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Unified Diff: third_party/logilab/logilab/common/cache.py

Issue 1920403002: [content/test/gpu] Run pylint check of gpu tests in unittest instead of PRESUBMIT (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Update path to LICENSE.txt of logilab/README.chromium Created 4 years, 7 months ago
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Index: third_party/logilab/logilab/common/cache.py
diff --git a/third_party/logilab/logilab/common/cache.py b/third_party/logilab/logilab/common/cache.py
new file mode 100644
index 0000000000000000000000000000000000000000..11ed1370d581852a5722747437574c2843e5deec
--- /dev/null
+++ b/third_party/logilab/logilab/common/cache.py
@@ -0,0 +1,114 @@
+# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
+# This file is part of logilab-common.
+#
+# logilab-common is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation, either version 2.1 of the License, or (at your option) any
+# later version.
+#
+# logilab-common is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with logilab-common. If not, see <http://www.gnu.org/licenses/>.
+"""Cache module, with a least recently used algorithm for the management of the
+deletion of entries.
+
+
+
+
+"""
+__docformat__ = "restructuredtext en"
+
+from threading import Lock
+
+from logilab.common.decorators import locked
+
+_marker = object()
+
+class Cache(dict):
+ """A dictionary like cache.
+
+ inv:
+ len(self._usage) <= self.size
+ len(self.data) <= self.size
+ """
+
+ def __init__(self, size=100):
+ """ Warning : Cache.__init__() != dict.__init__().
+ Constructor does not take any arguments beside size.
+ """
+ assert size >= 0, 'cache size must be >= 0 (0 meaning no caching)'
+ self.size = size
+ self._usage = []
+ self._lock = Lock()
+ super(Cache, self).__init__()
+
+ def _acquire(self):
+ self._lock.acquire()
+
+ def _release(self):
+ self._lock.release()
+
+ def _update_usage(self, key):
+ if not self._usage:
+ self._usage.append(key)
+ elif self._usage[-1] != key:
+ try:
+ self._usage.remove(key)
+ except ValueError:
+ # we are inserting a new key
+ # check the size of the dictionary
+ # and remove the oldest item in the cache
+ if self.size and len(self._usage) >= self.size:
+ super(Cache, self).__delitem__(self._usage[0])
+ del self._usage[0]
+ self._usage.append(key)
+ else:
+ pass # key is already the most recently used key
+
+ def __getitem__(self, key):
+ value = super(Cache, self).__getitem__(key)
+ self._update_usage(key)
+ return value
+ __getitem__ = locked(_acquire, _release)(__getitem__)
+
+ def __setitem__(self, key, item):
+ # Just make sure that size > 0 before inserting a new item in the cache
+ if self.size > 0:
+ super(Cache, self).__setitem__(key, item)
+ self._update_usage(key)
+ __setitem__ = locked(_acquire, _release)(__setitem__)
+
+ def __delitem__(self, key):
+ super(Cache, self).__delitem__(key)
+ self._usage.remove(key)
+ __delitem__ = locked(_acquire, _release)(__delitem__)
+
+ def clear(self):
+ super(Cache, self).clear()
+ self._usage = []
+ clear = locked(_acquire, _release)(clear)
+
+ def pop(self, key, default=_marker):
+ if key in self:
+ self._usage.remove(key)
+ #if default is _marker:
+ # return super(Cache, self).pop(key)
+ return super(Cache, self).pop(key, default)
+ pop = locked(_acquire, _release)(pop)
+
+ def popitem(self):
+ raise NotImplementedError()
+
+ def setdefault(self, key, default=None):
+ raise NotImplementedError()
+
+ def update(self, other):
+ raise NotImplementedError()
+
+
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