Current File : //lib/python3/dist-packages/twisted/protocols/memcache.py
# -*- test-case-name: twisted.test.test_memcache -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Memcache client protocol. Memcached is a caching server, storing data in the
form of pairs key/value, and memcache is the protocol to talk with it.
To connect to a server, create a factory for L{MemCacheProtocol}::
from twisted.internet import reactor, protocol
from twisted.protocols.memcache import MemCacheProtocol, DEFAULT_PORT
d = protocol.ClientCreator(reactor, MemCacheProtocol
).connectTCP("localhost", DEFAULT_PORT)
def doSomething(proto):
# Here you call the memcache operations
return proto.set("mykey", "a lot of data")
d.addCallback(doSomething)
reactor.run()
All the operations of the memcache protocol are present, but
L{MemCacheProtocol.set} and L{MemCacheProtocol.get} are the more important.
See U{http://code.sixapart.com/svn/memcached/trunk/server/doc/protocol.txt} for
more information about the protocol.
"""
from collections import deque
from twisted.internet.defer import Deferred, TimeoutError, fail
from twisted.protocols.basic import LineReceiver
from twisted.protocols.policies import TimeoutMixin
from twisted.python import log
from twisted.python.compat import nativeString, networkString
DEFAULT_PORT = 11211
class NoSuchCommand(Exception):
"""
Exception raised when a non existent command is called.
"""
class ClientError(Exception):
"""
Error caused by an invalid client call.
"""
class ServerError(Exception):
"""
Problem happening on the server.
"""
class Command:
"""
Wrap a client action into an object, that holds the values used in the
protocol.
@ivar _deferred: the L{Deferred} object that will be fired when the result
arrives.
@type _deferred: L{Deferred}
@ivar command: name of the command sent to the server.
@type command: L{bytes}
"""
def __init__(self, command, **kwargs):
"""
Create a command.
@param command: the name of the command.
@type command: L{bytes}
@param kwargs: this values will be stored as attributes of the object
for future use
"""
self.command = command
self._deferred = Deferred()
for k, v in kwargs.items():
setattr(self, k, v)
def success(self, value):
"""
Shortcut method to fire the underlying deferred.
"""
self._deferred.callback(value)
def fail(self, error):
"""
Make the underlying deferred fails.
"""
self._deferred.errback(error)
class MemCacheProtocol(LineReceiver, TimeoutMixin):
"""
MemCache protocol: connect to a memcached server to store/retrieve values.
@ivar persistentTimeOut: the timeout period used to wait for a response.
@type persistentTimeOut: L{int}
@ivar _current: current list of requests waiting for an answer from the
server.
@type _current: L{deque} of L{Command}
@ivar _lenExpected: amount of data expected in raw mode, when reading for
a value.
@type _lenExpected: L{int}
@ivar _getBuffer: current buffer of data, used to store temporary data
when reading in raw mode.
@type _getBuffer: L{list}
@ivar _bufferLength: the total amount of bytes in C{_getBuffer}.
@type _bufferLength: L{int}
@ivar _disconnected: indicate if the connectionLost has been called or not.
@type _disconnected: L{bool}
"""
MAX_KEY_LENGTH = 250
_disconnected = False
def __init__(self, timeOut=60):
"""
Create the protocol.
@param timeOut: the timeout to wait before detecting that the
connection is dead and close it. It's expressed in seconds.
@type timeOut: L{int}
"""
self._current = deque()
self._lenExpected = None
self._getBuffer = None
self._bufferLength = None
self.persistentTimeOut = self.timeOut = timeOut
def _cancelCommands(self, reason):
"""
Cancel all the outstanding commands, making them fail with C{reason}.
"""
while self._current:
cmd = self._current.popleft()
cmd.fail(reason)
def timeoutConnection(self):
"""
Close the connection in case of timeout.
"""
self._cancelCommands(TimeoutError("Connection timeout"))
self.transport.loseConnection()
def connectionLost(self, reason):
"""
Cause any outstanding commands to fail.
"""
self._disconnected = True
self._cancelCommands(reason)
LineReceiver.connectionLost(self, reason)
def sendLine(self, line):
"""
Override sendLine to add a timeout to response.
"""
if not self._current:
self.setTimeout(self.persistentTimeOut)
LineReceiver.sendLine(self, line)
def rawDataReceived(self, data):
"""
Collect data for a get.
"""
self.resetTimeout()
self._getBuffer.append(data)
self._bufferLength += len(data)
if self._bufferLength >= self._lenExpected + 2:
data = b"".join(self._getBuffer)
buf = data[: self._lenExpected]
rem = data[self._lenExpected + 2 :]
val = buf
self._lenExpected = None
self._getBuffer = None
self._bufferLength = None
cmd = self._current[0]
if cmd.multiple:
flags, cas = cmd.values[cmd.currentKey]
cmd.values[cmd.currentKey] = (flags, cas, val)
else:
cmd.value = val
self.setLineMode(rem)
def cmd_STORED(self):
"""
Manage a success response to a set operation.
"""
self._current.popleft().success(True)
def cmd_NOT_STORED(self):
"""
Manage a specific 'not stored' response to a set operation: this is not
an error, but some condition wasn't met.
"""
self._current.popleft().success(False)
def cmd_END(self):
"""
This the end token to a get or a stat operation.
"""
cmd = self._current.popleft()
if cmd.command == b"get":
if cmd.multiple:
values = {key: val[::2] for key, val in cmd.values.items()}
cmd.success(values)
else:
cmd.success((cmd.flags, cmd.value))
elif cmd.command == b"gets":
if cmd.multiple:
cmd.success(cmd.values)
else:
cmd.success((cmd.flags, cmd.cas, cmd.value))
elif cmd.command == b"stats":
cmd.success(cmd.values)
else:
raise RuntimeError(
"Unexpected END response to {} command".format(
nativeString(cmd.command)
)
)
def cmd_NOT_FOUND(self):
"""
Manage error response for incr/decr/delete.
"""
self._current.popleft().success(False)
def cmd_VALUE(self, line):
"""
Prepare the reading a value after a get.
"""
cmd = self._current[0]
if cmd.command == b"get":
key, flags, length = line.split()
cas = b""
else:
key, flags, length, cas = line.split()
self._lenExpected = int(length)
self._getBuffer = []
self._bufferLength = 0
if cmd.multiple:
if key not in cmd.keys:
raise RuntimeError("Unexpected commands answer.")
cmd.currentKey = key
cmd.values[key] = [int(flags), cas]
else:
if cmd.key != key:
raise RuntimeError("Unexpected commands answer.")
cmd.flags = int(flags)
cmd.cas = cas
self.setRawMode()
def cmd_STAT(self, line):
"""
Reception of one stat line.
"""
cmd = self._current[0]
key, val = line.split(b" ", 1)
cmd.values[key] = val
def cmd_VERSION(self, versionData):
"""
Read version token.
"""
self._current.popleft().success(versionData)
def cmd_ERROR(self):
"""
A non-existent command has been sent.
"""
log.err("Non-existent command sent.")
cmd = self._current.popleft()
cmd.fail(NoSuchCommand())
def cmd_CLIENT_ERROR(self, errText):
"""
An invalid input as been sent.
"""
errText = repr(errText)
log.err("Invalid input: " + errText)
cmd = self._current.popleft()
cmd.fail(ClientError(errText))
def cmd_SERVER_ERROR(self, errText):
"""
An error has happened server-side.
"""
errText = repr(errText)
log.err("Server error: " + errText)
cmd = self._current.popleft()
cmd.fail(ServerError(errText))
def cmd_DELETED(self):
"""
A delete command has completed successfully.
"""
self._current.popleft().success(True)
def cmd_OK(self):
"""
The last command has been completed.
"""
self._current.popleft().success(True)
def cmd_EXISTS(self):
"""
A C{checkAndSet} update has failed.
"""
self._current.popleft().success(False)
def lineReceived(self, line):
"""
Receive line commands from the server.
"""
self.resetTimeout()
token = line.split(b" ", 1)[0]
# First manage standard commands without space
cmd = getattr(self, "cmd_" + nativeString(token), None)
if cmd is not None:
args = line.split(b" ", 1)[1:]
if args:
cmd(args[0])
else:
cmd()
else:
# Then manage commands with space in it
line = line.replace(b" ", b"_")
cmd = getattr(self, "cmd_" + nativeString(line), None)
if cmd is not None:
cmd()
else:
# Increment/Decrement response
cmd = self._current.popleft()
val = int(line)
cmd.success(val)
if not self._current:
# No pending request, remove timeout
self.setTimeout(None)
def increment(self, key, val=1):
"""
Increment the value of C{key} by given value (default to 1).
C{key} must be consistent with an int. Return the new value.
@param key: the key to modify.
@type key: L{bytes}
@param val: the value to increment.
@type val: L{int}
@return: a deferred with will be called back with the new value
associated with the key (after the increment).
@rtype: L{Deferred}
"""
return self._incrdecr(b"incr", key, val)
def decrement(self, key, val=1):
"""
Decrement the value of C{key} by given value (default to 1).
C{key} must be consistent with an int. Return the new value, coerced to
0 if negative.
@param key: the key to modify.
@type key: L{bytes}
@param val: the value to decrement.
@type val: L{int}
@return: a deferred with will be called back with the new value
associated with the key (after the decrement).
@rtype: L{Deferred}
"""
return self._incrdecr(b"decr", key, val)
def _incrdecr(self, cmd, key, val):
"""
Internal wrapper for incr/decr.
"""
if self._disconnected:
return fail(RuntimeError("not connected"))
if not isinstance(key, bytes):
return fail(
ClientError(f"Invalid type for key: {type(key)}, expecting bytes")
)
if len(key) > self.MAX_KEY_LENGTH:
return fail(ClientError("Key too long"))
fullcmd = b" ".join([cmd, key, b"%d" % (int(val),)])
self.sendLine(fullcmd)
cmdObj = Command(cmd, key=key)
self._current.append(cmdObj)
return cmdObj._deferred
def replace(self, key, val, flags=0, expireTime=0):
"""
Replace the given C{key}. It must already exist in the server.
@param key: the key to replace.
@type key: L{bytes}
@param val: the new value associated with the key.
@type val: L{bytes}
@param flags: the flags to store with the key.
@type flags: L{int}
@param expireTime: if different from 0, the relative time in seconds
when the key will be deleted from the store.
@type expireTime: L{int}
@return: a deferred that will fire with C{True} if the operation has
succeeded, and C{False} with the key didn't previously exist.
@rtype: L{Deferred}
"""
return self._set(b"replace", key, val, flags, expireTime, b"")
def add(self, key, val, flags=0, expireTime=0):
"""
Add the given C{key}. It must not exist in the server.
@param key: the key to add.
@type key: L{bytes}
@param val: the value associated with the key.
@type val: L{bytes}
@param flags: the flags to store with the key.
@type flags: L{int}
@param expireTime: if different from 0, the relative time in seconds
when the key will be deleted from the store.
@type expireTime: L{int}
@return: a deferred that will fire with C{True} if the operation has
succeeded, and C{False} with the key already exists.
@rtype: L{Deferred}
"""
return self._set(b"add", key, val, flags, expireTime, b"")
def set(self, key, val, flags=0, expireTime=0):
"""
Set the given C{key}.
@param key: the key to set.
@type key: L{bytes}
@param val: the value associated with the key.
@type val: L{bytes}
@param flags: the flags to store with the key.
@type flags: L{int}
@param expireTime: if different from 0, the relative time in seconds
when the key will be deleted from the store.
@type expireTime: L{int}
@return: a deferred that will fire with C{True} if the operation has
succeeded.
@rtype: L{Deferred}
"""
return self._set(b"set", key, val, flags, expireTime, b"")
def checkAndSet(self, key, val, cas, flags=0, expireTime=0):
"""
Change the content of C{key} only if the C{cas} value matches the
current one associated with the key. Use this to store a value which
hasn't been modified since last time you fetched it.
@param key: The key to set.
@type key: L{bytes}
@param val: The value associated with the key.
@type val: L{bytes}
@param cas: Unique 64-bit value returned by previous call of C{get}.
@type cas: L{bytes}
@param flags: The flags to store with the key.
@type flags: L{int}
@param expireTime: If different from 0, the relative time in seconds
when the key will be deleted from the store.
@type expireTime: L{int}
@return: A deferred that will fire with C{True} if the operation has
succeeded, C{False} otherwise.
@rtype: L{Deferred}
"""
return self._set(b"cas", key, val, flags, expireTime, cas)
def _set(self, cmd, key, val, flags, expireTime, cas):
"""
Internal wrapper for setting values.
"""
if self._disconnected:
return fail(RuntimeError("not connected"))
if not isinstance(key, bytes):
return fail(
ClientError(f"Invalid type for key: {type(key)}, expecting bytes")
)
if len(key) > self.MAX_KEY_LENGTH:
return fail(ClientError("Key too long"))
if not isinstance(val, bytes):
return fail(
ClientError(f"Invalid type for value: {type(val)}, expecting bytes")
)
if cas:
cas = b" " + cas
length = len(val)
fullcmd = (
b" ".join(
[cmd, key, networkString("%d %d %d" % (flags, expireTime, length))]
)
+ cas
)
self.sendLine(fullcmd)
self.sendLine(val)
cmdObj = Command(cmd, key=key, flags=flags, length=length)
self._current.append(cmdObj)
return cmdObj._deferred
def append(self, key, val):
"""
Append given data to the value of an existing key.
@param key: The key to modify.
@type key: L{bytes}
@param val: The value to append to the current value associated with
the key.
@type val: L{bytes}
@return: A deferred that will fire with C{True} if the operation has
succeeded, C{False} otherwise.
@rtype: L{Deferred}
"""
# Even if flags and expTime values are ignored, we have to pass them
return self._set(b"append", key, val, 0, 0, b"")
def prepend(self, key, val):
"""
Prepend given data to the value of an existing key.
@param key: The key to modify.
@type key: L{bytes}
@param val: The value to prepend to the current value associated with
the key.
@type val: L{bytes}
@return: A deferred that will fire with C{True} if the operation has
succeeded, C{False} otherwise.
@rtype: L{Deferred}
"""
# Even if flags and expTime values are ignored, we have to pass them
return self._set(b"prepend", key, val, 0, 0, b"")
def get(self, key, withIdentifier=False):
"""
Get the given C{key}. It doesn't support multiple keys. If
C{withIdentifier} is set to C{True}, the command issued is a C{gets},
that will return the current identifier associated with the value. This
identifier has to be used when issuing C{checkAndSet} update later,
using the corresponding method.
@param key: The key to retrieve.
@type key: L{bytes}
@param withIdentifier: If set to C{True}, retrieve the current
identifier along with the value and the flags.
@type withIdentifier: L{bool}
@return: A deferred that will fire with the tuple (flags, value) if
C{withIdentifier} is C{False}, or (flags, cas identifier, value)
if C{True}. If the server indicates there is no value
associated with C{key}, the returned value will be L{None} and
the returned flags will be C{0}.
@rtype: L{Deferred}
"""
return self._get([key], withIdentifier, False)
def getMultiple(self, keys, withIdentifier=False):
"""
Get the given list of C{keys}. If C{withIdentifier} is set to C{True},
the command issued is a C{gets}, that will return the identifiers
associated with each values. This identifier has to be used when
issuing C{checkAndSet} update later, using the corresponding method.
@param keys: The keys to retrieve.
@type keys: L{list} of L{bytes}
@param withIdentifier: If set to C{True}, retrieve the identifiers
along with the values and the flags.
@type withIdentifier: L{bool}
@return: A deferred that will fire with a dictionary with the elements
of C{keys} as keys and the tuples (flags, value) as values if
C{withIdentifier} is C{False}, or (flags, cas identifier, value) if
C{True}. If the server indicates there is no value associated with
C{key}, the returned values will be L{None} and the returned flags
will be C{0}.
@rtype: L{Deferred}
@since: 9.0
"""
return self._get(keys, withIdentifier, True)
def _get(self, keys, withIdentifier, multiple):
"""
Helper method for C{get} and C{getMultiple}.
"""
keys = list(keys)
if self._disconnected:
return fail(RuntimeError("not connected"))
for key in keys:
if not isinstance(key, bytes):
return fail(
ClientError(f"Invalid type for key: {type(key)}, expecting bytes")
)
if len(key) > self.MAX_KEY_LENGTH:
return fail(ClientError("Key too long"))
if withIdentifier:
cmd = b"gets"
else:
cmd = b"get"
fullcmd = b" ".join([cmd] + keys)
self.sendLine(fullcmd)
if multiple:
values = {key: (0, b"", None) for key in keys}
cmdObj = Command(cmd, keys=keys, values=values, multiple=True)
else:
cmdObj = Command(
cmd, key=keys[0], value=None, flags=0, cas=b"", multiple=False
)
self._current.append(cmdObj)
return cmdObj._deferred
def stats(self, arg=None):
"""
Get some stats from the server. It will be available as a dict.
@param arg: An optional additional string which will be sent along
with the I{stats} command. The interpretation of this value by
the server is left undefined by the memcache protocol
specification.
@type arg: L{None} or L{bytes}
@return: a deferred that will fire with a L{dict} of the available
statistics.
@rtype: L{Deferred}
"""
if arg:
cmd = b"stats " + arg
else:
cmd = b"stats"
if self._disconnected:
return fail(RuntimeError("not connected"))
self.sendLine(cmd)
cmdObj = Command(b"stats", values={})
self._current.append(cmdObj)
return cmdObj._deferred
def version(self):
"""
Get the version of the server.
@return: a deferred that will fire with the string value of the
version.
@rtype: L{Deferred}
"""
if self._disconnected:
return fail(RuntimeError("not connected"))
self.sendLine(b"version")
cmdObj = Command(b"version")
self._current.append(cmdObj)
return cmdObj._deferred
def delete(self, key):
"""
Delete an existing C{key}.
@param key: the key to delete.
@type key: L{bytes}
@return: a deferred that will be called back with C{True} if the key
was successfully deleted, or C{False} if not.
@rtype: L{Deferred}
"""
if self._disconnected:
return fail(RuntimeError("not connected"))
if not isinstance(key, bytes):
return fail(
ClientError(f"Invalid type for key: {type(key)}, expecting bytes")
)
self.sendLine(b"delete " + key)
cmdObj = Command(b"delete", key=key)
self._current.append(cmdObj)
return cmdObj._deferred
def flushAll(self):
"""
Flush all cached values.
@return: a deferred that will be called back with C{True} when the
operation has succeeded.
@rtype: L{Deferred}
"""
if self._disconnected:
return fail(RuntimeError("not connected"))
self.sendLine(b"flush_all")
cmdObj = Command(b"flush_all")
self._current.append(cmdObj)
return cmdObj._deferred
__all__ = [
"MemCacheProtocol",
"DEFAULT_PORT",
"NoSuchCommand",
"ClientError",
"ServerError",
]
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