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#!/usr/bin/env python3
"""
client module for memcached (memory cache daemon)
Overview
========
See U{the MemCached homepage<http://www.danga.com/memcached>} for more about memcached.
Usage summary
=============
This should give you a feel for how this module operates::
import memcache
mc = memcache.Client(['127.0.0.1:11211'], debug=0)
mc.set("some_key", "Some value")
value = mc.get("some_key")
mc.set("another_key", 3)
mc.delete("another_key")
mc.set("key", "1") # note that the key used for incr/decr must be a string.
mc.incr("key")
mc.decr("key")
The standard way to use memcache with a database is like this::
key = derive_key(obj)
obj = mc.get(key)
if not obj:
obj = backend_api.get(...)
mc.set(key, obj)
# we now have obj, and future passes through this code
# will use the object from the cache.
Detailed Documentation
======================
More detailed documentation is available in the L{Client} class.
"""
import sys
import socket
import time
import os
import re
import pickle
from io import StringIO, BytesIO
from binascii import crc32 # zlib version is not cross-platform
def cmemcache_hash(key):
return((((crc32(key) & 0xffffffff) >> 16) & 0x7fff) or 1)
serverHashFunction = cmemcache_hash
def useOldServerHashFunction():
"""Use the old python-memcache server hash function."""
global serverHashFunction
serverHashFunction = crc32
try:
from zlib import compress, decompress
_supports_compress = True
except ImportError:
_supports_compress = False
# quickly define a decompress just in case we recv compressed data.
def decompress(val):
raise _Error("received compressed data but I don't support compression (import error)")
invalid_key_characters = ''.join(map(chr, list(range(33)) + [127]))
# Original author: Evan Martin of Danga Interactive
__author__ = "Sean Reifschneider <jafo-memcached@tummy.com>"
__version__ = "1.51"
__copyright__ = "Copyright (C) 2003 Danga Interactive"
# http://en.wikipedia.org/wiki/Python_Software_Foundation_License
__license__ = "Python Software Foundation License"
SERVER_MAX_KEY_LENGTH = 250
# Storing values larger than 1MB requires recompiling memcached. If you do,
# this value can be changed by doing "memcache.SERVER_MAX_VALUE_LENGTH = N"
# after importing this module.
SERVER_MAX_VALUE_LENGTH = 1024*1024
class _Error(Exception):
pass
class _ConnectionDeadError(Exception):
pass
from threading import local
_DEAD_RETRY = 30 # number of seconds before retrying a dead server.
_SOCKET_TIMEOUT = 3 # number of seconds before sockets timeout.
class Client(local):
"""
Object representing a pool of memcache servers.
See L{memcache} for an overview.
In all cases where a key is used, the key can be either:
1. A simple hashable type (string, integer, etc.).
2. A tuple of C{(hashvalue, key)}. This is useful if you want to avoid
making this module calculate a hash value. You may prefer, for
example, to keep all of a given user's objects on the same memcache
server, so you could use the user's unique id as the hash value.
@group Setup: __init__, set_servers, forget_dead_hosts, disconnect_all, debuglog
@group Insertion: set, add, replace, set_multi
@group Retrieval: get, get_multi
@group Integers: incr, decr
@group Removal: delete, delete_multi
@sort: __init__, set_servers, forget_dead_hosts, disconnect_all, debuglog,\
set, set_multi, add, replace, get, get_multi, incr, decr, delete, delete_multi
"""
_FLAG_PICKLE = 1<<0
_FLAG_INTEGER = 1<<1
_FLAG_LONG = 1<<2
_FLAG_COMPRESSED = 1<<3
_SERVER_RETRIES = 10 # how many times to try finding a free server.
# exceptions for Client
class MemcachedKeyError(Exception):
pass
class MemcachedKeyLengthError(MemcachedKeyError):
pass
class MemcachedKeyCharacterError(MemcachedKeyError):
pass
class MemcachedKeyNoneError(MemcachedKeyError):
pass
class MemcachedKeyTypeError(MemcachedKeyError):
pass
class MemcachedStringEncodingError(Exception):
pass
def __init__(self, servers, debug=0, pickleProtocol=0,
pickler=pickle.Pickler, unpickler=pickle.Unpickler,
pload=None, pid=None,
server_max_key_length=SERVER_MAX_KEY_LENGTH,
server_max_value_length=SERVER_MAX_VALUE_LENGTH,
dead_retry=_DEAD_RETRY, socket_timeout=_SOCKET_TIMEOUT,
cache_cas = False, flush_on_reconnect=0, check_keys=True):
"""
Create a new Client object with the given list of servers.
@param servers: C{servers} is passed to L{set_servers}.
@param debug: whether to display error messages when a server can't be
contacted.
@param pickleProtocol: number to mandate protocol used by (c)Pickle.
@param pickler: optional override of default Pickler to allow subclassing.
@param unpickler: optional override of default Unpickler to allow subclassing.
@param pload: optional persistent_load function to call on pickle loading.
Useful for cPickle since subclassing isn't allowed.
@param pid: optional persistent_id function to call on pickle storing.
Useful for cPickle since subclassing isn't allowed.
@param dead_retry: number of seconds before retrying a blacklisted
server. Default to 30 s.
@param socket_timeout: timeout in seconds for all calls to a server. Defaults
to 3 seconds.
@param cache_cas: (default False) If true, cas operations will be
cached. WARNING: This cache is not expired internally, if you have
a long-running process you will need to expire it manually via
client.reset_cas(), or the cache can grow unlimited.
@param server_max_key_length: (default SERVER_MAX_KEY_LENGTH)
Data that is larger than this will not be sent to the server.
@param server_max_value_length: (default SERVER_MAX_VALUE_LENGTH)
Data that is larger than this will not be sent to the server.
@param flush_on_reconnect: optional flag which prevents a scenario that
can cause stale data to be read: If there's more than one memcached
server and the connection to one is interrupted, keys that mapped to
that server will get reassigned to another. If the first server comes
back, those keys will map to it again. If it still has its data, get()s
can read stale data that was overwritten on another server. This flag
is off by default for backwards compatibility.
@param check_keys: (default True) If True, the key is checked to
ensure it is the correct length and composed of the right characters.
"""
local.__init__(self)
self.debug = debug
self.dead_retry = dead_retry
self.socket_timeout = socket_timeout
self.flush_on_reconnect = flush_on_reconnect
self.set_servers(servers)
self.stats = {}
self.cache_cas = cache_cas
self.reset_cas()
self.do_check_key = check_keys
# Allow users to modify pickling/unpickling behavior
self.pickleProtocol = pickleProtocol
self.pickler = pickler
self.unpickler = unpickler
self.persistent_load = pload
self.persistent_id = pid
self.server_max_key_length = server_max_key_length
self.server_max_value_length = server_max_value_length
# figure out the pickler style
file = StringIO()
try:
pickler = self.pickler(file, protocol = self.pickleProtocol)
self.picklerIsKeyword = True
except TypeError:
self.picklerIsKeyword = False
def reset_cas(self):
"""
Reset the cas cache. This is only used if the Client() object
was created with "cache_cas=True". If used, this cache does not
expire internally, so it can grow unbounded if you do not clear it
yourself.
"""
self.cas_ids = {}
def set_servers(self, servers):
"""
Set the pool of servers used by this client.
@param servers: an array of servers.
Servers can be passed in two forms:
1. Strings of the form C{"host:port"}, which implies a default weight of 1.
2. Tuples of the form C{("host:port", weight)}, where C{weight} is
an integer weight value.
"""
self.servers = [_Host(s, self.debug, dead_retry=self.dead_retry,
socket_timeout=self.socket_timeout,
flush_on_reconnect=self.flush_on_reconnect)
for s in servers]
self._init_buckets()
def get_stats(self, stat_args = None):
'''Get statistics from each of the servers.
@param stat_args: Additional arguments to pass to the memcache
"stats" command.
@return: A list of tuples ( server_identifier, stats_dictionary ).
The dictionary contains a number of name/value pairs specifying
the name of the status field and the string value associated with
it. The values are not converted from strings.
'''
data = []
for s in self.servers:
if not s.connect(): continue
if s.family == socket.AF_INET:
name = '%s:%s (%s)' % ( s.ip, s.port, s.weight )
elif s.family == socket.AF_INET6:
name = '[%s]:%s (%s)' % ( s.ip, s.port, s.weight )
else:
name = 'unix:%s (%s)' % ( s.address, s.weight )
if not stat_args:
s.send_cmd(b'stats')
elif isinstance(stat_args, bytes):
s.send_cmd(b'stats ' + stat_args)
else:
s.send_cmd(b'stats ' + str(stat_args).encode('utf-8'))
serverData = {}
data.append(( name.encode('ascii'), serverData ))
readline = s.readline
while 1:
line = readline()
if not line or line.strip() == b'END': break
stats = line.decode('ascii').split(' ', 2)
serverData[stats[1].encode('ascii')] = stats[2].encode('ascii')
return(data)
def get_slabs(self):
data = []
for s in self.servers:
if not s.connect(): continue
if s.family == socket.AF_INET:
name = '%s:%s (%s)' % ( s.ip, s.port, s.weight )
elif s.family == socket.AF_INET6:
name = '[%s]:%s (%s)' % ( s.ip, s.port, s.weight )
else:
name = 'unix:%s (%s)' % ( s.address, s.weight )
serverData = {}
data.append(( name, serverData ))
s.send_cmd('stats items')
readline = s.readline
while 1:
line = readline()
if not line or line.strip() == b'END': break
item = line.split(' ', 2)
#0 = STAT, 1 = ITEM, 2 = Value
slab = item[1].split(':', 2)
#0 = items, 1 = Slab #, 2 = Name
if slab[1] not in serverData:
serverData[slab[1]] = {}
serverData[slab[1]][slab[2]] = item[2]
return data
def flush_all(self):
"""Expire all data in memcache servers that are reachable."""
for s in self.servers:
if not s.connect(): continue
s.flush()
def debuglog(self, str):
if self.debug:
sys.stderr.write("MemCached: %s\n" % str)
def _statlog(self, func):
if func not in self.stats:
self.stats[func] = 1
else:
self.stats[func] += 1
def forget_dead_hosts(self):
"""
Reset every host in the pool to an "alive" state.
"""
for s in self.servers:
s.deaduntil = 0
def _init_buckets(self):
self.buckets = []
for server in self.servers:
for i in range(server.weight):
self.buckets.append(server)
def _get_server(self, key):
if isinstance(key, tuple):
serverhash, key = key
else:
serverhash = serverHashFunction(key.encode('utf-8'))
for i in range(Client._SERVER_RETRIES):
server = self.buckets[serverhash % len(self.buckets)]
if server.connect():
#print "(using server %s)" % server,
return server, key
serverhash = serverHashFunction((str(serverhash) + str(i)).encode("ascii"))
return None, None
def disconnect_all(self):
for s in self.servers:
s.close_socket()
def delete_multi(self, keys, time=0, key_prefix=''):
'''
Delete multiple keys in the memcache doing just one query.
>>> notset_keys = mc.set_multi({'key1' : 'val1', 'key2' : 'val2'})
>>> mc.get_multi(['key1', 'key2']) == {'key1' : 'val1', 'key2' : 'val2'}
1
>>> mc.delete_multi(['key1', 'key2'])
1
>>> mc.get_multi(['key1', 'key2']) == {}
1
This method is recommended over iterated regular L{delete}s as it reduces total latency, since
your app doesn't have to wait for each round-trip of L{delete} before sending
the next one.
@param keys: An iterable of keys to clear
@param time: number of seconds any subsequent set / update commands should fail. Defaults to 0 for no delay.
@param key_prefix: Optional string to prepend to each key when sending to memcache.
See docs for L{get_multi} and L{set_multi}.
@return: 1 if no failure in communication with any memcacheds.
@rtype: int
'''
self._statlog('delete_multi')
server_keys, prefixed_to_orig_key = self._map_and_prefix_keys(keys, key_prefix)
# send out all requests on each server before reading anything
dead_servers = []
rc = 1
for server in server_keys.keys():
bigcmd = []
write = bigcmd.append
if time != None:
for key in server_keys[server]: # These are mangled keys
write("delete %s %d\r\n" % (key, time))
else:
for key in server_keys[server]: # These are mangled keys
write("delete %s\r\n" % key)
try:
server.send_cmds(''.join(bigcmd))
except socket.error as msg:
rc = 0
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
dead_servers.append(server)
# if any servers died on the way, don't expect them to respond.
for server in dead_servers:
del server_keys[server]
for server, keys in server_keys.items():
try:
for key in keys:
server.expect(b"DELETED")
except socket.error as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
rc = 0
return rc
def delete(self, key, time=0):
'''Deletes a key from the memcache.
@return: Nonzero on success.
@param time: number of seconds any subsequent set / update commands
should fail. Defaults to None for no delay.
@rtype: int
'''
if self.do_check_key:
self.check_key(key)
server, key = self._get_server(key)
if not server:
return 0
self._statlog('delete')
if time != None and time != 0:
cmd = "delete %s %d" % (key, time)
else:
cmd = "delete %s" % key
try:
server.send_cmd(cmd.encode('utf-8'))
line = server.readline()
if line and line.strip() in [b'DELETED', b'NOT_FOUND']: return 1
self.debuglog('Delete expected DELETED or NOT_FOUND, got: %s'
% repr(line))
except socket.error as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
return 0
def incr(self, key, delta=1):
"""
Sends a command to the server to atomically increment the value
for C{key} by C{delta}, or by 1 if C{delta} is unspecified.
Returns None if C{key} doesn't exist on server, otherwise it
returns the new value after incrementing.
Note that the value for C{key} must already exist in the memcache,
and it must be the string representation of an integer.
>>> mc.set("counter", "20") # returns 1, indicating success
1
>>> mc.incr("counter")
21
>>> mc.incr("counter")
22
Overflow on server is not checked. Be aware of values approaching
2**32. See L{decr}.
@param delta: Integer amount to increment by (should be zero or greater).
@return: New value after incrementing.
@rtype: int
"""
return self._incrdecr("incr", key, delta)
def decr(self, key, delta=1):
"""
Like L{incr}, but decrements. Unlike L{incr}, underflow is checked and
new values are capped at 0. If server value is 1, a decrement of 2
returns 0, not -1.
@param delta: Integer amount to decrement by (should be zero or greater).
@return: New value after decrementing or None on error.
@rtype: int
"""
return self._incrdecr("decr", key, delta)
def _incrdecr(self, cmd, key, delta):
if self.do_check_key:
self.check_key(key)
server, key = self._get_server(key)
if not server:
return None
self._statlog(cmd)
cmd = "%s %s %d" % (cmd, key, delta)
try:
server.send_cmd(cmd)
line = server.readline()
if line == None or line.strip() ==b'NOT_FOUND': return None
return int(line)
except socket.error as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
return None
def add(self, key, val, time = 0, min_compress_len = 0):
'''
Add new key with value.
Like L{set}, but only stores in memcache if the key doesn't already exist.
@return: Nonzero on success.
@rtype: int
'''
return self._set("add", key, val, time, min_compress_len)
def append(self, key, val, time=0, min_compress_len=0):
'''Append the value to the end of the existing key's value.
Only stores in memcache if key already exists.
Also see L{prepend}.
@return: Nonzero on success.
@rtype: int
'''
return self._set("append", key, val, time, min_compress_len)
def prepend(self, key, val, time=0, min_compress_len=0):
'''Prepend the value to the beginning of the existing key's value.
Only stores in memcache if key already exists.
Also see L{append}.
@return: Nonzero on success.
@rtype: int
'''
return self._set("prepend", key, val, time, min_compress_len)
def replace(self, key, val, time=0, min_compress_len=0):
'''Replace existing key with value.
Like L{set}, but only stores in memcache if the key already exists.
The opposite of L{add}.
@return: Nonzero on success.
@rtype: int
'''
return self._set("replace", key, val, time, min_compress_len)
def set(self, key, val, time=0, min_compress_len=0):
'''Unconditionally sets a key to a given value in the memcache.
The C{key} can optionally be an tuple, with the first element
being the server hash value and the second being the key.
If you want to avoid making this module calculate a hash value.
You may prefer, for example, to keep all of a given user's objects
on the same memcache server, so you could use the user's unique
id as the hash value.
@return: Nonzero on success.
@rtype: int
@param time: Tells memcached the time which this value should expire, either
as a delta number of seconds, or an absolute unix time-since-the-epoch
value. See the memcached protocol docs section "Storage Commands"
for more info on <exptime>. We default to 0 == cache forever.
@param min_compress_len: The threshold length to kick in auto-compression
of the value using the zlib.compress() routine. If the value being cached is
a string, then the length of the string is measured, else if the value is an
object, then the length of the pickle result is measured. If the resulting
attempt at compression yeilds a larger string than the input, then it is
discarded. For backwards compatability, this parameter defaults to 0,
indicating don't ever try to compress.
'''
return self._set("set", key, val, time, min_compress_len)
def cas(self, key, val, time=0, min_compress_len=0):
'''Sets a key to a given value in the memcache if it hasn't been
altered since last fetched. (See L{gets}).
The C{key} can optionally be an tuple, with the first element
being the server hash value and the second being the key.
If you want to avoid making this module calculate a hash value.
You may prefer, for example, to keep all of a given user's objects
on the same memcache server, so you could use the user's unique
id as the hash value.
@return: Nonzero on success.
@rtype: int
@param time: Tells memcached the time which this value should expire,
either as a delta number of seconds, or an absolute unix
time-since-the-epoch value. See the memcached protocol docs section
"Storage Commands" for more info on <exptime>. We default to
0 == cache forever.
@param min_compress_len: The threshold length to kick in
auto-compression of the value using the zlib.compress() routine. If
the value being cached is a string, then the length of the string is
measured, else if the value is an object, then the length of the
pickle result is measured. If the resulting attempt at compression
yeilds a larger string than the input, then it is discarded. For
backwards compatability, this parameter defaults to 0, indicating
don't ever try to compress.
'''
return self._set("cas", key, val, time, min_compress_len)
def _map_and_prefix_keys(self, key_iterable, key_prefix):
"""Compute the mapping of server (_Host instance) -> list of keys to stuff onto that server, as well as the mapping of
prefixed key -> original key.
"""
# Check it just once ...
key_extra_len=len(key_prefix)
if key_prefix and self.do_check_key:
self.check_key(key_prefix)
# server (_Host) -> list of unprefixed server keys in mapping
server_keys = {}
prefixed_to_orig_key = {}
# build up a list for each server of all the keys we want.
for orig_key in key_iterable:
if isinstance(orig_key, tuple):
# Tuple of hashvalue, key ala _get_server(). Caller is essentially telling us what server to stuff this on.
# Ensure call to _get_server gets a Tuple as well.
str_orig_key = str(orig_key[1])
server, key = self._get_server((orig_key[0], key_prefix + str_orig_key)) # Gotta pre-mangle key before hashing to a server. Returns the mangled key.
else:
str_orig_key = str(orig_key) # set_multi supports int / long keys.
server, key = self._get_server(key_prefix + str_orig_key)
# Now check to make sure key length is proper ...
if self.do_check_key:
self.check_key(str_orig_key, key_extra_len=key_extra_len)
if not server:
continue
if server not in server_keys:
server_keys[server] = []
server_keys[server].append(key)
prefixed_to_orig_key[key] = orig_key
return (server_keys, prefixed_to_orig_key)
def set_multi(self, mapping, time=0, key_prefix='', min_compress_len=0):
'''
Sets multiple keys in the memcache doing just one query.
>>> notset_keys = mc.set_multi({'key1' : 'val1', 'key2' : 'val2'})
>>> mc.get_multi(['key1', 'key2']) == {'key1' : 'val1', 'key2' : 'val2'}
1
This method is recommended over regular L{set} as it lowers the number of
total packets flying around your network, reducing total latency, since
your app doesn't have to wait for each round-trip of L{set} before sending
the next one.
@param mapping: A dict of key/value pairs to set.
@param time: Tells memcached the time which this value should expire, either
as a delta number of seconds, or an absolute unix time-since-the-epoch
value. See the memcached protocol docs section "Storage Commands"
for more info on <exptime>. We default to 0 == cache forever.
@param key_prefix: Optional string to prepend to each key when sending to memcache. Allows you to efficiently stuff these keys into a pseudo-namespace in memcache:
>>> notset_keys = mc.set_multi({'key1' : 'val1', 'key2' : 'val2'}, key_prefix='subspace_')
>>> len(notset_keys) == 0
True
>>> mc.get_multi(['subspace_key1', 'subspace_key2']) == {'subspace_key1' : 'val1', 'subspace_key2' : 'val2'}
True
Causes key 'subspace_key1' and 'subspace_key2' to be set. Useful in conjunction with a higher-level layer which applies namespaces to data in memcache.
In this case, the return result would be the list of notset original keys, prefix not applied.
@param min_compress_len: The threshold length to kick in auto-compression
of the value using the zlib.compress() routine. If the value being cached is
a string, then the length of the string is measured, else if the value is an
object, then the length of the pickle result is measured. If the resulting
attempt at compression yeilds a larger string than the input, then it is
discarded. For backwards compatability, this parameter defaults to 0,
indicating don't ever try to compress.
@return: List of keys which failed to be stored [ memcache out of memory, etc. ].
@rtype: list
'''
self._statlog('set_multi')
server_keys, prefixed_to_orig_key = self._map_and_prefix_keys(iter(mapping.keys()), key_prefix)
# send out all requests on each server before reading anything
dead_servers = []
notstored = [] # original keys.
for server in server_keys.keys():
bigcmd = bytearray()
write = bigcmd.extend
try:
newline = b"\r\n"
for key in server_keys[server]: # These are mangled keys
store_info = self._val_to_store_info(mapping[prefixed_to_orig_key[key]], min_compress_len)
if store_info:
cmd = bytearray(("set %s %d %d %d\r\n" % (key, store_info[0], time, store_info[1])).encode('utf-8'))
# now write to bigcmd: cmd + val + newline
write(cmd)
write(store_info[2])
write(newline)
else:
notstored.append(prefixed_to_orig_key[key])
server.send_cmds(bytes(bigcmd))
except socket.error as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
dead_servers.append(server)
# if any servers died on the way, don't expect them to respond.
for server in dead_servers:
del server_keys[server]
# short-circuit if there are no servers, just return all keys
if not server_keys: return(list(mapping.keys()))
for server, keys in server_keys.items():
try:
for key in keys:
line = server.readline()
if line == b'STORED':
continue
else:
notstored.append(prefixed_to_orig_key[key]) #un-mangle.
except (_Error, socket.error) as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
return notstored
def _val_to_store_info(self, val, min_compress_len):
"""
Transform val to a storable representation, returning a tuple of the flags, the length of the new value, and the new value itself.
"""
flags = 0
# check types exactly rather than using isinstance, or subclasses
# will be deserialized into instances of the parent class
# (most blatantly, bool --> int)
if type(val) == str:
val = val.encode('utf-8')
elif type(val) == int:
flags |= Client._FLAG_INTEGER
val = str(val).encode('ascii')
# force no attempt to compress this silly string.
min_compress_len = 0
else:
flags |= Client._FLAG_PICKLE
file = BytesIO()
if self.picklerIsKeyword:
pickler = self.pickler(file, protocol = self.pickleProtocol)
else:
pickler = self.pickler(file, self.pickleProtocol)
if self.persistent_id:
pickler.persistent_id = self.persistent_id
pickler.dump(val)
val = file.getvalue()
lv = len(val)
# We should try to compress if min_compress_len > 0 and we could
# import zlib and this string is longer than our min threshold.
if min_compress_len and _supports_compress and lv > min_compress_len:
comp_val = compress(val)
# Only retain the result if the compression result is smaller
# than the original.
if len(comp_val) < lv:
flags |= Client._FLAG_COMPRESSED
val = comp_val
# silently do not store if value length exceeds maximum
if self.server_max_value_length != 0 and \
len(val) > self.server_max_value_length: return(0)
return (flags, len(val), val)
def _cmd_builder(self, cmd, key, time, store_info):
'''A utility method to build platform specific fullcmd, mainly due
to pickle return value type.
'''
if cmd == 'cas':
c = "cas %s %d %d %d %d\r\n" % (
key, store_info[0], time, store_info[1], self.cas_ids[key])
else:
c = "%s %s %d %d %d\r\n" % (
cmd, key, store_info[0], time, store_info[1])
if isinstance(store_info[2], bytes):
return c.encode('utf-8') + store_info[2]
else:
raise _Error("_cmd_builder: unknown data type (%s)" %
type(store_info[2]))
def _set(self, cmd, key, val, time, min_compress_len = 0):
if self.do_check_key:
self.check_key(key)
server, key = self._get_server(key)
if not server:
return 0
def _unsafe_set():
self._statlog(cmd)
store_info = self._val_to_store_info(val, min_compress_len)
if not store_info: return(0)
if cmd == 'cas':
if key not in self.cas_ids:
return self._set('set', key, val, time, min_compress_len)
fullcmd = self._cmd_builder(cmd, key, time, store_info)
else:
fullcmd = self._cmd_builder(cmd, key, time, store_info)
try:
server.send_cmd(fullcmd)
return(server.expect(b"STORED", raise_exception=True)
== b"STORED")
except socket.error as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
return 0
try:
return _unsafe_set()
except _ConnectionDeadError:
# retry once
try:
if server._get_socket():
return _unsafe_set()
except (_ConnectionDeadError, socket.error) as msg:
server.mark_dead(msg)
return 0
def _get(self, cmd, key):
if self.do_check_key:
self.check_key(key)
server, key = self._get_server(key)
if not server:
return None
def _unsafe_get():
self._statlog(cmd)
try:
server.send_cmd("{0} {1}".format(cmd, key).encode("utf-8"))
rkey = flags = rlen = cas_id = None
if cmd == 'gets':
rkey, flags, rlen, cas_id, = self._expect_cas_value(server,
raise_exception=True)
if rkey and self.cache_cas:
self.cas_ids[rkey] = cas_id
else:
rkey, flags, rlen, = self._expectvalue(server,
raise_exception=True)
if not rkey:
return None
try:
value = self._recv_value(server, flags, rlen)
finally:
server.expect(b"END", raise_exception=True)
except (_Error, socket.error) as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
return None
return value
try:
return _unsafe_get()
except _ConnectionDeadError:
# retry once
try:
if server.connect():
return _unsafe_get()
return None
except (_ConnectionDeadError, socket.error) as msg:
server.mark_dead(msg)
return None
def get(self, key):
'''Retrieves a key from the memcache.
@return: The value or None.
'''
return self._get('get', key)
def gets(self, key):
'''Retrieves a key from the memcache. Used in conjunction with 'cas'.
@return: The value or None.
'''
return self._get('gets', key)
def get_multi(self, keys, key_prefix=''):
'''
Retrieves multiple keys from the memcache doing just one query.
>>> success = mc.set("foo", "bar")
>>> success = mc.set("baz", 42)
>>> mc.get_multi(["foo", "baz", "foobar"]) == {"foo": "bar", "baz": 42}
1
>>> mc.set_multi({'k1' : 1, 'k2' : 2}, key_prefix='pfx_') == []
1
This looks up keys 'pfx_k1', 'pfx_k2', ... . Returned dict will just have unprefixed keys 'k1', 'k2'.
>>> mc.get_multi(['k1', 'k2', 'nonexist'], key_prefix='pfx_') == {'k1' : 1, 'k2' : 2}
1
get_mult [ and L{set_multi} ] can take str()-ables like ints / longs as keys too. Such as your db pri key fields.
They're rotored through str() before being passed off to memcache, with or without the use of a key_prefix.
In this mode, the key_prefix could be a table name, and the key itself a db primary key number.
>>> mc.set_multi({42: 'douglass adams', 46 : 'and 2 just ahead of me'}, key_prefix='numkeys_') == []
1
>>> mc.get_multi([46, 42], key_prefix='numkeys_') == {42: 'douglass adams', 46 : 'and 2 just ahead of me'}
1
This method is recommended over regular L{get} as it lowers the number of
total packets flying around your network, reducing total latency, since
your app doesn't have to wait for each round-trip of L{get} before sending
the next one.
See also L{set_multi}.
@param keys: An array of keys.
@param key_prefix: A string to prefix each key when we communicate with memcache.
Facilitates pseudo-namespaces within memcache. Returned dictionary keys will not have this prefix.
@return: A dictionary of key/value pairs that were available. If key_prefix was provided, the keys in the retured dictionary will not have it present.
'''
self._statlog('get_multi')
server_keys, prefixed_to_orig_key = self._map_and_prefix_keys(keys, key_prefix)
# send out all requests on each server before reading anything
dead_servers = []
for server in server_keys.keys():
try:
server.send_cmd("get %s" % " ".join(server_keys[server]))
except socket.error as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
dead_servers.append(server)
# if any servers died on the way, don't expect them to respond.
for server in dead_servers:
del server_keys[server]
retvals = {}
for server in server_keys.keys():
try:
line = server.readline()
while line and line != b'END':
rkey, flags, rlen = self._expectvalue(server, line)
# Bo Yang reports that this can sometimes be None
if rkey is not None:
if isinstance(rkey,bytes):
rkey = rkey.decode()
val = self._recv_value(server, flags, rlen)
retvals[prefixed_to_orig_key[rkey]] = val # un-prefix returned key.
line = server.readline()
except (_Error, socket.error) as msg:
if isinstance(msg, tuple): msg = msg[1]
server.mark_dead(msg)
return retvals
def _expect_cas_value(self, server, line=None, raise_exception=False):
if not line:
line = server.readline(raise_exception)
if line and line[:5] == b'VALUE':
resp, rkey, flags, len, cas_id = line.split()
return (rkey, int(flags), int(len), int(cas_id))
else:
return (None, None, None, None)
def _expectvalue(self, server, line=None, raise_exception=False):
if not line:
line = server.readline(raise_exception)
if line and line[:5] == b'VALUE':
resp, rkey, flags, len = line.split()
flags = int(flags)
rlen = int(len)
return (rkey, flags, rlen)
else:
return (None, None, None)
def _recv_value(self, server, flags, rlen):
rlen += 2 # include \r\n
buf = server.recv(rlen)
if len(buf) != rlen:
raise _Error("received %d bytes when expecting %d" % (len(buf), rlen))
if len(buf) == rlen:
buf = buf[:-2] # strip \r\n
if flags & Client._FLAG_COMPRESSED:
buf = decompress(buf)
if flags == 0 or flags == Client._FLAG_COMPRESSED:
# Either a bare string or a compressed string now decompressed...
val = buf.decode('utf-8')
elif flags & Client._FLAG_INTEGER:
val = int(buf)
elif flags & Client._FLAG_LONG:
val = int(buf)
elif flags & Client._FLAG_PICKLE:
try:
file = BytesIO(buf)
unpickler = self.unpickler(file)
if self.persistent_load:
unpickler.persistent_load = self.persistent_load
val = unpickler.load()
except Exception as e:
self.debuglog('Pickle error: %s\n' % e)
val = None
else:
self.debuglog("unknown flags on get: %x\n" % flags)
return val
def check_key(self, key, key_extra_len=0):
"""Checks sanity of key. Fails if:
Key length is > SERVER_MAX_KEY_LENGTH (Raises MemcachedKeyLength).
Contains control characters (Raises MemcachedKeyCharacterError).
Is not a string (Raises MemcachedKeyError)
Is None (Raises MemcachedKeyError)
"""
if isinstance(key, tuple): key = key[1]
if not key:
raise Client.MemcachedKeyNoneError("Key is None")
if not isinstance(key, str):
raise Client.MemcachedKeyTypeError("Key must be str()'s")
if isinstance(key, bytes):
keylen = len(key)
else:
keylen = len(key.encode("utf-8"))
if self.server_max_key_length != 0 and \
keylen + key_extra_len > self.server_max_key_length:
raise Client.MemcachedKeyLengthError("Key length is > %s"
% self.server_max_key_length)
after_translate = key.translate(key.maketrans('', '', invalid_key_characters))
if len(key) != len(after_translate):
raise Client.MemcachedKeyCharacterError(
"Control characters not allowed")
class _Host(object):
def __init__(self, host, debug=0, dead_retry=_DEAD_RETRY,
socket_timeout=_SOCKET_TIMEOUT, flush_on_reconnect=0):
self.dead_retry = dead_retry
self.socket_timeout = socket_timeout
self.debug = debug
self.flush_on_reconnect = flush_on_reconnect
if isinstance(host, tuple):
host, self.weight = host
else:
self.weight = 1
# parse the connection string
m = re.match(r'^(?P<proto>unix):(?P<path>.*)$', host)
if not m:
m = re.match(r'^(?P<proto>inet6):'
r'\[(?P<host>[^\[\]]+)\](:(?P<port>[0-9]+))?$', host)
if not m:
m = re.match(r'^(?P<proto>inet):'
r'(?P<host>[^:]+)(:(?P<port>[0-9]+))?$', host)
if not m: m = re.match(r'^(?P<host>[^:]+)(:(?P<port>[0-9]+))?$', host)
if not m:
raise ValueError('Unable to parse connection string: "%s"' % host)
hostData = m.groupdict()
if hostData.get('proto') == 'unix':
self.family = socket.AF_UNIX
self.address = hostData['path']
elif hostData.get('proto') == 'inet6':
self.family = socket.AF_INET6
self.ip = hostData['host']
self.port = int(hostData.get('port') or 11211)
self.address = ( self.ip, self.port )
else:
self.family = socket.AF_INET
self.ip = hostData['host']
self.port = int(hostData.get('port') or 11211)
self.address = ( self.ip, self.port )
self.deaduntil = 0
self.socket = None
self.flush_on_next_connect = 0
self.buffer = b''
def debuglog(self, str):
if self.debug:
sys.stderr.write("MemCached: %s\n" % str)
def _check_dead(self):
if self.deaduntil and self.deaduntil > time.time():
return 1
self.deaduntil = 0
return 0
def connect(self):
if self._get_socket():
return 1
return 0
def mark_dead(self, reason):
self.debuglog("MemCache: %s: %s. Marking dead." % (self, reason))
self.deaduntil = time.time() + self.dead_retry
if self.flush_on_reconnect:
self.flush_on_next_connect = 1
self.close_socket()
def _get_socket(self):
if self._check_dead():
return None
if self.socket:
return self.socket
s = socket.socket(self.family, socket.SOCK_STREAM)
if hasattr(s, 'settimeout'): s.settimeout(self.socket_timeout)
try:
s.connect(self.address)
except socket.timeout as msg:
self.mark_dead("connect: %s" % msg)
return None
except socket.error as msg:
if isinstance(msg, tuple): msg = msg[1]
self.mark_dead("connect: %s" % msg)
return None
self.socket = s
self.buffer = b''
if self.flush_on_next_connect:
self.flush()
self.flush_on_next_connect = 0
return s
def close_socket(self):
if self.socket:
self.socket.close()
self.socket = None
def send_cmd(self, cmd):
if not isinstance(cmd, bytes):
self.socket.sendall((cmd + '\r\n').encode('ascii'))
else:
self.socket.sendall(cmd + b'\r\n')
def send_cmds(self, cmds):
""" cmds already has trailing \r\n's applied """
if not isinstance(cmds, bytes):
self.socket.sendall(cmds.encode('ascii'))
else:
self.socket.sendall(cmds)
def readline(self, raise_exception=False):
"""Read a line and return it. If "raise_exception" is set,
raise _ConnectionDeadError if the read fails, otherwise return
an empty string.
"""
buf = self.buffer
recv = self.socket.recv
while True:
index = buf.find(b'\r\n')
if index >= 0:
break
data = recv(4096)
if not data:
# connection close, let's kill it and raise
self.close_socket()
if raise_exception:
raise _ConnectionDeadError()
else:
return b''
buf += data
self.buffer = buf[index+2:]
return buf[:index]
def expect(self, text, raise_exception=False):
line = self.readline(raise_exception)
if line != text:
self.debuglog("while expecting '%s', got unexpected response '%s'"
% (text, line))
return line
def recv(self, rlen):
self_socket_recv = self.socket.recv
buf = self.buffer
while len(buf) < rlen:
foo = self_socket_recv(max(rlen - len(buf), 4096))
buf += foo
if not foo:
raise _Error( 'Read %d bytes, expecting %d, '
'read returned 0 length bytes' % ( len(buf), rlen ))
self.buffer = buf[rlen:]
return buf[:rlen]
def flush(self):
self.send_cmd(b'flush_all')
self.expect(b'OK')
def __str__(self):
d = ''
if self.deaduntil:
d = " (dead until %d)" % self.deaduntil
if self.family == socket.AF_INET:
return "inet:%s:%d%s" % (self.address[0], self.address[1], d)
elif self.family == socket.AF_INET6:
return "inet6:[%s]:%d%s" % (self.address[0], self.address[1], d)
else:
return "unix:%s%s" % (self.address, d)
def _doctest():
import doctest, memcache
servers = ["127.0.0.1:11211"]
mc = Client(servers, debug=1)
globs = {"mc": mc}
return doctest.testmod(memcache, globs=globs)
if __name__ == "__main__":
print("Testing docstrings...")
_doctest()
print("Running tests:")
print()
serverList = [["127.0.0.1:11211"]]
if '--do-unix' in sys.argv:
serverList.append([os.path.join(os.getcwd(), 'memcached.socket')])
for servers in serverList:
mc = Client(servers, debug=1)
def to_s(val):
if not isinstance(val, str):
return "%s (%s)" % (val, type(val))
return "%s" % val
def test_setget(key, val):
print("Testing set/get {'%s': %s} ..." % (to_s(key), to_s(val)), end=' ')
mc.set(key, val)
newval = mc.get(key)
if newval == val and type(newval) == type(val):
print("OK")
return 1
else:
print("FAIL")
return 0
class FooStruct:
def __init__(self):
self.bar = "baz"
def __str__(self):
return "A FooStruct"
def __eq__(self, other):
if isinstance(other, FooStruct):
return self.bar == other.bar
return 0
class StrSubclass(str):
pass
test_setget("a_string", "some random string")
test_setget("a_string_subclass", StrSubclass("L337 57R"))
test_setget("an_integer", 42)
test_setget("bool_True", True)
test_setget("bool_False", False)
if test_setget("long", int(1<<30)):
print("Testing delete ...", end=' ')
if mc.delete("long"):
print("OK")
else:
print("FAIL")
print("Testing get_multi ...", end=' ')
print(mc.get_multi(["a_string", "an_integer"]))
print("Testing get(unknown value) ...", end=' ')
print(to_s(mc.get("unknown_value")))
f = FooStruct()
test_setget("foostruct", f)
print("Testing incr ...", end=' ')
x = mc.incr("an_integer", 1)
if x == 43:
print("OK")
else:
print("FAIL")
print("Testing decr ...", end=' ')
x = mc.decr("an_integer", 1)
if x == 42:
print("OK")
else:
print("FAIL")
# sanity tests
print("Testing sending spaces...", end=' ')
try:
x = mc.set("this has spaces", 1)
except Client.MemcachedKeyCharacterError as msg:
print("OK")
else:
print("FAIL")
print("Testing sending control characters...", end=' ')
try:
x = mc.set("this\x10has\x11control characters\x02", 1)
except Client.MemcachedKeyCharacterError as msg:
print("OK")
else:
print("FAIL")
print("Testing using insanely long key...", end=' ')
try:
x = mc.set('a'*SERVER_MAX_KEY_LENGTH + 'aaaa', 1)
except Client.MemcachedKeyLengthError as msg:
print("OK")
else:
print("FAIL")
print("Testing sending a unicode-string key...", end=' ')
try:
x = mc.set('', 1)
except Client.MemcachedStringEncodingError as msg:
print("FAIL", end=' ')
else:
print("OK", end=' ')
import pickle
s = pickle.loads(b'V\\u4f1a\np0\n.')
print("Testing sending a key of type bytes")
try:
x = mc.set((s*SERVER_MAX_KEY_LENGTH).encode('utf-8'), 1)
except Client.MemcachedKeyTypeError:
print("OK")
else:
print("FAIL")
print("Testing using a value larger than the memcached value limit...")
print('NOTE: "MemCached: while expecting[...]" is normal...')
x = mc.set('keyhere', 'a'*SERVER_MAX_VALUE_LENGTH)
if mc.get('keyhere') == None:
print("OK", end=' ')
else:
print("FAIL", end=' ')
x = mc.set('keyhere', 'a'*SERVER_MAX_VALUE_LENGTH + 'aaa')
if mc.get('keyhere') == None:
print("OK")
else:
print("FAIL")
print("Testing set_multi() with no memcacheds running", end=' ')
mc.disconnect_all()
errors = mc.set_multi({'keyhere' : 'a', 'keythere' : 'b'})
if errors != []:
print("FAIL")
else:
print("OK")
print("Testing delete_multi() with no memcacheds running", end=' ')
mc.disconnect_all()
ret = mc.delete_multi({'keyhere' : 'a', 'keythere' : 'b'})
if ret != 1:
print("FAIL")
else:
print("OK")
# vim: ts=4 sw=4 et :