assert null == blockReplyStream : "Previous blockReplyStream unclosed";
blockReplyStream = new DataInputStream(NetUtils.getInputStream(s));
// send the request
new Sender(out).writeBlock(block, accessToken, dfsClient.clientName,
nodes, null, recoveryFlag? stage.getRecoveryStage() : stage,
nodes.length, block.getNumBytes(), bytesSent, newGS, checksum);
// receive ack for connect
BlockOpResponseProto resp = BlockOpResponseProto.parseFrom(