nova-api accumulates coverage data and other nova services does not

[Mitsuhiko Yamazaki]

When measuring coverage repeatedly, nova-api and other nova services represent a different approach to coverage data.
On the one hand nova-api accumulates each data, but other services reset data each time.

For example:
 $ nova coverage-start
 $ nova coverage-report result01
 $ nova coverage-start
 $ nova boot --image da16693a-1048-417a-8e88-976d817b4403 --flavor 1 --poll server01
 $ nova coverage-report result02
 $ nova coverage-start
 $ nova coverage-report result03

The coverage data of nova-api, nova-compute and nova-scheduler are:

 [nova-api]
           Name Stmts Miss Branch BrPart Cover Missing
           ----------------------------------------------------------------------------------------------------------------------------------
  result01 TOTAL 50695 50127 12403 12204 1%
  result02 TOTAL 50695 48841 12403 11800 4%
  result03 TOTAL 50695 48841 12403 11800 4%

 [nova-compute]
            Name Stmts Miss Branch BrPart Cover Missing
            ----------------------------------------------------------------------------------------------------------------------------------
  result01: TOTAL 50695 50445 12403 12289 1%
  result02: TOTAL 50695 48403 12403 11690 5%
  result03: TOTAL 50695 50694 12403 12358 1%

 [nova-scheduler]
            Name Stmts Miss Branch BrPart Cover Missing
            ----------------------------------------------------------------------------------------------------------------------------------
  result01: TOTAL 50695 50548 12403 12317 1%
  result02: TOTAL 50695 49807 12403 12105 2%
  result03: TOTAL 50695 50694 12403 12358 1%

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/21853

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/21853
Committed: http://github.com/openstack/nova/commit/9e53cbbe18e7aa292ed585958f18eda516e2bb84
Submitter: Jenkins
Branch: master

commit 9e53cbbe18e7aa292ed585958f18eda516e2bb84
Author: Mitsuhiko Yamazaki <email address hidden>
Date: Tue Feb 12 17:50:06 2013 +0900

    Standardize the coverage initializations.

    Now when we measure coverage repeatedly, the coverage data of
    nova-api is accumulated but the ones of other nova services are
    reset each time.
    This is due to create new "coverage" class each time
    "_start_coverage_telnet" method is executed.

    This patch limits creating "coverage" class the first time
    the method is executed.

    Fixes bug 1122720

    Change-Id: Ia900c96113bee65362ccb7c4c1975535d814d835