#!/usr/bin/env python """ client module for memcached (memory cache daemon) Overview ======== See U{the MemCached homepage} 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 try: import cPickle as pickle except ImportError: import pickle 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)") try: from cStringIO import StringIO except ImportError: from StringIO import StringIO # Original author: Evan Martin of Danga Interactive __author__ = "Sean Reifschneider " __version__ = "1.48" __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 try: # Only exists in Python 2.4+ from threading import local except ImportError: # TODO: add the pure-python local implementation class local(object): pass _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): """ 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. """ local.__init__(self) self.debug = debug self.dead_retry = dead_retry self.socket_timeout = socket_timeout self.set_servers(servers) self.stats = {} self.cache_cas = cache_cas self.reset_cas() # 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) 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 ) else: name = 'unix:%s (%s)' % ( s.address, s.weight ) if not stat_args: s.send_cmd('stats') else: s.send_cmd('stats ' + stat_args) 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 slab[1] not in serverData: 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 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) 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 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.iteritems(): try: for key in keys: server.expect("DELETED") except socket.error, 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 ''' 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) line = server.readline() if line and line.strip() in ['DELETED', 'NOT_FOUND']: return 1 self.debuglog('Delete expected DELETED or NOT_FOUND, got: %s' % repr(line)) except socket.error, 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. @rtype: int """ return self._incrdecr("decr", key, delta) def _incrdecr(self, cmd, key, delta): self.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() if line == None or line.strip() =='NOT_FOUND': return None return int(line) except socket.error, 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 . 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 . 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: 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 ... 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 . 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 = [] notstored = [] # original keys. 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) if store_info: write("set %s %d %d %d\r\n%s\r\n" % (key, store_info[0], time, store_info[1], store_info[2])) else: notstored.append(prefixed_to_orig_key[key]) server.send_cmds(''.join(bigcmd)) except socket.error, 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(mapping.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 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 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 self.server_max_value_length != 0 and \ len(val) > self.server_max_value_length: return(0) return (flags, len(val), val) def _set(self, cmd, key, val, time, min_compress_len = 0): 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 = "%s %s %d %d %d %d\r\n%s" % ( cmd, key, store_info[0], time, store_info[1], self.cas_ids[key], store_info[2]) else: 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 isinstance(msg, tuple): msg = msg[1] server.mark_dead(msg) return 0 try: return _unsafe_set() except _ConnectionDeadError: # retry once try: server._get_socket() return _unsafe_set() except (_ConnectionDeadError, socket.error), msg: server.mark_dead(msg) return 0 def _get(self, cmd, 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("%s %s" % (cmd, key)) rkey = flags = rlen = cas_id = None if cmd == 'gets': rkey, flags, rlen, cas_id, = self._expect_cas_value(server) if rkey and self.cache_cas: self.cas_ids[rkey] = cas_id else: rkey, flags, rlen, = self._expectvalue(server) if not rkey: return None try: value = self._recv_value(server, flags, rlen) finally: server.expect("END") except (_Error, socket.error), 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), 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.iterkeys(): try: server.send_cmd("get %s" % " ".join(server_keys[server])) except socket.error, 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.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 isinstance(msg, tuple): msg = msg[1] server.mark_dead(msg) return retvals def _expect_cas_value(self, server, line=None): if not line: line = server.readline() if line and line[:5] == '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): if not line: line = server.readline() if line and 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) return 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 MemcachedStringEncodingError) Is an unicode string (Raises MemcachedStringEncodingError) 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 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 self.server_max_key_length != 0 and \ len(key) + key_extra_len > self.server_max_key_length: raise Client.MemcachedKeyLengthError("Key length is > %s" % self.server_max_key_length) for char in key: if ord(char) < 33 or ord(char) == 127: raise Client.MemcachedKeyCharacterError( "Control characters not allowed") class _Host(object): def __init__(self, host, debug=0, dead_retry=_DEAD_RETRY, socket_timeout=_SOCKET_TIMEOUT): self.dead_retry = dead_retry self.socket_timeout = socket_timeout self.debug = debug if isinstance(host, tuple): host, self.weight = host else: self.weight = 1 # parse the connection string m = re.match(r'^(?Punix):(?P.*)$', host) if not m: m = re.match(r'^(?Pinet):' r'(?P[^:]+)(:(?P[0-9]+))?$', host) if not m: m = re.match(r'^(?P[^:]+)(:(?P[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 ) self.deaduntil = 0 self.socket = None self.buffer = '' 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 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 isinstance(msg, tuple): 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: # connection close, let's kill it and raise self.close_socket() raise _ConnectionDeadError() buf += data self.buffer = buf[index+2:] return buf[:index] 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(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 __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 _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__": failures = 0 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, basestring): return "%s (%s)" % (val, type(val)) return "%s" % val def test_setget(key, val): global failures 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"; failures = failures + 1 return 0 class FooStruct(object): 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"; failures = failures + 1 print "Checking results of delete ..." if mc.get("long") == None: print "OK" else: print "FAIL"; failures = failures + 1 print "Testing get_multi ...", print mc.get_multi(["a_string", "an_integer"]) # removed from the protocol #if test_setget("timed_delete", 'foo'): # print "Testing timed delete ...", # if mc.delete("timed_delete", 1): # print "OK" # else: # print "FAIL"; failures = failures + 1 # print "Checking results of timed delete ..." # if mc.get("timed_delete") == None: # print "OK" # else: # print "FAIL"; failures = failures + 1 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"; failures = failures + 1 print "Testing decr ...", x = mc.decr("an_integer", 1) if x == 42: print "OK" else: print "FAIL"; failures = failures + 1 sys.stdout.flush() # sanity tests print "Testing sending spaces...", sys.stdout.flush() try: x = mc.set("this has spaces", 1) except Client.MemcachedKeyCharacterError, msg: print "OK" else: print "FAIL"; failures = failures + 1 print "Testing sending control characters...", try: x = mc.set("this\x10has\x11control characters\x02", 1) except Client.MemcachedKeyCharacterError, msg: print "OK" else: print "FAIL"; failures = failures + 1 print "Testing using insanely long key...", try: x = mc.set('a'*SERVER_MAX_KEY_LENGTH, 1) except Client.MemcachedKeyLengthError, msg: print "FAIL"; failures = failures + 1 else: print "OK" try: x = mc.set('a'*SERVER_MAX_KEY_LENGTH + 'a', 1) except Client.MemcachedKeyLengthError, msg: print "OK" else: print "FAIL"; failures = failures + 1 print "Testing sending a unicode-string key...", try: x = mc.set(u'keyhere', 1) except Client.MemcachedStringEncodingError, msg: print "OK", else: print "FAIL",; failures = failures + 1 try: x = mc.set((u'a'*SERVER_MAX_KEY_LENGTH).encode('utf-8'), 1) except: print "FAIL",; failures = failures + 1 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"; failures = failures + 1 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",; failures = failures + 1 x = mc.set('keyhere', 'a'*SERVER_MAX_VALUE_LENGTH + 'aaa') if mc.get('keyhere') == None: print "OK" else: print "FAIL"; failures = failures + 1 print "Testing set_multi() with no memcacheds running", mc.disconnect_all() errors = mc.set_multi({'keyhere' : 'a', 'keythere' : 'b'}) if errors != []: print "FAIL"; failures = failures + 1 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"; failures = failures + 1 else: print "OK" if failures > 0: print '*** THERE WERE FAILED TESTS' sys.exit(1) sys.exit(0) # vim: ts=4 sw=4 et :