flag.String("ca_file", "testdata/ca.pem", "The file containning the CA root cert file")    serverAddr         = flag.String("server_addr", "127.0.0.1:10000", "The server address in the format of host:port")    serverHostOverride = flag.String("server_host_override", "x.test.youtube.com", "The server name use to verify the hostname returned by TLS handshake"))// printFeature gets the feature for the given point.func printFeature(client pb.RouteGuideClient, point *pb.Point) {    grpclog.Printf("Getting feature for point (%d, %d)", point.Latitude, point.Longitude)    feature, err := client.GetFeature(context.Background(), point)    if err != nil {        grpclog.Fatalf("%v.GetFeatures(_) = _, %v: ", client, err)    }    grpclog.Println(feature)}// printFeatures lists all the features within the given bounding Rectangle.func printFeatures(client pb.RouteGuideClient, rect *pb.Rectangle) {    grpclog.Printf("Looking for features within %v", rect)    stream, err := client.ListFeatures(context.Background(), rect)    if err != nil {        grpclog.Fatalf("%v.ListFeatures(_) = _, %v", client, err)    }    for {        feature, err := stream.Recv()        if err == io.EOF {            break        }        if err != nil {            grpclog.Fatalf("%v.ListFeatures(_) = _, %v", client, err)        }        grpclog.Println(feature)    }}// runRecordRoute sends a sequence of points to server and expects to get a RouteSummary from server.func runRecordRoute(client pb.RouteGuideClient) {    // Create a random number of random points    r := rand.New(rand.NewSource(time.Now().UnixNano()))    pointCount := int(r.Int31n(100)) + 2 // Traverse at least two points    var points []*pb.Point    for i := 0; i < pointCount; i++ {        points = append(points, randomPoint(r))    }    grpclog.Printf("Traversing %d points.", len(points))    stream, err := client.RecordRoute(context.Background())    if err != nil {        grpclog.Fatalf("%v.RecordRoute(_) = _, %v", client, err)    }    for _, point := range points {        if err := stream.Send(point); err != nil {            grpclog.Fatalf("%v.Send(%v) = %v", stream, point, err)        }    }    reply, err := stream.CloseAndRecv()    if err != nil {        grpclog.Fatalf("%v.CloseAndRecv() got error %v, want %v", stream, err, nil)    }    grpclog.Printf("Route summary: %v", reply)}// runRouteChat receives a sequence of route notes, while sending notes for various locations.func runRouteChat(client pb.RouteGuideClient) {    notes := []*pb.RouteNote{        {&pb.Point{Latitude: 0, Longitude: 1}, "First message"},        {&pb.Point{Latitude: 0, Longitude: 2}, "Second message"},        {&pb.Point{Latitude: 0, Longitude: 3}, "Third message"},        {&pb.Point{Latitude: 0, Longitude: 1}, "Fourth message"},        {&pb.Point{Latitude: 0, Longitude: 2}, "Fifth message"},        {&pb.Point{Latitude: 0, Longitude: 3}, "Sixth message"},    }    stream, err := client.RouteChat(context.Background())    if err != nil {        grpclog.Fatalf("%v.RouteChat(_) = _, %v", client, err)    }    waitc := make(chan struct{})    go func() {        for {            in, err := stream.Recv()            if err == io.EOF {                // read done.                close(waitc)                return            }            if err != nil {                grpclog.Fatalf("Failed to receive a note : %v", err)            }            grpclog.Printf("Got message %s at point(%d, %d)", in.Message, in.Location.Latitude, in.Location.Longitude)        }    }()    for _, note := range notes {        if err := stream.Send(note); err != nil {            grpclog.Fatalf("Failed to send a note: %v", err)        }    }    stream.CloseSend()    <-waitc}func randomPoint(r *rand.Rand) *pb.Point {    lat := (r.Int31n(180) - 90) * 1e7    long := (r.Int31n(360) - 180) * 1e7    return &pb.Point{Latitude: lat, Longitude: long}}func main() {    flag.Parse()    var opts []grpc.DialOption    if *tls {        var sn string        if *serverHostOverride != "" {            sn = *serverHostOverride        }        var creds credentials.TransportCredentials        if *caFile != "" {            var err error            creds, err = credentials.NewClientTLSFromFile(*caFile, sn)            if err != nil {                grpclog.Fatalf("Failed to create TLS credentials %v", err)            }        } else {            creds = credentials.NewClientTLSFromCert(nil, sn)        }        opts = append(opts, grpc.WithTransportCredentials(creds))    } else {        opts = append(opts, grpc.WithInsecure())    }    conn, err := grpc.Dial(*serverAddr, opts...)    if err != nil {        grpclog.Fatalf("fail to dial: %v", err)    }    defer conn.Close()    client := pb.NewRouteGuideClient(conn)    // 获取一个合法的Feature    printFeature(client, &pb.Point{Latitude: 409146138, Longitude: -746188906})    // 这个Feature在服务端没有回返回空    printFeature(client, &pb.Point{Latitude: 0, Longitude: 0})    // Looking for features between 40, -75 and 42, -73.    printFeatures(client, &pb.Rectangle{        Lo: &pb.Point{Latitude: 400000000, Longitude: -750000000},        Hi: &pb.Point{Latitude: 420000000, Longitude: -730000000},    })    // RecordRoute    runRecordRoute(client)    // RouteChat    runRouteChat(client)}

这个例子里面涉及到多个函数接口的调用，以及stream的使用。