[#301] rpc: Make client stream initialization get cancelled by dial timeout

* `c.conn` may be already invalidated but the rpc client can't detect this.
  `NewStream` may hang trying to open a stream with invalidated connection.
  Using timer with `dialTimeout` for `NewStream` fixes this problem.

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

api/rpc/client/init.go

@@ -3,6 +3,7 @@ package client
 import (
 	"context"
 	"io"
+	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/api/rpc/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/api/rpc/message"
@@ -51,13 +52,40 @@ func (c *Client) Init(info common.CallMethodInfo, opts ...CallOption) (MessageRe
 	}
 
 	ctx, cancel := context.WithCancel(prm.ctx)
-	stream, err := c.conn.NewStream(ctx, &grpc.StreamDesc{
-		StreamName:    info.Name,
-		ServerStreams: info.ServerStream(),
-		ClientStreams: info.ClientStream(),
-	}, toMethodName(info))
+	defer cancel()
+
+	// `conn.NewStream` doesn't check if `conn` may turn up invalidated right before this invocation.
+	// In such cases, the operation can hang indefinitely, with the context timeout being the only
+	// mechanism to cancel it.
+	//
+	// We use a separate timer instead of context timeout because the latter
+	// would propagate to all subsequent read/write operations on the opened stream,
+	// which is not desired for the stream's lifecycle management.
+	dialTimeoutTimer := time.NewTimer(c.dialTimeout)
+	defer dialTimeoutTimer.Stop()
+	newStreamCh := make(chan struct{})
+
+	var stream grpc.ClientStream
+	var err error
+	go func() {
+		stream, err = c.conn.NewStream(ctx, &grpc.StreamDesc{
+			StreamName:    info.Name,
+			ServerStreams: info.ServerStream(),
+			ClientStreams: info.ClientStream(),
+		}, toMethodName(info))
+		close(newStreamCh)
+	}()
+	select {
+	case <-dialTimeoutTimer.C:
+		select {
+		case <-newStreamCh:
+		default:
+			return nil, context.Canceled
+		}
+	case <-newStreamCh:
+	}
+
 	if err != nil {
-		cancel()
 		return nil, err
 	}