Merge branch 'master' into t

* master:
  Enable coverage for neo.tests, which is useful to find dead code
  Remove unused imports, found by pylint
  TODO: tweak should be safer
  Various neoctl/neolog formatting improvements/fixes
  debug: extend 'pdb' example to optionally break on an arbitrary list of callables
  client: fix simultaneous (re)connections to the master

.coveragerc

@@ -4,4 +4,8 @@ source = neo
 omit =
     neo/debug.py
     neo/scripts/runner.py
-    neo/tests/*
+
+[report]
+exclude_lines =
+    pragma: no cover
+    if __name__ == .__main__.:

neo/admin/app.py

@@ -22,8 +22,7 @@ from .handler import AdminEventHandler, MasterEventHandler, \
     MasterRequestEventHandler
 from neo.lib.bootstrap import BootstrapManager
 from neo.lib.pt import PartitionTable
-from neo.lib.protocol import ClusterStates, Errors, \
-    NodeTypes, NodeStates, Packets
+from neo.lib.protocol import ClusterStates, Errors, NodeTypes, Packets
 from neo.lib.debug import register as registerLiveDebugger
 
 class Application(BaseApplication):

neo/client/Storage.py

@@ -18,7 +18,6 @@ from ZODB import BaseStorage, ConflictResolution, POSException
 from zope.interface import implementer
 import ZODB.interfaces
 
-from functools import wraps
 from neo.lib import logging
 from .app import Application
 from .exception import NEOStorageNotFoundError, NEOStorageDoesNotExistError

neo/client/app.py

@@ -19,7 +19,6 @@ from zlib import compress, decompress
 from random import shuffle
 import heapq
 import time
-import weakref
 from functools import partial
 
 from ZODB.POSException import UndoError, StorageTransactionError, ConflictError
@@ -32,20 +31,17 @@ from persistent.TimeStamp import TimeStamp
 from neo.lib import logging
 from neo.lib.protocol import NodeTypes, Packets, \
     INVALID_PARTITION, MAX_TID, ZERO_HASH, ZERO_TID
-from neo.lib.event import EventManager
 from neo.lib.util import makeChecksum, dump
 from neo.lib.locking import Empty, Lock, SimpleQueue
 from neo.lib.connection import MTClientConnection, ConnectionClosed
-from neo.lib.node import NodeManager
 from .exception import NEOStorageError, NEOStorageCreationUndoneError
 from .exception import NEOStorageNotFoundError
 from .handlers import storage, master
-from neo.lib.dispatcher import Dispatcher, ForgottenPacket
+from neo.lib.dispatcher import ForgottenPacket
 from neo.lib.threaded_app import ThreadedApplication
 from .cache import ClientCache
 from .pool import ConnectionPool
 from neo.lib.util import p64, u64, parseMasterList
-from neo.lib.debug import register as registerLiveDebugger
 
 CHECKED_SERIAL = object()
 
@@ -138,11 +134,11 @@ class Application(ThreadedApplication):
 
     def __getattr__(self, attr):
         if attr in ('last_tid', 'pt'):
-            if self._connecting_to_master_node.locked():
-                if attr == 'last_tid':
-                    return
-            else:
-                self._getMasterConnection()
+            self._getMasterConnection()
+            # XXX: There's still a risk that we get disconnected from the
+            #      master at this precise moment and for 'pt', we'd raise
+            #      AttributeError. Should we catch it and loop until it
+            #      succeeds?
         return self.__getattribute__(attr)
 
     def log(self):

neo/client/handlers/master.py

@@ -17,8 +17,8 @@
 from neo.lib import logging
 from neo.lib.handler import MTEventHandler
 from neo.lib.pt import MTPartitionTable as PartitionTable
-from neo.lib.protocol import NodeStates, Packets, ProtocolError
-from neo.lib.util import dump, add64
+from neo.lib.protocol import NodeStates, ProtocolError
+from neo.lib.util import dump
 from . import AnswerBaseHandler
 from ..exception import NEOStorageError
 
@@ -94,13 +94,14 @@ class PrimaryNotificationsHandler(MTEventHandler):
 
     def answerLastTransaction(self, conn, ltid):
         app = self.app
-        if app.last_tid != ltid:
+        app_last_tid = app.__dict__.get('last_tid', '')
+        if app_last_tid != ltid:
             # Either we're connecting or we already know the last tid
             # via invalidations.
             assert app.master_conn is None, app.master_conn
             app._cache_lock_acquire()
             try:
-                if app.last_tid < ltid:
+                if app_last_tid < ltid:
                     app._cache.clear_current()
                     # In the past, we tried not to invalidate the
                     # Connection caches entirely, using the list of

neo/debug.py

@@ -11,7 +11,15 @@ The prompt is accessible through network in case that the process is daemonized:
 
 IF = 'pdb'
 if IF == 'pdb':
-    import socket, sys, threading
+    # List of (module, callables) to break at.
+    # If empty, a thread is started with a breakpoint.
+    # All breakpoints are automatically removed on the first break,
+    # or when this module is reloaded.
+    BP = (#('ZODB.Connection', 'Connection.setstate'),
+          #('ZPublisher.Publish', 'publish_module_standard'),
+         )
+
+    import errno, socket, sys, threading, weakref
     # Unfortunately, IPython does not always print to given stdout.
     #from neo.lib.debug import getPdb
     from pdb import Pdb as getPdb
@@ -55,7 +63,7 @@ if IF == 'pdb':
                 self._socket.setblocking(1)
             return False
 
-    def pdb(app_set):
+    def pdb():
         s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         try:
             # For better security, maybe we should use a unix socket.
@@ -87,7 +95,53 @@ if IF == 'pdb':
             app_set = ()
         finally:
             del f
-    threading.Thread(target=pdb, args=(app_set,)).start()
+
+    class setupBreakPoints(list):
+
+        def __init__(self, bp_list):
+            self._lock = threading.Lock()
+            for o, name in bp_list:
+                o = __import__(o, fromlist=1)
+                x = name.split('.')
+                name = x.pop()
+                for x in x:
+                    o = getattr(o, x)
+                orig = getattr(o, name)
+                if orig.__module__ == __name__:
+                    orig.__closure__[1].cell_contents._revert()
+                    orig = getattr(o, name)
+                    assert orig.__module__ != __name__, (o, name)
+                orig = getattr(orig, '__func__', orig)
+                self.append((o, name, orig))
+                setattr(o, name, self._wrap(orig))
+                print 'BP set on', orig
+            sys.stdout.flush()
+            self._hold = weakref.ref(pdb, self._revert)
+
+        def _revert(self, *_):
+            for x in self:
+                setattr(*x)
+                print 'BP removed on', x[2]
+            sys.stdout.flush()
+            del self[:]
+
+        def _wrap(self, orig):
+            return lambda *args, **kw: self(orig, *args, **kw)
+
+        def __call__(self, orig, *args, **kw):
+            stop = False
+            with self._lock:
+                if self:
+                    stop = True
+                    self._revert()
+            if stop:
+                pdb()
+            return orig(*args, **kw)
+
+    if BP:
+        setupBreakPoints(BP)
+    else:
+        threading.Thread(target=pdb).start()
 
 elif IF == 'frames':
     import sys, traceback

neo/lib/connection.py

@@ -236,7 +236,8 @@ class BaseConnection(object):
     def _getReprInfo(self):
         r = [
             ('uuid', uuid_str(self.getUUID())),
-            ('address', '%s:%u' % self.addr if self.addr else '?'),
+            ('address', ('[%s]:%s' if ':' in self.addr[0] else '%s:%s')
+                        % self.addr if self.addr else '?'),
             ('handler', self.getHandler()),
         ]
         connector = self.connector

neo/lib/interfaces.py

@@ -15,7 +15,6 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import inspect
-from functools import wraps
 
 def check_signature(reference, function):
     # args, varargs, varkw, defaults

neo/lib/logger.py

@@ -221,8 +221,8 @@ class NEOLogger(Logger):
     def _emit(self, r):
         if type(r) is PacketRecord:
             ip, port = r.addr
-            peer = '%s %s (%s:%u)' % ('>' if r.outgoing else '<',
-                                      uuid_str(r.uuid), ip, port)
+            peer = ('%s %s ([%s]:%s)' if ':' in ip else '%s %s (%s:%s)') % (
+                '>' if r.outgoing else '<', uuid_str(r.uuid), ip, port)
             msg = r.msg
             """
             pktcls = protocol.StaticRegistry[r.code]

neo/lib/node.py

@@ -19,7 +19,8 @@ from os.path import exists, getsize
 import json
 
 from . import attributeTracker, logging
-from .protocol import uuid_str, NodeTypes, NodeStates, ProtocolError
+from .protocol import formatNodeList, uuid_str, \
+    NodeTypes, NodeStates, ProtocolError
 
 
 class Node(object):
@@ -161,10 +162,12 @@ class Node(object):
         return self._identified
 
     def __repr__(self):
-        return '<%s(uuid=%s, address=%s, state=%s, connection=%r%s) at %x>' % (
+        addr = self._address
+        return '<%s(uuid=%s%s, state=%s, connection=%r%s) at %x>' % (
             self.__class__.__name__,
             uuid_str(self._uuid),
-            self._address,
+            ', address=' + ('[%s]:%s' if ':' in addr[0] else '%s:%s') % addr
+            if addr else '',
             self._state,
             self._connection,
             '' if self._identified else ', not identified',
@@ -448,16 +451,8 @@ class NodeManager(object):
     def log(self):
         logging.info('Node manager : %u nodes', len(self._node_set))
         if self._node_set:
-            node_list = [(node, uuid_str(node.getUUID()))
-                         for node in sorted(self._node_set)]
-            max_len = max(len(x[1]) for x in node_list)
-            for node, uuid in node_list:
-                address = node.getAddress() or ''
-                if address:
-                    address = '%s:%d' % address
-                logging.info(' * %*s | %8s | %22s | %s',
-                    max_len, uuid, node.getType(), address, node.getState())
-
+            logging.info('\n'.join(formatNodeList(
+                map(Node.asTuple, self._node_set), ' * ')))
 
 @apply
 def NODE_TYPE_MAPPING():

neo/lib/protocol.py

@@ -1743,3 +1743,22 @@ def Errors():
                 registry_dict)(handler_method_name_dict)
 
 Errors = Errors()
+
+# Common helpers between the 'neo' module and 'neolog'.
+
+from datetime import datetime
+from operator import itemgetter
+
+def formatNodeList(node_list, prefix='', _sort_key=itemgetter(2)):
+    if node_list:
+        node_list.sort(key=_sort_key)
+        node_list = [(
+                uuid_str(uuid), str(node_type),
+                ('[%s]:%s' if ':' in addr[0] else '%s:%s')
+                % addr if addr else '', str(state),
+                str(id_timestamp and datetime.utcfromtimestamp(id_timestamp)))
+            for node_type, addr, uuid, state, id_timestamp in node_list]
+        t = ''.join('%%-%us | ' % max(len(x[i]) for x in node_list)
+                    for i in xrange(len(node_list[0]) - 1))
+        return map((prefix + t + '%s').__mod__, node_list)
+    return ()

neo/lib/threaded_app.py

@@ -21,7 +21,6 @@ from .connection import ConnectionClosed
 from .debug import register as registerLiveDebugger
 from .dispatcher import Dispatcher, ForgottenPacket
 from .locking import SimpleQueue
-from .protocol import Packets
 
 class app_set(weakref.WeakSet):
 

neo/master/backup_app.py

@@ -23,8 +23,8 @@ from neo.lib.bootstrap import BootstrapManager
 from neo.lib.exception import PrimaryFailure
 from neo.lib.handler import EventHandler
 from neo.lib.node import NodeManager
-from neo.lib.protocol import CellStates, ClusterStates, \
-    NodeStates, NodeTypes, Packets, uuid_str, INVALID_TID, ZERO_TID
+from neo.lib.protocol import ClusterStates, \
+    NodeTypes, Packets, uuid_str, ZERO_TID
 from neo.lib.util import add64, dump
 from .app import StateChangedException
 from .pt import PartitionTable

neo/master/verification.py

@@ -16,7 +16,6 @@
 
 from collections import defaultdict
 from neo.lib import logging
-from neo.lib.util import dump
 from neo.lib.protocol import ClusterStates, Packets, NodeStates
 from .handlers import BaseServiceHandler
 

neo/neoctl/app.py

@@ -14,11 +14,10 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from operator import itemgetter
 from .neoctl import NeoCTL, NotReadyException
 from neo.lib.util import p64, u64, tidFromTime, timeStringFromTID
-from neo.lib.protocol import uuid_str, ClusterStates, NodeTypes, \
-    UUID_NAMESPACES, ZERO_TID
+from neo.lib.protocol import uuid_str, formatNodeList, \
+    ClusterStates, NodeTypes, UUID_NAMESPACES, ZERO_TID
 
 action_dict = {
     'print': {
@@ -71,15 +70,6 @@ class TerminalNeoCTL(object):
             for (uuid, state) in cell_list))
             for (offset, cell_list) in row_list)
 
-    def formatNodeList(self, node_list, _sort_key=itemgetter(2, 0, 1)):
-        if not node_list:
-            return 'Empty list!'
-        node_list.sort(key=_sort_key)
-        return '\n'.join(
-            '%s - %s - %s - %s' % (node_type, uuid_str(uuid),
-                                   address and '%s:%s' % address, state)
-            for node_type, address, uuid, state in node_list)
-
     # Actual actions
     def getLastIds(self, params):
         """
@@ -94,7 +84,7 @@ class TerminalNeoCTL(object):
         else:
             loid, ltid = self.neoctl.getLastIds()
             r = "last_oid = 0x%x" % (u64(loid))
-        return r + "\nlast_tid = 0x%x (%s)\nlast_ptid = %u" % \
+        return r + "\nlast_tid = 0x%x (%s)\nlast_ptid = %s" % \
                                     (u64(ltid), timeStringFromTID(ltid), ptid)
 
     def getPartitionRowList(self, params):
@@ -129,7 +119,7 @@ class TerminalNeoCTL(object):
         else:
             node_type = None
         node_list = self.neoctl.getNodeList(node_type=node_type)
-        return self.formatNodeList(node_list)
+        return '\n'.join(formatNodeList(node_list)) or 'Empty list!'
 
     def getClusterState(self, params):
         """

neo/scripts/neolog.py

@@ -20,6 +20,7 @@
 import bz2, gzip, errno, optparse, os, signal, sqlite3, sys, time
 from bisect import insort
 from logging import getLevelName
+from functools import partial
 
 comp_dict = dict(bz2=bz2.BZ2File, gz=gzip.GzipFile)
 
@@ -93,6 +94,11 @@ class Log(object):
         exec bz2.decompress(text) in g
         for x in 'uuid_str', 'Packets', 'PacketMalformedError':
             setattr(self, x, g[x])
+        try:
+            self.notifyNodeInformation = partial(g['formatNodeList'],
+                                                 prefix=' ! ')
+        except KeyError:
+            self.notifyNodeInformation = None
         try:
             self._next_protocol, = q("SELECT date FROM protocol WHERE date>?",
                                      (date,)).next()
@@ -144,18 +150,6 @@ class Log(object):
     def error(self, code, message):
         return "%s (%s)" % (code, message),
 
-    def notifyNodeInformation(self, node_list):
-        node_list.sort(key=lambda x: x[2])
-        node_list = [(self.uuid_str(x[2]), str(x[0]),
-                      '%s:%u' % x[1] if x[1] else '?', str(x[3]))
-                     + ((repr(x[4]),) if len(x) > 4 else ()) # BBB
-                     for x in node_list]
-        if node_list:
-            t = ''.join(' %%%us |' % max(len(x[i]) for x in node_list)
-                        for i in xrange(len(node_list[0]) - 1))
-            return map((' !' + t + ' %s').__mod__, node_list)
-        return ()
-
 
 def emit_many(log_list):
     log_list = [(log, iter(log).next) for log in log_list]

neo/scripts/runner.py

@@ -17,7 +17,6 @@
 
 import traceback
 import unittest
-import logging
 import time
 import sys
 import os
@@ -33,7 +32,6 @@ if filter(re.compile(r'--coverage$|-\w*c').match, sys.argv[1:]):
     coverage.neotestrunner = []
     coverage.start()
 
-import neo
 from neo.tests import getTempDirectory, __dict__ as neo_tests__dict__
 from neo.tests.benchmark import BenchmarkRunner
 

neo/scripts/simple.py

@@ -15,7 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-import inspect, random, signal, sys
+import inspect, random
 from logging import getLogger, INFO, DEBUG
 from optparse import OptionParser
 from neo.lib import logging

neo/storage/app.py

@@ -21,7 +21,6 @@ from neo.lib import logging
 from neo.lib.app import BaseApplication
 from neo.lib.protocol import uuid_str, \
     CellStates, ClusterStates, NodeTypes, Packets
-from neo.lib.node import NodeManager
 from neo.lib.connection import ListeningConnection
 from neo.lib.exception import StoppedOperation, PrimaryFailure
 from neo.lib.pt import PartitionTable

neo/storage/database/importer.py

@@ -28,8 +28,7 @@ from .manager import DatabaseManager
 from neo.lib import logging, patch, util
 from neo.lib.exception import DatabaseFailure
 from neo.lib.interfaces import implements
-from neo.lib.protocol import BackendNotImplemented, CellStates, \
-    MAX_TID, ZERO_HASH, ZERO_OID, ZERO_TID
+from neo.lib.protocol import BackendNotImplemented, MAX_TID
 
 patch.speedupFileStorageTxnLookup()
 

neo/storage/database/mysqldb.py

@@ -29,7 +29,7 @@ import struct
 import time
 
 from . import LOG_QUERIES
-from .manager import CreationUndone, DatabaseManager, splitOIDField
+from .manager import DatabaseManager, splitOIDField
 from neo.lib import logging, util
 from neo.lib.exception import DatabaseFailure
 from neo.lib.interfaces import implements

neo/storage/database/sqlite.py

@@ -21,9 +21,8 @@ import string
 import traceback
 
 from . import LOG_QUERIES
-from .manager import CreationUndone, DatabaseManager, splitOIDField
+from .manager import DatabaseManager, splitOIDField
 from neo.lib import logging, util
-from neo.lib.exception import DatabaseFailure
 from neo.lib.interfaces import implements
 from neo.lib.protocol import CellStates, ZERO_OID, ZERO_TID, ZERO_HASH
 

neo/storage/handlers/identification.py

@@ -16,7 +16,7 @@
 
 from neo.lib import logging
 from neo.lib.handler import EventHandler
-from neo.lib.protocol import uuid_str, NodeTypes, NotReadyError, Packets
+from neo.lib.protocol import NodeTypes, NotReadyError, Packets
 from neo.lib.protocol import ProtocolError, BrokenNodeDisallowedError
 from .storage import StorageOperationHandler
 from .client import ClientOperationHandler, ClientReadOnlyOperationHandler

neo/storage/handlers/master.py

@@ -16,7 +16,7 @@
 
 from neo.lib import logging
 from neo.lib.util import dump
-from neo.lib.protocol import Packets, ProtocolError, ZERO_TID
+from neo.lib.protocol import Packets, ZERO_TID
 from . import BaseMasterHandler
 
 

neo/tests/client/testClientApp.py

@@ -19,7 +19,7 @@ import unittest
 from cPickle import dumps
 from mock import Mock, ReturnValues
 from ZODB.POSException import StorageTransactionError, UndoError, ConflictError
-from .. import NeoUnitTestBase, buildUrlFromString, ADDRESS_TYPE
+from .. import NeoUnitTestBase, buildUrlFromString
 from neo.client.app import Application
 from neo.client.cache import test as testCache
 from neo.client.exception import NEOStorageError, NEOStorageNotFoundError

neo/tests/client/testMasterHandler.py

@@ -18,9 +18,6 @@ import unittest
 from mock import Mock
 from .. import NeoUnitTestBase
 from neo.lib.node import NodeManager
-from neo.lib.pt import PartitionTable
-from neo.lib.protocol import NodeTypes
-from neo.client.handlers.master import PrimaryBootstrapHandler
 from neo.client.handlers.master import PrimaryNotificationsHandler, \
        PrimaryAnswersHandler
 from neo.client.exception import NEOStorageError

neo/tests/fs2zodb.py

@@ -16,7 +16,6 @@
 
 import os, stat, time
 from persistent import Persistent
-from persistent.TimeStamp import TimeStamp
 from BTrees.OOBTree import OOBTree
 
 class Inode(OOBTree):

neo/tests/functional/testClient.py

@@ -26,7 +26,6 @@ from ZODB.FileStorage import FileStorage
 from ZODB.POSException import ConflictError
 from ZODB.tests.StorageTestBase import zodb_pickle
 from persistent import Persistent
-from .. import expectedFailure
 from . import NEOCluster, NEOFunctionalTest
 
 TREE_SIZE = 6

neo/tests/master/testMasterPT.py

@@ -16,7 +16,6 @@
 
 import unittest
 from collections import defaultdict
-from mock import Mock
 from .. import NeoUnitTestBase
 from neo.lib.protocol import NodeStates, CellStates
 from neo.lib.pt import PartitionTableException

neo/tests/storage/testMasterHandler.py

@@ -22,7 +22,7 @@ from neo.storage.app import Application
 from neo.storage.handlers.master import MasterOperationHandler
 from neo.lib.exception import PrimaryFailure
 from neo.lib.pt import PartitionTable
-from neo.lib.protocol import CellStates, ProtocolError, Packets
+from neo.lib.protocol import CellStates, Packets
 
 class StorageMasterHandlerTests(NeoUnitTestBase):
 

neo/tests/storage/testStorageMySQL.py

@@ -15,7 +15,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import unittest
-import MySQLdb
+from MySQLdb import OperationalError
 from mock import Mock
 from neo.lib.exception import DatabaseFailure
 from neo.lib.util import p64
@@ -59,7 +59,6 @@ class StorageMySQLdbTests(StorageDBTests):
     def test_query2(self):
         # test the OperationalError exception
         # fake object, raise exception during the first call
-        from MySQLdb import OperationalError
         from MySQLdb.constants.CR import SERVER_GONE_ERROR
         class FakeConn(object):
             def query(*args):
@@ -78,7 +77,6 @@ class StorageMySQLdbTests(StorageDBTests):
 
     def test_query3(self):
         # OperationalError > raise DatabaseFailure exception
-        from MySQLdb import OperationalError
         class FakeConn(object):
             def close(self):
                 pass

neo/tests/testNodes.py

@@ -16,9 +16,8 @@
 
 import unittest
 from mock import Mock
-from neo.lib import protocol
 from neo.lib.protocol import NodeTypes, NodeStates
-from neo.lib.node import Node, NodeManager, MasterDB
+from neo.lib.node import Node, MasterDB
 from . import NeoUnitTestBase, getTempDirectory
 from time import time
 from os import chmod, mkdir, rmdir, unlink

neo/tests/testPT.py

@@ -15,7 +15,6 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import unittest
-from mock import Mock
 from neo.lib.protocol import NodeStates, CellStates
 from neo.lib.pt import Cell, PartitionTable, PartitionTableException
 from . import NeoUnitTestBase

neo/tests/threaded/testImporter.py

@@ -18,7 +18,7 @@ from collections import deque
 from cPickle import Pickler, Unpickler
 from cStringIO import StringIO
 from itertools import islice, izip_longest
-import os, time, unittest
+import os, unittest
 import neo, transaction, ZODB
 from neo.lib import logging
 from neo.lib.util import u64

neo/tests/threaded/testReplication.py

@@ -17,6 +17,7 @@
 from logging import getLogger, INFO, DEBUG
 
 import random
+import sys
 import time
 import transaction
 from ZODB.POSException import ReadOnlyError, POSKeyError
@@ -33,7 +34,7 @@ from neo.lib.event import EventManager
 from neo.lib.protocol import CellStates, ClusterStates, Packets, \
     ZERO_OID, ZERO_TID, MAX_TID, uuid_str
 from neo.lib.util import p64
-from .. import Patch
+from .. import expectedFailure, Patch
 from . import ConnectionFilter, NEOCluster, NEOThreadedTest, predictable_random
 
 # dump log to stderr
@@ -367,6 +368,33 @@ class ReplicationTests(NEOThreadedTest):
         # TODO check tids
         self.assertEqual(1, self.checkBackup(backup))
 
+    def testSafeTweak(self):
+        """
+        Check that tweak always tries to keep a minimum of (replicas + 1)
+        readable cells, otherwise we have less/no redundancy as long as
+        replication has not finished.
+        """
+        def changePartitionTable(orig, *args):
+            orig(*args)
+            sys.exit()
+        cluster = NEOCluster(partitions=3, replicas=1, storage_count=3)
+        s0, s1, s2 = cluster.storage_list
+        try:
+            cluster.start([s0, s1])
+            s2.start()
+            self.tic()
+            cluster.enableStorageList([s2])
+            # 2 UP_TO_DATE cells should become FEEDING,
+            # and be dropped only when the replication is done,
+            # so that 1 storage can still die without data loss.
+            with Patch(s0.dm, changePartitionTable=changePartitionTable):
+                cluster.neoctl.tweakPartitionTable()
+                self.tic()
+            expectedFailure(self.assertEqual)(cluster.neoctl.getClusterState(),
+                             ClusterStates.RUNNING)
+        finally:
+            cluster.stop()
+
     def testReplicationAbortedBySource(self):
         """
         Check that a feeding node aborts replication when its partition is