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# (c) 2014, Brian Coca, Josh Drake, et al
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
import collections
import os
import sys
import time
import threading
from itertools import chain
from ansible import constants as C
from ansible.cache.base import BaseCacheModule
try:
import memcache
except ImportError:
print 'python-memcached is required for the memcached fact cache'
sys.exit(1)
class ProxyClientPool(object):
"""
Memcached connection pooling for thread/fork safety. Inspired by py-redis
connection pool.
Available connections are maintained in a deque and released in a FIFO manner.
"""
def __init__(self, *args, **kwargs):
self.max_connections = kwargs.pop('max_connections', 1024)
self.connection_args = args
self.connection_kwargs = kwargs
self.reset()
def reset(self):
self.pid = os.getpid()
self._num_connections = 0
self._available_connections = collections.deque(maxlen=self.max_connections)
self._locked_connections = set()
self._lock = threading.Lock()
def _check_safe(self):
if self.pid != os.getpid():
with self._lock:
if self.pid == os.getpid():
# bail out - another thread already acquired the lock
return
self.disconnect_all()
self.reset()
def get_connection(self):
self._check_safe()
try:
connection = self._available_connections.popleft()
except IndexError:
connection = self.create_connection()
self._locked_connections.add(connection)
return connection
def create_connection(self):
if self._num_connections >= self.max_connections:
raise RuntimeError("Too many memcached connections")
self._num_connections += 1
return memcache.Client(*self.connection_args, **self.connection_kwargs)
def release_connection(self, connection):
self._check_safe()
self._locked_connections.remove(connection)
self._available_connections.append(connection)
def disconnect_all(self):
for conn in chain(self._available_connections, self._locked_connections):
conn.disconnect_all()
def __getattr__(self, name):
def wrapped(*args, **kwargs):
return self._proxy_client(name, *args, **kwargs)
return wrapped
def _proxy_client(self, name, *args, **kwargs):
conn = self.get_connection()
try:
return getattr(conn, name)(*args, **kwargs)
finally:
self.release_connection(conn)
class CacheModuleKeys(collections.MutableSet):
"""
A set subclass that keeps track of insertion time and persists
the set in memcached.
"""
PREFIX = 'ansible_cache_keys'
def __init__(self, cache, *args, **kwargs):
self._cache = cache
self._keyset = dict(*args, **kwargs)
def __contains__(self, key):
return key in self._keyset
def __iter__(self):
return iter(self._keyset)
def __len__(self):
return len(self._keyset)
def add(self, key):
self._keyset[key] = time.time()
self._cache.set(self.PREFIX, self._keyset)
def discard(self, key):
del self._keyset[key]
self._cache.set(self.PREFIX, self._keyset)
def remove_by_timerange(self, s_min, s_max):
for k in self._keyset.keys():
t = self._keyset[k]
if s_min < t < s_max:
del self._keyset[k]
self._cache.set(self.PREFIX, self._keyset)
class CacheModule(BaseCacheModule):
def __init__(self, *args, **kwargs):
if C.CACHE_PLUGIN_CONNECTION:
connection = C.CACHE_PLUGIN_CONNECTION.split(',')
else:
connection = ['127.0.0.1:11211']
self._timeout = C.CACHE_PLUGIN_TIMEOUT
self._prefix = C.CACHE_PLUGIN_PREFIX
self._cache = ProxyClientPool(connection, debug=0)
self._keys = CacheModuleKeys(self._cache, self._cache.get(CacheModuleKeys.PREFIX) or [])
def _make_key(self, key):
return "{0}{1}".format(self._prefix, key)
def _expire_keys(self):
if self._timeout > 0:
expiry_age = time.time() - self._timeout
self._keys.remove_by_timerange(0, expiry_age)
def get(self, key):
value = self._cache.get(self._make_key(key))
# guard against the key not being removed from the keyset;
# this could happen in cases where the timeout value is changed
# between invocations
if value is None:
self.delete(key)
raise KeyError
return value
def set(self, key, value):
self._cache.set(self._make_key(key), value, time=self._timeout, min_compress_len=1)
self._keys.add(key)
def keys(self):
self._expire_keys()
return list(iter(self._keys))
def contains(self, key):
self._expire_keys()
return key in self._keys
def delete(self, key):
self._cache.delete(self._make_key(key))
self._keys.discard(key)
def flush(self):
for key in self.keys():
self.delete(key)
def copy(self):
return self._keys.copy()
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