From: Leif Ryge <leif@synthesize.us>
Date: Tue, 16 Apr 2013 06:59:10 +0000 (+0000)
Subject: new feature: preferred storage servers
X-Git-Url: https://git.rkrishnan.org/%5B/%5D%20/uri/%22doc.html/configuration.rst?a=commitdiff_plain;h=94cdf703e854b30cb6a9351720c9c050a99edb8e;p=tahoe-lafs%2Ftahoe-lafs.git
new feature: preferred storage servers
---
diff --git a/docs/configuration.rst b/docs/configuration.rst
index 26d8c58b..79272a41 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -386,6 +386,24 @@ Client Configuration
.. _performance.rst: performance.rst
.. _mutable.rst: specifications/mutable.rst
+``peers.preferred = (string, optional)``
+
+ This is an optional comma-separated list of storage server node IDs that
+ will be tried first when selecting storage servers for reading or writing.
+
+ Every selected node, 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 64b09c07..e06dad66 100644
--- a/src/allmydata/client.py
+++ b/src/allmydata/client.py
@@ -342,7 +342,8 @@ 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)
+ preferred_peers = [p.strip() for p in self.get_config("client", "peers.preferred", "").split(",") 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 39753e0c..4a6d6928 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
@@ -124,7 +125,10 @@ class StorageFarmBroker:
def _permuted(server):
seed = server.get_permutation_seed()
return sha1(peer_selection_index + seed).digest()
- return sorted(self.get_connected_servers(), key=_permuted)
+ connected_servers = self.get_connected_servers()
+ preferred_servers = frozenset([s for s in connected_servers if s.get_longname() in self.preferred_peers])
+ unpreferred_servers = connected_servers - preferred_servers
+ return sorted(preferred_servers, key=_permuted) + sorted(unpreferred_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 531215f6..104f064f 100644
--- a/src/allmydata/test/test_client.py
+++ b/src/allmydata/test/test_client.py
@@ -6,7 +6,7 @@ import allmydata
from allmydata.node import Node, OldConfigError, OldConfigOptionError, MissingConfigEntry, UnescapedHashError
from allmydata import client
from allmydata.storage_client import StorageFarmBroker
-from allmydata.util import base32, fileutil
+from allmydata.util import base32, fileutil, idlib
from allmydata.interfaces import IFilesystemNode, IFileNode, \
IImmutableFileNode, IMutableFileNode, IDirectoryNode
from foolscap.api import flushEventualQueue
@@ -177,7 +177,7 @@ class Basic(testutil.ReallyEqualMixin, unittest.TestCase):
return [ s.get_longname() for s in sb.get_servers_for_psi(key) ]
def test_permute(self):
- sb = StorageFarmBroker(None, True)
+ sb = StorageFarmBroker(None, True, [])
for k in ["%d" % i for i in range(5)]:
ann = {"anonymous-storage-FURL": "pb://abcde@nowhere/fake",
"permutation-seed-base32": base32.b2a(k) }
@@ -188,6 +188,16 @@ 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, map(idlib.nodeid_b2a, ['1','4']))
+ for k in ["%d" % i for i in range(5)]:
+ sb.test_add_rref(k, "rref")
+
+ 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)