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Limit duration of file locks

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This prevents starvation of writers in other processes
This commit is contained in:
Unrud 2016-05-22 22:41:19 +02:00
parent 14daa88772
commit 6b1acd14d7
1 changed files with 8 additions and 0 deletions
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8
radicale/storage.py
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@ -92,6 +92,7 @@ def load(configuration, logger):
MIMETYPES = {"VADDRESSBOOK": "text/vcard", "VCALENDAR": "text/calendar"} MIMETYPES = {"VADDRESSBOOK": "text/vcard", "VCALENDAR": "text/calendar"}
MAX_FILE_LOCK_DURATION = 0.25
def get_etag(text): def get_etag(text):
@ -528,6 +529,7 @@ class Collection(BaseCollection):
_waiters = [] _waiters = []
_lock_file = None _lock_file = None
_lock_file_locked = False _lock_file_locked = False
_lock_file_time = 0
_readers = 0 _readers = 0
_writer = False _writer = False
@ -535,6 +537,11 @@ class Collection(BaseCollection):
@contextmanager @contextmanager
def acquire_lock(cls, mode): def acquire_lock(cls, mode):
def condition(): def condition():
# Prevent starvation of writers in other processes
if cls._lock_file_locked:
time_delta = time.time() - cls._lock_file_time
if time_delta < 0 or time_delta > MAX_FILE_LOCK_DURATION:
return False
if mode == "r": if mode == "r":
return not cls._writer return not cls._writer
else: else:
@ -588,6 +595,7 @@ class Collection(BaseCollection):
except OSError: except OSError:
cls.logger.debug("Locking not supported") cls.logger.debug("Locking not supported")
cls._lock_file_locked = True cls._lock_file_locked = True
cls._lock_file_time = time.time()
yield yield
with cls._lock: with cls._lock:
if mode == "r": if mode == "r":