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client.py
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client.py
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"""
@file client.py
"""
import itertools
from twisted.internet import defer
from twisted.internet.protocol import ReconnectingClientFactory
try:
import hiredis
except ImportError:
pass
from txredis import exceptions
from txredis.protocol import RedisBase, HiRedisBase
class RedisClient(RedisBase):
"""The main Redis client."""
def __init__(self, *args, **kwargs):
RedisBase.__init__(self, *args, **kwargs)
# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
# REDIS COMMANDS
#
def ping(self):
"""
Test command. Expect PONG as a reply.
"""
self._send('PING')
return self.getResponse()
def shutdown(self):
"""
Synchronously save the dataset to disk and then shut down the server
"""
self._send('SHUTDOWN')
return self.getResponse()
def slaveof(self, host, port):
"""
Make the server a slave of another instance, or promote it as master
The SLAVEOF command can change the replication settings of a slave on
the fly. If a Redis server is arleady acting as slave, the command
SLAVEOF NO ONE will turn off the replicaiton turning the Redis server
into a MASTER. In the proper form SLAVEOF hostname port will make the
server a slave of the specific server listening at the specified
hostname and port.
If a server is already a slave of some master, SLAVEOF hostname port
will stop the replication against the old server and start the
synchrnonization against the new one discarding the old dataset.
The form SLAVEOF no one will stop replication turning the server into a
MASTER but will not discard the replication. So if the old master stop
working it is possible to turn the slave into a master and set the
application to use the new master in read/write. Later when the other
Redis server will be fixed it can be configured in order to work as
slave.
"""
self._send('SLAVEOF', host, port)
return self.getResponse()
def get_config(self, pattern):
"""
Get configuration for Redis at runtime.
"""
self._send('CONFIG', 'GET', pattern)
def post_process(values):
# transform into dict
res = {}
if not values:
return res
for i in xrange(0, len(values) - 1, 2):
res[values[i]] = values[i + 1]
return res
return self.getResponse().addCallback(post_process)
def set_config(self, parameter, value):
"""
Set configuration at runtime.
"""
self._send('CONFIG', 'SET', parameter, value)
return self.getResponse()
# Commands operating on string values
def set(self, key, value, preserve=False, getset=False, expire=None):
"""
Set the string value of a key
"""
# The following will raise an error for unicode values that can't be
# encoded to ascii. We could probably add an 'encoding' arg to init,
# but then what do we do with get()? Convert back to unicode? And what
# about ints, or pickled values?
if getset:
command = 'GETSET'
elif preserve:
return self.setnx(key, value)
else:
command = 'SET'
if expire:
self._send('SETEX', key, expire, value)
else:
self._send(command, key, value)
return self.getResponse()
def setnx(self, key, value):
"""
Set key to hold string value if key does not exist. In that case, it is
equal to SET. When key already holds a value, no operation is
performed. SETNX is short for "SET if Not eXists".
"""
self._send('SETNX', key, value)
return self.getResponse()
def msetnx(self, mapping):
"""
Sets the given keys to their respective values. MSETNX will not perform
any operation at all even if just a single key already exists.
Because of this semantic MSETNX can be used in order to set different
keys representing different fields of an unique logic object in a way
that ensures that either all the fields or none at all are set.
MSETNX is atomic, so all given keys are set at once. It is not possible
for clients to see that some of the keys were updated while others are
unchanged.
"""
self._send('msetnx', *list(itertools.chain(*mapping.iteritems())))
return self.getResponse()
def mset(self, mapping, preserve=False):
"""
Set multiple keys to multiple values
"""
if preserve:
command = 'MSETNX'
else:
command = 'MSET'
self._send(command, *list(itertools.chain(*mapping.iteritems())))
return self.getResponse()
def append(self, key, value):
"""
Append a value to a key
"""
self._send('APPEND', key, value)
return self.getResponse()
def getrange(self, key, start, end):
"""
Get a substring of the string stored at a key
"""
self._send('GETRANGE', key, start, end)
return self.getResponse()
substr = getrange
def get(self, key):
"""
Get the value of a key
"""
self._send('GET', key)
return self.getResponse()
def getset(self, key, value):
"""
Set the string value of a key and return its old value
"""
return self.set(key, value, getset=True)
def mget(self, *args):
"""
Get the values of all the given keys
"""
self._send('MGET', *args)
return self.getResponse()
def incr(self, key, amount=1):
"""
Increment the integer value of a key by the given amount (default 1)
"""
if amount == 1:
self._send('INCR', key)
else:
self._send('INCRBY', key, amount)
return self.getResponse()
def decr(self, key, amount=1):
"""
Decrement the integer value of a key by the given amount (default 1)
"""
if amount == 1:
self._send('DECR', key)
else:
self._send('DECRBY', key, amount)
return self.getResponse()
def exists(self, key):
"""
Determine if a key exists
"""
self._send('EXISTS', key)
return self.getResponse()
def delete(self, key, *keys):
"""
Delete one or more keys
"""
self._send('DEL', key, *keys)
return self.getResponse()
def get_type(self, key):
"""
Determine the type stored at key
"""
self._send('TYPE', key)
return self.getResponse()
def get_object(self, key, refcount=False, encoding=False, idletime=False):
"""
Inspect the internals of Redis objects.
@param key : The Redis key you want to inspect
@param refcount: Returns the number of refereces of the value
associated with the specified key.
@param encoding: Returns the kind of internal representation for
value.
@param idletime: Returns the number of seconds since the object stored
at the specified key is idle. (Currently the actual
resolution is 10 seconds.)
"""
subcommand = ''
if idletime:
subcommand = 'IDLETIME'
elif encoding:
subcommand = 'ENCODING'
elif refcount:
subcommand = 'REFCOUNT'
if not subcommand:
raise exceptions.InvalidCommand('Need a subcommand')
self._send('OBJECT', subcommand, key)
return self.getResponse()
# Bit operations
def getbit(self, key, offset):
"""
Returns the bit value at offset in the string value stored at key.
@param key: The Redis key to get bit from.
@param offset: The offset to get bit from.
"""
self._send('GETBIT', key, offset)
return self.getResponse()
def setbit(self, key, offset, value):
"""
Sets the bit value at offset in the string value stored at key.
@param key: The Redis key to set bit on.
@param offset: The offset for the bit to set.
@param value: The bit value (0 or 1)
"""
self._send('SETBIT', key, offset, value)
return self.getResponse()
def bitcount(self, key, start=None, end=None):
"""
Count the number of set bits (population counting) in a string.
@param key: The Redis key to get bit count from.
@param start: Optional starting index for bytes to scan (inclusive)
@param end: Optional ending index for bytes to scan (inclusive).
End index is required when start is given.
"""
start_end = []
if start is not None:
start_end.append(start)
start_end.append(end)
self._send('BITCOUNT', key, *start_end)
return self.getResponse()
# Commands operating on the key space
def keys(self, pattern):
"""
Find all keys matching the given pattern
"""
self._send('KEYS', pattern)
def post_process(res):
if res is not None:
# XXX is sort ok?
res.sort()
else:
res = []
return res
return self.getResponse().addCallback(post_process)
def randomkey(self):
"""
Return a random key from the keyspace
"""
#raise NotImplementedError("Implemented but buggy, do not use.")
self._send('RANDOMKEY')
return self.getResponse()
def rename(self, src, dst, preserve=False):
"""
Rename a key
"""
self._send('RENAMENX' if preserve else 'RENAME', src, dst)
return self.getResponse()
def dbsize(self):
"""
Return the number of keys in the selected database
"""
self._send('DBSIZE')
return self.getResponse()
def expire(self, key, time):
"""
Set a key's time to live in seconds
"""
self._send('EXPIRE', key, time)
return self.getResponse()
def expireat(self, key, time):
"""
Set the expiration for a key as a UNIX timestamp
"""
self._send('EXPIREAT', key, time)
return self.getResponse()
def ttl(self, key):
"""
Get the time to live for a key
"""
self._send('TTL', key)
return self.getResponse()
# transaction commands:
def multi(self):
"""
Mark the start of a transaction block
"""
self._send('MULTI')
return self.getResponse()
def execute(self):
"""
Sends the EXEC command
Called execute because exec is a reserved word in Python.
"""
self._send('EXEC')
return self.getResponse()
def discard(self):
"""
Discard all commands issued after MULTI
"""
self._send('DISCARD')
return self.getResponse()
def watch(self, *keys):
"""
Watch the given keys to determine execution of the MULTI/EXEC block
"""
self._send('WATCH', *keys)
return self.getResponse()
def unwatch(self):
"""
Forget about all watched keys
"""
self._send('UNWATCH')
return self.getResponse()
# # # # # # # # #
# List Commands:
# RPUSH
# LPUSH
# RPUSHX
# LPUSHX
# LLEN
# LRANGE
# LTRIM
# LINDEX
# LSET
# LREM
# LPOP
# RPOP
# BLPOP
# BRPOP
# RPOPLPUSH
# SORT
def push(self, key, value, tail=False, no_create=False):
"""
@param key Redis key
@param value String element of list
Add the string value to the head (LPUSH/LPUSHX) or tail
(RPUSH/RPUSHX) of the list stored at key key. If the key does
not exist and no_create is False (the default) an empty list
is created just before the append operation. If the key exists
but is not a List an error is returned.
@note Time complexity: O(1)
"""
if tail:
if no_create:
return self.rpushx(key, value)
else:
return self.rpush(key, value)
else:
if no_create:
return self.lpushx(key, value)
else:
return self.lpush(key, value)
def lpush(self, key, *values, **kwargs):
"""
Add string to head of list.
@param key : List key
@param values : Sequence of values to push
@param value : For backwards compatibility, a single value.
"""
if not kwargs:
self._send('LPUSH', key, *values)
elif 'value' in kwargs:
self._send('LPUSH', key, kwargs['value'])
else:
raise exceptions.InvalidCommand('Need arguments for LPUSH')
return self.getResponse()
def rpush(self, key, *values, **kwargs):
"""
Add string to end of list.
@param key : List key
@param values : Sequence of values to push
@param value : For backwards compatibility, a single value.
"""
if not kwargs:
self._send('RPUSH', key, *values)
elif 'value' in kwargs:
self._send('RPUSH', key, kwargs['value'])
else:
raise exceptions.InvalidCommand('Need arguments for RPUSH')
return self.getResponse()
def lpushx(self, key, value):
self._send('LPUSHX', key, value)
return self.getResponse()
def rpushx(self, key, value):
self._send('RPUSHX', key, value)
return self.getResponse()
def llen(self, key):
"""
@param key Redis key
Return the length of the list stored at the key key. If the
key does not exist zero is returned (the same behavior as for
empty lists). If the value stored at key is not a list an error is
returned.
@note Time complexity: O(1)
"""
self._send('LLEN', key)
return self.getResponse()
def lrange(self, key, start, end):
"""
@param key Redis key
@param start first element
@param end last element
Return the specified elements of the list stored at the key key.
Start and end are zero-based indexes. 0 is the first element
of the list (the list head), 1 the next element and so on.
For example LRANGE foobar 0 2 will return the first three elements
of the list.
start and end can also be negative numbers indicating offsets from
the end of the list. For example -1 is the last element of the
list, -2 the penultimate element and so on.
Indexes out of range will not produce an error: if start is over
the end of the list, or start > end, an empty list is returned. If
end is over the end of the list Redis will threat it just like the
last element of the list.
@note Time complexity: O(n) (with n being the length of the range)
"""
self._send('LRANGE', key, start, end)
return self.getResponse()
def ltrim(self, key, start, end):
"""
@param key Redis key
@param start first element
@param end last element
Trim an existing list so that it will contain only the specified
range of elements specified. Start and end are zero-based indexes.
0 is the first element of the list (the list head), 1 the next
element and so on.
For example LTRIM foobar 0 2 will modify the list stored at foobar
key so that only the first three elements of the list will remain.
start and end can also be negative numbers indicating offsets from
the end of the list. For example -1 is the last element of the
list, -2 the penultimate element and so on.
Indexes out of range will not produce an error: if start is over
the end of the list, or start > end, an empty list is left as
value. If end over the end of the list Redis will threat it just
like the last element of the list.
@note Time complexity: O(n) (with n being len of list - len of range)
"""
self._send('LTRIM', key, start, end)
return self.getResponse()
def lindex(self, key, index):
"""
@param key Redis key
@param index index of element
Return the specified element of the list stored at the specified
key. 0 is the first element, 1 the second and so on. Negative
indexes are supported, for example -1 is the last element, -2 the
penultimate and so on.
If the value stored at key is not of list type an error is
returned. If the index is out of range an empty string is returned.
@note Time complexity: O(n) (with n being the length of the list)
Note that even if the average time complexity is O(n) asking for
the first or the last element of the list is O(1).
"""
self._send('LINDEX', key, index)
return self.getResponse()
def rpop(self, key):
self._send('RPOP', key)
return self.getResponse()
def lpop(self, key):
self._send('LPOP', key)
return self.getResponse()
def pop(self, key, tail=False):
"""
@param key Redis key
@param tail pop element from tail instead of head
Atomically return and remove the first (LPOP) or last (RPOP)
element of the list. For example if the list contains the elements
"a","b","c" LPOP will return "a" and the list will become "b","c".
If the key does not exist or the list is already empty the special
value 'nil' is returned.
"""
return self.rpop(key) if tail else self.lpop(key)
def brpop(self, keys, timeout=30):
"""
Issue a BRPOP - blockling list pop from the right.
@param keys is a list of one or more Redis keys
@param timeout max number of seconds to block for
"""
self._send('BRPOP', *(list(keys) + [str(timeout)]))
return self.getResponse()
def brpoplpush(self, source, destination, timeout=30):
"""
Blocking variant of RPOPLPUSH.
@param source - Source list.
@param destination - Destination list
@param timeout - max number of seconds to block for (a
timeout of 0 will block indefinitely)
"""
self._send('BRPOPLPUSH', source, destination, str(timeout))
return self.getResponse()
def bpop(self, keys, tail=False, timeout=30):
"""
@param keys a list of one or more Redis keys of non-empty list(s)
@param tail pop element from tail instead of head
@param timeout max number of seconds block for (0 is forever)
BLPOP (and BRPOP) is a blocking list pop primitive. You can see
this commands as blocking versions of LPOP and RPOP able to block
if the specified keys don't exist or contain empty lists.
The following is a description of the exact semantic. We
describe BLPOP but the two commands are identical, the only
difference is that BLPOP pops the element from the left (head)
of the list, and BRPOP pops from the right (tail).
Non blocking behavior
When BLPOP is called, if at least one of the specified keys
contain a non empty list, an element is popped from the head of
the list and returned to the caller together with the name of
the key (BLPOP returns a two elements array, the first element
is the key, the second the popped value).
Keys are scanned from left to right, so for instance if you
issue BLPOP list1 list2 list3 0 against a dataset where list1
does not exist but list2 and list3 contain non empty lists,
BLPOP guarantees to return an element from the list stored at
list2 (since it is the first non empty list starting from the
left).
Blocking behavior
If none of the specified keys exist or contain non empty lists,
BLPOP blocks until some other client performs a LPUSH or an
RPUSH operation against one of the lists.
Once new data is present on one of the lists, the client
finally returns with the name of the key unblocking it and the
popped value.
When blocking, if a non-zero timeout is specified, the client
will unblock returning a nil special value if the specified
amount of seconds passed without a push operation against at
least one of the specified keys.
A timeout of zero means instead to block forever.
Multiple clients blocking for the same keys
Multiple clients can block for the same key. They are put into
a queue, so the first to be served will be the one that started
to wait earlier, in a first-blpopping first-served fashion.
Return value
BLPOP returns a two-elements array via a multi bulk reply in
order to return both the unblocking key and the popped value.
When a non-zero timeout is specified, and the BLPOP operation
timed out, the return value is a nil multi bulk reply. Most
client values will return false or nil accordingly to the
programming language used.
"""
cmd = 'BRPOP' if tail else 'BLPOP'
self._send(cmd, *(list(keys) + [str(timeout)]))
return self.getResponse()
def rpoplpush(self, srckey, dstkey):
"""
@param srckey key of list to pop tail element of
@param dstkey key of list to push to
Atomically return and remove the last (tail) element of the srckey
list, and push the element as the first (head) element of the
dstkey list. For example if the source list contains the elements
"a","b","c" and the destination list contains the elements
"foo","bar" after an RPOPLPUSH command the content of the two lists
will be "a","b" and "c","foo","bar".
If the key does not exist or the list is already empty the special
value 'nil' is returned. If the srckey and dstkey are the same the
operation is equivalent to removing the last element from the list
and pusing it as first element of the list, so it's a "list
rotation" command.
Programming patterns: safe queues
Redis lists are often used as queues in order to exchange messages
between different programs. A program can add a message performing
an LPUSH operation against a Redis list (we call this program a
Producer), while another program (that we call Consumer)
can process the messages performing an RPOP command in
order to start reading the messages from the oldest.
Unfortunately if a Consumer crashes just after an RPOP
operation the message gets lost. RPOPLPUSH solves this
problem since the returned message is added to another
"backup" list. The Consumer can later remove the message
from the backup list using the LREM command when the
message was correctly processed.
Another process, called Helper, can monitor the "backup"
list to check for timed out entries to repush against the
main queue.
Programming patterns: server-side O(N) list traversal
Using RPOPPUSH with the same source and destination key a
process can visit all the elements of an N-elements List in
O(N) without to transfer the full list from the server to
the client in a single LRANGE operation. Note that a
process can traverse the list even while other processes
are actively RPUSHing against the list, and still no
element will be skipped.
Return value
Bulk reply
"""
self._send('RPOPLPUSH', srckey, dstkey)
return self.getResponse()
def lset(self, key, index, value):
"""
@param key Redis key
@param index index of element
@param value new value of element at index
Set the list element at index (see LINDEX for information about the
index argument) with the new value. Out of range indexes will
generate an error. Note that setting the first or last elements of
the list is O(1).
Similarly to other list commands accepting indexes, the index can
be negative to access elements starting from the end of the list.
So -1 is the last element, -2 is the penultimate, and so forth.
@note Time complexity: O(N) (with N being the length of the list)
"""
self._send('LSET', key, index, value)
return self.getResponse()
def lrem(self, key, value, count=0):
"""
@param key Redis key
@param value value to match
@param count number of occurrences of value
Remove the first count occurrences of the value element from the
list. If count is zero all the elements are removed. If count is
negative elements are removed from tail to head, instead to go from
head to tail that is the normal behavior. So for example LREM with
count -2 and hello as value to remove against the list
(a,b,c,hello,x,hello,hello) will lave the list (a,b,c,hello,x). The
number of removed elements is returned as an integer, see below for
more information about the returned value. Note that non existing
keys are considered like empty lists by LREM, so LREM against non
existing keys will always return 0.
@retval deferred that returns the number of removed elements
(int) if the operation succeeded
@note Time complexity: O(N) (with N being the length of the list)
"""
self._send('LREM', key, count, value)
return self.getResponse()
# Commands operating on sets
def _list_to_set(self, res):
if type(res) is list:
return set(res)
return res
def sadd(self, key, *values, **kwargs):
"""
Add a member to a set
@param key : SET key to add values to.
@param values : sequence of values to add to set
@param value : For backwards compatibility, add one value.
"""
if not kwargs:
self._send('SADD', key, *values)
elif 'value' in kwargs:
self._send('SADD', key, kwargs['value'])
else:
raise exceptions.InvalidCommand('Need arguments for SADD')
return self.getResponse()
def srem(self, key, *values, **kwargs):
"""
Remove a member from a set
@param key : Set key
@param values : Sequence of values to remove
@param value : For backwards compatibility, single value to remove.
"""
if not kwargs:
self._send('SREM', key, *values)
elif 'value' in kwargs:
self._send('SREM', key, kwargs['value'])
else:
raise exceptions.InvalidCommand('Need arguments for SREM')
return self.getResponse()
def spop(self, key):
"""
Remove and return a random member from a set
"""
self._send('SPOP', key)
return self.getResponse()
def scard(self, key):
"""
Get the number of members in a set
"""
self._send('SCARD', key)
return self.getResponse()
def sismember(self, key, value):
"""
Determine if a given value is a member of a set
"""
self._send('SISMEMBER', key, value)
return self.getResponse()
def sdiff(self, *args):
"""
Subtract multiple sets
"""
self._send('SDIFF', *args)
return self.getResponse()
def sdiffstore(self, dstkey, *args):
"""
Subtract multiple sets and store the resulting set in dstkey
"""
self._send('SDIFFSTORE', dstkey, *args)
return self.getResponse()
def srandmember(self, key):
"""
Get a random member from a set
"""
self._send('SRANDMEMBER', key)
return self.getResponse()
def sinter(self, *args):
"""
Intersect multiple sets
"""
self._send('SINTER', *args)
return self.getResponse().addCallback(self._list_to_set)
def sinterstore(self, dest, *args):
"""
Intersect multiple sets and store the resulting set in dest
"""
self._send('SINTERSTORE', dest, *args)
return self.getResponse()
def smembers(self, key):
"""
Get all the members in a set
"""
self._send('SMEMBERS', key)
return self.getResponse().addCallback(self._list_to_set)
def smove(self, srckey, dstkey, member):
"""Move member from the set at srckey to the set at dstkey."""
self._send('SMOVE', srckey, dstkey, member)
return self.getResponse()
def sunion(self, *args):
"""
Add multiple sets
"""
self._send('SUNION', *args)
return self.getResponse().addCallback(self._list_to_set)
def sunionstore(self, dest, *args):
"""
Add multiple sets and store the resulting set in dest
"""
self._send('SUNIONSTORE', dest, *args)
return self.getResponse()
# Multiple databases handling commands
def select(self, db):
"""
Select the DB with having the specified zero-based numeric index. New
connections always use DB 0.
"""
self._send('SELECT', db)
return self.getResponse()
def move(self, key, db):
"""
Move a key to another database
"""
self._send('MOVE', key, db)
return self.getResponse()
def flush(self, all_dbs=False):
"""
Remove all keys from the current database or, if all_dbs is True,
all databases.
"""
if all_dbs:
return self.flushall()
else:
return self.flushdb()
def flushall(self):
"""
Remove all keys from all databases
"""
self._send('FLUSHALL')
return self.getResponse()
def flushdb(self):
"""
Remove all keys from the current database
"""
self._send('FLUSHDB')
return self.getResponse()
# Persistence control commands
def bgrewriteaof(self):
"""
Rewrites the append-only file to reflect the current dataset in memory.
If BGREWRITEAOF fails, no data gets lost as the old AOF will be
untouched.
"""
self._send('BGREWRITEAOF')
return self.getResponse()
def bgsave(self):
"""
Save the DB in background. The OK code is immediately returned. Redis
forks, the parent continues to server the clients, the child saves the
DB on disk then exit. A client my be able to check if the operation
succeeded using the LASTSAVE command.
"""
self._send('BGSAVE')
return self.getResponse()
def save(self, background=False):
"""
Synchronously save the dataset to disk.
"""
if background:
return self.bgsave()
else:
self._send('SAVE')
return self.getResponse()
def lastsave(self):
"""
Return the UNIX TIME of the last DB save executed with success. A
client may check if a BGSAVE command succeeded reading the LASTSAVE
value, then issuing a BGSAVE command and checking at regular intervals
every N seconds if LASTSAVE changed.
"""
self._send('LASTSAVE')
return self.getResponse()
def info(self):
"""
The info command returns different information and statistics about the
server in an format that's simple to parse by computers and easy to red
by huamns.
"""
self._send('INFO')
def post_process(res):
info = dict()
res = res.split('\r\n')
for l in res:
if not l or l[0] == '#':
continue
k, v = l.split(':')
info[k] = int(v) if v.isdigit() else v
return info
return self.getResponse().addCallback(post_process)
def sort(self, key, by=None, get=None, start=None, num=None, desc=False,
alpha=False):
"""
Sort the elements in a list, set or sorted set
"""
stmt = ['SORT', key]
if by:
stmt.extend(['BY', by])
if start and num:
stmt.extend(['LIMIT', start, num])
if get is None:
pass
elif isinstance(get, basestring):
stmt.extend(['GET', get])
elif isinstance(get, list) or isinstance(get, tuple):
for g in get:
stmt.extend(['GET', g])
else:
raise exceptions.RedisError(
"Invalid parameter 'get' for Redis sort")
if desc:
stmt.append("DESC")
if alpha:
stmt.append("ALPHA")
self._send(*stmt)
return self.getResponse()
def quit(self):
"""
Ask the server to close the connection. The connection is closed as
soon as all pending replies have been written to the client.
"""
self._send('QUIT')
return self.getResponse()
def echo(self, msg):
"""
Returns message.
"""
self._send('ECHO', msg)
return self.getResponse()
# # # # # # # # #
# Hash Commands:
# HSET
# HGET
# HMSET