qemu/include/block
Stefan Hajnoczi 7719f3c968 block: extract AIO_WAIT_WHILE() from BlockDriverState
BlockDriverState has the BDRV_POLL_WHILE() macro to wait on event loop
activity while a condition evaluates to true.  This is used to implement
synchronous operations where it acts as a condvar between the IOThread
running the operation and the main loop waiting for the operation.  It
can also be called from the thread that owns the AioContext and in that
case it's just a nested event loop.

BlockBackend needs this behavior but doesn't always have a
BlockDriverState it can use.  This patch extracts BDRV_POLL_WHILE() into
the AioWait abstraction, which can be used with AioContext and isn't
tied to BlockDriverState anymore.

This feature could be built directly into AioContext but then all users
would kick the event loop even if they signal different conditions.
Imagine an AioContext with many BlockDriverStates, each time a request
completes any waiter would wake up and re-check their condition.  It's
nicer to keep a separate AioWait object for each condition instead.

Please see "block/aio-wait.h" for details on the API.

The name AIO_WAIT_WHILE() avoids the confusion between AIO_POLL_WHILE()
and AioContext polling.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-03-02 18:39:07 +01:00
..
accounting.h block: make accounting thread-safe 2017-06-16 07:55:00 +08:00
aio-wait.h block: extract AIO_WAIT_WHILE() from BlockDriverState 2018-03-02 18:39:07 +01:00
aio.h aio: rename aio_context_in_iothread() to in_aio_context_home_thread() 2018-03-02 18:39:07 +01:00
block.h block: extract AIO_WAIT_WHILE() from BlockDriverState 2018-03-02 18:39:07 +01:00
block_backup.h backup: Switch block_backup.h to byte-based 2017-07-10 13:18:06 +02:00
block_int.h block: extract AIO_WAIT_WHILE() from BlockDriverState 2018-03-02 18:39:07 +01:00
blockjob.h blockjob: reimplement block_job_sleep_ns to allow cancellation 2017-11-29 15:26:21 +01:00
blockjob_int.h blockjob: reimplement block_job_sleep_ns to allow cancellation 2017-11-29 15:26:21 +01:00
dirty-bitmap.h block: maintain persistent disabled bitmaps 2018-02-13 16:59:58 +01:00
nbd.h nbd: BLOCK_STATUS constants 2018-03-01 14:05:24 -06:00
nvme.h block: Move NVMe constants to a separate header 2018-02-08 09:22:03 +08:00
qapi.h Drop superfluous includes of qapi-types.h and test-qapi-types.h 2018-02-09 05:05:11 +01:00
raw-aio.h linux-aio: share one LinuxAioState within an AioContext 2016-07-18 15:09:31 +01:00
snapshot.h Move include qemu/option.h from qemu-common.h to actual users 2018-02-09 13:52:16 +01:00
thread-pool.h Clean up decorations and whitespace around header guards 2016-07-12 16:20:46 +02:00
throttle-groups.h block: add throttle block filter driver 2017-09-06 10:12:02 +02:00
write-threshold.h Use scripts/clean-includes to drop redundant qemu/typedefs.h 2016-03-22 22:20:16 +01:00