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/*
*
* Copyright 2018 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
// Binary wait_for_ready is an example for "wait for ready".
package main
import (
"context"
"fmt"
"log"
"net"
"sync"
"time"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
pb "google.golang.org/grpc/examples/features/proto/echo"
)
// server is used to implement EchoServer.
type server struct {
pb.UnimplementedEchoServer
}
func (s *server) UnaryEcho(ctx context.Context, req *pb.EchoRequest) (*pb.EchoResponse, error) {
return &pb.EchoResponse{Message: req.Message}, nil
}
// serve starts listening with a 2 seconds delay.
func serve() {
lis, err := net.Listen("tcp", ":50053")
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
s := grpc.NewServer()
pb.RegisterEchoServer(s, &server{})
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
func main() {
conn, err := grpc.Dial("localhost:50053", grpc.WithInsecure())
if err != nil {
log.Fatalf("did not connect: %v", err)
}
defer conn.Close()
c := pb.NewEchoClient(conn)
var wg sync.WaitGroup
wg.Add(3)
// "Wait for ready" is not enabled, returns error with code "Unavailable".
go func() {
defer wg.Done()
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
_, err := c.UnaryEcho(ctx, &pb.EchoRequest{Message: "Hi!"})
got := status.Code(err)
fmt.Printf("[1] wanted = %v, got = %v\n", codes.Unavailable, got)
}()
// "Wait for ready" is enabled, returns nil error.
go func() {
defer wg.Done()
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
_, err := c.UnaryEcho(ctx, &pb.EchoRequest{Message: "Hi!"}, grpc.WaitForReady(true))
got := status.Code(err)
fmt.Printf("[2] wanted = %v, got = %v\n", codes.OK, got)
}()
// "Wait for ready" is enabled but exceeds the deadline before server starts listening,
// returns error with code "DeadlineExceeded".
go func() {
defer wg.Done()
ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
defer cancel()
_, err := c.UnaryEcho(ctx, &pb.EchoRequest{Message: "Hi!"}, grpc.WaitForReady(true))
got := status.Code(err)
fmt.Printf("[3] wanted = %v, got = %v\n", codes.DeadlineExceeded, got)
}()
time.Sleep(2 * time.Second)
go serve()
wg.Wait()
}
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