# (c) 2014, Brian Coca, Josh Drake, et al # (c) 2017 Ansible Project # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt) from __future__ import (absolute_import, division, print_function) __metaclass__ = type DOCUMENTATION = ''' cache: memcached short_description: Use memcached DB for cache description: - This cache uses JSON formatted, per host records saved in memcached. version_added: "1.9" requirements: - memcache (python lib) options: _uri: description: - List of connection information for the memcached DBs default: ['127.0.0.1:11211'] type: list env: - name: ANSIBLE_CACHE_PLUGIN_CONNECTION ini: - key: fact_caching_connection section: defaults _prefix: description: User defined prefix to use when creating the DB entries env: - name: ANSIBLE_CACHE_PLUGIN_PREFIX ini: - key: fact_caching_prefix section: defaults _timeout: default: 86400 description: Expiration timeout for the cache plugin data env: - name: ANSIBLE_CACHE_PLUGIN_TIMEOUT ini: - key: fact_caching_timeout section: defaults type: integer ''' import collections import os import time from multiprocessing import Lock from itertools import chain from ansible import constants as C from ansible.errors import AnsibleError from ansible.plugins.cache import BaseCacheModule try: import memcache except ImportError: raise AnsibleError("python-memcached is required for the memcached fact cache") 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 = 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 = {} self._db = ProxyClientPool(connection, debug=0) self._keys = CacheModuleKeys(self._db, self._db.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): if key not in self._cache: value = self._db.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 self._cache[key] = value return self._cache.get(key) def set(self, key, value): self._db.set(self._make_key(key), value, time=self._timeout, min_compress_len=1) self._cache[key] = value 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): del self._cache[key] self._db.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() def __getstate__(self): return dict() def __setstate__(self, data): self.__init__()