[CalendarServer-changes] [3957] CalendarServer/trunk/memcache.py
source_changes at macosforge.org
source_changes at macosforge.org
Tue Apr 7 12:09:46 PDT 2009
Revision: 3957
http://trac.macosforge.org/projects/calendarserver/changeset/3957
Author: sagen at apple.com
Date: 2009-04-07 12:09:46 -0700 (Tue, 07 Apr 2009)
Log Message:
-----------
Adding (blocking) memcache module
Added Paths:
-----------
CalendarServer/trunk/memcache.py
Added: CalendarServer/trunk/memcache.py
===================================================================
--- CalendarServer/trunk/memcache.py (rev 0)
+++ CalendarServer/trunk/memcache.py 2009-04-07 19:09:46 UTC (rev 3957)
@@ -0,0 +1,1150 @@
+#!/usr/bin/env python
+
+"""
+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(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 types
+try:
+ import cPickle as pickle
+except ImportError:
+ import pickle
+
+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 compession (import error)")
+
+try:
+ from cStringIO import StringIO
+except ImportError:
+ from StringIO import StringIO
+
+from binascii import crc32 # zlib version is not cross-platform
+serverHashFunction = crc32
+
+__author__ = "Evan Martin <martine at danga.com>"
+__version__ = "1.44"
+__copyright__ = "Copyright (C) 2003 Danga Interactive"
+__license__ = "Python"
+
+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
+
+try:
+ # Only exists in Python 2.4+
+ from threading import local
+except ImportError:
+ # TODO: add the pure-python local implementation
+ class local(object):
+ pass
+
+
+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):
+ """
+ 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.
+ """
+ local.__init__(self)
+ self.set_servers(servers)
+ self.debug = debug
+ self.stats = {}
+
+ # Allow users to modify pickling/unpickling behavior
+ self.pickleProtocol = pickleProtocol
+ self.pickler = pickler
+ self.unpickler = unpickler
+ self.persistent_load = pload
+ self.persistent_id = pid
+
+ # figure out the pickler style
+ file = StringIO()
+ try:
+ pickler = self.pickler(file, protocol = self.pickleProtocol)
+ self.picklerIsKeyword = True
+ except TypeError:
+ self.picklerIsKeyword = False
+
+ 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.debuglog) for s in servers]
+ self._init_buckets()
+
+ def get_stats(self):
+ '''Get statistics from each of the servers.
+
+ @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 )
+ else:
+ name = 'unix:%s (%s)' % ( s.address, s.weight )
+ s.send_cmd('stats')
+ serverData = {}
+ data.append(( name, serverData ))
+ readline = s.readline
+ while 1:
+ line = readline()
+ if not line or line.strip() == 'END': break
+ stats = line.split(' ', 2)
+ serverData[stats[1]] = stats[2]
+
+ 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 )
+ 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() == 'END': break
+ item = line.split(' ', 2)
+ #0 = STAT, 1 = ITEM, 2 = Value
+ slab = item[1].split(':', 2)
+ #0 = items, 1 = Slab #, 2 = Name
+ if not serverData.has_key(slab[1]):
+ serverData[slab[1]] = {}
+ serverData[slab[1]][slab[2]] = item[2]
+ return data
+
+ def flush_all(self):
+ 'Expire all data currently in the memcache servers.'
+ for s in self.servers:
+ if not s.connect(): continue
+ s.send_cmd('flush_all')
+ s.expect("OK")
+
+ def debuglog(self, str):
+ if self.debug:
+ sys.stderr.write("MemCached: %s\n" % str)
+
+ def _statlog(self, func):
+ if not self.stats.has_key(func):
+ 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 type(key) == types.TupleType:
+ serverhash, key = key
+ else:
+ serverhash = serverHashFunction(key)
+
+ 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))
+ 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.iterkeys():
+ 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, msg:
+ rc = 0
+ if type(msg) is types.TupleType: 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]
+
+ notstored = [] # original keys.
+ for server, keys in server_keys.iteritems():
+ try:
+ for key in keys:
+ server.expect("DELETED")
+ except socket.error, msg:
+ if type(msg) is types.TupleType: 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 0 for no delay.
+ @rtype: int
+ '''
+ check_key(key)
+ server, key = self._get_server(key)
+ if not server:
+ return 0
+ self._statlog('delete')
+ if time != None:
+ cmd = "delete %s %d" % (key, time)
+ else:
+ cmd = "delete %s" % key
+
+ try:
+ server.send_cmd(cmd)
+ server.expect("DELETED")
+ except socket.error, msg:
+ if type(msg) is types.TupleType: msg = msg[1]
+ server.mark_dead(msg)
+ return 0
+ return 1
+
+ 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.
+ @rtype: int
+ """
+ return self._incrdecr("decr", key, delta)
+
+ def _incrdecr(self, cmd, key, delta):
+ check_key(key)
+ server, key = self._get_server(key)
+ if not server:
+ return 0
+ self._statlog(cmd)
+ cmd = "%s %s %d" % (cmd, key, delta)
+ try:
+ server.send_cmd(cmd)
+ line = server.readline()
+ return int(line)
+ except socket.error, msg:
+ if type(msg) is types.TupleType: 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
+ , 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 _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:
+ 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 type(orig_key) is types.TupleType:
+ # 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 ...
+ check_key(str_orig_key, key_extra_len=key_extra_len)
+
+ if not server:
+ continue
+
+ if not server_keys.has_key(server):
+ 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(mapping.iterkeys(), key_prefix)
+
+ # send out all requests on each server before reading anything
+ dead_servers = []
+
+ for server in server_keys.iterkeys():
+ bigcmd = []
+ write = bigcmd.append
+ try:
+ 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)
+ write("set %s %d %d %d\r\n%s\r\n" % (key, store_info[0], time, store_info[1], store_info[2]))
+ server.send_cmds(''.join(bigcmd))
+ except socket.error, msg:
+ if type(msg) is types.TupleType: 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(mapping.keys())
+
+ notstored = [] # original keys.
+ for server, keys in server_keys.iteritems():
+ try:
+ for key in keys:
+ line = server.readline()
+ if line == 'STORED':
+ continue
+ else:
+ notstored.append(prefixed_to_orig_key[key]) #un-mangle.
+ except (_Error, socket.error), msg:
+ if type(msg) is types.TupleType: 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
+ if isinstance(val, str):
+ pass
+ elif isinstance(val, int):
+ flags |= Client._FLAG_INTEGER
+ val = "%d" % val
+ # force no attempt to compress this silly string.
+ min_compress_len = 0
+ elif isinstance(val, long):
+ flags |= Client._FLAG_LONG
+ val = "%d" % val
+ # force no attempt to compress this silly string.
+ min_compress_len = 0
+ else:
+ flags |= Client._FLAG_PICKLE
+ file = StringIO()
+ 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 len(val) >= SERVER_MAX_VALUE_LENGTH: return(0)
+
+ return (flags, len(val), val)
+
+ def _set(self, cmd, key, val, time, min_compress_len = 0):
+ check_key(key)
+ server, key = self._get_server(key)
+ if not server:
+ return 0
+
+ self._statlog(cmd)
+
+ store_info = self._val_to_store_info(val, min_compress_len)
+ if not store_info: return(0)
+
+ fullcmd = "%s %s %d %d %d\r\n%s" % (cmd, key, store_info[0], time, store_info[1], store_info[2])
+ try:
+ server.send_cmd(fullcmd)
+ return(server.expect("STORED") == "STORED")
+ except socket.error, msg:
+ if type(msg) is types.TupleType: msg = msg[1]
+ server.mark_dead(msg)
+ return 0
+
+ def get(self, key):
+ '''Retrieves a key from the memcache.
+
+ @return: The value or None.
+ '''
+ check_key(key)
+ server, key = self._get_server(key)
+ if not server:
+ return None
+
+ self._statlog('get')
+
+ try:
+ server.send_cmd("get %s" % key)
+ rkey, flags, rlen, = self._expectvalue(server)
+ if not rkey:
+ return None
+ value = self._recv_value(server, flags, rlen)
+ server.expect("END")
+ except (_Error, socket.error), msg:
+ if type(msg) is types.TupleType: msg = msg[1]
+ server.mark_dead(msg)
+ return None
+ return value
+
+ 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.iterkeys():
+ try:
+ server.send_cmd("get %s" % " ".join(server_keys[server]))
+ except socket.error, msg:
+ if type(msg) is types.TupleType: 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.iterkeys():
+ try:
+ line = server.readline()
+ while line and line != 'END':
+ rkey, flags, rlen = self._expectvalue(server, line)
+ # Bo Yang reports that this can sometimes be None
+ if rkey is not None:
+ 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), msg:
+ if type(msg) is types.TupleType: msg = msg[1]
+ server.mark_dead(msg)
+ return retvals
+
+ def _expectvalue(self, server, line=None):
+ if not line:
+ line = server.readline()
+
+ if line[:5] == '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
+ elif flags & Client._FLAG_INTEGER:
+ val = int(buf)
+ elif flags & Client._FLAG_LONG:
+ val = long(buf)
+ elif flags & Client._FLAG_PICKLE:
+ try:
+ file = StringIO(buf)
+ unpickler = self.unpickler(file)
+ if self.persistent_load:
+ unpickler.persistent_load = self.persistent_load
+ val = unpickler.load()
+ except Exception, e:
+ self.debuglog('Pickle error: %s\n' % e)
+ val = None
+ else:
+ self.debuglog("unknown flags on get: %x\n" % flags)
+
+ return val
+
+
+class _Host:
+ _DEAD_RETRY = 30 # number of seconds before retrying a dead server.
+ _SOCKET_TIMEOUT = 3 # number of seconds before sockets timeout.
+
+ def __init__(self, host, debugfunc=None):
+ if isinstance(host, types.TupleType):
+ host, self.weight = host
+ else:
+ self.weight = 1
+
+ # parse the connection string
+ m = re.match(r'^(?P<proto>unix):(?P<path>.*)$', host)
+ if not m:
+ m = re.match(r'^(?P<proto>inet):'
+ r'(?P<host>[^:]+)(:(?P<port>[0-9]+))?$', 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']
+ else:
+ self.family = socket.AF_INET
+ self.ip = hostData['host']
+ self.port = int(hostData.get('port', 11211))
+ self.address = ( self.ip, self.port )
+
+ if not debugfunc:
+ debugfunc = lambda x: x
+ self.debuglog = debugfunc
+
+ self.deaduntil = 0
+ self.socket = None
+
+ self.buffer = ''
+
+ 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() + _Host._DEAD_RETRY
+ 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, msg:
+ self.mark_dead("connect: %s" % msg)
+ return None
+ except socket.error, msg:
+ if type(msg) is types.TupleType: msg = msg[1]
+ self.mark_dead("connect: %s" % msg[1])
+ return None
+ self.socket = s
+ self.buffer = ''
+ return s
+
+ def close_socket(self):
+ if self.socket:
+ self.socket.close()
+ self.socket = None
+
+ def send_cmd(self, cmd):
+ self.socket.sendall(cmd + '\r\n')
+
+ def send_cmds(self, cmds):
+ """ cmds already has trailing \r\n's applied """
+ self.socket.sendall(cmds)
+
+ def readline(self):
+ buf = self.buffer
+ recv = self.socket.recv
+ while True:
+ index = buf.find('\r\n')
+ if index >= 0:
+ break
+ data = recv(4096)
+ if not data:
+ self.mark_dead('Connection closed while reading from %s'
+ % repr(self))
+ break
+ buf += data
+ if index >= 0:
+ self.buffer = buf[index+2:]
+ buf = buf[:index]
+ else:
+ self.buffer = ''
+ return buf
+
+ def expect(self, text):
+ line = self.readline()
+ 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(4096)
+ buf += foo
+ if len(foo) == 0:
+ raise _Error, ( 'Read %d bytes, expecting %d, '
+ 'read returned 0 length bytes' % ( len(buf), rlen ))
+ self.buffer = buf[rlen:]
+ return buf[:rlen]
+
+ 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)
+ else:
+ return "unix:%s%s" % (self.address, d)
+
+def check_key(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 MemcachedStringEncodingError)
+ Is an unicode string (Raises MemcachedStringEncodingError)
+ Is not a string (Raises MemcachedKeyError)
+ Is None (Raises MemcachedKeyError)
+ """
+ if type(key) == types.TupleType: key = key[1]
+ if not key:
+ raise Client.MemcachedKeyNoneError, ("Key is None")
+ if isinstance(key, unicode):
+ raise Client.MemcachedStringEncodingError, ("Keys must be str()'s, not "
+ "unicode. Convert your unicode strings using "
+ "mystring.encode(charset)!")
+ if not isinstance(key, str):
+ raise Client.MemcachedKeyTypeError, ("Key must be str()'s")
+
+ if isinstance(key, basestring):
+ if len(key) + key_extra_len > SERVER_MAX_KEY_LENGTH:
+ raise Client.MemcachedKeyLengthError, ("Key length is > %s"
+ % SERVER_MAX_KEY_LENGTH)
+ for char in key:
+ if ord(char) < 32 or ord(char) == 127:
+ raise Client.MemcachedKeyCharacterError, "Control characters not allowed"
+
+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, types.StringTypes):
+ 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)),
+ mc.set(key, val)
+ newval = mc.get(key)
+ if newval == 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
+
+ test_setget("a_string", "some random string")
+ test_setget("an_integer", 42)
+ if test_setget("long", long(1<<30)):
+ print "Testing delete ...",
+ if mc.delete("long"):
+ print "OK"
+ else:
+ print "FAIL"
+ print "Testing get_multi ...",
+ print mc.get_multi(["a_string", "an_integer"])
+
+ print "Testing get(unknown value) ...",
+ print to_s(mc.get("unknown_value"))
+
+ f = FooStruct()
+ test_setget("foostruct", f)
+
+ print "Testing incr ...",
+ x = mc.incr("an_integer", 1)
+ if x == 43:
+ print "OK"
+ else:
+ print "FAIL"
+
+ print "Testing decr ...",
+ x = mc.decr("an_integer", 1)
+ if x == 42:
+ print "OK"
+ else:
+ print "FAIL"
+
+ # sanity tests
+ print "Testing sending spaces...",
+ try:
+ x = mc.set("this has spaces", 1)
+ except Client.MemcachedKeyCharacterError, msg:
+ print "OK"
+ else:
+ print "FAIL"
+
+ print "Testing sending control characters...",
+ try:
+ x = mc.set("this\x10has\x11control characters\x02", 1)
+ except Client.MemcachedKeyCharacterError, msg:
+ print "OK"
+ else:
+ print "FAIL"
+
+ print "Testing using insanely long key...",
+ try:
+ x = mc.set('a'*SERVER_MAX_KEY_LENGTH + 'aaaa', 1)
+ except Client.MemcachedKeyLengthError, msg:
+ print "OK"
+ else:
+ print "FAIL"
+
+ print "Testing sending a unicode-string key...",
+ try:
+ x = mc.set(u'keyhere', 1)
+ except Client.MemcachedStringEncodingError, msg:
+ print "OK",
+ else:
+ print "FAIL",
+ try:
+ x = mc.set((u'a'*SERVER_MAX_KEY_LENGTH).encode('utf-8'), 1)
+ except:
+ print "FAIL",
+ else:
+ print "OK",
+ import pickle
+ s = pickle.loads('V\\u4f1a\np0\n.')
+ try:
+ x = mc.set((s*SERVER_MAX_KEY_LENGTH).encode('utf-8'), 1)
+ except Client.MemcachedKeyLengthError:
+ print "OK"
+ else:
+ print "FAIL"
+
+ print "Testing using a value larger than the memcached value limit...",
+ x = mc.set('keyhere', 'a'*SERVER_MAX_VALUE_LENGTH)
+ if mc.get('keyhere') == None:
+ print "OK",
+ else:
+ print "FAIL",
+ 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",
+ 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",
+ 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 :
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.macosforge.org/pipermail/calendarserver-changes/attachments/20090407/48339fe2/attachment-0001.html>
More information about the calendarserver-changes
mailing list