/usr/lib/python2.7/dist-packages/trytond/cache.py is in tryton-server 3.0.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#this repository contains the full copyright notices and license terms.
import datetime
from threading import Lock
from trytond.transaction import Transaction
from trytond.config import CONFIG
from trytond import backend
from trytond.tools import OrderedDict
__all__ = ['Cache', 'LRUDict']
def freeze(o):
if isinstance(o, (set, tuple, list)):
return tuple(freeze(x) for x in o)
elif isinstance(o, dict):
return frozenset((x, freeze(y)) for x, y in o.iteritems())
else:
return o
class Cache(object):
"""
A key value LRU cache with size limit.
"""
_cache_instance = []
_resets = {}
_resets_lock = Lock()
def __init__(self, name, size_limit=1024, context=True):
self.size_limit = size_limit
self.context = context
self._cache = {}
self._cache_instance.append(self)
self._name = name
self._timestamp = None
self._lock = Lock()
def _key(self, key):
if self.context:
return (key, Transaction().user, freeze(Transaction().context))
return key
def get(self, key, default=None):
cursor = Transaction().cursor
key = self._key(key)
with self._lock:
cache = self._cache.setdefault(cursor.dbname,
LRUDict(self.size_limit))
try:
result = cache[key] = cache.pop(key)
return result
except (KeyError, TypeError):
return default
def set(self, key, value):
cursor = Transaction().cursor
key = self._key(key)
with self._lock:
cache = self._cache.setdefault(cursor.dbname,
LRUDict(self.size_limit))
try:
cache[key] = value
except TypeError:
pass
return value
def clear(self):
cursor = Transaction().cursor
Cache.reset(cursor.dbname, self._name)
with self._lock:
self._cache[cursor.dbname] = LRUDict(self.size_limit)
@staticmethod
def clean(dbname):
if not CONFIG['multi_server']:
return
database = backend.get('Database')(dbname).connect()
cursor = database.cursor()
try:
cursor.execute('SELECT "timestamp", "name" FROM ir_cache')
timestamps = {}
for timestamp, name in cursor.fetchall():
timestamps[name] = timestamp
finally:
cursor.commit()
cursor.close()
for inst in Cache._cache_instance:
if inst._name in timestamps:
with inst._lock:
if (not inst._timestamp
or timestamps[inst._name] > inst._timestamp):
inst._timestamp = timestamps[inst._name]
inst._cache[dbname] = LRUDict(inst.size_limit)
@staticmethod
def reset(dbname, name):
if not CONFIG['multi_server']:
return
with Cache._resets_lock:
Cache._resets.setdefault(dbname, set())
Cache._resets[dbname].add(name)
@staticmethod
def resets(dbname):
if not CONFIG['multi_server']:
return
database = backend.get('Database')(dbname).connect()
cursor = database.cursor()
try:
with Cache._resets_lock:
Cache._resets.setdefault(dbname, set())
for name in Cache._resets[dbname]:
cursor.execute('SELECT name FROM ir_cache WHERE name = %s',
(name,))
if cursor.fetchone():
# It would be better to insert only
cursor.execute('UPDATE ir_cache SET "timestamp" = %s '
'WHERE name = %s', (datetime.datetime.now(), name))
else:
cursor.execute('INSERT INTO ir_cache '
'("timestamp", "name") '
'VALUES (%s, %s)', (datetime.datetime.now(), name))
Cache._resets[dbname].clear()
finally:
cursor.commit()
cursor.close()
class LRUDict(OrderedDict):
"""
Dictionary with a size limit.
If size limit is reached, it will remove the first added items.
"""
def __init__(self, size_limit, *args, **kwargs):
assert size_limit > 0
self.size_limit = size_limit
super(LRUDict, self).__init__(*args, **kwargs)
self._check_size_limit()
def __setitem__(self, key, value):
super(LRUDict, self).__setitem__(key, value)
self._check_size_limit()
def update(self, *args, **kwargs):
super(LRUDict, self).update(*args, **kwargs)
self._check_size_limit()
def setdefault(self, key, default=None):
default = super(LRUDict, self).setdefault(key, default=default)
self._check_size_limit()
return default
def _check_size_limit(self):
while len(self) > self.size_limit:
self.popitem(last=False)
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