ZOOKEEPER-4648 Add audit log for request process result or response.

[curie71]

ZOOKEEPER-4648 FinalRequestProcessor addAuditLog before the process of request and make failedTxn=false. But I think failedTxn should be true if the request can not pass the checkACL and throw KeeperException or other exceptions, since the err code after request processing is also important for audit.

@param failedTxn whether audit is being done failed transaction for normal transaction

public void processRequest(Request request) {
        ......
        Code err = Code.OK;
        try {
            ......
            AuditHelper.addAuditLog(request, rc);

            switch (request.type) {
            ......
            case OpCode.getAllChildrenNumber: {
                lastOp = "GETACN";
                ......
                zks.checkACL(
                    request.cnxn,
                    zks.getZKDatabase().aclForNode(n),
                    ZooDefs.Perms.READ,
                    request.authInfo,
                    path,
                    null);
                ......
                break;
            }
            ......
            }
        } catch (SessionMovedException e) {
            ......
        } catch (KeeperException e) {
            err = e.code();
        } catch (Exception e) {
            ......
        }

if the failedTxn == true or the rc.err != Code.OK, the log result will be FAILURE:

    private static Result getResult(ProcessTxnResult rc, boolean failedTxn) {
        if (failedTxn) {
            return Result.FAILURE;
        } else {
            return rc.err == KeeperException.Code.OK.intValue() ? Result.SUCCESS : Result.FAILURE;
        }
    }

So we could add audit log after request processing and record the err code like below, the log info maybe more accurate.

        Code err = Code.OK;
        try { 
             ......
        } catch (SessionMovedException e) {
            ......
        } catch (KeeperException e) {
            err = e.code();
        } catch (Exception e) {
            ......
        }
        rc.err = err.intValue();
        AuditHelper.addAuditLog(request, rc);

[curie71]

@dobozysaurus Could you please to take a look at this issue?
I found only the request audit log is recorded here in zookeeper.
But I think "the err code after request processing" or a "response log" is also important for audit.

[eolivelli]

can you please rebase ?