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tahoe-lafs/src/allmydata/storage_client.py
Jean-Paul Calderone ad29e627cc refer to the interface
2019-06-11 16:32:29 -04:00

578 lines
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"""
I contain the client-side code which speaks to storage servers, in particular
the foolscap-based server implemented in src/allmydata/storage/*.py .
"""
# roadmap:
#
# 1: implement StorageFarmBroker (i.e. "storage broker"), change Client to
# create it, change uploader/servermap to get rrefs from it. ServerFarm calls
# IntroducerClient.subscribe_to . ServerFarm hides descriptors, passes rrefs
# to clients. webapi status pages call broker.get_info_about_serverid.
#
# 2: move get_info methods to the descriptor, webapi status pages call
# broker.get_descriptor_for_serverid().get_info
#
# 3?later?: store descriptors in UploadResults/etc instead of serverids,
# webapi status pages call descriptor.get_info and don't use storage_broker
# or Client
#
# 4: enable static config: tahoe.cfg can add descriptors. Make the introducer
# optional. This closes #467
#
# 5: implement NativeStorageClient, pass it to Tahoe2PeerSelector and other
# clients. Clients stop doing callRemote(), use NativeStorageClient methods
# instead (which might do something else, i.e. http or whatever). The
# introducer and tahoe.cfg only create NativeStorageClients for now.
#
# 6: implement other sorts of IStorageClient classes: S3, etc
import re, time, hashlib
import attr
from zope.interface import implementer
from twisted.internet import defer
from twisted.application import service
from foolscap.api import eventually
from allmydata.interfaces import (
IStorageBroker,
IDisplayableServer,
IServer,
IStorageServer,
)
from allmydata.util import log, base32, connection_status
from allmydata.util.assertutil import precondition
from allmydata.util.observer import ObserverList
from allmydata.util.rrefutil import add_version_to_remote_reference
from allmydata.util.hashutil import permute_server_hash
# who is responsible for de-duplication?
# both?
# IC remembers the unpacked announcements it receives, to provide for late
# subscribers and to remove duplicates
# if a client subscribes after startup, will they receive old announcements?
# yes
# who will be responsible for signature checking?
# make it be IntroducerClient, so they can push the filter outwards and
# reduce inbound network traffic
# what should the interface between StorageFarmBroker and IntroducerClient
# look like?
# don't pass signatures: only pass validated blessed-objects
@implementer(IStorageBroker)
class StorageFarmBroker(service.MultiService):
"""I live on the client, and know about storage servers. For each server
that is participating in a grid, I either maintain a connection to it or
remember enough information to establish a connection to it on demand.
I'm also responsible for subscribing to the IntroducerClient to find out
about new servers as they are announced by the Introducer.
"""
def __init__(self, permute_peers, tub_maker, preferred_peers=()):
service.MultiService.__init__(self)
assert permute_peers # False not implemented yet
self.permute_peers = permute_peers
self._tub_maker = tub_maker
self.preferred_peers = preferred_peers
# self.servers maps serverid -> IServer, and keeps track of all the
# storage servers that we've heard about. Each descriptor manages its
# own Reconnector, and will give us a RemoteReference when we ask
# them for it.
self.servers = {}
self._static_server_ids = set() # ignore announcements for these
self.introducer_client = None
self._threshold_listeners = [] # tuples of (threshold, Deferred)
self._connected_high_water_mark = 0
def set_static_servers(self, servers):
for (server_id, server) in servers.items():
assert isinstance(server_id, unicode) # from YAML
server_id = server_id.encode("ascii")
self._static_server_ids.add(server_id)
handler_overrides = server.get("connections", {})
s = NativeStorageServer(server_id, server["ann"],
self._tub_maker, handler_overrides)
s.on_status_changed(lambda _: self._got_connection())
s.setServiceParent(self)
self.servers[server_id] = s
s.start_connecting(self._trigger_connections)
def when_connected_enough(self, threshold):
"""
:returns: a Deferred that fires if/when our high water mark for
number of connected servers becomes (or ever was) above
"threshold".
"""
d = defer.Deferred()
self._threshold_listeners.append( (threshold, d) )
self._check_connected_high_water_mark()
return d
# these two are used in unit tests
def test_add_rref(self, serverid, rref, ann):
s = NativeStorageServer(serverid, ann.copy(), self._tub_maker, {})
s._rref = rref
s._is_connected = True
self.servers[serverid] = s
def test_add_server(self, server_id, s):
s.on_status_changed(lambda _: self._got_connection())
self.servers[server_id] = s
def use_introducer(self, introducer_client):
self.introducer_client = ic = introducer_client
ic.subscribe_to("storage", self._got_announcement)
def _got_connection(self):
# this is called by NativeStorageClient when it is connected
self._check_connected_high_water_mark()
def _check_connected_high_water_mark(self):
current = len(self.get_connected_servers())
if current > self._connected_high_water_mark:
self._connected_high_water_mark = current
remaining = []
for threshold, d in self._threshold_listeners:
if self._connected_high_water_mark >= threshold:
eventually(d.callback, None)
else:
remaining.append( (threshold, d) )
self._threshold_listeners = remaining
def _got_announcement(self, key_s, ann):
precondition(isinstance(key_s, str), key_s)
precondition(key_s.startswith("v0-"), key_s)
precondition(ann["service-name"] == "storage", ann["service-name"])
server_id = key_s
if server_id in self._static_server_ids:
log.msg(format="ignoring announcement for static server '%(id)s'",
id=server_id,
facility="tahoe.storage_broker", umid="AlxzqA",
level=log.UNUSUAL)
return
s = NativeStorageServer(server_id, ann, self._tub_maker, {})
s.on_status_changed(lambda _: self._got_connection())
server_id = s.get_serverid()
old = self.servers.get(server_id)
if old:
if old.get_announcement() == ann:
return # duplicate
# replacement
del self.servers[server_id]
old.stop_connecting()
old.disownServiceParent()
# NOTE: this disownServiceParent() returns a Deferred that
# doesn't fire until Tub.stopService fires, which will wait for
# any existing connections to be shut down. This doesn't
# generally matter for normal runtime, but unit tests can run
# into DirtyReactorErrors if they don't block on these. If a test
# replaces one server with a newer version, then terminates
# before the old one has been shut down, it might get
# DirtyReactorErrors. The fix would be to gather these Deferreds
# into a structure that will block StorageFarmBroker.stopService
# until they have fired (but hopefully don't keep reference
# cycles around when they fire earlier than that, which will
# almost always be the case for normal runtime).
# now we forget about them and start using the new one
s.setServiceParent(self)
self.servers[server_id] = s
s.start_connecting(self._trigger_connections)
# the descriptor will manage their own Reconnector, and each time we
# need servers, we'll ask them if they're connected or not.
def _trigger_connections(self):
# when one connection is established, reset the timers on all others,
# to trigger a reconnection attempt in one second. This is intended
# to accelerate server connections when we've been offline for a
# while. The goal is to avoid hanging out for a long time with
# connections to only a subset of the servers, which would increase
# the chances that we'll put shares in weird places (and not update
# existing shares of mutable files). See #374 for more details.
for dsc in self.servers.values():
dsc.try_to_connect()
def get_servers_for_psi(self, peer_selection_index):
# return a list of server objects (IServers)
assert self.permute_peers == True
connected_servers = self.get_connected_servers()
preferred_servers = frozenset(s for s in connected_servers if s.get_longname() in self.preferred_peers)
def _permuted(server):
seed = server.get_permutation_seed()
is_unpreferred = server not in preferred_servers
return (is_unpreferred,
permute_server_hash(peer_selection_index, seed))
return sorted(connected_servers, key=_permuted)
def get_all_serverids(self):
return frozenset(self.servers.keys())
def get_connected_servers(self):
return frozenset([s for s in self.servers.values() if s.is_connected()])
def get_known_servers(self):
return frozenset(self.servers.values())
def get_nickname_for_serverid(self, serverid):
if serverid in self.servers:
return self.servers[serverid].get_nickname()
return None
def get_stub_server(self, serverid):
if serverid in self.servers:
return self.servers[serverid]
# some time before 1.12, we changed "serverid" to be "key_s" (the
# printable verifying key, used in V2 announcements), instead of the
# tubid. When the immutable uploader delegates work to a Helper,
# get_stub_server() is used to map the returning server identifiers
# to IDisplayableServer instances (to get a name, for display on the
# Upload Results web page). If the Helper is running 1.12 or newer,
# it will send pubkeys, but if it's still running 1.11, it will send
# tubids. This clause maps the old tubids to our existing servers.
for s in self.servers.values():
if isinstance(s, NativeStorageServer):
if serverid == s._tubid:
return s
return StubServer(serverid)
@implementer(IDisplayableServer)
class StubServer(object):
def __init__(self, serverid):
self.serverid = serverid # binary tubid
def get_serverid(self):
return self.serverid
def get_name(self):
return base32.b2a(self.serverid)[:8]
def get_longname(self):
return base32.b2a(self.serverid)
def get_nickname(self):
return "?"
@implementer(IServer)
class NativeStorageServer(service.MultiService):
"""I hold information about a storage server that we want to connect to.
If we are connected, I hold the RemoteReference, their host address, and
the their version information. I remember information about when we were
last connected too, even if we aren't currently connected.
@ivar last_connect_time: when we last established a connection
@ivar last_loss_time: when we last lost a connection
@ivar version: the server's versiondict, from the most recent announcement
@ivar nickname: the server's self-reported nickname (unicode), same
@ivar rref: the RemoteReference, if connected, otherwise None
@ivar remote_host: the IAddress, if connected, otherwise None
"""
VERSION_DEFAULTS = {
"http://allmydata.org/tahoe/protocols/storage/v1" :
{ "maximum-immutable-share-size": 2**32 - 1,
"maximum-mutable-share-size": 2*1000*1000*1000, # maximum prior to v1.9.2
"tolerates-immutable-read-overrun": False,
"delete-mutable-shares-with-zero-length-writev": False,
"available-space": None,
},
"application-version": "unknown: no get_version()",
}
def __init__(self, server_id, ann, tub_maker, handler_overrides):
service.MultiService.__init__(self)
assert isinstance(server_id, str)
self._server_id = server_id
self.announcement = ann
self._tub_maker = tub_maker
self._handler_overrides = handler_overrides
assert "anonymous-storage-FURL" in ann, ann
furl = str(ann["anonymous-storage-FURL"])
m = re.match(r'pb://(\w+)@', furl)
assert m, furl
tubid_s = m.group(1).lower()
self._tubid = base32.a2b(tubid_s)
if "permutation-seed-base32" in ann:
ps = base32.a2b(str(ann["permutation-seed-base32"]))
elif re.search(r'^v0-[0-9a-zA-Z]{52}$', server_id):
ps = base32.a2b(server_id[3:])
else:
log.msg("unable to parse serverid '%(server_id)s as pubkey, "
"hashing it to get permutation-seed, "
"may not converge with other clients",
server_id=server_id,
facility="tahoe.storage_broker",
level=log.UNUSUAL, umid="qu86tw")
ps = hashlib.sha256(server_id).digest()
self._permutation_seed = ps
assert server_id
self._long_description = server_id
if server_id.startswith("v0-"):
# remove v0- prefix from abbreviated name
self._short_description = server_id[3:3+8]
else:
self._short_description = server_id[:8]
self.last_connect_time = None
self.last_loss_time = None
self.remote_host = None
self._rref = None
self._is_connected = False
self._reconnector = None
self._trigger_cb = None
self._on_status_changed = ObserverList()
def on_status_changed(self, status_changed):
"""
:param status_changed: a callable taking a single arg (the
NativeStorageServer) that is notified when we become connected
"""
return self._on_status_changed.subscribe(status_changed)
# Special methods used by copy.copy() and copy.deepcopy(). When those are
# used in allmydata.immutable.filenode to copy CheckResults during
# repair, we want it to treat the IServer instances as singletons, and
# not attempt to duplicate them..
def __copy__(self):
return self
def __deepcopy__(self, memodict):
return self
def __repr__(self):
return "<NativeStorageServer for %s>" % self.get_name()
def get_serverid(self):
return self._server_id
def get_permutation_seed(self):
return self._permutation_seed
def get_version(self):
if self._rref:
return self._rref.version
return None
def get_name(self): # keep methodname short
# TODO: decide who adds [] in the short description. It should
# probably be the output side, not here.
return self._short_description
def get_longname(self):
return self._long_description
def get_lease_seed(self):
return self._tubid
def get_foolscap_write_enabler_seed(self):
return self._tubid
def get_nickname(self):
return self.announcement.get("nickname", "")
def get_announcement(self):
return self.announcement
def get_remote_host(self):
return self.remote_host
def get_connection_status(self):
last_received = None
if self._rref:
last_received = self._rref.getDataLastReceivedAt()
return connection_status.from_foolscap_reconnector(self._reconnector,
last_received)
def is_connected(self):
return self._is_connected
def get_available_space(self):
version = self.get_version()
if version is None:
return None
protocol_v1_version = version.get('http://allmydata.org/tahoe/protocols/storage/v1', {})
available_space = protocol_v1_version.get('available-space')
if available_space is None:
available_space = protocol_v1_version.get('maximum-immutable-share-size', None)
return available_space
def start_connecting(self, trigger_cb):
self._tub = self._tub_maker(self._handler_overrides)
self._tub.setServiceParent(self)
furl = str(self.announcement["anonymous-storage-FURL"])
self._trigger_cb = trigger_cb
self._reconnector = self._tub.connectTo(furl, self._got_connection)
def _got_connection(self, rref):
lp = log.msg(format="got connection to %(name)s, getting versions",
name=self.get_name(),
facility="tahoe.storage_broker", umid="coUECQ")
if self._trigger_cb:
eventually(self._trigger_cb)
default = self.VERSION_DEFAULTS
d = add_version_to_remote_reference(rref, default)
d.addCallback(self._got_versioned_service, lp)
d.addCallback(lambda ign: self._on_status_changed.notify(self))
d.addErrback(log.err, format="storageclient._got_connection",
name=self.get_name(), umid="Sdq3pg")
def _got_versioned_service(self, rref, lp):
log.msg(format="%(name)s provided version info %(version)s",
name=self.get_name(), version=rref.version,
facility="tahoe.storage_broker", umid="SWmJYg",
level=log.NOISY, parent=lp)
self.last_connect_time = time.time()
self.remote_host = rref.getLocationHints()
self._rref = rref
self._is_connected = True
rref.notifyOnDisconnect(self._lost)
def get_rref(self):
return self._rref
def get_storage_server(self):
"""
See ``IServer.get_storage_server``.
"""
if self._rref is None:
return None
# Pass in an accessor for our _rref attribute. The value of the
# attribute may change over time as connections are lost and
# re-established. The _StorageServer should always be able to get the
# most up-to-date value.
return _StorageServer(get_rref=self.get_rref)
def _lost(self):
log.msg(format="lost connection to %(name)s", name=self.get_name(),
facility="tahoe.storage_broker", umid="zbRllw")
self.last_loss_time = time.time()
# self._rref is now stale: all callRemote()s will get a
# DeadReferenceError. We leave the stale reference in place so that
# uploader/downloader code (which received this IServer through
# get_connected_servers() or get_servers_for_psi()) can continue to
# use s.get_rref().callRemote() and not worry about it being None.
self._is_connected = False
self.remote_host = None
def stop_connecting(self):
# used when this descriptor has been superceded by another
self._reconnector.stopConnecting()
def try_to_connect(self):
# used when the broker wants us to hurry up
self._reconnector.reset()
class UnknownServerTypeError(Exception):
pass
@implementer(IStorageServer)
@attr.s
class _StorageServer(object):
"""
``_StorageServer`` is a direct pass-through to an ``RIStorageServer`` via
a ``RemoteReference``.
"""
_get_rref = attr.ib()
@property
def _rref(self):
return self._get_rref()
def get_version(self):
return self._rref.callRemote(
"get_version",
)
def allocate_buckets(
self,
storage_index,
renew_secret,
cancel_secret,
sharenums,
allocated_size,
canary,
):
return self._rref.callRemote(
"allocate_buckets",
storage_index,
renew_secret,
cancel_secret,
sharenums,
allocated_size,
canary,
)
def add_lease(
self,
storage_index,
renew_secret,
cancel_secret,
):
return self._rref.callRemote(
"add_lease",
storage_index,
renew_secret,
cancel_secret,
)
def renew_lease(
self,
storage_index,
renew_secret,
):
return self._rref.callRemote(
"renew_lease",
storage_index,
renew_secret,
)
def get_buckets(
self,
storage_index,
):
return self._rref.callRemote(
"get_buckets",
storage_index,
)
def slot_readv(
self,
storage_index,
shares,
readv,
):
return self._rref.callRemote(
"slot_readv",
storage_index,
shares,
readv,
)
def slot_testv_and_readv_and_writev(
self,
storage_index,
secrets,
tw_vectors,
r_vector,
):
return self._rref.callRemote(
"slot_testv_and_readv_and_writev",
storage_index,
secrets,
tw_vectors,
r_vector,
)
def advise_corrupt_share(
self,
share_type,
storage_index,
shnum,
reason,
):
return self._rref.callRemoteOnly(
"advise_corrupt_share",
share_type,
storage_index,
shnum,
reason,
)
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