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Don't read cache entry twice with exclusive access

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Unrud 2017-08-01 17:16:58 +02:00
parent 1576f9b7fb
commit ed3708db22
1 changed files with 9 additions and 11 deletions
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20
radicale/storage.py
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@ -1299,17 +1299,15 @@ class Collection(BaseCollection):
href) href)
vobject_item = None vobject_item = None
if input_hash != cache_hash: if input_hash != cache_hash:
# Lock the item cache to prevent multpile processes from generating with contextlib.ExitStack() as lock_stack:
# the same data in parallel. This is only needed for performance. # Lock the item cache to prevent multpile processes from
if self._lock.locked() == "w": # generating the same data in parallel.
# The access is already exclusive, use dummy context manager. # This improves the performance for multiple requests.
lock = contextlib.suppress() if self._lock.locked() == "r":
else: lock_stack.enter_context(self._acquire_cache_lock("item"))
lock = self._acquire_cache_lock("item") # Check if another process created the file in the meantime
with lock: cache_hash, uid, etag, text, tag, start, end = \
# Check if another process created the file in the meantime. self._load_item_cache(href)
cache_hash, uid, etag, text, tag, start, end = \
self._load_item_cache(href)
if input_hash != cache_hash: if input_hash != cache_hash:
try: try:
vobject_items = tuple(vobject.readComponents( vobject_items = tuple(vobject.readComponents(