peer/cmd/request: Introduce request timeout option

MinBFT never fails in theory as long as we meet the requirement of
"<= f faulty nodes", but unfortunately there's no bug-free softwares,
so it's better to prepare for such potential issues to avoid infinite wait.
This patch suggests to add timeout to the sample application.
Note that if timeout value is not specified, sample application waits
forever as it does now.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Author: Naoya Horiguchi

sample/peer/cmd/request.go

@@ -19,8 +19,10 @@ package cmd
 
 import (
 	"bufio"
+	"context"
 	"fmt"
 	"os"
+	"time"
 
 	"github.com/hyperledger-labs/minbft/api"
 	"github.com/hyperledger-labs/minbft/client"
@@ -57,19 +59,43 @@ func init() {
 	requestCmd.Flags().Int("id", 0, "ID of the client")
 	must(viper.BindPFlag("client.id",
 		requestCmd.Flags().Lookup("id")))
+	requestCmd.Flags().String("timeout", "0", "Timeout for the request")
+	must(viper.BindPFlag("client.timeout", requestCmd.Flags().Lookup("timeout")))
 }
 
 type clientStack struct {
 	api.Authenticator
 	api.ReplicaConnector
 }
 
-func request(client client.Client, arg string) {
-	req := []byte(arg)
+func requestInternal(ctx context.Context, ch chan bool, client client.Client, req []byte) {
+	defer func() {
+		ch <- true
+	}()
 	res := <-client.Request(req)
 	fmt.Println("Reply:", string(res))
 }
 
+func request(client client.Client, arg string) {
+	timeout := viper.GetDuration("client.timeout")
+	ctx := context.Background()
+	ch := make(chan bool)
+	req := []byte(arg)
+
+	if timeout > time.Duration(0) {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, timeout)
+		time.AfterFunc(timeout, cancel)
+	}
+
+	go requestInternal(ctx, ch, client, req)
+	select {
+	case <-ctx.Done():
+		fmt.Println("Client Request timer expired.")
+	case <-ch:
+	}
+}
+
 func requests(args []string) ([]byte, error) {
 	id := uint32(viper.GetInt("client.id"))
 

sample/peer/peer.yaml

@@ -16,6 +16,9 @@ client:
   # ID of the client instance
   id: 0
 
+  # Client request timeout (default: 0s, i.e. never timeout)
+  timeout: 3s
+
 # USIG options
 usig:
   # USIG enclave file (environment expansion is supported)