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Only one lock file per process (lockf() works now)

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lockf() is more portable than flock()
This commit is contained in:
Unrud 2016-05-22 09:47:36 +02:00
parent eb9218354c
commit 49bc0728e3
1 changed files with 29 additions and 30 deletions
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59
radicale/storage.py
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@ -518,6 +518,7 @@ class Collection(BaseCollection):
return ""
_lock = threading.Condition()
_lock_file = None
_readers = 0
_writer = False
@ -542,40 +543,38 @@ class Collection(BaseCollection):
cls._lock.notify()
else:
cls._writer = True
folder = os.path.expanduser(
cls.configuration.get("storage", "filesystem_folder"))
if not os.path.exists(folder):
os.makedirs(folder, exist_ok=True)
lock_path = os.path.join(folder, "Radicale.lock")
lock_file = open(lock_path, "w+")
# set access rights to a necessary minimum to prevent locking by
# arbitrary users
try:
os.chmod(lock_path, stat.S_IWUSR | stat.S_IRUSR)
except OSError:
cls.logger.debug("Failed to set permissions on lock file")
if os.name == "nt":
handle = msvcrt.get_osfhandle(lock_file.fileno())
flags = LOCKFILE_EXCLUSIVE_LOCK if mode == "w" else 0
overlapped = Overlapped()
if not lock_file_ex(handle, flags, 0, 1, 0, overlapped):
cls.logger.debug("Locking not supported")
elif os.name == "posix":
operation = fcntl.LOCK_EX if mode == "w" else fcntl.LOCK_SH
# According to documentation flock() is emulated with fcntl() on
# some platforms. fcntl() locks are not associated with an open
# file descriptor. The same file can be locked multiple times
# within the same process and if any fd of the file is closed,
# all locks are released.
# flock() does not work on NFS shares.
try:
fcntl.flock(lock_file.fileno(), operation)
except OSError:
cls.logger.debug("Locking not supported")
if not cls._lock_file:
folder = os.path.expanduser(
cls.configuration.get("storage", "filesystem_folder"))
if not os.path.exists(folder):
os.makedirs(folder, exist_ok=True)
lock_path = os.path.join(folder, "Radicale.lock")
cls._lock_file = open(lock_path, "w+")
# set access rights to a necessary minimum to prevent locking
# by arbitrary users
try:
os.chmod(lock_path, stat.S_IWUSR | stat.S_IRUSR)
except OSError:
cls.logger.debug("Failed to set permissions on lock file")
if os.name == "nt":
handle = msvcrt.get_osfhandle(cls._lock_file.fileno())
flags = LOCKFILE_EXCLUSIVE_LOCK if mode == "w" else 0
overlapped = Overlapped()
if not lock_file_ex(handle, flags, 0, 1, 0, overlapped):
cls.logger.debug("Locking not supported")
elif os.name == "posix":
_cmd = fcntl.LOCK_EX if mode == "w" else fcntl.LOCK_SH
try:
fcntl.lockf(cls._lock_file.fileno(), _cmd)
except OSError:
cls.logger.debug("Locking not supported")
yield
with cls._lock:
if mode == "r":
cls._readers -= 1
else:
cls._writer = False
if cls._readers == 0:
cls._lock_file.close()
cls._lock_file = None
cls._lock.notify()