[HBASE-4777] Write back to client 'incompatible' if we show up with wrong version

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.92.0
• Hadoop Flags: Reviewed
• Assignee: Michael Stack
• Reporter: Michael Stack
• Created: 12/Nov/11 00:51
• Updated: 20/Nov/15 11:55
• Resolved: 13/Nov/11 04:58

Description

We changed the RPC_VERSION to 4 in hbase-3939. If a client comes in volunteering RPC_VERSION is 3, currently, we'll log 'wrong version' but we'll close the connection; the client has no chance of knowing why the server went away.

Returning -1 as id up out of here is what causes the connection close:

    private void setupBadVersionResponse(int clientVersion) throws IOException {
      String errMsg = "Server IPC version " + CURRENT_VERSION +
      " cannot communicate with client version " + clientVersion;
      ByteArrayOutputStream buffer = new ByteArrayOutputStream();

      if (clientVersion >= 3) {
        Call fakeCall =  new Call(-1, null, this, responder);
        // Versions 3 and greater can interpret this exception
        // response in the same manner
        setupResponse(buffer, fakeCall, Status.FATAL,
            null, VersionMismatch.class.getName(), errMsg);

        responder.doRespond(fakeCall);
      }
    }

Instead, we need to return an id that does not close the connection so cilent gets chance to read the response.

Suggestion is that we return a 0 for the id.... the connection will stay up.

If an old client and it sends the wrong version, it'll move on to do getProtocolVersion... and will fail there.

Other clients, e.g. asynchbase, if they get a response will have a response to switch what they send to suit the new server.

(There are other issues – e.g. Invocation is versioned now – but Benoit needs some means of figuring whats on other side)

Issue Links

• relates to: HBASE-3939 Some crossports of Hadoop IPC fixes