Initial YakPanel commit

class/cachelib/redis.py

@@ -0,0 +1,154 @@
+# -*- coding: utf-8 -*-
+from __future__ import absolute_import
+try:
+    import cPickle as pickle
+except ImportError:  # pragma: no cover
+    import pickle
+
+from cachelib.base import BaseCache, _items
+from cachelib._compat import string_types, integer_types
+
+
+class RedisCache(BaseCache):
+    """Uses the Redis key-value store as a cache backend.
+
+    The first argument can be either a string denoting address of the Redis
+    server or an object resembling an instance of a redis.Redis class.
+
+    Note: Python Redis API already takes care of encoding unicode strings on
+    the fly.
+
+    :param host: address of the Redis server or an object which API is
+                 compatible with the official Python Redis client (redis-py).
+    :param port: port number on which Redis server listens for connections.
+    :param password: password authentication for the Redis server.
+    :param db: db (zero-based numeric index) on Redis Server to connect.
+    :param default_timeout: the default timeout that is used if no timeout is
+                            specified on :meth:`~BaseCache.set`. A timeout of
+                            0 indicates that the cache never expires.
+    :param key_prefix: A prefix that should be added to all keys.
+
+    Any additional keyword arguments will be passed to ``redis.Redis``.
+    """
+
+    def __init__(self, host='localhost', port=6379, password=None,
+                 db=0, default_timeout=300, key_prefix=None, **kwargs):
+        BaseCache.__init__(self, default_timeout)
+        if host is None:
+            raise ValueError('RedisCache host parameter may not be None')
+        if isinstance(host, string_types):
+            try:
+                import redis
+            except ImportError:
+                raise RuntimeError('no redis module found')
+            if kwargs.get('decode_responses', None):
+                raise ValueError('decode_responses is not supported by '
+                                 'RedisCache.')
+            self._client = redis.Redis(host=host, port=port, password=password,
+                                       db=db, **kwargs)
+        else:
+            self._client = host
+        self.key_prefix = key_prefix or ''
+
+    def _normalize_timeout(self, timeout):
+        timeout = BaseCache._normalize_timeout(self, timeout)
+        if timeout == 0:
+            timeout = -1
+        return timeout
+
+    def dump_object(self, value):
+        """Dumps an object into a string for redis.  By default it serializes
+        integers as regular string and pickle dumps everything else.
+        """
+        t = type(value)
+        if t in integer_types:
+            return str(value).encode('ascii')
+        return b'!' + pickle.dumps(value)
+
+    def load_object(self, value):
+        """The reversal of :meth:`dump_object`.  This might be called with
+        None.
+        """
+        if value is None:
+            return None
+        if value.startswith(b'!'):
+            try:
+                return pickle.loads(value[1:])
+            except pickle.PickleError:
+                return None
+        try:
+            return int(value)
+        except ValueError:
+            # before 0.8 we did not have serialization.  Still support that.
+            return value
+
+    def get(self, key):
+        return self.load_object(self._client.get(self.key_prefix + key))
+
+    def get_many(self, *keys):
+        if self.key_prefix:
+            keys = [self.key_prefix + key for key in keys]
+        return [self.load_object(x) for x in self._client.mget(keys)]
+
+    def set(self, key, value, timeout=None):
+        timeout = self._normalize_timeout(timeout)
+        dump = self.dump_object(value)
+        if timeout == -1:
+            result = self._client.set(name=self.key_prefix + key,
+                                      value=dump)
+        else:
+            result = self._client.setex(name=self.key_prefix + key,
+                                        value=dump, time=timeout)
+        return result
+
+    def add(self, key, value, timeout=None):
+        timeout = self._normalize_timeout(timeout)
+        dump = self.dump_object(value)
+        return (
+            self._client.setnx(name=self.key_prefix + key, value=dump) and
+            self._client.expire(name=self.key_prefix + key, time=timeout)
+        )
+
+    def set_many(self, mapping, timeout=None):
+        timeout = self._normalize_timeout(timeout)
+        # Use transaction=False to batch without calling redis MULTI
+        # which is not supported by twemproxy
+        pipe = self._client.pipeline(transaction=False)
+
+        for key, value in _items(mapping):
+            dump = self.dump_object(value)
+            if timeout == -1:
+                pipe.set(name=self.key_prefix + key, value=dump)
+            else:
+                pipe.setex(name=self.key_prefix + key, value=dump,
+                           time=timeout)
+        return pipe.execute()
+
+    def delete(self, key):
+        return self._client.delete(self.key_prefix + key)
+
+    def delete_many(self, *keys):
+        if not keys:
+            return
+        if self.key_prefix:
+            keys = [self.key_prefix + key for key in keys]
+        return self._client.delete(*keys)
+
+    def has(self, key):
+        return self._client.exists(self.key_prefix + key)
+
+    def clear(self):
+        status = False
+        if self.key_prefix:
+            keys = self._client.keys(self.key_prefix + '*')
+            if keys:
+                status = self._client.delete(*keys)
+        else:
+            status = self._client.flushdb()
+        return status
+
+    def inc(self, key, delta=1):
+        return self._client.incr(name=self.key_prefix + key, amount=delta)
+
+    def dec(self, key, delta=1):
+        return self._client.decr(name=self.key_prefix + key, amount=delta)