[v3,0/4] qmp: Optionally run handlers in coroutines

Message

Kevin Wolf Jan. 15, 2020, 12:23 p.m. UTC

Some QMP command handlers can block the main loop for a relatively long
time, for example because they perform some I/O. This is quite nasty.
Allowing such handlers to run in a coroutine where they can yield (and
therefore release the BQL) while waiting for an event such as I/O
completion solves the problem.

This series adds the infrastructure to allow this and switches
block_resize to run in a coroutine as a first example.

This is an alternative solution to Marc-André's "monitor: add
asynchronous command type" series.

v3:
- Fix race between monitor thread and dispatcher that could schedule the
  dispatcher coroutine twice if a second requests comes in before the
  dispatcher can wake up [Patchew]

v2:
- Fix typo in a commit message [Eric]
- Use hyphen instead of underscore for the test command [Eric]
- Mark qmp_block_resize() as coroutine_fn [Stefan]

Kevin Wolf (4):
  qapi: Add a 'coroutine' flag for commands
  vl: Initialise main loop earlier
  qmp: Move dispatcher to a coroutine
  block: Mark 'block_resize' as coroutine

 qapi/block-core.json                    |  3 +-
 tests/qapi-schema/qapi-schema-test.json |  1 +
 docs/devel/qapi-code-gen.txt            |  4 ++
 include/qapi/qmp/dispatch.h             |  3 +
 monitor/monitor-internal.h              |  5 +-
 blockdev.c                              |  6 +-
 monitor/monitor.c                       | 24 ++++---
 monitor/qmp.c                           | 83 ++++++++++++++++---------
 qapi/qmp-dispatch.c                     | 38 ++++++++++-
 tests/test-qmp-cmds.c                   |  4 ++
 vl.c                                    | 10 +--
 scripts/qapi/commands.py                | 17 +++--
 scripts/qapi/doc.py                     |  2 +-
 scripts/qapi/expr.py                    |  4 +-
 scripts/qapi/introspect.py              |  2 +-
 scripts/qapi/schema.py                  |  9 ++-
 tests/qapi-schema/qapi-schema-test.out  |  2 +
 tests/qapi-schema/test-qapi.py          |  7 ++-
 18 files changed, 158 insertions(+), 66 deletions(-)