mirror of
https://github.com/sprockets/sprockets.clients.memcached.git
synced 2024-11-25 19:29:52 +00:00
151 lines
6.1 KiB
Python
151 lines
6.1 KiB
Python
"""
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Memcache Client API
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===================
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The memcache client API wraps the :py:class:`memcache.Client` adding
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environment variable based configuration.
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Example environment variable configuration:
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``<PREFIX>_MEMCACHED_SERVERS = '10.0.0.1:11211:64,10.0.0.2:11211:64'``
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"""
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import logging
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import os
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import pickle
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import memcache
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version_info = (0, 0, 0)
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__version__ = '.'.join(str(v) for v in version_info)
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LOGGER = logging.getLogger(__name__)
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DEFAULT_SERVER = '127.0.0.1:11211'
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from memcache import _DEAD_RETRY
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from memcache import _SOCKET_TIMEOUT
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from memcache import SERVER_MAX_KEY_LENGTH
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from memcache import SERVER_MAX_VALUE_LENGTH
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def _get_servers(prefix):
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"""Return the list of memcached servers from the environment variable
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value, defaulting to ``DEFAULT_SERVER`` if it is not set.
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If prefix is not set, then the environment variable ``MEMCACHED_SERVERS``
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will be be used. If both ``<PREFIX>_MEMCACHED_SERVERS`` and
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``MEMCACHED_SERVERS`` are not set, the default server value of
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``127.0.0.1`` will be returned.
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:param str prefix: The environment variable prefix
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:rtype: list
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"""
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key = '%s_MEMCACHED_SERVERS' % prefix if prefix else 'MEMCACHED_SERVERS'
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return os.environ.get(key, DEFAULT_SERVER).split(',')
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class Client(memcache.Client):
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"""Wraps :py:class:`memcache.Client`, passing in the environment
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variable prefix. If prefix is set, the environment variable key is in the
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format ``<PREFIX>_MEMCACHED_SERVERS``. If the prefix is not set, the list
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will attempt to be retrieved from the ``MEMCACHED_SERVERS``. If neither
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environment variable is set, the default value of ``127.0.0.1:11211`` is
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used.
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The per server format in the comma separated list is:
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``[HOST]:[PORT]<:WEIGHT>``
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Where host and port are required but weight is optional.
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:param str prefix: The environment variable prefix. Default: ``None``
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:param int debug: Display error messages when a server can't be contacted.
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Default: ``0``
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:param int pickle_protocol: number to mandate protocol used by (c)Pickle.
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:param pickler: optional override of default Pickler for subclassing
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:type pickler: :py:class:`pickle.Pickler`
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:param unpickler: optional override of default Unpickler for subclassing
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:type unpickler: :py:class:`pickle.Unpickler`
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:param pload: optional persistent_load function to call on pickle loading
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:type pload: :py:meth:`pickle.loads`
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:param str pid: optional persistent_id function to call on pickle storing
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:param int dead_retry: Number of seconds before retrying a blacklisted
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server. Default: ``30``
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:param int socket_timeout: Timeout in seconds for all calls to a server.
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Default: ``3``
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:param server_max_key_length: Data that is larger than this will not be
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sent to the server.
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Default: ``SERVER_MAX_KEY_LENGTH``
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:type server_max_key_length: int
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:param server_max_value_length: Data that is larger than this will not be
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sent to the server.
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Default: ``SERVER_MAX_VALUE_LENGTH``
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:type server_max_value_length: int
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:param bool cache_cas: If true, cas operations will be cached. WARNING:
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This cache is not expired internally, if you have
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a long-running process you will need to expire it
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manually via :py:meth:`Client.reset_cas`, or the
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cache can grow unlimited.
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Default: ``False``
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:param int flush_on_reconnect: Optional flag which prevents a scenario
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that can cause stale data to be read. If
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there is more than one memcached server
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and the connection to one is interrupted,
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keys that mapped to that server will get
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reassigned to another. If the first server
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comes back, those keys will map to it
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again. If it still has its data, ``get()``
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can read stale data that was overwritten
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on another server. This flag is off by
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default for backwards compatibility.
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Default: ``0``
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:param bool check_keys: If ``True``, the key is checked to ensure it is
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the correct length and composed of the right
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characters.
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Default: ``True``
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"""
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def __init__(self,
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prefix=None,
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debug=0,
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pickle_protocol=0,
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pickler=pickle.Pickler,
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unpickler=pickle.Unpickler,
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pload=None,
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pid=None,
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server_max_key_length=SERVER_MAX_KEY_LENGTH,
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server_max_value_length=SERVER_MAX_VALUE_LENGTH,
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dead_retry=_DEAD_RETRY,
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socket_timeout=_SOCKET_TIMEOUT,
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cache_cas=False,
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flush_on_reconnect=0,
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check_keys=True):
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servers = _get_servers(prefix.upper() if prefix else '')
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LOGGER.debug('Connecting to %r', servers)
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super(Client, self).__init__(servers,
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debug,
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pickle_protocol,
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pickler,
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unpickler,
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pload,
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pid,
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server_max_key_length,
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server_max_value_length,
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dead_retry,
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socket_timeout,
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cache_cas,
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flush_on_reconnect,
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check_keys)
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