Refactored cache verification to fix threading bugs during connection.

Changed connections to work with unset (None) clients.  Messages
aren't forwarded until the client is set.  This is to prevent sending
spurious invalidation messages until a client is ready to recieve them.

src/ZEO/ClientStorage.py

@@ -274,9 +274,9 @@ class ClientStorage(object):
 
         # _server_addr is used by sortKey()
         self._server_addr = None
-        
-        self._verification_invalidations = None
 
+        self._pickler = self._tfile = None
+        
         self._info = {'length': 0, 'size': 0, 'name': 'ZEO Client',
                       'supportsUndo': 0, 'interfaces': ()}
 
@@ -502,6 +502,7 @@ class ClientStorage(object):
             # If we are upgrading from a read-only fallback connection,
             # we must close the old connection to prevent it from being
             # used while the cache is verified against the new connection.
+            self._connection.register_object(None) # Don't call me!
             self._connection.close()
             self._connection = None
             self._ready.clear()
@@ -576,60 +577,6 @@ class ClientStorage(object):
         else:
             return '%s:%s' % (self._storage, self._server_addr)
 
-    def verify_cache(self, server):
-        """Internal routine called to verify the cache.
-
-        The return value (indicating which path we took) is used by
-        the test suite.
-        """
-        # If verify_cache() finishes the cache verification process,
-        # it should set self._server.  If it goes through full cache
-        # verification, then endVerify() should set self._server.
-
-        ltid = server.lastTransaction()
-
-        if not self._cache:
-            log2("No verification necessary -- empty cache")
-            self._server = server
-            if ltid and ltid != utils.z64:
-                self._cache.setLastTid(ltid)
-            self._ready.set()
-            return "full verification"
-
-        last_inval_tid = self._cache.getLastTid()
-        if last_inval_tid is not None:
-            if ltid == last_inval_tid:
-                log2("No verification necessary (last_inval_tid up-to-date)")
-                self._server = server
-                self._ready.set()
-                return "no verification"
-
-            # log some hints about last transaction
-            log2("last inval tid: %r %s\n"
-                 % (last_inval_tid, tid2time(last_inval_tid)))
-            log2("last transaction: %r %s" %
-                 (ltid, ltid and tid2time(ltid)))
-
-            pair = server.getInvalidations(last_inval_tid)
-            if pair is not None:
-                log2("Recovering %d invalidations" % len(pair[1]))
-                self.invalidateTransaction(*pair)
-                self._server = server
-                self._ready.set()
-                return "quick verification"
-        
-        log2("Verifying cache")
-        # setup tempfile to hold zeoVerify results
-        self._verification_invalidations = []
-
-        # TODO:  should batch these operations for efficiency; would need
-        # to acquire lock ...
-        for oid, tid in self._cache.contents():
-            server.verify(oid, tid)
-        self._pending_server = server
-        server.endZeoVerify()
-        return "full verification"
-
     ### Is there a race condition between notifyConnected and
     ### notifyDisconnected? In Particular, what if we get
     ### notifyDisconnected in the middle of notifyConnected?
@@ -746,7 +693,7 @@ class ClientStorage(object):
         try:
             t = self._cache.load(oid)
             if t:
-                return t[:2] # XXX strip version
+                return t
         finally:
             self._lock.release()
 
@@ -1133,7 +1080,7 @@ class ClientStorage(object):
             return
 
         for oid, data in self._tbuf:
-            self._cache.invalidate(oid, tid)
+            self._cache.invalidate(oid, tid, False)
             # If data is None, we just invalidate.
             if data is not None:
                 s = self._seriald[oid]
@@ -1218,6 +1165,63 @@ class ClientStorage(object):
         """Server callback to update the info dictionary."""
         self._info.update(dict)
 
+    def verify_cache(self, server):
+        """Internal routine called to verify the cache.
+
+        The return value (indicating which path we took) is used by
+        the test suite.
+        """
+
+        self._pending_server = server
+
+        # setup tempfile to hold zeoVerify results and interim
+        # invalidation results
+        self._tfile = tempfile.TemporaryFile(suffix=".inv")
+        self._pickler = cPickle.Pickler(self._tfile, 1)
+        self._pickler.fast = 1 # Don't use the memo
+
+        # allow incoming invalidations:
+        self._connection.register_object(self)
+
+        # If verify_cache() finishes the cache verification process,
+        # it should set self._server.  If it goes through full cache
+        # verification, then endVerify() should self._server.
+
+        ltid = server.lastTransaction()
+        if not self._cache:
+            log2("No verification necessary -- empty cache")
+            if ltid and ltid != utils.z64:
+                self._cache.setLastTid(ltid)
+            self.finish_verification()
+            return "full verification"
+
+        last_inval_tid = self._cache.getLastTid()
+        if last_inval_tid is not None:
+            if ltid == last_inval_tid:
+                log2("No verification necessary (last_inval_tid up-to-date)")
+                self.finish_verification()
+                return "no verification"
+
+            # log some hints about last transaction
+            log2("last inval tid: %r %s\n"
+                 % (last_inval_tid, tid2time(last_inval_tid)))
+            log2("last transaction: %r %s" %
+                 (ltid, ltid and tid2time(ltid)))
+
+            pair = server.getInvalidations(last_inval_tid)
+            if pair is not None:
+                log2("Recovering %d invalidations" % len(pair[1]))
+                self.finish_verification(pair)
+                return "quick verification"
+        elif ltid and ltid != utils.z64:
+            self._cache.setLastTid(ltid)
+
+        log2("Verifying cache")
+        for oid, tid in self._cache.contents():
+            server.verify(oid, tid)
+        server.endZeoVerify()
+        return "full verification"
+
     def invalidateVerify(self, args):
         """Server callback to invalidate an (oid, '') pair.
 
@@ -1225,53 +1229,78 @@ class ClientStorage(object):
         """
         # Invalidation as result of verify_cache().
         # Queue an invalidate for the end the verification procedure.
-        if self._verification_invalidations is None:
-            # This should never happen.  TODO:  assert it doesn't, or log
-            # if it does.
+        if self._pickler is None:
+            log2("invalidateVerify with no _pickler", level = logging.ERROR)
             return
-        self._verification_invalidations.append(args[0])
+        self._pickler.dump((None, [args[0]]))
 
-    def _process_invalidations(self, tid, oids):
+    def endVerify(self):
+        """Server callback to signal end of cache validation."""
+
+        log2("endVerify finishing")
+        self.finish_verification()
+        log2("endVerify finished")
+
+    def finish_verification(self, catch_up=None):
         self._lock.acquire()
         try:
-            for oid in oids:
-                if oid == self._load_oid:
-                    self._load_status = 0
-                self._cache.invalidate(oid, tid)
-
-            if self._db is not None:
-                self._db.invalidate(tid, oids)
+            if catch_up:
+                # process catch-up invalidations
+                tid, invalidations = catch_up
+                self._process_invalidations(
+                    tid, (arg[0] for arg in invalidations)
+                    )
+            
+            if self._pickler is None:
+                return
+            # write end-of-data marker
+            self._pickler.dump((None, None))
+            self._pickler = None
+            self._tfile.seek(0)
+            unpickler = cPickle.Unpickler(self._tfile)
+            min_tid = self._cache.getLastTid()
+            while 1:
+                tid, oids = unpickler.load()
+                if oids is None:
+                    break
+                if ((tid is None)
+                    or (min_tid is None)
+                    or (tid > min_tid)
+                    ):
+                    self._process_invalidations(tid, oids)
+
+            self._tfile.close()
+            self._tfile = None
         finally:
             self._lock.release()
 
-    def endVerify(self):
-        """Server callback to signal end of cache validation."""
-        if self._verification_invalidations is None:
-            return
-        # write end-of-data marker
-        self._process_invalidations(None, self._verification_invalidations)
-        self._verification_invalidations = None
-
-        log2("endVerify finishing")
         self._server = self._pending_server
         self._ready.set()
-        self._pending_conn = None
-        log2("endVerify finished")
+        self._pending_server = None
+
 
     def invalidateTransaction(self, tid, args):
-        """Invalidate objects modified by tid."""
-        oids = (a[0] for a in args)
+        """Server callback: Invalidate objects modified by tid."""
         self._lock.acquire()
         try:
-            self._cache.setLastTid(tid)
+            if self._pickler is not None:
+                log2("Transactional invalidation during cache verification",
+                     level=BLATHER)
+                self._pickler.dump((tid, [arg[0] for arg in args]))
+            else:
+                self._process_invalidations(tid, (arg[0] for arg in args))
         finally:
             self._lock.release()
-        if self._verification_invalidations is not None:
-            log2("Transactional invalidation during cache verification",
-                 level=BLATHER)
-            self._verification_invalidations.extend(oids)
-            return
-        self._process_invalidations(tid, list(oids))
+
+    def _process_invalidations(self, tid, oids):
+        oids = list(oids)
+        for oid in oids:
+            if oid == self._load_oid:
+                self._load_status = 0
+            self._cache.invalidate(oid, tid)
+
+        if self._db is not None:
+            self._db.invalidate(tid, oids)
 
     # The following are for compatibility with protocol version 2.0.0
 

src/ZEO/tests/invalidations_while_connecting.test

+Invalidations while connecting
+==============================
+
+As soon as a client registers with a server, it will recieve
+invalidations from the server.  The client must be careful to queue
+these invalidations until it is ready to deal with them.  At the time
+of the writing of this test, clients weren't careful enogh about
+queing invalidations.  This led to cache corruption in the form of
+both low-level file corruption as well as out-of-date records marked
+as current.
+
+This tests tries to provoke this bug by:
+
+- starting a server
+
+    >>> import ZEO.tests.testZEO, ZEO.tests.forker
+    >>> addr = 'localhost', ZEO.tests.testZEO.get_port()
+    >>> zconf = ZEO.tests.forker.ZEOConfig(addr)
+    >>> sconf = '<filestorage 1>\npath Data.fs\n</filestorage>\n'
+    >>> _, adminaddr, pid, conf_path = ZEO.tests.forker.start_zeo_server(
+    ...     sconf, zconf, addr[1])
+
+- opening a client to the server that writes some objects, filling
+  it's cache at the same time,
+
+    >>> import ZEO.ClientStorage, ZODB.tests.MinPO, transaction
+    >>> db = ZODB.DB(ZEO.ClientStorage.ClientStorage(addr, client='x'))
+    >>> conn = db.open()
+    >>> nobs = 1000
+    >>> for i in range(nobs):
+    ...     conn.root()[i] = ZODB.tests.MinPO.MinPO(0)
+    >>> transaction.commit()
+
+- disconnecting the first client (closing it with a persistent cache),
+
+    >>> db.close()
+
+- starting a second client that writes objects more or less
+  constantly,
+
+    >>> import random, threading
+    >>> stop = False
+    >>> db2 = ZODB.DB(ZEO.ClientStorage.ClientStorage(addr))
+    >>> tm = transaction.TransactionManager()
+    >>> conn2 = db2.open(transaction_manager=tm)
+    >>> random = random.Random(0)
+    >>> lock = threading.Lock()
+    >>> def run():
+    ...     while 1:
+    ...         i = random.randint(0, nobs-1)
+    ...         if stop:
+    ...             return
+    ...         lock.acquire()
+    ...         try:
+    ...             conn2.root()[i].value += 1
+    ...             tm.commit()
+    ...         finally:
+    ...             lock.release()
+    ...             time.sleep(0)
+    >>> thread = threading.Thread(target=run)
+    >>> thread.start()
+
+- restarting the first client, and 
+- testing for cache validity.
+
+    >>> import zope.testing.loggingsupport, logging
+    >>> handler = zope.testing.loggingsupport.InstalledHandler(
+    ...    'ZEO', level=logging.ERROR)
+
+    >>> import time
+    >>> for c in range(10):
+    ...    time.sleep(.1)
+    ...    db = ZODB.DB(ZEO.ClientStorage.ClientStorage(addr, client='x'))
+    ...    _ = lock.acquire()
+    ...    try:
+    ...      time.sleep(.1)
+    ...      assert (db._storage.lastTransaction()
+    ...              == db._storage._server.lastTransaction()), (
+    ...                  db._storage.lastTransaction(),
+    ...                  db._storage._server.lastTransactiion())
+    ...      conn = db.open()
+    ...      for i in range(1000):
+    ...        if conn.root()[i].value != conn2.root()[i].value:
+    ...            print 'bad', c, i, conn.root()[i].value,
+    ...            print  conn2.root()[i].value
+    ...    finally:
+    ...      _ = lock.release()
+    ...    db.close()
+
+    >>> stop = True
+    >>> thread.join(10)
+    >>> thread.isAlive()
+    False
+
+    >>> for record in handler.records:
+    ...     print record.name, record.levelname
+    ...     print handler.format(record)
+
+    >>> handler.uninstall()
+
+    >>> db.close()
+    >>> db2.close()

src/ZEO/tests/testConnection.py

@@ -21,7 +21,7 @@ platform-dependent scaffolding.
 import unittest
 # Import the actual test class
 from ZEO.tests import ConnectionTests, InvalidationTests
-
+from zope.testing import doctest, setupstack
 
 class FileStorageConfig:
     def getConfig(self, path, create, read_only):
@@ -135,6 +135,10 @@ def test_suite():
     for klass in test_classes:
         sub = unittest.makeSuite(klass, 'check')
         suite.addTest(sub)
+    suite.addTest(doctest.DocFileSuite(
+        'invalidations_while_connecting.test',
+        setUp=setupstack.setUpDirectory, tearDown=setupstack.tearDown,
+        ))
     return suite
 
 

src/ZEO/zrpc/client.py

@@ -447,8 +447,7 @@ class ConnectWrapper:
         Call the client's testConnection(), giving the client a chance
         to do app-level check of the connection.
         """
-        self.conn = ManagedClientConnection(self.sock, self.addr,
-                                            self.client, self.mgr)
+        self.conn = ManagedClientConnection(self.sock, self.addr, self.mgr)
         self.sock = None # The socket is now owned by the connection
         try:
             self.preferred = self.client.testConnection(self.conn)

src/ZEO/zrpc/connection.py

@@ -544,14 +544,23 @@ class Connection(smac.SizedMessageAsyncConnection, object):
             self.replies_cond.release()
 
     def handle_request(self, msgid, flags, name, args):
-        if not self.check_method(name):
-            msg = "Invalid method name: %s on %s" % (name, repr(self.obj))
+        obj = self.obj
+        
+        if name.startswith('_') or not hasattr(obj, name):
+            if obj is None:
+                if __debug__:
+                    self.log("no object calling %s%s"
+                             % (name, short_repr(args)),
+                             level=logging.DEBUG)
+                return
+                
+            msg = "Invalid method name: %s on %s" % (name, repr(obj))
             raise ZRPCError(msg)
         if __debug__:
             self.log("calling %s%s" % (name, short_repr(args)),
                      level=logging.DEBUG)
 
-        meth = getattr(self.obj, name)
+        meth = getattr(obj, name)
         try:
             self.waiting_for_reply = True
             try:
@@ -590,12 +599,6 @@ class Connection(smac.SizedMessageAsyncConnection, object):
                  level=logging.ERROR, exc_info=True)
         self.close()
 
-    def check_method(self, name):
-        # TODO:  This is hardly "secure".
-        if name.startswith('_'):
-            return None
-        return hasattr(self.obj, name)
-
     def send_reply(self, msgid, ret):
         # encode() can pass on a wide variety of exceptions from cPickle.
         # While a bare `except` is generally poor practice, in this case
@@ -813,7 +816,7 @@ class ManagedClientConnection(Connection):
     __super_close = Connection.close
     base_message_output = Connection.message_output
 
-    def __init__(self, sock, addr, obj, mgr):
+    def __init__(self, sock, addr, mgr):
         self.mgr = mgr
 
         # We can't use the base smac's message_output directly because the
@@ -830,7 +833,7 @@ class ManagedClientConnection(Connection):
         self.queue_output = True
         self.queued_messages = []
 
-        self.__super_init(sock, addr, obj, tag='C', map=client_map)
+        self.__super_init(sock, addr, None, tag='C', map=client_map)
         self.trigger = client_trigger
         client_trigger.pull_trigger()