/usr/lib/python2.7/dist-packages/trytond/cache.py is in tryton-server 3.4.0-3+deb8u3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 | #This file is part of Tryton. The COPYRIGHT file at the top level of
#this repository contains the full copyright notices and license terms.
from threading import Lock
from collections import OrderedDict
from sql import Table
from sql.functions import Now
from trytond.transaction import Transaction
__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):
with Transaction().new_cursor():
cursor = Transaction().cursor
table = Table('ir_cache')
cursor.execute(*table.select(table.timestamp, table.name))
timestamps = {}
for timestamp, name in cursor.fetchall():
timestamps[name] = timestamp
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):
with Cache._resets_lock:
Cache._resets.setdefault(dbname, set())
Cache._resets[dbname].add(name)
@staticmethod
def resets(dbname):
with Transaction().new_cursor():
cursor = Transaction().cursor
table = Table('ir_cache')
with Cache._resets_lock:
Cache._resets.setdefault(dbname, set())
for name in Cache._resets[dbname]:
cursor.execute(*table.select(table.name,
where=table.name == name))
if cursor.fetchone():
# It would be better to insert only
cursor.execute(*table.update([table.timestamp],
[Now()], where=table.name == name))
else:
cursor.execute(*table.insert(
[table.timestamp, table.name],
[[Now(), name]]))
Cache._resets[dbname].clear()
cursor.commit()
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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