class MemcacheHashCli(object):
def __init__(self, hosts):
self.client = HashClient(hosts)
def set(self, key, value, expire):
try:
return self.client.set(key, value, expire)
except Exception as e:
return False
def get(self, key):
try:
return self.client.get(key, default=None)
except Exception as e:
return None
def mset(self, values, expire):
try:
return self.client.set_many(values, expire)
except Exception as e:
return False
def mget(self, keys):
try:
return self.client.get_many(keys)
except Exception as e:
return None
def test_no_servers_left_with_set_many(self):
from pymemcache.client.hash import HashClient
client = HashClient(
[], use_pooling=True,
ignore_exc=True,
timeout=1, connect_timeout=1
)
result = client.set_many({'foo': 'bar'})
assert result == ['foo']
class MemcachedCache(CacheBase):
"""
Memcached-backed cache implementation.
Compatible with AWS ElastiCache when using their memcached interface.
"""
def __init__(
self,
servers: Optional[Tuple[str, int]] = None,
connect_timeout=None,
read_timeout=None,
serde=None,
testing=False,
ignore_exc=False,
):
client_kwargs = dict(
connect_timeout=connect_timeout,
timeout=read_timeout,
serde=serde or JsonSerializerDeserializer(),
ignore_exc=ignore_exc,
)
if testing:
self.client = MockMemcacheClient(
server=None,
**client_kwargs,
)
else:
self.client = HashClient(
servers=servers,
**client_kwargs,
)
def get(self, key: str):
"""
Return the value for a key, or None if not found
"""
return self.client.get(key)
def add(self, key: str, value, ttl=None):
"""
Set the value for a key, but only that key hasn't been set.
"""
if ttl is None:
# pymemcache interprets 0 as no expiration
ttl = 0
# NB: If input is malformed, this will not raise errors.
# set `noreply` to False for further debugging
return self.client.add(key, value, expire=ttl)
def set(self, key: str, value, ttl=None):
"""
Set the value for a key, but overwriting existing values
"""
if ttl is None:
# pymemcache interprets 0 as no expiration
ttl = 0
# NB: If input is malformed, this will not raise errors.
# set `noreply` to False for further debugging
return self.client.set(key, value, expire=ttl)
def set_many(self, values, ttl=None):
"""
Set the many key-value pairs at a time, overwriting existing values
"""
if ttl is None:
# pymemcache interprets 0 as no expiration
ttl = 0
return self.client.set_many(values, expire=ttl)
class CouchbaseMemcacheMirror(object):
def __init__(self, couchbase_uri, memcached_hosts, primary=PRIMARY_COUCHBASE):
"""
:param couchbase_uri: Connection string for Couchbase
:param memcached_hosts: List of Memcached nodes
:param primary: Determines which datastore is authoritative.
This affects how get operations are performed and which datastore
is used for CAS operations.
PRIMARY_COUCHBASE: Couchbase is authoritative
PRIMARY_MEMCACHED: Memcached is authoritative
By default, Couchbase is the primary store
:return:
"""
self.cb = CbBucket(couchbase_uri)
self.mc = McClient(memcached_hosts)
self._primary = primary
@property
def primary(self):
return self._primary
def _cb_get(self, key):
try:
return self.cb.get(key).value
except NotFoundError:
return None
def get(self, key, try_alternate=True):
"""
Gets a document
:param key: The key to retrieve
:param try_alternate: Whether to try the secondary data source if the
item is not found in the primary.
:return: The value as a Python object
"""
if self._primary == PRIMARY_COUCHBASE:
order = [self._cb_get, self.mc.get]
else:
order = [self.mc.get, self._cb_get]
for meth in order:
ret = meth(key)
if ret or not try_alternate:
return ret
return None
def _cb_mget(self, keys):
"""
Internal method to execute a Couchbase multi-get
:param keys: The keys to retrieve
:return: A tuple of {found_key:found_value, ...}, [missing_key1,...]
"""
try:
ok_rvs = self.cb.get_multi(keys)
bad_rvs = {}
except NotFoundError as e:
ok_rvs, bad_rvs = e.split_results()
ok_dict = {k: (v.value, v.cas) for k, v in ok_rvs}
return ok_dict, bad_rvs.keys()
def get_multi(self, keys, try_alternate=True):
"""
Gets multiple items from the server
:param keys: The keys to fetch as an iterable
:param try_alternate: Whether to fetch missing items from alternate store
:return: A dictionary of key:value. Only contains keys which exist and have values
"""
if self._primary == PRIMARY_COUCHBASE:
ok, err = self._cb_get(keys)
if err and try_alternate:
ok.update(self.mc.get_many(err))
return ok
else:
ok = self.mc.get_many(keys)
if len(ok) < len(keys) and try_alternate:
keys_err = set(keys) - set(ok)
ok.update(self._cb_mget(list(keys_err))[0])
return ok
def gets(self, key):
"""
Get an item with its CAS. The item will always be fetched from the primary
data store.
:param key: the key to get
:return: the value of the key, or None if no such value
"""
if self._primary == PRIMARY_COUCHBASE:
try:
rv = self.cb.get(key)
return key, rv.cas
except NotFoundError:
return None, None
else:
return self.mc.gets(key)
def gets_multi(self, keys):
if self._primary == PRIMARY_COUCHBASE:
try:
rvs = self.cb.get_multi(keys)
except NotFoundError as e:
rvs, _ = e.split_results()
return {k: (v.value, v.cas) for k, v in rvs}
else:
# TODO: I'm not sure if this is implemented in HasClient :(
return self.mc.gets_many(keys)
def delete(self, key):
st = Status()
try:
self.cb.remove(key)
except NotFoundError as e:
st.cb_error = e
st.mc_status = self.mc.delete(key)
return st
def delete_multi(self, keys):
st = Status()
try:
self.cb.remove_multi(keys)
except NotFoundError as e:
st.cb_error = e
st.mc_status = self.mc.delete_many(keys)
def _do_incrdecr(self, key, value, is_incr):
cb_value = value if is_incr else -value
mc_meth = self.mc.incr if is_incr else self.mc.decr
st = Status()
try:
self.cb.counter(key, delta=cb_value)
except NotFoundError as e:
st.cb_error = e
st.mc_status = mc_meth(key, value)
def incr(self, key, value):
return self._do_incrdecr(key, value, True)
def decr(self, key, value):
return self._do_incrdecr(key, value, False)
def touch(self, key, expire=0):
st = Status()
try:
self.cb.touch(key, ttl=expire)
except NotFoundError as e:
st.cb_error = st
st.mc_status = self.mc.touch(key)
def set(self, key, value, expire=0):
"""
Write first to Couchbase, and then to Memcached
:param key: Key to use
:param value: Value to use
:param expire: If set, the item will expire in the given amount of time
:return: Status object if successful (will always be success).
on failure an exception is raised
"""
self.cb.upsert(key, value, ttl=expire)
self.mc.set(key, value, expire=expire)
return Status()
def set_multi(self, values, expire=0):
"""
Set multiple items.
:param values: A dictionary of key, value indicating values to store
:param expire: If present, expiration time for all the items
:return:
"""
self.cb.upsert_multi(values, ttl=expire)
self.mc.set_many(values, expire=expire)
return Status()
def replace(self, key, value, expire=0):
"""
Replace existing items
:param key: key to replace
:param value: new value
:param expire: expiration for item
:return: Status object. Will be OK
"""
status = Status()
try:
self.cb.replace(key, value, ttl=expire)
except NotFoundError as e:
status.cb_error = e
status.mc_status = self.mc.replace(key, value, expire=expire)
return status
def add(self, key, value, expire=0):
status = Status()
try:
self.cb.insert(key, value, ttl=expire)
except KeyExistsError as e:
status.cb_error = e
status.mc_status = self.mc.add(key, value, expire=expire)
return status
def _append_prepend(self, key, value, is_append):
cb_meth = self.cb.append if is_append else self.cb.prepend
mc_meth = self.mc.append if is_append else self.mc.prepend
st = Status()
try:
cb_meth(key, value, format=FMT_UTF8)
except (NotStoredError, NotFoundError) as e:
st.cb_error = e
st.mc_status = mc_meth(key, value)
def append(self, key, value):
return self._append_prepend(key, value, True)
def prepend(self, key, value):
return self._append_prepend(key, value, False)
def cas(self, key, value, cas, expire=0):
if self._primary == PRIMARY_COUCHBASE:
try:
self.cb.replace(key, value, cas=cas, ttl=expire)
self.mc.set(key, value, ttl=expire)
return True
except KeyExistsError:
return False
except NotFoundError:
return None
else:
return self.mc.cas(key, value, cas)
