[libvirt] [PATCH RFC 0/5] drop nested job concept

[Nikolay Shirokovskiy]

Instead I suggest to serialize qemu monitor commands.

My original motivation is to prepare job exclusion code to add agent jobs. This
job is a special job to operate on guest agent only so first it can be run in
parallel with sync, async and nested jobs and second it should not block any
qemu monitor job at all. Eventually I want to move from a lot of different
types of jobs to just a job with some kind of matrix which describes what jobs
can run in a parallel. As a first step I want to drop nested jobs.

AFAIU *main* nested job purpuse is to serialize requests to monitor from async
jobs and allowed sync jobs as monitor does not do it by himself now. Strictly
speaking this assertion is rather rough because nested jobs and sync jobs
serialized at job level and thus chunks of code that serialized differ from
case when only monitor requests are serialized. Nevertheless IFAIU this part of
libvirt is not strict too. We have a lot of query commands and async commands
that can execute in parallel and have no definition of what query job or async
job are. Thus it is not clear is this code correct or not. So the same argument
is applicable to new approach: query jobs are safe to be called during async
jobs.  (Except that new approach opens situation when async job interrupts
query job itself but it generally not clear how this can break query job).

On this path job became high level concept which I think it should be.  Also we
drop boring passing of current async job which we need only for safety check
deep down below the stack.  We drop driver passing for nested jobs which
I guess we really don't need to pass at all as we need it only to check queue
size and nested job probably should skip this check.

The diff stat looks large but most of code is dumb renaming or dropping unused
parameter in patches 4 and 5. To reduce risk of introducing an error on this
tedious task I used sed and perl where I can.

I ran only a simple test with this series of quering a domain during its
migration.

Nikolay Shirokovskiy (5):
  qemu: monitor: serialize send command requests
  qemu: job: drop nested job
  qemu: monitor: add closed monitor flag
  qemu: drop driver parameter on domain enter/exit monitor
  qemu: drop qemuDomainObjEnterMonitorAsync

 src/qemu/qemu_domain.c    | 154 ++++---------------
 src/qemu/qemu_domain.h    |  43 ++----
 src/qemu/qemu_driver.c    | 374 ++++++++++++++++++++--------------------------
 src/qemu/qemu_hotplug.c   | 282 ++++++++++++++++------------------
 src/qemu/qemu_hotplug.h   |  21 +--
 src/qemu/qemu_migration.c | 292 +++++++++++++-----------------------
 src/qemu/qemu_migration.h |   7 +-
 src/qemu/qemu_monitor.c   |  93 ++++++++++--
 src/qemu/qemu_process.c   | 279 +++++++++++++---------------------
 src/qemu/qemu_process.h   |  20 +--
 tests/qemuhotplugtest.c   |   2 +-
 11 files changed, 636 insertions(+), 931 deletions(-)

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1.8.3.1