fakeredis.py

import random
import warnings
import copy
from ctypes import CDLL, POINTER, c_double, c_char_p, pointer
from ctypes.util import find_library
import fnmatch
from collections import MutableMapping
from datetime import datetime, timedelta
import operator
import sys
import time
import types
import re

import redis
from redis.exceptions import ResponseError
import redis.client

try:
    # Python 2.6, 2.7
    from Queue import Queue, Empty
except:
    # Python 3
    from queue import Queue, Empty

PY2 = sys.version_info[0] == 2

if not PY2:
    long = int


__version__ = '0.8.2'


if sys.version_info[0] == 2:
    text_type = unicode
    string_types = (str, unicode)
    redis_string_types = (str, unicode, bytes)
    byte_to_int = ord
    int_to_byte = chr

    def to_bytes(x, charset=sys.getdefaultencoding(), errors='strict'):
        if isinstance(x, (bytes, bytearray, buffer)) or hasattr(x, '__str__'):
            return bytes(x)
        if isinstance(x, unicode):
            return x.encode(charset, errors)
        if hasattr(x, '__unicode__'):
            return unicode(x).encode(charset, errors)
        raise TypeError('expected bytes or unicode, not ' + type(x).__name__)

    def to_native(x, charset=sys.getdefaultencoding(), errors='strict'):
        if x is None or isinstance(x, str):
            return x
        return x.encode(charset, errors)

    iterkeys = lambda d: d.iterkeys()
    itervalues = lambda d: d.itervalues()
    iteritems = lambda d: d.iteritems()
    from urlparse import urlparse
else:
    basestring = str
    text_type = str
    string_types = (str,)
    redis_string_types = (bytes, str)

    def byte_to_int(b):
        if isinstance(b, int):
            return b
        raise TypeError('an integer is required')

    int_to_byte = operator.methodcaller('to_bytes', 1, 'big')

    def to_bytes(x, charset=sys.getdefaultencoding(), errors='strict'):
        if isinstance(x, (bytes, bytearray, memoryview)):
            return bytes(x)
        if isinstance(x, str):
            return x.encode(charset, errors)
        if hasattr(x, '__str__'):
            return str(x).encode(charset, errors)
        raise TypeError('expected bytes or str, not ' + type(x).__name__)

    def to_native(x, charset=sys.getdefaultencoding(), errors='strict'):
        if x is None or isinstance(x, str):
            return x
        return x.decode(charset, errors)

    iterkeys = lambda d: iter(d.keys())
    itervalues = lambda d: iter(d.values())
    iteritems = lambda d: iter(d.items())
    from urllib.parse import urlparse


DATABASES = {}

_libc_library = find_library('c') or find_library('msvcrt')

if not _libc_library:
    raise ImportError('fakeredis: unable to find libc or equivalent')

_libc = CDLL(_libc_library)
_libc.strtod.restype = c_double
_libc.strtod.argtypes = [c_char_p, POINTER(c_char_p)]
_strtod = _libc.strtod


def timedelta_total_seconds(delta):
    return delta.days * 86400 + delta.seconds + delta.microseconds / 1E6


class _StrKeyDict(MutableMapping):
    def __init__(self, *args, **kwargs):
        self._dict = dict(*args, **kwargs)
        self._ex_keys = {}

    def __getitem__(self, key):
        self._update_expired_keys()
        return self._dict[to_bytes(key)]

    def __setitem__(self, key, value):
        self._dict[to_bytes(key)] = value

    def __delitem__(self, key):
        del self._dict[to_bytes(key)]

    def __len__(self):
        return len(self._dict)

    def __iter__(self):
        return iter(self._dict)

    def expire(self, key, timestamp):
        self._ex_keys[key] = timestamp

    def persist(self, key):
        try:
            del self._ex_keys[key]
        except KeyError:
            pass

    def expiring(self, key):
        if key not in self._ex_keys:
            return None
        return self._ex_keys[key]

    def _update_expired_keys(self):
        now = datetime.now()
        deleted = []
        for key in self._ex_keys:
            if now > self._ex_keys[key]:
                deleted.append(key)

        for key in deleted:
            del self._ex_keys[key]
            del self[key]

    def copy(self):
        new_copy = _StrKeyDict()
        for key, value in self._dict.items():
            new_copy[key] = value
        return new_copy

    def clear(self):
        super(_StrKeyDict, self).clear()
        self._ex_keys.clear()

    def to_bare_dict(self):
        return copy.deepcopy(self._dict)


class _ZSet(_StrKeyDict):
    redis_type = b'zset'


class _Hash(_StrKeyDict):
    redis_type = b'hash'


def DecodeGenerator(gen):
    for item in gen:
        yield _decode(item)


def _decode(value):
    if isinstance(value, bytes):
        value = value.decode()
    elif isinstance(value, dict):
        value = dict((_decode(k), _decode(v)) for k, v in value.items())
    elif isinstance(value, (list, set, tuple)):
        value = value.__class__(_decode(x) for x in value)
    elif isinstance(value, types.GeneratorType):
        value = DecodeGenerator(value)
    return value


def _make_decode_func(func):
    def decode_response(*args, **kwargs):
        val = _decode(func(*args, **kwargs))
        return val
    return decode_response


def _patch_responses(obj):
    for attr_name in dir(obj):
        attr = getattr(obj, attr_name)
        if not callable(attr) or attr_name.startswith('_'):
            continue
        func = _make_decode_func(attr)
        setattr(obj, attr_name, func)


class FakeStrictRedis(object):
    @classmethod
    def from_url(cls, url, db=None, **kwargs):
        url = urlparse(url)
        if db is None:
            try:
                db = int(url.path.replace('/', ''))
            except (AttributeError, ValueError):
                db = 0
        return cls(db=db, **kwargs)

    def __init__(self, db=0, charset='utf-8', errors='strict',
                 decode_responses=False, **kwargs):
        if db not in DATABASES:
            DATABASES[db] = _StrKeyDict()
        self._db = DATABASES[db]
        self._db_num = db
        self._encoding = charset
        self._encoding_errors = errors
        self._pubsubs = []
        self._decode_responses = decode_responses
        if decode_responses:
            _patch_responses(self)

    def flushdb(self):
        DATABASES[self._db_num].clear()
        return True

    def flushall(self):
        for db in DATABASES:
            DATABASES[db].clear()

        del self._pubsubs[:]

    # Basic key commands
    def append(self, key, value):
        self._db.setdefault(key, b'')
        self._db[key] += to_bytes(value)
        return len(self._db[key])

    def bitcount(self, name, start=0, end=-1):
        if end == -1:
            end = None
        else:
            end += 1
        try:
            s = self._db[name][start:end]
            return sum([bin(byte_to_int(l)).count('1') for l in s])
        except KeyError:
            return 0

    def decr(self, name, amount=1):
        try:
            self._db[name] = int(self._db.get(name, '0')) - amount
        except (TypeError, ValueError):
            raise redis.ResponseError("value is not an integer or out of "
                                      "range.")
        return self._db[name]

    def exists(self, name):
        return name in self._db
    __contains__ = exists

    def expire(self, name, time):
        return self._expire(name, time)

    def pexpire(self, name, millis):
        return self._expire(name, millis, 1000)

    def _expire(self, name, time, multiplier=1):
        if isinstance(time, timedelta):
            time = int(timedelta_total_seconds(time) * multiplier)
        if not isinstance(time, int):
            raise redis.ResponseError("value is not an integer or out of "
                                      "range.")
        if self.exists(name):
            self._db.expire(name, datetime.now() +
                            timedelta(seconds=time / float(multiplier)))
            return True
        else:
            return False

    def expireat(self, name, when):
        return self._expireat(name, when)

    def pexpireat(self, name, when):
        return self._expireat(name, when, 1000)

    def _expireat(self, name, when, multiplier=1):
        if not isinstance(when, datetime):
            when = datetime.fromtimestamp(when / float(multiplier))
        if self.exists(name):
            self._db.expire(name, when)
            return True
        else:
            return False

    def echo(self, value):
        if isinstance(value, text_type):
            return value.encode('utf-8')
        return value

    def get(self, name):
        value = self._db.get(name)
        if isinstance(value, _StrKeyDict):
            raise redis.ResponseError("WRONGTYPE Operation against a key "
                                      "holding the wrong kind of value")
        if value is not None:
            return to_bytes(value)

    def __getitem__(self, name):
        return self.get(name)

    def getbit(self, name, offset):
        """Returns a boolean indicating the value of ``offset`` in ``name``"""
        val = self._db.get(name, '\x00')
        byte = offset // 8
        remaining = offset % 8
        actual_bitoffset = 7 - remaining
        try:
            actual_val = byte_to_int(val[byte])
        except IndexError:
            return 0
        return 1 if (1 << actual_bitoffset) & actual_val else 0

    def getset(self, name, value):
        """
        Set the value at key ``name`` to ``value`` if key doesn't exist
        Return the value at key ``name`` atomically
        """
        val = self._db.get(name)
        self._db[name] = value
        return val

    def incr(self, name, amount=1):
        """
        Increments the value of ``key`` by ``amount``.  If no key exists,
        the value will be initialized as ``amount``
        """
        try:
            if not isinstance(amount, int):
                raise redis.ResponseError("value is not an integer or out "
                                          "of range.")
            self._db[name] = to_bytes(int(self._db.get(name, '0')) + amount)
        except (TypeError, ValueError):
            raise redis.ResponseError("value is not an integer or out of "
                                      "range.")
        return int(self._db[name])

    def incrby(self, name, amount=1):
        """
        Alias for command ``incr``
        """
        return self.incr(name, amount)

    def incrbyfloat(self, name, amount=1.0):
        try:
            self._db[name] = float(self._db.get(name, '0')) + amount
        except (TypeError, ValueError):
            raise redis.ResponseError("value is not a valid float.")
        return self._db[name]

    def keys(self, pattern=None):
        return [key for key in self._db
                if not key or not pattern or
                fnmatch.fnmatch(to_native(key), to_native(pattern))]

    def mget(self, keys, *args):
        all_keys = self._list_or_args(keys, args)
        found = []
        if not all_keys:
            raise redis.ResponseError(
                "wrong number of arguments for 'mget' command")
        for key in all_keys:
            found.append(self._db.get(key))
        return found

    def mset(self, *args, **kwargs):
        if args:
            if len(args) != 1 or not isinstance(args[0], dict):
                raise redis.RedisError(
                    'MSET requires **kwargs or a single dict arg')
            kwargs.update(args[0])
        for key, val in iteritems(kwargs):
            self.set(key, val)
        return True

    def msetnx(self, mapping):
        """
        Sets each key in the ``mapping`` dict to its corresponding value if
        none of the keys are already set
        """
        if not any(k in self._db for k in mapping):
            for key, val in iteritems(mapping):
                self.set(key, val)
            return True
        return False

    def move(self, name, db):
        pass

    def persist(self, name):
        self._db.persist(name)

    def ping(self):
        return True

    def randomkey(self):
        pass

    def rename(self, src, dst):
        try:
            value = self._db[src]
        except KeyError:
            raise redis.ResponseError("No such key: %s" % src)
        self._db[dst] = value
        del self._db[src]
        return True

    def renamenx(self, src, dst):
        if dst in self._db:
            return False
        else:
            return self.rename(src, dst)

    def set(self, name, value, ex=None, px=None, nx=False, xx=False):
        if (not nx and not xx) or (nx and self._db.get(name, None) is None) \
                or (xx and not self._db.get(name, None) is None):
            if ex is not None:
                if isinstance(ex, timedelta):
                    ex = ex.seconds + ex.days * 24 * 3600
                if ex < 0:
                    raise ResponseError('invalid expire time in SETEX')
                if ex > 0:
                    self._db.expire(name, datetime.now() +
                                    timedelta(seconds=ex))
            elif px is not None:
                if isinstance(px, timedelta):
                    ms = int(px.microseconds / 1000)
                    px = (px.seconds + px.days * 24 * 3600) * 1000 + ms
                if px < 0:
                    raise ResponseError('invalid expire time in SETEX')
                if px > 0:
                    self._db.expire(name, datetime.now() +
                                    timedelta(milliseconds=px))
            else:
                self._db.persist(name)
            self._db[name] = to_bytes(value)
            return True
        else:
            return None

    __setitem__ = set

    def setbit(self, name, offset, value):
        val = self._db.get(name, b'\x00')
        byte = offset // 8
        remaining = offset % 8
        actual_bitoffset = 7 - remaining
        if len(val) - 1 < byte:
            # We need to expand val so that we can set the appropriate
            # bit.
            needed = byte - (len(val) - 1)
            val += b'\x00' * needed
        if value == 1:
            new_byte = byte_to_int(val[byte]) | (1 << actual_bitoffset)
        else:
            new_byte = byte_to_int(val[byte]) ^ (1 << actual_bitoffset)
        reconstructed = bytearray(val)
        reconstructed[byte] = new_byte
        self._db[name] = bytes(reconstructed)

    def setex(self, name, time, value):
        if isinstance(time, timedelta):
            time = int(timedelta_total_seconds(time))
        if not isinstance(time, int):
            raise ResponseError(
                'value is not an integer or out of range')
        return self.set(name, value, ex=time)

    def psetex(self, name, time_ms, value):
        if isinstance(time_ms, timedelta):
            time_ms = int(timedelta_total_seconds(time_ms) * 1000)
        if time_ms == 0:
            raise ResponseError("invalid expire time in SETEX")
        return self.set(name, value, px=time_ms)

    def setnx(self, name, value):
        result = self.set(name, value, nx=True)
        # Real Redis returns False from setnx, but None from set(nx=...)
        if not result:
            return False
        return result

    def setrange(self, name, offset, value):
        pass

    def strlen(self, name):
        try:
            return len(self._db[name])
        except KeyError:
            return 0

    def substr(self, name, start, end=-1):
        if end == -1:
            end = None
        else:
            end += 1
        try:
            return self._db[name][start:end]
        except KeyError:
            return b''
    # Redis >= 2.0.0 this command is called getrange
    # according to the docs.
    getrange = substr

    def ttl(self, name):
        return self._ttl(name)

    def pttl(self, name):
        return self._ttl(name, 1000)

    def _ttl(self, name, multiplier=1):
        if name not in self._db:
            return -2

        exp_time = self._db.expiring(name)
        if not exp_time:
            return -1

        now = datetime.now()
        if now > exp_time:
            return None
        else:
            return long(round(((exp_time - now).days * 3600 * 24 +
                        (exp_time - now).seconds +
                        (exp_time - now).microseconds / 1E6) * multiplier))

    def type(self, name):
        key = self._db.get(name)
        if hasattr(key.__class__, 'redis_type'):
            return key.redis_type
        if isinstance(key, redis_string_types):
            return b'string'
        elif isinstance(key, list):
            return b'list'
        elif isinstance(key, set):
            return b'set'
        else:
            assert key is None
            return b'none'

    def watch(self, *names):
        pass

    def unwatch(self):
        pass

    def delete(self, *names):
        deleted = 0
        for name in names:
            try:
                del self._db[name]
                if name in self._db._ex_keys:
                    del self._db._ex_keys[name]
                deleted += 1
            except KeyError:
                continue
        return deleted

    def sort(self, name, start=None, num=None, by=None, get=None, desc=False,
             alpha=False, store=None):
        """Sort and return the list, set or sorted set at ``name``.

        ``start`` and ``num`` allow for paging through the sorted data

        ``by`` allows using an external key to weight and sort the items.
            Use an "*" to indicate where in the key the item value is located

        ``get`` allows for returning items from external keys rather than the
            sorted data itself.  Use an "*" to indicate where int he key
            the item value is located

        ``desc`` allows for reversing the sort

        ``alpha`` allows for sorting lexicographically rather than numerically

        ``store`` allows for storing the result of the sort into
            the key ``store``

        """
        if (start is None and num is not None) or \
                (start is not None and num is None):
            raise redis.RedisError(
                "RedisError: ``start`` and ``num`` must both be specified")
        try:
            data = list(self._db[name])[:]
            if by is not None:
                # _sort_using_by_arg mutates data so we don't
                # need need a return value.
                self._sort_using_by_arg(data, by=by)
            elif not alpha:
                data.sort(key=self._strtod_key_func)
            else:
                data.sort()
            if desc:
                data = list(reversed(data))
            if not (start is None and num is None):
                data = data[start:start + num]
            if store is not None:
                self._db[store] = data
                return len(data)
            else:
                return self._retrive_data_from_sort(data, get)
        except KeyError:
            return []

    def _retrive_data_from_sort(self, data, get):
        if get is not None:
            if isinstance(get, string_types):
                get = [get]
            new_data = []
            for k in data:
                for g in get:
                    single_item = self._get_single_item(k, g)
                    new_data.append(single_item)
            data = new_data
        return data

    def _get_single_item(self, k, g):
        g = to_bytes(g)
        if b'*' in g:
            g = g.replace(b'*', k)
            if b'->' in g:
                key, hash_key = g.split(b'->')
                single_item = self._db.get(key, {}).get(hash_key)
            else:
                single_item = self._db.get(g)
        elif b'#' in g:
            single_item = k
        else:
            single_item = None
        return single_item

    def _strtod_key_func(self, arg):
        # str()'ing the arg is important! Don't ever remove this.
        arg = to_bytes(arg)
        end = c_char_p()
        val = _strtod(arg, pointer(end))
        # real Redis also does an isnan check, not sure if
        # that's needed here or not.
        if end.value:
            raise redis.ResponseError(
                "One or more scores can't be converted into double")
        else:
            return val

    def _sort_using_by_arg(self, data, by):
        by = to_bytes(by)

        def _by_key(arg):
            key = by.replace(b'*', arg)
            if b'->' in by:
                key, hash_key = key.split(b'->')
                return self._db.get(key, {}).get(hash_key)
            else:
                return self._db.get(key)

        data.sort(key=_by_key)

    def lpush(self, name, *values):
        self._db.setdefault(name, [])[0:0] = list(reversed(
            [to_bytes(x) for x in values]))
        return len(self._db[name])

    def lrange(self, name, start, end):
        if end == -1:
            end = None
        else:
            end += 1
        return self._db.get(name, [])[start:end]

    def llen(self, name):
        return len(self._db.get(name, []))

    def lrem(self, name, count, value):
        value = to_bytes(value)
        a_list = self._db.get(name, [])
        found = []
        for i, el in enumerate(a_list):
            if el == value:
                found.append(i)
        if count > 0:
            indices_to_remove = found[:count]
        elif count < 0:
            indices_to_remove = found[count:]
        else:
            indices_to_remove = found
        # Iterating in reverse order to ensure the indices
        # remain valid during deletion.
        for index in reversed(indices_to_remove):
            del a_list[index]
        return len(indices_to_remove)

    def rpush(self, name, *values):
        self._db.setdefault(name, []).extend([to_bytes(x) for x in values])
        return len(self._db[name])

    def lpop(self, name):
        try:
            return self._db.get(name, []).pop(0)
        except IndexError:
            return None

    def lset(self, name, index, value):
        try:
            self._db.get(name, [])[index] = to_bytes(value)
        except IndexError:
            raise redis.ResponseError("index out of range")

    def rpushx(self, name, value):
        try:
            self._db[name].append(to_bytes(value))
        except KeyError:
            return

    def ltrim(self, name, start, end):
        try:
            val = self._db[name]
        except KeyError:
            return True
        if end == -1:
            end = None
        else:
            end += 1
        self._db[name] = val[start:end]
        return True

    def lindex(self, name, index):
        try:
            return self._db.get(name, [])[index]
        except IndexError:
            return None

    def lpushx(self, name, value):
        try:
            self._db[name].insert(0, to_bytes(value))
        except KeyError:
            return

    def rpop(self, name):
        try:
            return self._db.get(name, []).pop()
        except IndexError:
            return None

    def linsert(self, name, where, refvalue, value):
        index = self._db.get(name, []).index(to_bytes(refvalue))
        self._db.get(name, []).insert(index, to_bytes(value))

    def rpoplpush(self, src, dst):
        el = self.rpop(src)
        if el is not None:
            el = to_bytes(el)
            try:
                self._db[dst].insert(0, el)
            except KeyError:
                self._db[dst] = [el]
        return el

    def blpop(self, keys, timeout=0):
        # This has to be a best effort approximation which follows
        # these rules:
        # 1) For each of those keys see if there's something we can
        #    pop from.
        # 2) If this is not the case then simulate a timeout.
        # This means that there's not really any blocking behavior here.
        if isinstance(keys, string_types):
            keys = [to_bytes(keys)]
        else:
            keys = [to_bytes(k) for k in keys]
        for key in keys:
            if self._db.get(key, []):
                return (key, self._db[key].pop(0))

    def brpop(self, keys, timeout=0):
        if isinstance(keys, string_types):
            keys = [to_bytes(keys)]
        else:
            keys = [to_bytes(k) for k in keys]
        for key in keys:
            if self._db.get(key, []):
                return (key, self._db[key].pop())

    def brpoplpush(self, src, dst, timeout=0):
        el = self.rpop(src)
        if el is not None:
            el = to_bytes(el)
            try:
                self._db[dst].insert(0, el)
            except KeyError:
                self._db[dst] = [el]
        return el

    def hdel(self, name, *keys):
        h = self._db.get(name, {})
        rem = 0
        for k in keys:
            if k in h:
                del h[k]
                rem += 1
        return rem

    def hexists(self, name, key):
        "Returns a boolean indicating if ``key`` exists within hash ``name``"
        if self._db.get(name, {}).get(key) is None:
            return 0
        else:
            return 1

    def hget(self, name, key):
        "Return the value of ``key`` within the hash ``name``"
        return self._db.get(name, {}).get(key)

    def hgetall(self, name):
        "Return a Python dict of the hash's name/value pairs"
        all_items = self._db.get(name, {})
        if hasattr(all_items, 'to_bare_dict'):
            all_items = all_items.to_bare_dict()
        return all_items

    def hincrby(self, name, key, amount=1):
        "Increment the value of ``key`` in hash ``name`` by ``amount``"
        new = int(self._db.setdefault(name, _Hash()).get(key, '0')) + amount
        self._db[name][key] = new
        return new

    def hincrbyfloat(self, name, key, amount=1.0):
        """Increment the value of key in hash name by floating amount"""
        try:
            amount = float(amount)
        except ValueError:
            raise redis.ResponseError("value is not a valid float")
        try:
            current = float(self._db.setdefault(name, _Hash()).get(key, '0'))
        except ValueError:
            raise redis.ResponseError("hash value is not a valid float")
        new = current + amount
        self._db[name][key] = new
        return new

    def hkeys(self, name):
        "Return the list of keys within hash ``name``"
        return list(self._db.get(name, {}))

    def hlen(self, name):
        "Return the number of elements in hash ``name``"
        return len(self._db.get(name, {}))

    def hset(self, name, key, value):
        """
        Set ``key`` to ``value`` within hash ``name``
        Returns 1 if HSET created a new field, otherwise 0
        """
        key_is_new = key not in self._db.get(name, {})
        self._db.setdefault(name, _Hash())[key] = to_bytes(value)
        return 1 if key_is_new else 0

    def hsetnx(self, name, key, value):
        """
        Set ``key`` to ``value`` within hash ``name`` if ``key`` does not
        exist.  Returns 1 if HSETNX created a field, otherwise 0.
        """
        if key in self._db.get(name, {}):
            return False
        self._db.setdefault(name, _Hash())[key] = to_bytes(value)
        return True

    def hmset(self, name, mapping):
        """
        Sets each key in the ``mapping`` dict to its corresponding value
        in the hash ``name``
        """
        if not mapping:
            raise redis.DataError("'hmset' with 'mapping' of length 0")
        new_mapping = {}
        for k, v in mapping.items():
            new_mapping[k] = to_bytes(v)
        self._db.setdefault(name, _Hash()).update(new_mapping)
        return True

    def hmget(self, name, keys, *args):
        "Returns a list of values ordered identically to ``keys``"
        h = self._db.get(name, {})
        all_keys = self._list_or_args(keys, args)
        return [h.get(k) for k in all_keys]

    def hvals(self, name):
        "Return the list of values within hash ``name``"
        return list(self._db.get(name, {}).values())

    def sadd(self, name, *values):
        "Add ``value`` to set ``name``"
        a_set = self._db.setdefault(name, set())
        card = len(a_set)
        a_set |= set(to_bytes(x) for x in values)
        return len(a_set) - card

    def scard(self, name):
        "Return the number of elements in set ``name``"
        return len(self._db.get(name, set()))

    def sdiff(self, keys, *args):
        "Return the difference of sets specified by ``keys``"
        all_keys = (to_bytes(x) for x in self._list_or_args(keys, args))
        diff = self._db.get(next(all_keys), set()).copy()
        for key in all_keys:
            diff -= self._db.get(key, set())
        return diff

    def sdiffstore(self, dest, keys, *args):
        """
        Store the difference of sets specified by ``keys`` into a new
        set named ``dest``.  Returns the number of keys in the new set.
        """
        diff = self.sdiff(keys, *args)
        self._db[dest] = set(to_bytes(x) for x in diff)
        return len(diff)

    def sinter(self, keys, *args):
        "Return the intersection of sets specified by ``keys``"
        all_keys = (to_bytes(x) for x in self._list_or_args(keys, args))
        intersect = self._db.get(next(all_keys), set()).copy()
        for key in all_keys:
            intersect.intersection_update(self._db.get(key, set()))
        return intersect

    def sinterstore(self, dest, keys, *args):
        """
        Store the intersection of sets specified by ``keys`` into a new
        set named ``dest``.  Returns the number of keys in the new set.
        """
        intersect = self.sinter(keys, *args)
        self._db[dest] = set(to_bytes(x) for x in intersect)
        return len(intersect)

    def sismember(self, name, value):
        "Return a boolean indicating if ``value`` is a member of set ``name``"
        return to_bytes(value) in self._db.get(name, set())

    def smembers(self, name):
        "Return all members of the set ``name``"
        return self._db.get(name, set())

    def smove(self, src, dst, value):
        value = to_bytes(value)
        try:
            self._db.get(src, set()).remove(value)
            self._db.setdefault(dst, set()).add(value)
            return True
        except KeyError:
            return False

    def spop(self, name):
        "Remove and return a random member of set ``name``"
        try:
            return self._db.get(name, set()).pop()
        except KeyError:
            return None

    def srandmember(self, name):
        "Return a random member of set ``name``"
        members = self._db.get(name, set())
        if members:
            index = random.randint(0, len(members) - 1)
            return list(members)[index]

    def srem(self, name, *values):
        "Remove ``value`` from set ``name``"
        a_set = self._db.setdefault(name, set())
        card = len(a_set)
        a_set -= set(to_bytes(x) for x in values)
        return card - len(a_set)

    def sunion(self, keys, *args):
        "Return the union of sets specifiued by ``keys``"
        all_keys = (to_bytes(x) for x in self._list_or_args(keys, args))
        union = self._db.get(next(all_keys), set()).copy()
        for key in all_keys:
            union.update(self._db.get(key, set()))
        return union

    def sunionstore(self, dest, keys, *args):
        """
        Store the union of sets specified by ``keys`` into a new
        set named ``dest``.  Returns the number of keys in the new set.
        """
        union = self.sunion(keys, *args)
        self._db[dest] = set(to_bytes(x) for x in union)
        return len(union)

    def _get_zelement_range_filter_func(self, min_val, max_val):
        # This will return a filter function based on the
        # min and max values.  It takes a single argument
        # and return True if it matches the range filter
        # criteria, and False otherwise.

        # This will also handle the case when
        # min/max are '-inf', '+inf'.
        # It needs to handle exclusive intervals
        # where the min/max value is something like
        # '(0'
        #     a             <    x        <           b
        #     ^             ^             ^           ^
        # actual_min   left_comp     right_comp  actual_max
        left_comparator, actual_min = self._get_comparator_and_val(min_val)
        right_comparator, actual_max = self._get_comparator_and_val(max_val)

        def _matches(x):
            return (left_comparator(actual_min, x) and
                    right_comparator(x, actual_max))
        return _matches

    def _get_comparator_and_val(self, value):
        try:
            if isinstance(value, string_types) and value.startswith('('):
                comparator = operator.lt
                actual_value = float(value[1:])
            else:
                comparator = operator.le
                actual_value = float(value)
        except ValueError:
            raise redis.ResponseError('min or max is not a float')
        return comparator, actual_value

    def _get_zelement_lexrange_filter_func(self, min_str, max_str):
        # This will return a filter function based on the
        # min_str and max_str values.  It takes a single argument
        # and return True if it matches the range filter
        # criteria, and False otherwise.

        # This will handles inclusive '[' and exclusive '('
        # boundaries, as well as '-' and '+' which are
        # considered 'negative infinitiy string' and
        # maximum infinity string, which are handled by comparing
        # against empty string.
        #     a        < or <=    x     < or <=       b
        #     ^          ^                ^           ^
        # actual_min   left_comp     right_comp  actual_max
        min_str = to_bytes(min_str)
        max_str = to_bytes(max_str)

        left_comparator, actual_min = self._get_lexcomp_and_str(min_str)
        right_comparator, actual_max = self._get_lexcomp_and_str(max_str)

        def _matches(x):
            return (left_comparator(actual_min, x) and
                    right_comparator(x, actual_max))
        return _matches

    def _get_lexcomp_and_str(self, value):
        if value.startswith(b'('):
            comparator = operator.lt
            actual_value = value[1:]
        elif value.startswith(b'['):
            comparator = operator.le
            actual_value = value[1:]
        elif value == b'-':
            # negative infinity string -- all strings greater than
            # compares: '' < X
            comparator = operator.le
            actual_value = b''
        elif value == b'+':
            # positive infinity string -- all strings less than
            # compares: '' > X
            comparator = operator.ge
            actual_value = b''
        else:
            msg = ('min and max must start with ( or [, ' +
                   ' or min may be - and max may be +')
            raise redis.ResponseError(msg)

        return comparator, actual_value

    def zadd(self, name, *args, **kwargs):
        """
        Set any number of score, element-name pairs to the key ``name``. Pairs
        can be specified in two ways:

        As *args, in the form of: score1, name1, score2, name2, ...
        or as **kwargs, in the form of: name1=score1, name2=score2, ...

        The following example would add four values to the 'my-key' key:
        redis.zadd('my-key', 1.1, 'name1', 2.2, 'name2', name3=3.3, name4=4.4)
        """
        if len(args) % 2 != 0:
            raise redis.RedisError("ZADD requires an equal number of "
                                   "values and scores")
        zset = self._db.setdefault(name, _ZSet())
        added = 0
        for score, value in zip(*[args[i::2] for i in range(2)]):
            if value not in zset:
                added += 1
            try:
                zset[value] = float(score)
            except ValueError:
                raise redis.ResponseError("value is not a valid float")
        for value, score in kwargs.items():
            if value not in zset:
                added += 1
            try:
                zset[value] = float(score)
            except ValueError:
                raise redis.ResponseError("value is not a valid float")
        return added

    def zcard(self, name):
        "Return the number of elements in the sorted set ``name``"
        return len(self._db.get(name, {}))

    def zcount(self, name, min, max):
        found = 0
        filter_func = self._get_zelement_range_filter_func(min, max)
        for score in self._db.get(name, {}).values():
            if filter_func(score):
                found += 1
        return found

    def zincrby(self, name, value, amount=1):
        "Increment the score of ``value`` in sorted set ``name`` by ``amount``"
        d = self._db.setdefault(name, _ZSet())
        score = d.get(value, 0) + amount
        d[value] = score
        return score

    def zinterstore(self, dest, keys, aggregate=None):
        """
        Intersect multiple sorted sets specified by ``keys`` into
        a new sorted set, ``dest``. Scores in the destination will be
        aggregated based on the ``aggregate``, or SUM if none is provided.
        """
        if not keys:
            raise redis.ResponseError("At least one key must be specified "
                                      "for ZINTERSTORE/ZUNIONSTORE")
        # keys can be a list or a dict so it needs to be converted to
        # a list first.
        list_keys = list(keys)
        valid_keys = set(self._db.get(list_keys[0], {}))
        for key in list_keys[1:]:
            valid_keys.intersection_update(self._db.get(key, {}))
        return self._zaggregate(dest, keys, aggregate,
                                lambda x: x in
                                valid_keys)

    def zrange(self, name, start, end, desc=False, withscores=False):
        """
        Return a range of values from sorted set ``name`` between
        ``start`` and ``end`` sorted in ascending order.

        ``start`` and ``end`` can be negative, indicating the end of the range.

        ``desc`` indicates to sort in descending order.

        ``withscores`` indicates to return the scores along with the values.
        The return type is a list of (value, score) pairs
        """
        if end == -1:
            end = None
        else:
            end += 1
        all_items = self._db.get(name, {})
        if desc:
            reverse = True
        else:
            reverse = False
        in_order = self._get_zelements_in_order(all_items, reverse)
        items = in_order[start:end]
        if not withscores:
            return items
        else:
            return [(k, all_items[k]) for k in items]

    def _get_zelements_in_order(self, all_items, reverse=False):
        by_keyname = sorted(
            all_items.items(), key=lambda x: x[0], reverse=reverse)
        in_order = sorted(by_keyname, key=lambda x: x[1], reverse=reverse)
        return [el[0] for el in in_order]

    def zrangebyscore(self, name, min, max,
                      start=None, num=None, withscores=False):
        """
        Return a range of values from the sorted set ``name`` with scores
        between ``min`` and ``max``.

        If ``start`` and ``num`` are specified, then return a slice
        of the range.

        ``withscores`` indicates to return the scores along with the values.
        The return type is a list of (value, score) pairs
        """
        return self._zrangebyscore(name, min, max, start, num, withscores,
                                   reverse=False)

    def _zrangebyscore(self, name, min, max, start, num, withscores, reverse):
        if (start is not None and num is None) or \
                (num is not None and start is None):
            raise redis.RedisError("``start`` and ``num`` must both "
                                   "be specified")
        all_items = self._db.get(name, {})
        in_order = self._get_zelements_in_order(all_items, reverse=reverse)
        filter_func = self._get_zelement_range_filter_func(min, max)
        matches = []
        for item in in_order:
            if filter_func(all_items[item]):
                matches.append(item)
        if start is not None:
            matches = matches[start:start + num]
        if withscores:
            return [(k, all_items[k]) for k in matches]
        return matches

    def zrangebylex(self, name, min, max,
                    start=None, num=None):
        """
        Returns lexicographically ordered values
        from sorted set ``name`` between values ``min`` and ``max``.

        The ``min`` and ``max`` params must:
            - start with ``(`` for exclusive boundary
            - start with ``[`` (inclusive boundary)
            - equal ``-`` for negative infinite string (start)
            - equal ``+`` for positive infinite string (stop)

        If ``start`` and ``num`` are specified, then a slice
        of the range is returned.

        """
        return self._zrangebylex(name, min, max, start, num,
                                 reverse=False)

    def _zrangebylex(self, name, min, max, start, num, reverse):
        if (start is not None and num is None) or \
                (num is not None and start is None):
            raise redis.RedisError("``start`` and ``num`` must both "
                                   "be specified")
        all_items = self._db.get(name, {})
        in_order = self._get_zelements_in_order(all_items, reverse=reverse)
        filter_func = self._get_zelement_lexrange_filter_func(min, max)
        matches = []
        for item in in_order:
            if filter_func(item):
                matches.append(item)
        if start is not None:
            if num < 0:
                num = len(matches)
            matches = matches[start:start + num]
        return matches

    def zrank(self, name, value):
        """
        Returns a 0-based value indicating the rank of ``value`` in sorted set
        ``name``
        """
        all_items = self._db.get(name, {})
        in_order = sorted(all_items, key=lambda x: all_items[x])
        try:
            return in_order.index(to_bytes(value))
        except ValueError:
            return None

    def zrem(self, name, *values):
        "Remove member ``value`` from sorted set ``name``"
        z = self._db.get(name, {})
        rem = 0
        for v in values:
            if v in z:
                del z[v]
                rem += 1
        return rem

    def zremrangebyrank(self, name, min, max):
        """
        Remove all elements in the sorted set ``name`` with ranks between
        ``min`` and ``max``. Values are 0-based, ordered from smallest score
        to largest. Values can be negative indicating the highest scores.
        Returns the number of elements removed
        """
        all_items = self._db.get(name, {})
        in_order = self._get_zelements_in_order(all_items)
        num_deleted = 0
        if max == -1:
            max = None
        else:
            max += 1
        for key in in_order[min:max]:
            del all_items[key]
            num_deleted += 1
        return num_deleted

    def zremrangebyscore(self, name, min, max):
        """
        Remove all elements in the sorted set ``name`` with scores
        between ``min`` and ``max``. Returns the number of elements removed.
        """
        all_items = self._db.get(name, {})
        filter_func = self._get_zelement_range_filter_func(min, max)
        removed = 0
        for key in all_items.copy():
            if filter_func(all_items[key]):
                del all_items[key]
                removed += 1
        return removed

    def zremrangebylex(self, name, min, max):
        """
        Remove all elements in the sorted set ``name``
        that are in lexicograpically between ``min`` and ``max``

        The ``min`` and ``max`` params must:
            - start with ``(`` for exclusive boundary
            - start with ``[`` (inclusive boundary)
            - equal ``-`` for negative infinite string (start)
            - equal ``+`` for positive infinite string (stop)
        """
        all_items = self._db.get(name, {})
        filter_func = self._get_zelement_lexrange_filter_func(min, max)
        removed = 0
        for key in all_items.copy():
            if filter_func(key):
                del all_items[key]
                removed += 1
        return removed

    def zlexcount(self, name, min, max):
        """
        Returns a count of elements in the sorted set ``name``
        that are in lexicograpically between ``min`` and ``max``

        The ``min`` and ``max`` params must:
            - start with ``(`` for exclusive boundary
            - start with ``[`` (inclusive boundary)
            - equal ``-`` for negative infinite string (start)
            - equal ``+`` for positive infinite string (stop)
        """
        all_items = self._db.get(name, {})
        filter_func = self._get_zelement_lexrange_filter_func(min, max)
        found = 0
        for key in all_items.copy():
            if filter_func(key):
                found += 1
        return found

    def zrevrange(self, name, start, num, withscores=False):
        """
        Return a range of values from sorted set ``name`` between
        ``start`` and ``num`` sorted in descending order.

        ``start`` and ``num`` can be negative, indicating the end of the range.

        ``withscores`` indicates to return the scores along with the values
        The return type is a list of (value, score) pairs
        """
        return self.zrange(name, start, num, True, withscores)

    def zrevrangebyscore(self, name, max, min,
                         start=None, num=None, withscores=False):
        """
        Return a range of values from the sorted set ``name`` with scores
        between ``min`` and ``max`` in descending order.

        If ``start`` and ``num`` are specified, then return a slice
        of the range.

        ``withscores`` indicates to return the scores along with the values.
        The return type is a list of (value, score) pairs
        """
        return self._zrangebyscore(name, min, max, start, num, withscores,
                                   reverse=True)

    def zrevrangebylex(self, name, max, min,
                       start=None, num=None):
        """
        Returns reverse lexicographically ordered values
        from sorted set ``name`` between values ``min`` and ``max``.

        The ``min`` and ``max`` params must:
            - start with ``(`` for exclusive boundary
            - start with ``[`` (inclusive boundary)
            - equal ``-`` for negative infinite string (start)
            - equal ``+`` for positive infinite string (stop)

        If ``start`` and ``num`` are specified, then a slice
        of the range is returned.

        """
        return self._zrangebylex(name, min, max, start, num,
                                 reverse=True)

    def zrevrank(self, name, value):
        """
        Returns a 0-based value indicating the descending rank of
        ``value`` in sorted set ``name``
        """
        num_items = len(self._db.get(name, {}))
        zrank = self.zrank(name, value)
        if zrank is not None:
            return num_items - self.zrank(name, value) - 1

    def zscore(self, name, value):
        "Return the score of element ``value`` in sorted set ``name``"
        try:
            return self._db[name][value]
        except KeyError:
            return None

    def zunionstore(self, dest, keys, aggregate=None):
        """
        Union multiple sorted sets specified by ``keys`` into
        a new sorted set, ``dest``. Scores in the destination will be
        aggregated based on the ``aggregate``, or SUM if none is provided.
        """
        if not keys:
            raise redis.ResponseError("At least one key must be specified "
                                      "for ZINTERSTORE/ZUNIONSTORE")
        self._zaggregate(dest, keys, aggregate, lambda x: True)

    def _zaggregate(self, dest, keys, aggregate, should_include):
        new_zset = _ZSet()
        if aggregate is None:
            aggregate = 'SUM'
        # This is what the actual redis client uses, so we'll use
        # the same type check.
        if isinstance(keys, dict):
            keys_weights = [(k, keys[k]) for k in keys]
        else:
            keys_weights = [(k, 1) for k in keys]
        for key, weight in keys_weights:
            current_zset = self._db.get(key, {})
            if isinstance(current_zset, set):
                # When casting set to zset redis uses a default score of 1.0
                current_zset = dict((k, 1.0) for k in current_zset)
            for el in current_zset:
                if not should_include(el):
                    continue
                if el not in new_zset:
                    new_zset[el] = current_zset[el] * weight
                elif aggregate == 'SUM':
                    new_zset[el] += current_zset[el] * weight
                elif aggregate == 'MAX':
                    new_zset[el] = max([new_zset[el],
                                        current_zset[el] * weight])
                elif aggregate == 'MIN':
                    new_zset[el] = min([new_zset[el],
                                        current_zset[el] * weight])
        self._db[dest] = new_zset

    def _list_or_args(self, keys, args):
        # Returns a single list combining keys and args.
        # Copy of list_or_args from redis-py.
        try:
            iter(keys)
            # a string or bytes instance can be iterated, but indicates
            # keys wasn't passed as a list
            if isinstance(keys, (basestring, bytes)):
                keys = [keys]
        except TypeError:
            keys = [keys]
        if args:
            keys.extend(args)
        return keys

    def pipeline(self, transaction=True):
        """Return an object that can be used to issue Redis commands in a batch.

        Arguments --
            transaction (bool) -- whether the buffered commands
                are issued atomically. True by default.
        """
        return FakePipeline(self, transaction)

    def transaction(self, func, *keys):
        # We use a for loop instead of while
        # because if the test this is being used in
        # goes wrong we don't want an infinite loop!
        with self.pipeline() as p:
            for _ in range(5):
                try:
                    p.watch(*keys)
                    func(p)
                    return p.execute()
                except redis.WatchError:
                    continue
        raise redis.WatchError('Could not run transaction after 5 tries')

    def pubsub(self, ignore_subscribe_messages=False):
        """
        Returns a new FakePubSub instance
        """
        ps = FakePubSub(decode_responses=self._decode_responses,
                        ignore_subscribe_messages=ignore_subscribe_messages)
        self._pubsubs.append(ps)

        return ps

    def publish(self, channel, message):
        """
        Loops throug all available pubsub objects and publishes the
        ``message`` to then for the given ``channel``.
        """
        count = 0
        for i, ps in enumerate(self._pubsubs):
            if not ps.subscribed:
                del self._pubsubs[i]
                continue

            count += ps.put(channel, message, 'message')

        return count

    # HYPERLOGLOG COMMANDS
    def pfadd(self, name, *values):
        "Adds the specified elements to the specified HyperLogLog."
        # Simulate the behavior of HyperLogLog by using SETs underneath to
        # approximate the behavior.
        result = self.sadd(name, *values)

        # Per the documentation:
        # - 1 if at least 1 HyperLogLog internal register was altered. 0 otherwise.
        return 1 if result > 0 else 0

    def pfcount(self, *sources):
        """
        Return the approximated cardinality of
        the set observed by the HyperLogLog at key(s).
        """
        return len(self.sunion(*sources))

    def pfmerge(self, dest, *sources):
        "Merge N different HyperLogLogs into a single one."
        self.sunionstore(dest, sources)
        return True

    # SCAN commands
    def _scan(self, keys, cursor, match, count):
        """
        This is the basis of most of the ``scan`` methods.

        This implementation is KNOWN to be un-performant, as it requires
        grabbing the full set of keys over which we are investigating subsets.
        """
        if cursor >= len(keys):
            return 0, []
        data = sorted(keys)
        result_cursor = cursor + count
        result_data = []
        # subset =
        for val in data[cursor:result_cursor]:
            if not match or fnmatch.fnmatch(to_native(val), to_native(match)):
                result_data.append(val)
        if result_cursor >= len(data):
            result_cursor = 0
        return result_cursor, result_data

    def scan(self, cursor=0, match=None, count=None):
        return self._scan(self.keys(), int(cursor), match, count or 10)

    def sscan(self, name, cursor=0, match=None, count=None):
        return self._scan(self.smembers(name), int(cursor), match, count or 10)

    def hscan(self, name, cursor=0, match=None, count=None):
        cursor, keys = self._scan(self.hkeys(name), int(cursor), match, count or 10)
        results = {}
        for k in keys:
            results[k] = self.hget(name, k)
        return cursor, results

    def scan_iter(self, match=None, count=None):
        # This is from redis-py
        cursor = '0'
        while cursor != 0:
            cursor, data = self.scan(cursor=cursor, match=match, count=count)
            for item in data:
                yield item

    def sscan_iter(self, name, match=None, count=None):
        # This is from redis-py
        cursor = '0'
        while cursor != 0:
            cursor, data = self.sscan(name, cursor=cursor,
                                      match=match, count=count)
            for item in data:
                yield item

    def hscan_iter(self, name, match=None, count=None):
        # This is from redis-py
        cursor = '0'
        while cursor != 0:
            cursor, data = self.hscan(name, cursor=cursor,
                                      match=match, count=count)
            for item in data.items():
                yield item


class FakeRedis(FakeStrictRedis):
    def setex(self, name, value, time):
        return super(FakeRedis, self).setex(name, time, value)

    def lrem(self, name, value, num=0):
        return super(FakeRedis, self).lrem(name, num, value)

    def zadd(self, name, value=None, score=None, **pairs):
        """
        For each kwarg in ``pairs``, add that item and it's score to the
        sorted set ``name``.

        The ``value`` and ``score`` arguments are deprecated.
        """
        if value is not None or score is not None:
            if value is None or score is None:
                raise redis.RedisError(
                    "Both 'value' and 'score' must be specified to ZADD")
            warnings.warn(DeprecationWarning(
                "Passing 'value' and 'score' has been deprecated. "
                "Please pass via kwargs instead."))
            pairs = {str(value): score}
        elif not pairs:
            raise redis.RedisError("ZADD is missing kwargs param")
        return super(FakeRedis, self).zadd(name, **pairs)

    def ttl(self, name):
        r = super(FakeRedis, self).ttl(name)
        return r if r >= 0 else None

    def pttl(self, name):
        r = super(FakeRedis, self).pttl(name)
        return r if r >= 0 else None


class FakePipeline(object):
    """Helper class for FakeStrictRedis to implement pipelines.

    A pipeline is a collection of commands that
    are buffered until you call ``execute``, at which
    point they are called sequentially and a list
    of their return values is returned.

    """
    def __init__(self, owner, transaction=True):
        """Create a pipeline for the specified FakeStrictRedis instance.

        Arguments --
            owner -- a FakeStrictRedis instance.

        """
        self.owner = owner
        self.transaction = transaction
        self.commands = []
        self.need_reset = False
        self.is_immediate = False
        self.watching = {}

    def __getattr__(self, name):
        """Magic method to allow FakeStrictRedis commands to be called.

        Returns a method that records the command for later.

        """
        if not hasattr(self.owner, name):
            raise AttributeError('%r: does not have attribute %r' %
                                 (self.owner, name))

        def meth(*args, **kwargs):
            if self.is_immediate:
                # Special mode during watch_multi sequence.
                return getattr(self.owner, name)(*args, **kwargs)
            self.commands.append((name, args, kwargs))
            return self

        setattr(self, name, meth)
        return meth

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.reset()

    def execute(self, raise_on_error=True):
        """Run all the commands in the pipeline and return the results."""
        try:
            if self.watching:
                mismatches = [
                    (k, v, u) for (k, v, u) in
                    [(k, v, self.owner._db.get(k))
                        for (k, v) in self.watching.items()]
                    if v != u]
                if mismatches:
                    self.commands = []
                    self.watching = {}
                    raise redis.WatchError(
                        'Watched key%s %s changed' % (
                            '' if len(mismatches) == 1 else
                            's', ', '.join(k for (k, _, _) in mismatches)))
            if raise_on_error:
                ret = [getattr(self.owner, name)(*args, **kwargs)
                       for name, args, kwargs in self.commands]
            else:
                ret = []
                for name, args, kwargs in self.commands:
                    try:
                        ret.append(getattr(self.owner, name)(*args, **kwargs))
                    except Exception as exc:
                        ret.append(exc)
            return ret
        finally:
            # Redis-py will reset in all cases, so do that.
            self.commands = []
            self.watching = {}

    def watch(self, *keys):
        self.watching.update((key, copy.deepcopy(self.owner._db.get(key)))
                             for key in keys)
        self.need_reset = True
        self.is_immediate = True

    def multi(self):
        self.is_immediate = False

    def reset(self):
        self.need_reset = False


class FakePubSub(object):

    PUBLISH_MESSAGE_TYPES = ['message', 'pmessage']
    SUBSCRIBE_MESSAGE_TYPES = ['subscribe', 'psubscribe']
    UNSUBSCRIBE_MESSAGE_TYPES = ['unsubscribe', 'punsubscribe']
    PATTERN_MESSAGE_TYPES = ['psubscribe', 'punsubscribe']
    LISTEN_DELAY = 0.1          # delay between listen loops (seconds)

    def __init__(self, decode_responses=False, *args, **kwargs):
        self.channels = {}
        self.patterns = {}
        self._q = Queue()
        self.subscribed = False
        if decode_responses:
            _patch_responses(self)
        self.ignore_subscribe_messages = kwargs.get(
            'ignore_subscribe_messages', False)

    def put(self, channel, message, message_type, pattern=None):
        """
        Utility function to be used as the publishing entrypoint for this
        pubsub object
        """
        if message_type in self.SUBSCRIBE_MESSAGE_TYPES or\
                message_type in self.UNSUBSCRIBE_MESSAGE_TYPES:
            return self._send(message_type, None, channel, message)

        count = 0

        # Send the message on the given channel
        if channel in self.channels:
            count += self._send(message_type, None, channel, message)

        # See if any of the patterns match the given channel
        for pattern, pattern_obj in iteritems(self.patterns):
            match = re.match(pattern_obj['regex'], channel)
            if match:
                count += self._send('pmessage', pattern, channel, message)

        return count

    def _send(self, message_type, pattern, channel, data):
        msg = {
            'type': message_type,
            'pattern': pattern,
            'channel': channel.encode(),
            'data': data.encode() if type(data) == str else data
        }

        self._q.put(msg)

        return 1

    def psubscribe(self, *args, **kwargs):
        """
        Subcribe to channel patterns.
        """

        def _subscriber(pattern, handler):
            regex = self._parse_pattern(pattern)
            return {
                'regex': regex,
                'handler': handler
            }

        total_subscriptions =\
            len(self.channels.keys()) + len(self.patterns.keys())
        self._subscribe(self.patterns, 'psubscribe', total_subscriptions,
                        _subscriber, *args, **kwargs)

    def punsubscribe(self, *args):
        """
        Unsubscribes from one or more patterns.
        """
        total_subscriptions =\
            len(self.channels.keys()) + len(self.patterns.keys())
        self._usubscribe(self.patterns, 'punsubscribe', total_subscriptions,
                         *args)

    def _parse_pattern(self, pattern):
        temp_pattern = pattern
        if '?' in temp_pattern:
            temp_pattern = temp_pattern.replace('?', '.')

        if '*' in temp_pattern:
            temp_pattern = temp_pattern.replace('*', '.*')

        if ']' in temp_pattern:
            temp_pattern = temp_pattern.replace(']', ']?')

        return temp_pattern

    def subscribe(self, *args, **kwargs):
        """
        Subscribes to one or more given ``channels``.
        """

        def _subscriber(channel, handler):
            return handler

        total_subscriptions =\
            len(self.channels.keys()) + len(self.patterns.keys())
        self._subscribe(self.channels, 'subscribe', total_subscriptions,
                        _subscriber, *args, **kwargs)

    def _subscribe(self, subscribed_dict, message_type, total_subscriptions,
                   subscriber, *args, **kwargs):

        new_channels = {}
        if args:
            for arg in args:
                new_channels[arg] = subscriber(arg, None)

        for channel, handler in iteritems(kwargs):
            new_channels[channel] = handler

        subscribed_dict.update(new_channels)
        self.subscribed = True

        for channel in new_channels:
            total_subscriptions += 1
            self.put(channel, long(total_subscriptions), message_type)

    def unsubscribe(self, *args):
        """
        Unsubscribes from one or more given ``channels``.
        """
        total_subscriptions =\
            len(self.channels.keys()) + len(self.patterns.keys())
        self._usubscribe(self.channels, 'unsubscribe', total_subscriptions,
                         *args)

    def _usubscribe(self, subscribed_dict, message_type, total_subscriptions,
                    *args):

        if args:
            for channel in args:
                if channel in subscribed_dict:
                    total_subscriptions -= 1
                    self.put(channel, long(total_subscriptions), message_type)
        else:
            for channel in subscribed_dict:
                total_subscriptions -= 1
                self.put(channel, long(total_subscriptions), message_type)
            subscribed_dict.clear()

        if total_subscriptions == 0:
            self.subscribed = False

    def listen(self):
        """
        Listens for queued messages and yields the to the calling process
        """
        while self.subscribed:
            message = self.get_message()
            if message:
                yield message
                continue

            time.sleep(self.LISTEN_DELAY)

    def close(self):
        """
        Stops the listen function by calling unsubscribe
        """
        self.unsubscribe()
        self.punsubscribe()

    def get_message(self, ignore_subscribe_messages=False, timeout=0):
        """
        Returns the next available message.
        """

        try:
            message = self._q.get(True, timeout)
            return self.handle_message(message, ignore_subscribe_messages)
        except Empty:
            return None

    def handle_message(self, message, ignore_subscribe_messages=False):
        """
        Parses a pubsub message. It invokes the handler of a message type,
        if the handler is avaialble. If the message is of type ``subscribe``
        and ignore_subscribe_messages if True, then it returns None. Otherwise,
        it returns the message.
        """
        message_type = message['type']
        if message_type in self.UNSUBSCRIBE_MESSAGE_TYPES:
            subscribed_dict = None
            if message_type == 'punsubscribe':
                subscribed_dict = self.patterns
            else:
                subscribed_dict = self.channels

            try:
                channel = message['channel'].decode('utf-8')
                del subscribed_dict[channel]
            except:
                pass

        if message_type in self.PUBLISH_MESSAGE_TYPES:
            # if there's a message handler, invoke it
            handler = None
            if message_type == 'pmessage':
                pattern = self.patterns.get(message['pattern'], None)
                if pattern:
                    handler = pattern['handler']
            else:
                handler = self.channels.get(message['channel'], None)
            if handler:
                handler(message)
                return None
        else:
            # this is a subscribe/unsubscribe message. ignore if we don't
            # want them
            if ignore_subscribe_messages or self.ignore_subscribe_messages:
                return None

        return message