This series seeks to address two distinct but closely related issues concerning the job management API.
(1) For jobs that complete when a monitor is not attached and receiving events or notifications, there's no way to discern the job's final return code. Jobs must remain in the query list until dismissed for reliable management. (2) Jobs that change the block graph structure at an indeterminate point after the job starts compete with the management layer that relies on that graph structure to issue meaningful commands. This structure should change only at the behest of the management API, and not asynchronously at unknown points in time. Before a job issues such changes, it must rely on explicit and synchronous confirmation from the management API. This series is a rough sketch that solves these problems by adding three new distinct job states, and two new job command verbs. These changes are implemented by formalizing a State Transition Machine for the BlockJob subsystem. Job States: UNDEFINED Default state. Internal state only. CREATED Job has been created RUNNING Job has been started and is running PAUSED Job is not ready and has been paused READY Job is ready and is running STANDBY Job is ready and is paused WAITING Job is waiting on peers in transaction PENDING Job is waiting on ACK from QMP ABORTING Job is aborting or has been cancelled CONCLUDED Job has finished and has a retcode available NULL Job is being dismantled. Internal state only. Job Verbs: CANCEL Instructs a running job to terminate with error, (Except when that job is READY, which produces no error.) PAUSE Request a job to pause. RESUME Request a job to resume from a pause. SET-SPEED Change the speed limiting parameter of a job. COMPLETE Ask a READY job to finish and exit. FINALIZE Ask a PENDING job to perform its graph finalization. DISMISS Finish cleaning up an empty job. And here's my stab at a diagram: +---------+ |UNDEFINED| +--+------+ | +--v----+ |CREATED+-----------------+ +--+----+ | | | +--+----+ +------+ | +---------+RUNNING<----->PAUSED| | | +--+-+--+ +------+ | | | | | | | +------------------+ | | | | | | +--v--+ +-------+ | | +---------+READY<------->STANDBY| | | | +--+--+ +-------+ | | | | | | | +--v----+ | | +---------+WAITING+---------------+ | | +--+----+ | | | | | +--v----+ | +---------+PENDING| | | +--+----+ | | | | +--v-----+ +--v------+ | |ABORTING+--->CONCLUDED| | +--------+ +--+------+ | | | +--v-+ | |NULL+--------------------+ +----+ V4: - All jobs are now transactions. - All jobs now transition through states in a uniform way. - Verb permissions are now enforced. 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, still... - STANDBY is a dumb name, and maybe not even really needed or wanted. However, a Paused job will return to either READY or RUNNING depending on the state it was in when it was PAUSED. We can keep that in an internal variable, or we can make it explicit in the STM. - is "manual" descriptive as a property name? Kevin conceives of the new workflow as "No automatic transitions, please." (i.e. automatic-transitions: False) Whereas I think of it more like: "Enable manual workflow mode, please." (manual-transitions: True) I like the idea of the new property defaulting to false and have coded in a way mindful of that. - 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 ________________________________________________________________________________ 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-v4: https://github.com/jnsnow/qemu/releases/tag/block-job-reap-v4 John Snow (21): blockjobs: fix set-speed kick blockjobs: model single jobs as transactions blockjobs: add manual property blockjobs: add status enum blockjobs: add state transition table iotests: add pause_wait blockjobs: add block_job_verb permission table blockjobs: add ABORTING state blockjobs: add CONCLUDED state blockjobs: add NULL state blockjobs: add block_job_dismiss blockjobs: ensure abort is called for cancelled jobs blockjobs: add commit, abort, clean helpers blockjobs: add block_job_txn_apply function blockjobs: add prepare callback blockjobs: add waiting status blockjobs: add PENDING status and event blockjobs: add block-job-finalize blockjobs: Expose manual property iotests: test manual job dismissal blockjobs: add manual_mgmt option to transactions block/backup.c | 5 +- block/commit.c | 2 +- block/mirror.c | 2 +- block/stream.c | 2 +- block/trace-events | 7 + blockdev.c | 64 ++++++-- blockjob.c | 355 +++++++++++++++++++++++++++++++++++++----- include/block/blockjob.h | 57 ++++++- include/block/blockjob_int.h | 17 +- qapi/block-core.json | 193 ++++++++++++++++++++++- qapi/transaction.json | 3 +- tests/qemu-iotests/030 | 6 +- tests/qemu-iotests/055 | 17 +- tests/qemu-iotests/056 | 195 +++++++++++++++++++++++ tests/qemu-iotests/056.out | 4 +- tests/qemu-iotests/109.out | 24 +-- tests/qemu-iotests/iotests.py | 12 +- tests/test-bdrv-drain.c | 5 +- tests/test-blockjob-txn.c | 25 ++- tests/test-blockjob.c | 2 +- 20 files changed, 877 insertions(+), 120 deletions(-) -- 2.14.3