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gRPC Graceful Shutdown on Client and Server
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package main | |
import ( | |
"context" | |
"grpc-tutorial/greeter" | |
"io" | |
"log" | |
"os" | |
"os/signal" | |
"sync" | |
"syscall" | |
"time" | |
"github.com/golang/protobuf/ptypes/empty" | |
"google.golang.org/grpc" | |
"google.golang.org/grpc/codes" | |
"google.golang.org/grpc/status" | |
) | |
func main() { | |
ctx, cancel := context.WithCancel(context.Background()) | |
defer cancel() | |
conn, err := grpc.DialContext(ctx, "localhost:8080", grpc.WithBlock(), grpc.WithTimeout(3*time.Second), grpc.WithInsecure()) | |
if err != nil { | |
log.Fatalf("could not connect to server: %v", err) | |
} | |
defer conn.Close() | |
cli := greeter.NewGreeterClient(conn) | |
stream, err := cli.SayHelloStream(ctx, &greeter.HelloRequest{}) | |
if err != nil { | |
log.Fatalf("could not create streaming client: %v", err) | |
} | |
sigCh := make(chan os.Signal, 1) | |
signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM) | |
wg := sync.WaitGroup{} | |
wg.Add(1) | |
go func() { | |
defer wg.Done() | |
select { | |
case <-ctx.Done(): | |
return | |
case s := <-sigCh: | |
log.Printf("got signal %v, attempting graceful shutdown", s) | |
cancel() | |
} | |
}() | |
wg.Add(1) | |
go func() { | |
defer wg.Done() | |
time.Sleep(5 * time.Second) | |
resp, err := cli.SayHello(ctx, &empty.Empty{}) | |
if err != nil { | |
if status.Code(err) == codes.Canceled { | |
log.Println("context cancelled") | |
return | |
} | |
log.Fatalf("could not perform regular rpc request: %v", err) | |
} | |
log.Printf("received SayHello response: %+v", resp) | |
}() | |
wg.Add(1) | |
go func() { | |
defer wg.Done() | |
for { | |
r, err := stream.Recv() | |
if err != nil { | |
if err == io.EOF || status.Code(err) == codes.Canceled { | |
log.Println("stream closed (context cancelled)") | |
cancel() | |
return | |
} | |
log.Fatalf("error while receiving stream response: %v", err) | |
} | |
log.Printf("received value: %+v", r) | |
} | |
}() | |
wg.Wait() | |
} |
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package main | |
import ( | |
"context" | |
"fmt" | |
"grpc-tutorial/greeter" | |
pb "grpc-tutorial/greeter" | |
"log" | |
"math/rand" | |
"net" | |
"os" | |
"os/signal" | |
"strconv" | |
"sync" | |
"syscall" | |
"time" | |
"github.com/golang/protobuf/ptypes/empty" | |
"google.golang.org/grpc" | |
"google.golang.org/grpc/codes" | |
"google.golang.org/grpc/status" | |
) | |
type greeterServer struct { | |
intCh <-chan int | |
} | |
func generate(ctx context.Context) <-chan int { | |
ch := make(chan int) | |
go func() { | |
for { | |
select { | |
case <-time.Tick(time.Second): | |
rand.Seed(time.Now().UnixNano()) | |
n := rand.Int() | |
// log.Printf("generated %d", n) | |
ch <- n | |
case <-ctx.Done(): | |
close(ch) | |
return | |
} | |
} | |
}() | |
return ch | |
} | |
func (g *greeterServer) SayHelloStream(req *pb.HelloRequest, stream pb.Greeter_SayHelloStreamServer) error { | |
for n := range g.intCh { | |
resp := pb.HelloReply{ | |
Message: strconv.Itoa(n), | |
} | |
if err := stream.Send(&resp); err != nil { | |
if status.Code(err) == codes.Canceled { | |
log.Println("stream closed (context cancelled)") | |
return nil | |
} | |
log.Printf("could not send over stream: %v", err) | |
return err | |
} | |
log.Printf("sent %d", n) | |
} | |
return nil | |
} | |
func (g *greeterServer) SayHello(context.Context, *empty.Empty) (*greeter.HelloReply, error) { | |
resp := pb.HelloReply{ | |
Message: "this WORKED!", | |
} | |
return &resp, nil | |
} | |
func main() { | |
ctx, cancel := context.WithCancel(context.Background()) | |
defer cancel() | |
ch := generate(ctx) | |
gSrv := greeterServer{ | |
intCh: ch, | |
} | |
lis, err := net.Listen("tcp", fmt.Sprintf(":%d", 8080)) | |
if err != nil { | |
log.Fatalf("failed to listen: %v", err) | |
} | |
grpc := grpc.NewServer() | |
pb.RegisterGreeterServer(grpc, &gSrv) | |
sigCh := make(chan os.Signal, 1) | |
signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM) | |
wg := sync.WaitGroup{} | |
wg.Add(1) | |
go func() { | |
s := <-sigCh | |
log.Printf("got signal %v, attempting graceful shutdown", s) | |
cancel() | |
grpc.GracefulStop() | |
// grpc.Stop() // leads to error while receiving stream response: rpc error: code = Unavailable desc = transport is closing | |
wg.Done() | |
}() | |
log.Println("starting grpc server") | |
err = grpc.Serve(lis) | |
if err != nil { | |
log.Fatalf("could not serve: %v", err) | |
} | |
wg.Wait() | |
log.Println("clean shutdown") | |
} |
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