[IMPALA-5744] Add dummy 'use_krpc' flag and create DataStream interface

• Type: Task
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: Impala 2.10.0
• Component/s: Distributed Exec
• Epic Color: ghx-label-1
• Assignee: Sailesh Mukil
• Reporter: Sailesh Mukil
• Created: 31/Jul/17 22:32
• Updated: 10/Aug/17 18:58
• Resolved: 10/Aug/17 18:58

Description

Since we are planning to move our RPC stack to KRPC, an initial step is to create a 'use_krpc' startup flag that will allow a user to switch between KRPC and Thrift according to their requirements.

This patch should introduce this flag as a dummy flag and create an abstract interface for the DataStreamSender/Recvr/Mgr.

Once the KRPC code is ready, it can inherit from this interface and add its own implementation of DataStream*.