Comment 8 for bug 1439069

Reviewed: https://review.opencontrail.org/9146
Committed: http://github.org/Juniper/contrail-vrouter/commit/be6be5911040e338bfd9422be1b414f2c8e9b56b
Submitter: Zuul
Branch: R2.1

commit be6be5911040e338bfd9422be1b414f2c8e9b56b
Author: Anand H. Krishnan <email address hidden>
Date: Fri Apr 3 16:16:03 2015 +0530

Return error to agent if an entry already existed in the flow table

It is logically possible that agent and datapath are trying to create
same flow simultaneously. If it so happens that agent gets the entry
that datapath created and tries to update that entry assuming that the
entry was created by it, then the hold count will never be compensated
by a corresponding acted count, and hence vrouter's perception of the
number of active hold entries can go wrong. To fix this, return error
to agent if the flow it tried to create already existed.

Other fixes:

. If agent is changing the flow state to 'hold' from any other state,
update the hold count entry.

. Export the hold count statistics to 'flow' utility

Change-Id: I24087baa5bf853b863f34e1b55882927d9114349
Partial-BUG: #1439069