[FAB-4534] Use cancellation context in gossip

In gossip when a peer p closes a connection to another peer q
that it initiated connection with, it simply closes the gRPC stream,
but this doesn't always make the Recv() method to return and might
result in a stuck goroutine.

The solution would be to use a cancellation context when priming the stream object.

Change-Id: I6632333b09559b70670787418788674452749f0e
Signed-off-by: Yacov Manevich <[email protected]>

Author: yacovm

gossip/comm/comm_impl.go

@@ -187,7 +187,8 @@ func (c *commImpl) createConnection(endpoint string, expectedPKIID common.PKIidT
 		return nil, err
 	}
 
-	if stream, err = cl.GossipStream(context.Background()); err == nil {
+	ctx, cf := context.WithCancel(context.Background())
+	if stream, err = cl.GossipStream(ctx); err == nil {
 		connInfo, err = c.authenticateRemotePeer(stream)
 		if err == nil {
 			pkiID = connInfo.ID
@@ -201,6 +202,7 @@ func (c *commImpl) createConnection(endpoint string, expectedPKIID common.PKIidT
 			conn.pkiID = pkiID
 			conn.info = connInfo
 			conn.logger = c.logger
+			conn.cancel = cf
 
 			h := func(m *proto.SignedGossipMessage) {
 				c.logger.Debug("Got message:", m)

gossip/comm/conn.go

@@ -25,6 +25,7 @@ import (
 	"github.com/hyperledger/fabric/gossip/util"
 	proto "github.com/hyperledger/fabric/protos/gossip"
 	"github.com/op/go-logging"
+	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
 
@@ -206,6 +207,7 @@ func newConnection(cl proto.GossipClient, c *grpc.ClientConn, cs proto.Gossip_Go
 }
 
 type connection struct {
+	cancel       context.CancelFunc
 	info         *proto.ConnectionInfo
 	outBuff      chan *msgSending
 	logger       *logging.Logger                 // logger
@@ -241,6 +243,10 @@ func (conn *connection) close() {
 		conn.conn.Close()
 	}
 
+	if conn.cancel != nil {
+		conn.cancel()
+	}
+
 	conn.Unlock()
 
 }