openstack
/
tooz
Code Issues Proposed changes

file: update .metadata atomically 

This change the method writing the .metadata file for each group to do
it in an atomic fashion. This avoids the need to lock the whole driver
to read/write the group information.

Change-Id: Id615145b936463f13eb4d45717cd88f2ab34b105
This commit is contained in:
Julien Danjou 2016-07-27 15:28:40 +02:00
parent adbb5bf466
commit d48d8bc3fb
1 changed files with 9 additions and 7 deletions
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16
tooz/drivers/file.py
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@ -23,6 +23,7 @@ import os
import re
import shutil
import sys
import tempfile
import threading
import weakref
@ -210,10 +211,11 @@ class FileDriver(coordination._RunWatchersMixin,
self._dir = self._normalize_path(parsed_url.path)
self._executor = utils.ProxyExecutor.build("File", options)
self._group_dir = os.path.join(self._dir, 'groups')
self._tmpdir = os.path.join(self._dir, 'tmp')
self._driver_lock_path = os.path.join(self._dir, '.driver_lock')
self._driver_lock = self._get_raw_lock(self._driver_lock_path,
self._member_id)
self._reserved_dirs = [self._dir, self._group_dir]
self._reserved_dirs = [self._dir, self._group_dir, self._tmpdir]
self._reserved_paths = list(self._reserved_dirs)
self._reserved_paths.append(self._driver_lock_path)
self._joined_groups = set()
@ -269,17 +271,18 @@ class FileDriver(coordination._RunWatchersMixin,
}
details[u'encoded'] = details[u"group_id"] != group_id
details_blob = utils.dumps(details)
with open(path, "wb") as fh:
fd, name = tempfile.mkstemp("tooz", dir=self._tmpdir)
with os.fdopen(fd, "wb") as fh:
fh.write(details_blob)
os.rename(name, path)
def create_group(self, group_id):
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
group_meta_path = os.path.join(group_dir, '.metadata')
@_lock_me(self._driver_lock)
def _do_create_group():
if os.path.isdir(group_dir):
if os.path.exists(os.path.join(group_dir, ".metadata")):
# NOTE(sileht): We update the group metadata even
# they are already good, so ensure dict key are convert
# to unicode in case of the file have been written with
@ -299,7 +302,7 @@ class FileDriver(coordination._RunWatchersMixin,
@_lock_me(self._driver_lock)
def _do_join_group():
if not os.path.isdir(group_dir):
if not os.path.exists(os.path.join(group_dir, ".metadata")):
raise coordination.GroupNotCreated(group_id)
if os.path.isfile(me_path):
raise coordination.MemberAlreadyExist(group_id,
@ -326,7 +329,7 @@ class FileDriver(coordination._RunWatchersMixin,
@_lock_me(self._driver_lock)
def _do_leave_group():
if not os.path.isdir(group_dir):
if not os.path.exists(os.path.join(group_dir, ".metadata")):
raise coordination.GroupNotCreated(group_id)
try:
os.unlink(me_path)
@ -465,7 +468,6 @@ class FileDriver(coordination._RunWatchersMixin,
def get_groups(self):
@_lock_me(self._driver_lock)
def _do_get_groups():
groups = []
for entry in os.listdir(self._group_dir):