File operations always raise a ENOENT error when a file doesn't exist.
Checking the file exists before the operation adds a race condition
condition where the file could be removed between operations. As the
operation already raises an error on a missing file, avoid this race and
avoid checking the file exists twice. Instead only check a file exists
by catching the ENOENT error.
This also fixes a possible data eviction race condition between
setting and getting a key. Another thread could remove the key
before get_and_set() accesses it again. In this case, now the
default value will be returned instead of None.
The original intent in refs #20536 was to use the highest protocol.
Calling zlib.compress() with a compression level of -1 seems to
fall back to the default level of 6.
The new signature enables better support for routing RunPython and
RunSQL operations, especially w.r.t. reusable and third-party apps.
This commit also takes advantage of the deprecation cycle for the old
signature to remove the backward incompatibility introduced in #22583;
RunPython and RunSQL won't call allow_migrate() when when the router
has the old signature.
Thanks Aymeric Augustin and Tim Graham for helping shape up the patch.
Refs 22583.
Default Memcached configuration allows for a maximum object of 1MB and
will fail to set the key if it is too large. The key will be deleted from
memcached if it fails to be set. This is needed to avoid an issue with
cache_db session backend using the old value stored in memcached, instead
of the newer value stored in the database.
This feature allows the default `TIMEOUT` Cache argument to be set to `None`,
so that cache instances can set a non-expiring key as the default,
instead of using the default value of 5 minutes.
Previously, this was possible only by passing `None` as an argument to
the set() method of objects of type `BaseCache` (and subtypes).
This commit touchs various parts of the code base and test framework. Any
found usage of opening a cursor for the sake of initializing a connection
has been replaced with 'ensure_connection()'.
Thanks Curtis Malony and Florian Apolloner.
Squashed commit of the following:
commit 3380495e93
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sat Nov 23 14:18:07 2013 +0100
Looked up the template_fragments cache at runtime.
commit 905a74f52b
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sat Nov 23 14:19:48 2013 +0100
Removed all uses of create_cache.
Refactored the cache tests significantly.
Made it safe to override the CACHES setting.
commit 35e289fe92
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sat Nov 23 12:23:57 2013 +0100
Removed create_cache function.
commit 8e274f747a
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sat Nov 23 12:04:52 2013 +0100
Updated docs to describe a simplified cache backend API.
commit ee7eb0f73e
Author: Curtis Maloney <curtis@tinbrain.net>
Date: Sat Oct 19 09:49:24 2013 +1100
Fixed#21012 -- Thread-local caches, like databases.
* Safer for use in multiprocess environments
* Better random culling
* Cache files use less disk space
* Safer delete behavior
Also fixed#15806, fixed#15825.
The precision of time.time() is OS specific and it is possible for the
resolution to be low enough to allow reading a cache key previously set
with a timeout of 0.