New 'Importer' storage backend

README

@@ -33,7 +33,9 @@ ZODB API is fully implemented except:
         (full implementation is considered)
 - blobs: not implemented (not considered yet)
 
-There is a simple way to convert FileStorage to NEO and back again.
+Any ZODB like FileStorage can be converted to NEO instanteously,
+which means the database is operational before all data are imported.
+There's also a tool to convert back to FileStorage.
 
 See also http://www.neoppod.org/links for more detailed information about
 features related to scalability.
@@ -88,7 +90,7 @@ e. Clients can connect when the cluster is in RUNNING state::
     $ neoctl -a <admin> print cluster
     RUNNING
 
-f. See `neomigrate` command to import an existing FileStorage database,
+f. See `importer.conf` file to import an existing database,
    or `neoctl` command for more administrative tasks.
 
 Alternatively, you can use `neosimple` command to quickly setup a cluster for

importer.conf

+# This file describes how to use the NEO Importer storage backend,
+# which is the recommended way to import the data of an existing Zope database
+# into a NEO cluster.
+#
+# Note that the 'neomigrate' command is another way to migrate to NEO but:
+# - the database is unusable as long as migration is not finished;
+# - it can not merge bases at mountpoints;
+# - it can not resume an interrupted migration;
+# - it does not preserve metadata that are specific to "undo" transactions
+#   (which would then behave like normal transactions);
+# - it only supports conversion from FileStorage;
+# - it is slower.
+# The only advantage of 'neomigrate' over Importer is that data can be imported
+# directly to a NEO cluster with replicas or several storage nodes.
+# Importer backend can only be used with a single storage node.
+#
+# Here is how to proceed once this file ready:
+# 1. Restart ZODB clients to connect to new NEO cluster (not started yet).
+# 2. Start NEO cluster and use 'neoctl -a <admin> start' command.
+# 3. Your Zope applications should work and background migration of data
+#    started automatically. The only downtime depends on how fast you are to do
+#    the first 2 steps. The only limitations in this mode are that:
+#    - pack is not supported
+#    - IStorage.history() is not implemented (this is used for example by
+#      history tab in Zope Management Interface)
+# 4. A warning message reporting that "All data are imported"
+#    is emitted to storage node's log when the migration is finished.
+#    This can take days with big databases.
+# The following steps can be scheduled any time after migration is over,
+# at your convenience:
+# 5. Change NEO configuration to stop using Importer backend.
+# 6. Stop clients.
+# 7. Restart NEO cluster.
+# 8. Start clients. This was the second, very short, downtime.
+# 9. Optionally, add storage nodes and balance partitions.
+#
+# Data are migrated even if your ZODB clients are stopped.
+
+# The first section describes the destination NEO storage.
+# See neo.conf for description of parameters.
+[neo]
+# Once migration is finished, restart NEO storage to use the below directly
+# (instead of adapter=Importer & database=/path_to_this_file).
+adapter=MySQL
+database=neo
+
+# The other sections are for source databases.
+[root]
+# Example with FileStorage but this can be anything else.
+# ZEO is possible but less efficient: ZEO servers must be stopped
+# if NEO opens FileStorage DBs directly.
+storage=
+  <filestorage>
+    path /path/to/root.fs
+  </filestorage>
+# (leading spaces indicate value continuation)
+
+# This file can stop here if your source DB is not splitted.
+# Otherwise, you need to describe mountpoints and other ZODB.
+# OID mapping can't be changed once the NEO cluster is started with this
+# configuration.
+
+# Mountpoints for this ZODB (see the use case at the end of this file).
+# <section_name>=<oid>
+foo=421
+bar=666
+
+# Following sections must define 'oid' parameter.
+[foo]
+# Any reference to oid 421 in 'root' is changed to point to oid 123 of 'foo'.
+# Of course, original oid 421 in 'root' will become unreferenced.
+oid=123
+
+storage=
+  <filestorage>
+    path /path/to/foo.fs
+  </filestorage>
+baz=1000
+
+[bar]
+oid=4567
+storage=
+  <filestorage>
+    path /path/to/bar.fs
+  </filestorage>
+
+[baz]
+oid=2000
+storage=
+  <filestorage>
+    path /path/to/baz.fs
+  </filestorage>
+
+
+## Case of several databases linked with MountedObject objects
+#
+# MountedObject is provided by ZODBMountPoint Zope product.
+# It relies on IAcquirer and ITraversable to fetch the real object.
+#
+# Given the following multi-base:
+# - in 'foo', /a/b is the real object
+# - in 'root', /c/d is a MountedObject object configured to point to
+#   /a/b in 'foo'
+#
+# So you need to get the oid of /a/b in 'foo':
+#   unrestrictedTraverse("/a/b")._p_oid
+# which equals to 123 in the above example
+#
+# And that of /c/d in 'root':
+#   unrestrictedTraverse("/c").__dict__["d"]._p_oid -> 421
+# The way to retrieve the mount point depends on the container type.
+# For a BTreeFolder2, it would be: c._tree["d"]._p_oid

neo.conf

@@ -2,6 +2,9 @@
 # must be identical for all nodes in a given cluster.
 # This file is optionnal: parameters can be given at the command line.
 
+# See SafeConfigParser at https://docs.python.org/2/library/configparser.html
+# for more information about the syntax.
+
 # Common parameters.
 [DEFAULT]
 # The cluster name

neo/client/Storage.py

@@ -122,6 +122,11 @@ class Storage(BaseStorage.BaseStorage,
             raise POSException.POSKeyError(oid)
 
     def loadBefore(self, oid, tid):
+        # XXX: FileStorage return an empty string for a deleted object
+        #      but it may cause EOFError exceptions in ZODB.Connection
+        #      and it makes impossible to store empty values.
+        #      We think it's wrong behaviour and raise POSKeyError instead.
+        #      Or maybe we should return None?
         try:
             return self.app.load(oid, None, tid)
         except NEOStorageDoesNotExistError:

neo/scripts/neomigrate.py

@@ -46,9 +46,12 @@ def main(args=None):
     from ZODB.FileStorage import FileStorage
     from neo.client.Storage import Storage as NEOStorage
     if os.path.exists(source):
-        print("NOTE: NEO does not implement IStorageRestoreable interface,"
-              " which means that undo information is not preserved: conflict"
-              " resolution could happen when undoing an old transaction.")
+        print("WARNING: This is not the recommended way to import data to NEO:"
+              " you should use Imported backend instead.\n"
+              "NEO also does not implement IStorageRestoreable interface,"
+              " which means that undo information is not preserved when using"
+              " this tool: conflict resolution could happen when undoing an"
+              " old transaction.")
         src = FileStorage(file_name=source, read_only=True)
         dst = NEOStorage(master_nodes=destination, name=cluster,
                          logfile=options.logfile)

neo/scripts/runner.py

@@ -65,6 +65,7 @@ UNIT_TEST_MODULES = [
     'neo.tests.client.testConnectionPool',
     # light functional tests
     'neo.tests.threaded.test',
+    'neo.tests.threaded.testImporter',
     'neo.tests.threaded.testReplication',
 ]
 

neo/storage/app.py

@@ -289,7 +289,8 @@ class Application(object):
         """Handle everything, including replications and transactions."""
         logging.info('doing operation')
 
-        _poll = self._poll
+        poll = self._poll
+        _poll = self.em._poll
         isIdle = self.em.isIdle
 
         handler = master.MasterOperationHandler(self)
@@ -301,14 +302,18 @@ class Application(object):
 
         self.task_queue = task_queue = deque()
         try:
+            self.dm.doOperation(self)
             while True:
-                while task_queue and isIdle():
+                while task_queue:
                     try:
-                        task_queue[-1].next()
-                        task_queue.rotate()
+                        while isIdle():
+                            if task_queue[-1].next():
+                                _poll(0)
+                            task_queue.rotate()
+                        break
                     except StopIteration:
                         task_queue.pop()
-                _poll()
+                poll()
         finally:
             del self.task_queue
             # XXX: Although no handled exception should happen between

neo/storage/database/__init__.py

@@ -20,6 +20,7 @@ from neo.lib.exception import DatabaseFailure
 from .manager import DatabaseManager
 
 DATABASE_MANAGER_DICT = {
+    'Importer': 'importer.ImporterDatabaseManager',
     'MySQL': 'mysqldb.MySQLDatabaseManager',
     'SQLite': 'sqlite.SQLiteDatabaseManager',
 }

neo/storage/database/manager.py

@@ -81,6 +81,9 @@ class DatabaseManager(object):
         """
         raise NotImplementedError
 
+    def doOperation(self, app):
+        pass
+
     def commit(self):
         pass
 
@@ -198,6 +201,14 @@ class DatabaseManager(object):
         node, and a cell state."""
         raise NotImplementedError
 
+    def getLastTID(self, max_tid):
+        """Return greatest tid in trans table that is <= given 'max_tid'
+
+        Required only to import a DB using Importer backend.
+        max_tid must be in unpacked format.
+        """
+        raise NotImplementedError
+
     def _getLastIDs(self, all=True):
         raise NotImplementedError
 
@@ -228,6 +239,19 @@ class DatabaseManager(object):
         r = self.getObject(oid)
         return r and r[0]
 
+    def _getNextTID(self, partition, oid, tid):
+        """
+        partition (int)
+            Must be the result of (oid % self.getPartition(oid))
+        oid (int)
+            Identifier of object to retrieve.
+        tid (int)
+            Exact serial to retrieve.
+
+        If tid is the last revision of oid, None is returned.
+        """
+        raise NotImplementedError
+
     def _getObject(self, oid, tid=None, before_tid=None):
         """
         oid (int)

neo/storage/database/mysqldb.py

@@ -16,9 +16,9 @@
 
 from binascii import a2b_hex
 import MySQLdb
-from MySQLdb import IntegrityError, OperationalError
+from MySQLdb import DataError, IntegrityError, OperationalError
 from MySQLdb.constants.CR import SERVER_GONE_ERROR, SERVER_LOST
-from MySQLdb.constants.ER import DUP_ENTRY
+from MySQLdb.constants.ER import DATA_TOO_LONG, DUP_ENTRY
 from array import array
 from hashlib import sha1
 import re
@@ -237,16 +237,27 @@ class MySQLDatabaseManager(DatabaseManager):
         q = self.query
         e = self.escape
         self._config[key] = value
-        key = e(str(key))
+        k = e(str(key))
         if value is None:
-            q("DELETE FROM config WHERE name = '%s'" % key)
-        else:
-            value = e(str(value))
-            q("REPLACE INTO config VALUES ('%s', '%s')" % (key, value))
+            q("DELETE FROM config WHERE name = '%s'" % k)
+            return
+        value = str(value)
+        sql = "REPLACE INTO config VALUES ('%s', '%s')" % (k, e(value))
+        try:
+            q(sql)
+        except DataError, (code, _):
+            if code != DATA_TOO_LONG or len(value) < 256 or key != "zodb":
+                raise
+            q("ALTER TABLE config MODIFY value VARBINARY(%s) NULL" % len(value))
+            q(sql)
 
     def getPartitionTable(self):
         return self.query("SELECT * FROM pt")
 
+    def getLastTID(self, max_tid):
+        return self.query("SELECT MAX(tid) FROM trans WHERE tid<=%s"
+                          % max_tid)[0][0]
+
     def _getLastIDs(self, all=True):
         p64 = util.p64
         q = self.query
@@ -290,6 +301,12 @@ class MySQLDatabaseManager(DatabaseManager):
                        % (self._getPartition(oid), oid))
         return util.p64(r[0][0]) if r else None
 
+    def _getNextTID(self, *args): # partition, oid, tid
+        r = self.query("SELECT tid FROM obj"
+                       " WHERE partition=%d AND oid=%d AND tid>%d"
+                       " ORDER BY tid LIMIT 1" % args)
+        return r[0][0] if r else None
+
     def _getObject(self, oid, tid=None, before_tid=None):
         q = self.query
         partition = self._getPartition(oid)
@@ -309,10 +326,8 @@ class MySQLDatabaseManager(DatabaseManager):
             serial, compression, checksum, data, value_serial = r[0]
         except IndexError:
             return None
-        r = q("SELECT tid FROM obj WHERE partition=%d AND oid=%d AND tid>%d"
-              " ORDER BY tid LIMIT 1" % (partition, oid, serial))
-        return (serial, r[0][0] if r else None, compression, checksum, data,
-            value_serial)
+        return (serial, self._getNextTID(partition, oid, serial),
+                compression, checksum, data, value_serial)
 
     def changePartitionTable(self, ptid, cell_list, reset=False):
         offset_list = []

neo/storage/database/sqlite.py

@@ -208,6 +208,10 @@ class SQLiteDatabaseManager(DatabaseManager):
     def getPartitionTable(self):
         return self.query("SELECT * FROM pt")
 
+    def getLastTID(self, max_tid):
+        return self.query("SELECT MAX(tid) FROM trans WHERE tid<=?",
+                          (max_tid,)).next()[0]
+
     def _getLastIDs(self, all=True):
         p64 = util.p64
         q = self.query
@@ -252,6 +256,12 @@ class SQLiteDatabaseManager(DatabaseManager):
                        (self._getPartition(oid), oid)).fetchone()
         return r and util.p64(r[0])
 
+    def _getNextTID(self, *args): # partition, oid, tid
+        r = self.query("""SELECT tid FROM obj
+                          WHERE partition=? AND oid=? AND tid>?
+                          ORDER BY tid LIMIT 1""", args).fetchone()
+        return r and r[0]
+
     def _getObject(self, oid, tid=None, before_tid=None):
         q = self.query
         partition = self._getPartition(oid)
@@ -269,14 +279,11 @@ class SQLiteDatabaseManager(DatabaseManager):
             serial, compression, checksum, data, value_serial = r.fetchone()
         except TypeError:
             return None
-        r = q("""SELECT tid FROM obj
-                 WHERE partition=? AND oid=? AND tid>?
-                 ORDER BY tid LIMIT 1""",
-              (partition, oid, serial)).fetchone()
         if checksum:
             checksum = str(checksum)
             data = str(data)
-        return serial, r and r[0], compression, checksum, data, value_serial
+        return (serial, self._getNextTID(partition, oid, serial),
+                compression, checksum, data, value_serial)
 
     def changePartitionTable(self, ptid, cell_list, reset=False):
         q = self.query

neo/tests/fs2zodb.py

+#
+# Copyright (C) 2014  Nexedi SA
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# 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 os, stat, time
+from persistent import Persistent
+from persistent.TimeStamp import TimeStamp
+from BTrees.OOBTree import OOBTree
+
+class Inode(OOBTree):
+
+    data = None
+
+    def __init__(self, up=None, mode=stat.S_IFDIR):
+        self[os.pardir] = self if up is None else up
+        self.mode = mode
+        self.mtime = time.time()
+
+    def __getstate__(self):
+        return Persistent.__getstate__(self), OOBTree.__getstate__(self)
+
+    def __setstate__(self, state):
+        Persistent.__setstate__(self, state[0])
+        OOBTree.__setstate__(self, state[1])
+
+    def edit(self, data=None, mtime=None):
+        fmt = stat.S_IFMT(self.mode)
+        if data is None:
+            assert fmt == stat.S_IFDIR, oct(fmt)
+        else:
+            assert fmt == stat.S_IFREG or fmt == stat.S_IFLNK, oct(fmt)
+            if self.data != data:
+                self.data = data
+        if self.mtime != mtime:
+            self.mtime = mtime or time.time()
+
+    def root(self):
+        try:
+            self = self[os.pardir]
+        except KeyError:
+            return self
+        return self.root()
+
+    def traverse(self, path, followlinks=True):
+        path = iter(path.split(os.sep) if isinstance(path, basestring) and path
+                    else path)
+        for d in path:
+            if not d:
+                return self.root().traverse(path, followlinks)
+            if d != os.curdir:
+                d = self[d]
+                if followlinks and stat.S_ISLNK(d.mode):
+                    d = self.traverse(d.data, True)
+                return d.traverse(path, followlinks)
+        return self
+
+    def inodeFromFs(self, path):
+        s = os.lstat(path)
+        mode = s.st_mode
+        name = os.path.basename(path)
+        try:
+            i = self[name]
+            assert stat.S_IFMT(i.mode) == stat.S_IFMT(mode)
+            changed = False
+        except KeyError:
+            i = self[name] = self.__class__(self, mode)
+            changed = True
+        i.edit(open(path).read() if stat.S_ISREG(mode) else
+                      os.readlink(p) if stat.S_ISLNK(mode) else
+                      None, s.st_mtime)
+        return changed or i._p_changed
+
+    def treeFromFs(self, path, yield_interval=None, filter=None):
+        prefix_len = len(path) + len(os.sep)
+        n = 0
+        for dirpath, dirnames, filenames in os.walk(path):
+            inodeFromFs = self.traverse(dirpath[prefix_len:]).inodeFromFs
+            for names in dirnames, filenames:
+                skipped = []
+                for j, name in enumerate(names):
+                    p = os.path.join(dirpath, name)
+                    if filter and not filter(p[prefix_len:]):
+                        skipped.append(j)
+                    elif inodeFromFs(p):
+                        n += 1
+                        if n == yield_interval:
+                            n = 0
+                            yield self
+                while skipped:
+                    del names[skipped.pop()]
+        if n:
+            yield self
+
+    def walk(self):
+        s = [(None, self)]
+        while s:
+            top, self = s.pop()
+            dirs = []
+            nondirs = []
+            for name, inode in self.iteritems():
+                if name != os.pardir:
+                    (dirs if stat.S_ISDIR(inode.mode) else nondirs).append(name)
+            yield top or os.curdir, dirs, nondirs
+            for name in dirs:
+                s.append((os.path.join(top, name) if top else name, self[name]))

neo/tests/functional/__init__.py

@@ -30,6 +30,7 @@ import tempfile
 import traceback
 import threading
 import psutil
+from ConfigParser import SafeConfigParser
 
 import neo.scripts
 from neo.neoctl.neoctl import NeoCTL, NotReadyException
@@ -238,7 +239,7 @@ class NEOCluster(object):
                  cleanup_on_delete=False, temp_dir=None, clear_databases=True,
                  adapter=os.getenv('NEO_TESTS_ADAPTER'),
                  address_type=ADDRESS_TYPE, bind_ip=None, logger=True,
-        ):
+                 importer=None):
         if not adapter:
             adapter = 'MySQL'
         self.adapter = adapter
@@ -263,6 +264,21 @@ class NEOCluster(object):
         self.local_ip = local_ip = bind_ip or \
             IP_VERSION_FORMAT_DICT[self.address_type]
         self.setupDB(clear_databases)
+        if importer:
+            cfg = SafeConfigParser()
+            cfg.add_section("neo")
+            cfg.set("neo", "adapter", adapter)
+            cfg.set("neo", "database", self.db_template(*db_list))
+            for name, zodb in importer:
+                cfg.add_section(name)
+                for x in zodb.iteritems():
+                    cfg.set(name, *x)
+            importer_conf = os.path.join(temp_dir, 'importer.cfg')
+            with open(importer_conf, 'w') as f:
+                cfg.write(f)
+            adapter = "Importer"
+            self.db_template = str
+            db_list = importer_conf,
         self.process_dict = {}
         self.temp_dir = temp_dir
         self.port_allocator = PortAllocator()

neo/tests/functional/testClient.py

@@ -22,6 +22,7 @@ import socket
 
 from struct import pack
 from neo.neoctl.neoctl import NeoCTL
+from neo.lib.util import makeChecksum, u64
 from ZODB.FileStorage import FileStorage
 from ZODB.POSException import ConflictError
 from ZODB.tests.StorageTestBase import zodb_pickle
@@ -168,9 +169,7 @@ class ClientTests(NEOFunctionalTest):
         name = os.path.join(self.getTempDirectory(), 'data.fs')
         if reset and os.path.exists(name):
             os.remove(name)
-        storage = FileStorage(file_name=name)
-        db = ZODB.DB(storage=storage)
-        return (db, storage)
+        return FileStorage(file_name=name)
 
     def __populate(self, db, tree_size=TREE_SIZE):
         if isinstance(db.storage, FileStorage):
@@ -204,7 +203,8 @@ class ClientTests(NEOFunctionalTest):
     def testImport(self):
 
         # source database
-        dfs_db, dfs_storage  = self.__getDataFS()
+        dfs_storage  = self.__getDataFS()
+        dfs_db = ZODB.DB(dfs_storage)
         self.__populate(dfs_db)
 
         # create a neo storage
@@ -213,28 +213,48 @@ class ClientTests(NEOFunctionalTest):
 
         # copy data fs to neo
         neo_storage.copyTransactionsFrom(dfs_storage, verbose=0)
+        dfs_db.close()
 
         # check neo content
         (neo_db, neo_conn) = self.neo.getZODBConnection()
         self.__checkTree(neo_conn.root()['trees'])
 
+    def __dump(self, storage):
+        return {u64(t.tid): [(u64(o.oid), o.data_txn and u64(o.data_txn),
+                              None if o.data is None else makeChecksum(o.data))
+                             for o in t]
+                for t in storage.iterator()}
+
     def testExport(self):
 
         # create a neo storage
         self.neo.start()
         (neo_db, neo_conn) = self.neo.getZODBConnection()
         self.__populate(neo_db)
+        dump = self.__dump(neo_db.storage)
 
         # copy neo to data fs
-        dfs_db, dfs_storage  = self.__getDataFS(reset=True)
+        dfs_storage  = self.__getDataFS(reset=True)
         neo_storage = self.neo.getZODBStorage()
         dfs_storage.copyTransactionsFrom(neo_storage)
 
         # check data fs content
-        conn = dfs_db.open()
-        root = conn.root()
+        dfs_db = ZODB.DB(dfs_storage)
+        root = dfs_db.open().root()
 
         self.__checkTree(root['trees'])
+        dfs_db.close()
+        self.neo.stop()
+
+        self.neo = NEOCluster(db_list=['test_neo1'], partitions=3,
+            importer=[("root", {
+                "storage": "<filestorage>\npath %s\n</filestorage>"
+                            % dfs_storage.getName()})],
+            temp_dir=self.getTempDirectory())
+        self.neo.start()
+        neo_db, neo_conn = self.neo.getZODBConnection()
+        self.__checkTree(neo_conn.root()['trees'])
+        self.assertEqual(dump, self.__dump(neo_db.storage))
 
     def testLockTimeout(self):
         """ Hold a lock on an object to block a second transaction """

neo/tests/threaded/__init__.py

@@ -19,6 +19,7 @@
 import os, random, socket, sys, tempfile, threading, time, types, weakref
 import traceback
 from collections import deque
+from ConfigParser import SafeConfigParser
 from contextlib import contextmanager
 from itertools import count
 from functools import wraps
@@ -545,7 +546,8 @@ class NEOCluster(object):
     def __init__(self, master_count=1, partitions=1, replicas=0, upstream=None,
                        adapter=os.getenv('NEO_TESTS_ADAPTER', 'SQLite'),
                        storage_count=None, db_list=None, clear_databases=True,
-                       db_user=DB_USER, db_password='', compress=True):
+                       db_user=DB_USER, db_password='', compress=True,
+                       importer=None):
         self.name = 'neo_%s' % self._allocate('name',
             lambda: random.randint(0, 100))
         master_list = [MasterApplication.newAddress()
@@ -573,6 +575,19 @@ class NEOCluster(object):
             db = os.path.join(getTempDirectory(), '%s.sqlite')
         else:
             assert False, adapter
+        if importer:
+            cfg = SafeConfigParser()
+            cfg.add_section("neo")
+            cfg.set("neo", "adapter", adapter)
+            cfg.set("neo", "database", db % tuple(db_list))
+            for name, zodb in importer:
+                cfg.add_section(name)
+                for x in zodb.iteritems():
+                    cfg.set(name, *x)
+            db = os.path.join(getTempDirectory(), '%s.conf')
+            with open(db % tuple(db_list), "w") as f:
+                cfg.write(f)
+            kw["getAdapter"] = "Importer"
         self.storage_list = [StorageApplication(getDatabase=db % x, **kw)
                              for x in db_list]
         self.admin_list = [AdminApplication(**kw)]

neo/tests/threaded/testImporter.py

+#
+# Copyright (C) 2014  Nexedi SA
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# 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 collections import deque
+from itertools import islice, izip_longest
+import os, time, unittest
+import neo, transaction, ZODB
+from neo.lib import logging
+from neo.lib.util import u64
+from ..fs2zodb import Inode
+from .. import getTempDirectory
+from . import NEOCluster, NEOThreadedTest
+from ZODB.FileStorage import FileStorage
+
+
+class ImporterTests(NEOThreadedTest):
+
+    def test(self):
+        importer = []
+        fs_dir = os.path.join(getTempDirectory(), self.id())
+        os.mkdir(fs_dir)
+        src_root, = neo.__path__
+        fs_list = "root", "client", "master", "tests"
+        def root_filter(name):
+            if not name.endswith(".pyc"):
+                i = name.find(os.sep)
+                return i < 0 or name[:i] not in fs_list
+        def sub_filter(name):
+            return lambda n: n[-4:] != '.pyc' and \
+                n.split(os.sep, 1)[0] in (name, "scripts")
+        conn_list = []
+        iter_list = []
+        # Setup several FileStorage databases.
+        for i, name in enumerate(fs_list):
+            fs_path = os.path.join(fs_dir, name + ".fs")
+            c = ZODB.DB(FileStorage(fs_path)).open()
+            r = c.root()["neo"] = Inode()
+            transaction.commit()
+            conn_list.append(c)
+            iter_list.append(r.treeFromFs(src_root, 10,
+                sub_filter(name) if i else root_filter))
+            importer.append((name, {
+                "storage": "<filestorage>\npath %s\n</filestorage>" % fs_path
+                }))
+        # Populate FileStorage databases.
+        for iter_list in izip_longest(*iter_list):
+            for i in iter_list:
+                if i:
+                    transaction.commit()
+        del iter_list
+        # Get oids of mount points and close.
+        for (name, cfg), c in zip(importer, conn_list):
+            r = c.root()["neo"]
+            if name == "root":
+                for name in fs_list[1:]:
+                    cfg[name] = str(u64(r[name]._p_oid))
+            else:
+                cfg["oid"] = str(u64(r[name]._p_oid))
+            c.db().close()
+        #del importer[0][1][importer.pop()[0]]
+        # Start NEO cluster with transparent import of a multi-base ZODB.
+        cluster = NEOCluster(compress=False, importer=importer)
+        try:
+            # Suspend import for a while, so that import
+            # is finished in the middle of the below 'for' loop.
+            # Use a slightly different main loop for storage so that it
+            # does not import data too fast and we test read/write access
+            # by the client during the import.
+            dm = cluster.storage.dm
+            def doOperation(app):
+                del dm.doOperation
+                try:
+                    while True:
+                        if app.task_queue:
+                            app.task_queue[-1].next()
+                        app._poll()
+                except StopIteration:
+                    app.task_queue.pop()
+            dm.doOperation = doOperation
+            cluster.start()
+            t, c = cluster.getTransaction()
+            r = c.root()["neo"]
+            i = r.walk()
+            next(islice(i, 9, None))
+            dm.doOperation(cluster.storage) # resume
+            deque(i, maxlen=0)
+            last_import = None
+            for i, r in enumerate(r.treeFromFs(src_root, 10)):
+                t.commit()
+                if cluster.storage.dm._import:
+                    last_import = i
+            self.assertTrue(last_import and not cluster.storage.dm._import)
+            i = len(src_root) + 1
+            self.assertEqual(sorted(r.walk()), sorted(
+                (x[i:] or '.', sorted(y), sorted(z))
+                for x, y, z in os.walk(src_root)))
+            t.commit()
+        finally:
+            cluster.stop()
+
+
+if __name__ == "__main__":
+    unittest.main()

setup.py

@@ -23,13 +23,16 @@ if not os.path.exists('mock.py'):
         raise EnvironmentError("MD5 checksum mismatch downloading 'mock.py'")
     open('mock.py', 'w').write(mock_py)
 
+zodb_require = ['ZODB3>=3.10', 'ZODB3<3.11dev']
+
 extras_require = {
     'admin': [],
-    'client': ['ZODB3>=3.10', 'ZODB3<3.11dev'],
+    'client': zodb_require,
     'ctl': [],
     'master': [],
     'storage-sqlite': [],
     'storage-mysqldb': ['MySQL-python'],
+    'storage-importer': zodb_require,
 }
 extras_require['tests'] = ['zope.testing', 'psutil>=2',
     'neoppod[%s]' % ', '.join(extras_require)]