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storage/reflink: run synchronous volume methods in executor

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Convert create(), verify(), remove(), start(), stop(), revert(),
resize(), and import_volume() into coroutine methods, via a decorator
that runs them in the event loop's thread-based default executor.

This reduces UI hangs by unblocking the event loop, and can e.g. speed
up VM starts by starting multiple volumes in parallel.
This commit is contained in:
Rusty Bird 2018-09-11 23:50:15 +00:00
parent 3d986be02a
commit 1889c9b75f
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GPG Key ID: 469D78F47AAF2ADF
1 changed files with 25 additions and 0 deletions
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25
qubes/storage/reflink.py
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@ -22,9 +22,11 @@
but not required.
'''
import asyncio
import collections
import errno
import fcntl
import functools
import glob
import logging
import os
@ -115,20 +117,37 @@ class ReflinkPool(qubes.storage.Pool):
[pool for pool in app.pools.values() if pool is not self],
self.dir_path)
def _unblock(method):
''' Decorator transforming a synchronous volume method into a
coroutine that runs the original method in the event loop's
thread-based default executor, under a per-volume lock.
'''
@asyncio.coroutine
@functools.wraps(method)
def wrapper(self, *args, **kwargs):
with (yield from self._lock): # pylint: disable=protected-access
return (yield from asyncio.get_event_loop().run_in_executor(
None, functools.partial(method, self, *args, **kwargs)))
return wrapper
class ReflinkVolume(qubes.storage.Volume):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self._lock = asyncio.Lock()
self._path_vid = os.path.join(self.pool.dir_path, self.vid)
self._path_clean = self._path_vid + '.img'
self._path_dirty = self._path_vid + '-dirty.img'
self._path_import = self._path_vid + '-import.img'
self.path = self._path_dirty
@_unblock
def create(self):
if self.save_on_stop and not self.snap_on_start:
_create_sparse_file(self._path_clean, self.size)
return self
@_unblock
def verify(self):
if self.snap_on_start:
img = self.source._path_clean # pylint: disable=protected-access
@ -142,6 +161,7 @@ class ReflinkVolume(qubes.storage.Volume):
raise qubes.storage.StoragePoolException(
'Missing image file {!r} for volume {}'.format(img, self.vid))
@_unblock
def remove(self):
''' Drop volume object from pool; remove volume images from
oldest to newest; remove empty VM directory.
@ -170,6 +190,7 @@ class ReflinkVolume(qubes.storage.Volume):
def is_dirty(self):
return self.save_on_stop and os.path.exists(self._path_dirty)
@_unblock
def start(self):
self._cleanup()
if self.is_dirty(): # implies self.save_on_stop
@ -183,6 +204,7 @@ class ReflinkVolume(qubes.storage.Volume):
_create_sparse_file(self._path_dirty, self.size)
return self
@_unblock
def stop(self):
if self.save_on_stop:
self._commit(self._path_dirty)
@ -211,6 +233,7 @@ class ReflinkVolume(qubes.storage.Volume):
for number, timestamp in list(self.revisions.items())[:-keep or None]:
_remove_file(self._path_revision(number, timestamp))
@_unblock
def revert(self, revision=None):
if self.is_dirty():
raise qubes.storage.StoragePoolException(
@ -224,6 +247,7 @@ class ReflinkVolume(qubes.storage.Volume):
_rename_file(path_revision, self._path_clean)
return self
@_unblock
def resize(self, size):
''' Expand a read-write volume image; notify any corresponding
loop devices of the size change.
@ -269,6 +293,7 @@ class ReflinkVolume(qubes.storage.Volume):
_remove_file(self._path_import)
return self
@_unblock
def import_volume(self, src_volume):
if not self.save_on_stop:
return self