functional/tester: clean up "broadcastOperation"

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

functional/tester/cluster.go

@@ -24,6 +24,7 @@ import (
 	"net/url"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/coreos/etcd/functional/rpcpb"
@@ -302,23 +303,40 @@ func (clus *Cluster) Restart() error {
 }
 
 func (clus *Cluster) broadcastOperation(op rpcpb.Operation) error {
+	var wg sync.WaitGroup
+	wg.Add(len(clus.agentStreams))
+
+	errc := make(chan error, len(clus.agentStreams))
 	for i := range clus.agentStreams {
-		err := clus.sendOperation(i, op)
-		if err != nil {
-			if op == rpcpb.Operation_DestroyEtcdAgent &&
-				strings.Contains(err.Error(), "rpc error: code = Unavailable desc = transport is closing") {
-				// agent server has already closed;
-				// so this error is expected
-				clus.lg.Info(
-					"successfully destroyed",
-					zap.String("member", clus.Members[i].EtcdClientEndpoint),
-				)
-				continue
-			}
-			return err
-		}
+		go func(idx int, o rpcpb.Operation) {
+			defer wg.Done()
+			errc <- clus.sendOperation(idx, o)
+		}(i, op)
 	}
-	return nil
+	wg.Wait()
+	close(errc)
+
+	errs := []string{}
+	for err := range errc {
+		if err == nil {
+			continue
+		}
+
+		if err != nil &&
+			op == rpcpb.Operation_DestroyEtcdAgent &&
+			strings.Contains(err.Error(), "rpc error: code = Unavailable desc = transport is closing") {
+			// agent server has already closed;
+			// so this error is expected
+			clus.lg.Info("successfully destroyed all")
+			continue
+		}
+		errs = append(errs, err.Error())
+	}
+
+	if len(errs) == 0 {
+		return nil
+	}
+	return errors.New(strings.Join(errs, ", "))
 }
 
 func (clus *Cluster) sendOperation(idx int, op rpcpb.Operation) error {