Bug 1261140

+++ This bug was initially created as a clone of Bug #1260730 +++

Description of problem:
The DB on the brick is been accessed by CTR, for write and
tier migrator, for read and write. The write from tier migrator is reseting
the heat counters after a cycle. Since we are using sqlite, two connections
trying to write would cause a db lock contention. As a result CTR used to fail
to update the db.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.
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Actual results:


Expected results:


Additional info:

--- Additional comment from Vijay Bellur on 2015-09-07 10:27:02 EDT ---

REVIEW: http://review.gluster.org/12031 (tier/ctr: Solving DB Lock issue due to write contention from db connections) posted (#5) for review on master by Joseph Fernandes

--- Additional comment from Vijay Bellur on 2015-09-08 08:13:06 EDT ---

COMMIT: http://review.gluster.org/12031 committed in master by Dan Lambright (dlambrig) 
------
commit 96af474045c9ba5ab74ca76daa823d91a0a0c610
Author: Joseph Fernandes <josferna>
Date:   Thu Aug 27 17:23:07 2015 +0530

    tier/ctr: Solving DB Lock issue due to write contention from db connections
    
    Problem: The DB on the brick is been accessed by CTR, for write and
    tier migrator, for read and write. The write from tier migrator is reseting
    the heat counters after a cycle. Since we are using sqlite, two connections
    trying to write would cause a db lock contention. As a result CTR used to fail
    to update the db.
    
    Solution: Using the same db connection of CTR for reseting the heat counters.
    1) Introducted a new IPC FOP for CTR
    2) After the query do a ipc syncop to the underlying client xlator associated
       to the brick.
    3) CTR in brick will catch the IPC FOP and cleat the heat counters.
    
    Change-Id: I53306bfc08dcdba479deb4ccc154896521336150
    BUG: 1260730
    Signed-off-by: Joseph Fernandes <josferna>
    Reviewed-on: http://review.gluster.org/12031
    Tested-by: NetBSD Build System <jenkins.org>
    Tested-by: Gluster Build System <jenkins.com>
    Reviewed-by: Dan Lambright <dlambrig>
    Tested-by: Dan Lambright <dlambrig>