ceilometer db2 need to insert random strings to prevent multi-thread running case in db upgrade

[Kai Qiang Wu(Kennan)]

In simple single run, dbsync it would not have issue for that

if used configured tools, like chef, the recipe have signal mechnism, so it can have multi-thread hit the same path

/usr/lib/python2.6/site-packages/ceilometer/storage/impl_db2.py

def upgrade(self, version=None)

  ..

like ceilometer-api process run, and also dbsync run.

In order to better support, we initial table with random strings to prevent such case to happen

in db2, we can check logs as :

   com.ibm.nosql.db2wire.server.DB2CollectionHelper Error: An exception has been thrown: com.ibm.nosql.json.api.DBException : [nosql][1.3.44] Unable to perform the update: [nosql][1.3.44] One or more values in the INSERT statement, UPDATE statement, or foreign key update caused by a DELETE statement are not valid because the primary key, unique constraint or unique index identified by "1" constrains table "CEILODB2.resource" from having duplicate values for the index key.. SQLCODE=-803, SQLSTATE=23505, DRIVER=3.67.27;

in nosql logs find

[nosql][2015-03-03-18:40:03.252][NoSQLTCPThreads : 0][DBCollection@de69398d][insert] ENTRY {"_id":"xxxxxxxx....

[nosql][2015-03-03-18:40:03.254][NoSQLTCPThreads : 1][DBCollection@de69398d][insert] ENTRY {"_id":"xxxx...

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/161126

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/161126
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=45bb98531ba4ef757c50a080652c81bc21e3d9dd
Submitter: Jenkins
Branch: master

commit 45bb98531ba4ef757c50a080652c81bc21e3d9dd
Author: Kennan <email address hidden>
Date: Wed Mar 4 16:20:23 2015 +0800

    Fix db2 upgrade in multi-thread run issue

    In multi-thread run cases(like chef recipes run), it would hit insert same
    record issue, this fix make sure insert different data in db, thus not hit
    duplicated insert issue, it is mainly improve in multi-thread cases run.

    Change-Id: I1690dc5863cbd2b213d241477e23e82d295856fe
    Closes-Bug: #1427997