nova-api coverage data contains other services' data after a combined report

[Mitsuhiko Yamazaki]

When creating a combined coverage report, nova services' coverage data are combined into nova-api's.
So if combining a coverage report once, the next nova-api coverage report doesn't indicate that of just nova-api.

Example:

 [not combine data]
  $ nova coverage-start
  $ nova boot --image cirros-0.3.1-x86_64-uec --flavor 1 --poll server01
  $ nova coverage-report report
  $ nova coverage-start
  $ nova coverage-report report01

  coverage data of report01.api is:

  Name Stmts Miss Branch BrPart Cover Missing
  ---------------------------------------------------------------------------------------------------------------------------------------
  nova/compute/manager 1762 1762 483 483 0% 20-3853
  nova/conductor/manager 233 233 42 42 0% 15-424
  nova/scheduler/manager 116 116 32 32 0% 20-296

 [combine data]
  $ nova coverage-start --combine
  $ nova boot --image cirros-0.3.1-x86_64-uec --flavor 1 --poll server01
  $ nova coverage-report report
  $ nova coverage-start
  $ nova coverage-report report02

  coverage data of report02.api is:

  Name Stmts Miss Branch BrPart Cover Missing
  ---------------------------------------------------------------------------------------------------------------------------------------
  nova/compute/manager 1762 1621 483 453 8% 20-45, 50-51, 57-191, 195-220, 224-238, 248, 261-264, 270-275, 280-301, 305, 311, 315-318, 323-351, 354-362, 365, 374-375, 379-383, 392-393, 396-523, 530-548, 552-588, 593-658, 664, 670-722, 733, 742, 748, 751-752, 758, 790-809, 822-906, 913-923, 936-949, 952-954, 972, 976-982, 993-1010, 1020, 1036-1038, 1046, 1050-1055, 1067-1079, 1091-1145, 1151, 1153, 1165-3163, 3177, 3180, 3188-3193, 3198-3216, 3219-3224, 3227-3244, 3247-3300, 3303-3348, 3355-3456, 3460-3487, 3491-3538, 3548-3660, 3668-3683, 3694-3853
  nova/conductor/manager 233 192 42 35 17% 15-54, 63-85, 89-91, 100-105, 110-113, 121, 125-134, 140-207, 212, 217, 221-235, 240-286, 290, 294-330, 334, 338-350, 355-359, 364-389, 392, 395-424
  nova/scheduler/manager 116 104 32 27 11% 20-76, 80, 83, 87-103, 114, 128-284, 288-296

Report01.api indicates the data of just nova-api but report02.api doesn't.

Appendix:
To measure nova services' coverage data, add "backdoor_port=0" in nova.conf.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24028

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24028
Committed: http://github.com/openstack/nova/commit/ef4f75b088b09d4ed86ff02bb69cd4046cccb3f6
Submitter: Jenkins
Branch: master

commit ef4f75b088b09d4ed86ff02bb69cd4046cccb3f6
Author: Mitsuhiko Yamazaki <email address hidden>
Date: Fri Mar 8 17:01:09 2013 +0900

    Prevent nova services' coverage data from combining into nova-api's

    Now if combining a coverage report once, nova services' coverage
    data are combined into nova-api's.
    This renames nova-api coverage datafile to .nova-coverage.api and
    creates a new coverage instance to combine when reporting.

    Fixes bug: 1152475

    Change-Id: I90b6535d490cf0123a127f8752986edd782ef37e