From: Leif Ryge Date: Tue, 1 Dec 2015 18:47:50 +0000 (+0000) Subject: new feature: preferred storage servers X-Git-Url: https://git.rkrishnan.org/specifications/%5B%5E?a=commitdiff_plain;h=96eaca6a6dbea0f743694a9836993694f14b2f35;p=tahoe-lafs%2Ftahoe-lafs.git new feature: preferred storage servers this includes a squash merge of dca1de6856d0bacb0d57cedcf1a81896910f4efd which was previously seen in pull request #128, as well as daira's suggested changes from pull request #204. --- diff --git a/docs/configuration.rst b/docs/configuration.rst index ac75cca7..f9179376 100644 --- a/docs/configuration.rst +++ b/docs/configuration.rst @@ -396,6 +396,31 @@ Client Configuration .. _performance.rst: performance.rst .. _mutable.rst: specifications/mutable.rst +``peers.preferred = (string, optional)`` + + This is an optional comma-separated list of Node IDs of servers that will + be tried first when selecting storage servers for reading or writing. + + Servers should be identified here by their Node ID as it appears in the web + ui, underneath the server's nickname. For storage servers running tahoe + versions >=1.10 (if the introducer is also running tahoe >=1.10) this will + be a "Node Key" (which is prefixed with 'v0-'). For older nodes, it will be + a TubID instead. When a preferred server (and/or the introducer) is + upgraded to 1.10 or later, clients must adjust their configs accordingly. + + Every node selected for upload, whether preferred or not, will still + receive the same number of shares (one, if there are ``N`` or more servers + accepting uploads). Preferred nodes are simply moved to the front of the + server selection lists computed for each file. + + This is useful if a subset of your nodes have different availability or + connectivity characteristics than the rest of the grid. For instance, if + there are more than ``N`` servers on the grid, and ``K`` or more of them + are at a single physical location, it would make sense for clients at that + location to prefer their local servers so that they can maintain access to + all of their uploads without using the internet. + + Frontend Configuration ====================== diff --git a/src/allmydata/client.py b/src/allmydata/client.py index bb6dce23..41840e85 100644 --- a/src/allmydata/client.py +++ b/src/allmydata/client.py @@ -344,7 +344,9 @@ class Client(node.Node, pollmixin.PollMixin): def init_client_storage_broker(self): # create a StorageFarmBroker object, for use by Uploader/Downloader # (and everybody else who wants to use storage servers) - sb = storage_client.StorageFarmBroker(self.tub, permute_peers=True) + ps = self.get_config("client", "peers.preferred", "").split(",") + preferred_peers = tuple([p.strip() for p in ps if p != ""]) + sb = storage_client.StorageFarmBroker(self.tub, permute_peers=True, preferred_peers=preferred_peers) self.storage_broker = sb # load static server specifications from tahoe.cfg, if any. diff --git a/src/allmydata/storage_client.py b/src/allmydata/storage_client.py index e532db1a..dd9780f2 100644 --- a/src/allmydata/storage_client.py +++ b/src/allmydata/storage_client.py @@ -62,10 +62,11 @@ class StorageFarmBroker: 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, tub, permute_peers): + def __init__(self, tub, permute_peers, preferred_peers=()): self.tub = tub assert permute_peers # False not implemented yet self.permute_peers = permute_peers + 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 @@ -121,10 +122,13 @@ class StorageFarmBroker: 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() - return sha1(peer_selection_index + seed).digest() - return sorted(self.get_connected_servers(), key=_permuted) + is_unpreferred = server not in preferred_servers + return (is_unpreferred, sha1(peer_selection_index + seed).digest()) + return sorted(connected_servers, key=_permuted) def get_all_serverids(self): return frozenset(self.servers.keys()) diff --git a/src/allmydata/test/test_client.py b/src/allmydata/test/test_client.py index dfd9b8de..1819fa4a 100644 --- a/src/allmydata/test/test_client.py +++ b/src/allmydata/test/test_client.py @@ -262,6 +262,18 @@ class Basic(testutil.ReallyEqualMixin, unittest.TestCase): sb.servers.clear() self.failUnlessReallyEqual(self._permute(sb, "one"), []) + def test_permute_with_preferred(self): + sb = StorageFarmBroker(None, True, ['1','4']) + for k in ["%d" % i for i in range(5)]: + ann = {"anonymous-storage-FURL": "pb://abcde@nowhere/fake", + "permutation-seed-base32": base32.b2a(k) } + sb.test_add_rref(k, "rref", ann) + + self.failUnlessReallyEqual(self._permute(sb, "one"), ['1','4','3','0','2']) + self.failUnlessReallyEqual(self._permute(sb, "two"), ['4','1','0','2','3']) + sb.servers.clear() + self.failUnlessReallyEqual(self._permute(sb, "one"), []) + def test_versions(self): basedir = "test_client.Basic.test_versions" os.mkdir(basedir)