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 ac75cca76cbbe476cd736f620e303a36b782988e..f9179376a02c2ec9fa375e1b66f1f86d506accbd 100644 (file)
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -396,6 +396,31 @@ Client Configuration
 .. _performance.rst: performance.rst
 .. _mutable.rst: specifications/mutable.rst
 
 .. _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
 ======================
 
 Frontend Configuration
 ======================
 

diff --git a/src/allmydata/client.py b/src/allmydata/client.py
index bb6dce23096d4d0af7b89973af4e08394a0a460b..41840e85c6d613de7acbeb4c7328eee46c6a9d75 100644 (file)
--- 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)
     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.
         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 e532db1a68d8658d60d06cd347c25f90ba6b2fa0..dd9780f23a8c4efd8eefccd1de47cd3d7f92d060 100644 (file)
--- 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.
     """
     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.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
         # 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
     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()
         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())
 
     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 dfd9b8de7f954ddb0baa4371953d8b51fd5dbdd5..1819fa4a57666be9db48a792c07fb20b38138e27 100644 (file)
--- 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"), [])
 
         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)
     def test_versions(self):
         basedir = "test_client.Basic.test_versions"
         os.mkdir(basedir)