[Qemu-block] [RFC v3 00/14] blockjobs: add explicit job management

[John Snow]

For jobs that complete when a monitor isn't looking, there's no way to
tell what the job's final return code was. We need to allow jobs to
remain in the list until queried for reliable management.

Furthermore, it's not viable to have graph changes when the monitor
isn't looking either. We need at least another event for that.

This series is a rough sketch for the WAITING, PENDING and CONCLUDED
events that accompany an expanded job management scheme that a management
client can opt-in to.

V3:
 - Added WAITING and PENDING events
 - Added block_job_finalize verb
 - Added .pending() callback for jobs
 - Tweaked how .commit/.abort work

V2:
 - Added tests!
 - Changed property name (Jeff, Paolo)

RFC / Known problems:
- I need a lot more tests.
- Jobs need to actually implement their .pending callback for this to be of any
  actual use.
- Mirror needs to be refactored to use the commit/abort/pending/clean callbacks
  to fulfill the promise made by "no graph changes without user authorization"
  that PENDING is supposed to offer
- Jobs beyond backup will be able to opt-in to the new management scheme in the
  next version.
- V4 will include a forced synchronicity for jobs in a transaction; i.e. all
  jobs will be forced to use either the old or new styles, but not a mix.

Please take a look and shout loudly if I'm wandering in the wrong direction.

________________________________________________________________________________

For convenience, this branch is available at:
https://github.com/jnsnow/qemu.git branch block-job-reap
https://github.com/jnsnow/qemu/tree/block-job-reap

This version is tagged block-job-reap-v3:
https://github.com/jnsnow/qemu/releases/tag/block-job-reap-v3

John Snow (14):
  blockjobs: add manual property
  blockjobs: Add status enum
  blockjobs: add state transition table
  blockjobs: RFC add block_job_verb permission table
  blockjobs: add block_job_dismiss
  blockjobs: add CONCLUDED state
  blockjobs: ensure abort is called for cancelled jobs
  blockjobs: add commit, abort, clean helpers
  blockjobs: add prepare callback
  blockjobs: Add waiting event
  blockjobs: add PENDING status and event
  blockjobs: add block-job-finalize
  blockjobs: Expose manual property
  iotests: test manual job dismissal

 block/backup.c               |  22 ++--
 block/commit.c               |   2 +-
 block/mirror.c               |   2 +-
 block/replication.c          |   5 +-
 block/stream.c               |   2 +-
 block/trace-events           |   2 +
 blockdev.c                   |  42 ++++++-
 blockjob.c                   | 279 ++++++++++++++++++++++++++++++++++++++++---
 include/block/block_int.h    |   9 +-
 include/block/blockjob.h     |  38 ++++++
 include/block/blockjob_int.h |  12 +-
 qapi/block-core.json         | 135 +++++++++++++++++++--
 tests/qemu-iotests/056       | 241 +++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/056.out   |   4 +-
 tests/test-bdrv-drain.c      |   4 +-
 tests/test-blockjob-txn.c    |   2 +-
 tests/test-blockjob.c        |   4 +-
 17 files changed, 750 insertions(+), 55 deletions(-)

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2.14.3