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from .._compat import PY2
from beaker.container import NamespaceManager, Container
from beaker.crypto.util import sha1
from beaker.exceptions import InvalidCacheBackendError, MissingCacheParameter
from beaker.synchronization import file_synchronizer
from beaker.util import verify_directory, SyncDict, parse_memcached_behaviors
import warnings
MAX_KEY_LENGTH = 250
_client_libs = {}
def _load_client(name='auto'):
if name in _client_libs:
return _client_libs[name]
def _pylibmc():
global pylibmc
import pylibmc
return pylibmc
def _cmemcache():
global cmemcache
import cmemcache
warnings.warn("cmemcache is known to have serious "
"concurrency issues; consider using 'memcache' "
"or 'pylibmc'")
return cmemcache
def _memcache():
global memcache
import memcache
return memcache
def _bmemcached():
global bmemcached
import bmemcached
return bmemcached
def _auto():
for _client in (_pylibmc, _cmemcache, _memcache, _bmemcached):
try:
return _client()
except ImportError:
pass
else:
raise InvalidCacheBackendError(
"Memcached cache backend requires one "
"of: 'pylibmc' or 'memcache' to be installed.")
clients = {
'pylibmc': _pylibmc,
'cmemcache': _cmemcache,
'memcache': _memcache,
'bmemcached': _bmemcached,
'auto': _auto
}
_client_libs[name] = clib = clients[name]()
return clib
def _is_configured_for_pylibmc(memcache_module_config, memcache_client):
return memcache_module_config == 'pylibmc' or \
memcache_client.__name__.startswith('pylibmc')
class MemcachedNamespaceManager(NamespaceManager):
"""Provides the :class:`.NamespaceManager` API over a memcache client library."""
clients = SyncDict()
def __new__(cls, *args, **kw):
memcache_module = kw.pop('memcache_module', 'auto')
memcache_client = _load_client(memcache_module)
if _is_configured_for_pylibmc(memcache_module, memcache_client):
return object.__new__(PyLibMCNamespaceManager)
else:
return object.__new__(MemcachedNamespaceManager)
def __init__(self, namespace, url,
memcache_module='auto',
data_dir=None, lock_dir=None,
**kw):
NamespaceManager.__init__(self, namespace)
_memcache_module = _client_libs[memcache_module]
if not url:
raise MissingCacheParameter("url is required")
self.lock_dir = None
if lock_dir:
self.lock_dir = lock_dir
elif data_dir:
self.lock_dir = data_dir + "/container_mcd_lock"
if self.lock_dir:
verify_directory(self.lock_dir)
# Check for pylibmc namespace manager, in which case client will be
# instantiated by subclass __init__, to handle behavior passing to the
# pylibmc client
if not _is_configured_for_pylibmc(memcache_module, _memcache_module):
self.mc = MemcachedNamespaceManager.clients.get(
(memcache_module, url),
_memcache_module.Client,
url.split(';'))
def get_creation_lock(self, key):
return file_synchronizer(
identifier="memcachedcontainer/funclock/%s/%s" %
(self.namespace, key), lock_dir=self.lock_dir)
def _format_key(self, key):
if not isinstance(key, str):
key = key.decode('ascii')
formated_key = (self.namespace + '_' + key).replace(' ', '\302\267')
if len(formated_key) > MAX_KEY_LENGTH:
if not PY2:
formated_key = formated_key.encode('utf-8')
formated_key = sha1(formated_key).hexdigest()
return formated_key
def __getitem__(self, key):
return self.mc.get(self._format_key(key))
def __contains__(self, key):
value = self.mc.get(self._format_key(key))
return value is not None
def has_key(self, key):
return key in self
def set_value(self, key, value, expiretime=None):
if expiretime:
self.mc.set(self._format_key(key), value, time=expiretime)
else:
self.mc.set(self._format_key(key), value)
def __setitem__(self, key, value):
self.set_value(key, value)
def __delitem__(self, key):
self.mc.delete(self._format_key(key))
def do_remove(self):
self.mc.flush_all()
def keys(self):
raise NotImplementedError(
"Memcache caching does not "
"support iteration of all cache keys")
class PyLibMCNamespaceManager(MemcachedNamespaceManager):
"""Provide thread-local support for pylibmc."""
pools = SyncDict()
def __init__(self, *arg, **kw):
super(PyLibMCNamespaceManager, self).__init__(*arg, **kw)
memcache_module = kw.get('memcache_module', 'auto')
_memcache_module = _client_libs[memcache_module]
protocol = kw.get('protocol', 'text')
username = kw.get('username', None)
password = kw.get('password', None)
url = kw.get('url')
behaviors = parse_memcached_behaviors(kw)
self.mc = MemcachedNamespaceManager.clients.get(
(memcache_module, url),
_memcache_module.Client,
servers=url.split(';'), behaviors=behaviors,
binary=(protocol == 'binary'), username=username,
password=password)
self.pool = PyLibMCNamespaceManager.pools.get(
(memcache_module, url),
pylibmc.ThreadMappedPool, self.mc)
def __getitem__(self, key):
with self.pool.reserve() as mc:
return mc.get(self._format_key(key))
def __contains__(self, key):
with self.pool.reserve() as mc:
value = mc.get(self._format_key(key))
return value is not None
def has_key(self, key):
return key in self
def set_value(self, key, value, expiretime=None):
with self.pool.reserve() as mc:
if expiretime:
mc.set(self._format_key(key), value, time=expiretime)
else:
mc.set(self._format_key(key), value)
def __setitem__(self, key, value):
self.set_value(key, value)
def __delitem__(self, key):
with self.pool.reserve() as mc:
mc.delete(self._format_key(key))
def do_remove(self):
with self.pool.reserve() as mc:
mc.flush_all()
class MemcachedContainer(Container):
"""Container class which invokes :class:`.MemcacheNamespaceManager`."""
namespace_class = MemcachedNamespaceManager
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