Merge remote-tracking branch 'origin/asyncio' into simplify-server-commit-lock-management

Conflicts:
	src/ZEO/StorageServer.py

CHANGES.rst

 Changelog
 =========
 
+- Fixed: SSL clients of servers with signed certs didn't load default
+  certs and were unable to connect.
+
+
 5.0.0a0 (2016-07-08)
 --------------------
 

src/ZEO/ClientStorage.py

@@ -490,7 +490,7 @@ class ClientStorage(ZODB.ConflictResolution.ConflictResolvingStorage):
         return self._call('record_iternext', next)
 
     def getTid(self, oid):
-        # XXX deprecated: used by storage server for full cache verification.
+        # XXX deprecated: but ZODB tests use this. They shouldn't
         return self._call('getTid', oid)
 
     def loadSerial(self, oid, serial):
@@ -504,8 +504,15 @@ class ClientStorage(ZODB.ConflictResolution.ConflictResolvingStorage):
         return result[:2]
 
     def loadBefore(self, oid, tid):
+        result = self._cache.loadBefore(oid, tid)
+        if result:
+            return result
+
         return self._server.load_before(oid, tid)
 
+    def prefetch(self, oids, tid):
+        self._server.prefetch(oids, tid)
+
     def new_oid(self):
         """Storage API: return a new object identifier.
         """

src/ZEO/StorageServer.py

@@ -76,10 +76,6 @@ registered_methods = set(( 'get_info', 'lastTransaction',
 class ZEOStorage:
     """Proxy to underlying storage for a single remote client."""
 
-    # A list of extension methods.  A subclass with extra methods
-    # should override.
-    extensions = []
-
     connected = connection = stats = storage = storage_id = transaction = None
     blob_tempfile = None
     log_label = 'unconnected'
@@ -91,10 +87,6 @@ class ZEOStorage:
         self.client_conflict_resolution = server.client_conflict_resolution
         # timeout and stats will be initialized in register()
         self.read_only = read_only
-        # The authentication protocol may define extra methods.
-        self._extensions = {}
-        for func in self.extensions:
-            self._extensions[func.__name__] = None
         self._iterators = {}
         self._iterator_ids = itertools.count()
         # Stores the last item that was handed out for a
@@ -149,23 +141,13 @@ class ZEOStorage:
         if not info['supportsUndo']:
             self.undoLog = self.undoInfo = lambda *a,**k: ()
 
+        # XXX deprecated: but ZODB tests use getTid. They shouldn't
         self.getTid = storage.getTid
-        self.load = storage.load
+
         self.loadSerial = storage.loadSerial
         record_iternext = getattr(storage, 'record_iternext', None)
         if record_iternext is not None:
             self.record_iternext = record_iternext
-
-        try:
-            fn = storage.getExtensionMethods
-        except AttributeError:
-            pass # no extension methods
-        else:
-            d = fn()
-            self._extensions.update(d)
-            for name in d:
-                assert not hasattr(self, name)
-                setattr(self, name, getattr(storage, name))
         self.lastTransaction = storage.lastTransaction
 
         try:
@@ -252,7 +234,6 @@ class ZEOStorage:
                 'size': storage.getSize(),
                 'name': storage.getName(),
                 'supportsUndo': supportsUndo,
-                'extensionMethods': self.getExtensionMethods(),
                 'supports_record_iternext': hasattr(self, 'record_iternext'),
                 'interfaces': tuple(interfaces),
                 }
@@ -262,13 +243,6 @@ class ZEOStorage:
                 'size': self.storage.getSize(),
                 }
 
-    def getExtensionMethods(self):
-        return self._extensions
-
-    def loadEx(self, oid):
-        self.stats.loads += 1
-        return self.storage.load(oid, '')
-
     def loadBefore(self, oid, tid):
         self.stats.loads += 1
         return self.storage.loadBefore(oid, tid)
@@ -737,6 +711,7 @@ class StorageServer:
 
 
         self._lock = Lock()
+        self.ssl = ssl # For dev convenience
 
         self.read_only = read_only
         self.database = None

src/ZEO/asyncio/client.py

@@ -8,6 +8,7 @@ else:
 from ZEO.Exceptions import ClientDisconnected
 from ZODB.ConflictResolution import ResolvedSerial
 import concurrent.futures
+import functools
 import logging
 import random
 import threading
@@ -27,6 +28,37 @@ Fallback = object()
 
 local_random = random.Random() # use separate generator to facilitate tests
 
+def future_generator(func):
+    """Decorates a generator that generates futures
+    """
+
+    @functools.wraps(func)
+    def call_generator(*args, **kw):
+        gen = func(*args, **kw)
+        try:
+            f = next(gen)
+        except StopIteration:
+            gen.close()
+        else:
+            def store(gen, future):
+                @future.add_done_callback
+                def _(future):
+                    try:
+                        try:
+                            result = future.result()
+                        except Exception as exc:
+                            f = gen.throw(exc)
+                        else:
+                            f = gen.send(result)
+                    except StopIteration:
+                        gen.close()
+                    else:
+                        store(gen, f)
+
+            store(gen, f)
+
+    return call_generator
+
 class Protocol(base.Protocol):
     """asyncio low-level ZEO client interface
     """
@@ -127,15 +159,9 @@ class Protocol(base.Protocol):
             self.closed = True
             self.client.disconnected(self)
 
+    @future_generator
     def finish_connect(self, protocol_version):
-
-        # We use a promise model rather than coroutines here because
-        # for the most part, this class is reactive and coroutines
-        # aren't a good model of it's activities.  During
-        # initialization, however, we use promises to provide an
-        # imperative flow.
-
-        # The promise(/future) implementation we use differs from
+        # The future implementation we use differs from
         # asyncio.Future in that callbacks are called immediately,
         # rather than using the loops call_soon.  We want to avoid a
         # race between invalidations and cache initialization. In
@@ -150,56 +176,29 @@ class Protocol(base.Protocol):
             self.client.register_failed(
                 self, ZEO.Exceptions.ProtocolError(protocol_version))
             return
+
         self._write(self.protocol_version)
 
-        register = self.promise(
+        try:
+            try:
+                server_tid = yield self.fut(
                     'register', self.storage_key,
                     self.read_only if self.read_only is not Fallback else False,
                     )
-        if self.read_only is not Fallback:
-            # Get lastTransaction in flight right away to make
-            # successful connection quicker, but only if we're not
-            # doing read-only fallback.  If we might need to retry, we
-            # can't send lastTransaction because if the registration
-            # fails, it will be seen as an invalid message and the
-            # connection will close. :( It would be a lot better of
-            # registere returned the last transaction (and info while
-            # it's at it).
-            lastTransaction = self.promise('lastTransaction')
-        else:
-            lastTransaction = None # to make python happy
-
-        @register
-        def registered(_):
+            except ZODB.POSException.ReadOnlyError:
                 if self.read_only is Fallback:
-                self.read_only = False
-                r_lastTransaction = self.promise('lastTransaction')
-            else:
-                r_lastTransaction = lastTransaction
-            self.client.registered(self, r_lastTransaction)
-
-        @register.catch
-        def register_failed(exc):
-            if (isinstance(exc, ZODB.POSException.ReadOnlyError) and
-                self.read_only is Fallback):
-                # We tried a write connection, degrade to a read-only one
                     self.read_only = True
-                logger.info("%s write connection failed. Trying read-only",
-                            self)
-                register = self.promise('register', self.storage_key, True)
-                # get lastTransaction in flight.
-                lastTransaction = self.promise('lastTransaction')
-
-                @register
-                def registered(_):
-                    self.client.registered(self, lastTransaction)
-
-                @register.catch
-                def register_failed(exc):
-                    self.client.register_failed(self, exc)
-
+                    server_tid = yield self.fut(
+                        'register', self.storage_key, True)
                 else:
+                    raise
+            else:
+                if self.read_only is Fallback:
+                    self.read_only = False
+        except Exception as exc:
             self.client.register_failed(self, exc)
+        else:
+            self.client.registered(self, server_tid)
 
     exception_type_type = type(Exception)
     def message_received(self, data):
@@ -237,8 +236,19 @@ class Protocol(base.Protocol):
         self._write(self.encode(self.message_id, False, method, args))
         return future
 
-    def promise(self, method, *args):
-        return self.call(Promise(), method, args)
+    def fut(self, method, *args):
+        return self.call(Fut(), method, args)
+
+    def load_before(self, oid, tid):
+        # Special-case loadBefore, so we collapse outstanding requests
+        message_id = (oid, tid)
+        future = self.futures.get(message_id)
+        if future is None:
+            future = asyncio.Future(loop=self.loop)
+            self.futures[message_id] = future
+            self._write(
+                self.encode(message_id, False, 'loadBefore', (oid, tid)))
+        return future
 
     # Methods called by the server.
     # WARNING WARNING we can't call methods that call back to us
@@ -362,18 +372,18 @@ class Client(object):
                 for addr in self.addrs
                 ]
 
-    def registered(self, protocol, last_transaction_promise):
+    def registered(self, protocol, server_tid):
         if self.protocol is None:
             self.protocol = protocol
             if not (self.read_only is Fallback and protocol.read_only):
                 # We're happy with this protocol. Tell the others to
                 # stop trying.
                 self._clear_protocols(protocol)
-            self.verify(last_transaction_promise)
+            self.verify(server_tid)
         elif (self.read_only is Fallback and not protocol.read_only and
               self.protocol.read_only):
             self.upgrade(protocol)
-            self.verify(last_transaction_promise)
+            self.verify(server_tid)
         else:
             protocol.close() # too late, we went home with another
 
@@ -391,11 +401,14 @@ class Client(object):
                 self.try_connecting)
 
     verify_result = None # for tests
-    def verify(self, last_transaction_promise):
+
+    @future_generator
+    def verify(self, server_tid):
         protocol = self.protocol
+        if server_tid is None:
+            server_tid = yield protocol.fut('lastTransaction')
 
-        @last_transaction_promise
-        def finish_verify(server_tid):
+        try:
             cache = self.cache
             if cache:
                 cache_tid = cache.getLastTid()
@@ -404,7 +417,6 @@ class Client(object):
                     logger.error("Non-empty cache w/o tid -- clearing")
                     cache.clear()
                     self.client.invalidateCache()
-                    self.finished_verify(server_tid)
                 elif cache_tid > server_tid:
                     self.verify_result = "Cache newer than server"
                     logger.critical(
@@ -413,17 +425,14 @@ class Client(object):
                                          server_tid, cache_tid, protocol)
                 elif cache_tid == server_tid:
                     self.verify_result = "Cache up to date"
-                    self.finished_verify(server_tid)
                 else:
-                    @protocol.promise('getInvalidations', cache_tid)
-                    def verify_invalidations(vdata):
+                    vdata = yield protocol.fut('getInvalidations', cache_tid)
                     if vdata:
                         self.verify_result = "quick verification"
-                            tid, oids = vdata
+                        server_tid, oids = vdata
                         for oid in oids:
                             cache.invalidate(oid, None)
-                            self.client.invalidateTransaction(tid, oids)
-                            return tid
+                        self.client.invalidateTransaction(server_tid, oids)
                     else:
                         # cache is too old
                         self.verify_result = "cache too old, clearing"
@@ -438,37 +447,33 @@ class Client(object):
                             )
                         self.cache.clear()
                         self.client.invalidateCache()
-                            return server_tid
-
-                    verify_invalidations(
-                        self.finished_verify,
-                        self.connected.set_exception,
-                        )
             else:
                 self.verify_result = "empty cache"
-                self.finished_verify(server_tid)
 
-        @finish_verify.catch
-        def verify_failed(exc):
+        except Exception as exc:
             del self.protocol
             self.register_failed(protocol, exc)
-
-    def finished_verify(self, server_tid):
+        else:
             # The cache is validated and the last tid we got from the server.
             # Set ready so we apply any invalidations that follow.
             # We've been ignoring them up to this point.
             self.cache.setLastTid(server_tid)
             self.ready = True
 
-        @self.protocol.promise('get_info')
-        def got_info(info):
-            self.client.notify_connected(self, info)
-            self.connected.set_result(None)
+            try:
+                info = yield protocol.fut('get_info')
+            except Exception as exc:
+                # This is weird. We were connected and verified our cache, but
+                # Now we errored getting info.
 
-        @got_info.catch
-        def failed_info(exc):
+                # XXX Need a test fpr this. The lone before is what we
+                # had, but it's wrong.
                 self.register_failed(self, exc)
 
+            else:
+                self.client.notify_connected(self, info)
+                self.connected.set_result(None)
+
     def get_peername(self):
         return self.protocol.get_peername()
 
@@ -514,27 +519,49 @@ class Client(object):
 
     # Special methods because they update the cache.
 
+    @future_generator
     def load_before_threadsafe(self, future, oid, tid):
         data = self.cache.loadBefore(oid, tid)
         if data is not None:
             future.set_result(data)
         elif self.ready:
-            @self.protocol.promise('loadBefore', oid, tid)
-            def load_before(data):
+            try:
+                data = yield self.protocol.load_before(oid, tid)
+            except Exception as exc:
+                future.set_exception(exc)
+            else:
                 future.set_result(data)
                 if data:
                     data, start, end = data
                     self.cache.store(oid, start, end, data)
-
-            load_before.catch(future.set_exception)
         else:
             self._when_ready(self.load_before_threadsafe, future, oid, tid)
 
+    @future_generator
+    def _prefetch(self, oid, tid):
+        try:
+            data = yield self.protocol.load_before(oid, tid)
+            if data:
+                data, start, end = data
+                self.cache.store(oid, start, end, data)
+        except Exception:
+            logger.exception("prefetch %r %r" % (oid, tid))
+
+    def prefetch(self, future, oids, tid):
+        if self.ready:
+            for oid in oids:
+                if self.cache.loadBefore(oid, tid) is None:
+                    self._prefetch(oid, tid)
+
+            future.set_result(None)
+        else:
+            future.set_exception(ClientDisconnected())
+
+    @future_generator
     def tpc_finish_threadsafe(self, future, tid, updates, f):
         if self.ready:
-            @self.protocol.promise('tpc_finish', tid)
-            def committed(tid):
             try:
+                tid = yield self.protocol.fut('tpc_finish', tid)
                 cache = self.cache
                 for oid, data, resolved in updates:
                     cache.invalidate(oid, tid)
@@ -552,8 +579,6 @@ class Client(object):
             else:
                 f(tid)
                 future.set_result(tid)
-
-            committed.catch(future.set_exception)
         else:
             future.set_exception(ClientDisconnected())
 
@@ -648,6 +673,9 @@ class ClientRunner(object):
     def async_iter(self, it):
         return self.__call(self.client.call_async_iter_threadsafe, it)
 
+    def prefetch(self, oids, tid):
+        return self.__call(self.client.prefetch, oids, tid)
+
     def load_before(self, oid, tid):
         return self.__call(self.client.load_before_threadsafe, oid, tid)
 
@@ -754,95 +782,24 @@ class ClientThread(ClientRunner):
             if self.exception:
                 raise self.exception
 
-class Promise(object):
-    """Lightweight future with a partial promise API.
-
-    These are lighweight because they call callbacks synchronously
-    rather than through an event loop, and because they ony support
-    single callbacks.
+class Fut(object):
+    """Lightweight future that calls it's callback immediately rather than soon
     """
 
-    # Note that we can know that they are completed after callbacks
-    # are set up because they're used to make network requests.
-    # Requests are made by writing to a transport.  Because we're used
-    # in a single-threaded protocol, we can't get a response and be
-    # completed if the callbacks are set in the same code that
-    # created the promise, which they are.
-
-    next = success_callback = error_callback = cancelled = None
-
-    def __call__(self, success_callback = None, error_callback = None):
-        """Set the promises success and error handlers and beget a new promise
-
-        The promise returned provides for promise chaining, providing
-        a sane imperative flow.  Let's call this the "next" promise.
-        Any results or exceptions generated by the promise or it's
-        callbacks are passed on to the next promise.
-
-        When the promise completes successfully, if a success callback
-        isn't set, then the next promise is completed with the
-        successfull result.  If a success callback is provided, it's
-        called. If the call succeeds, and the result is a promise,
-        them the result is called with the next promise's set_result
-        and set_exception methods, chaining the result and next
-        promise. If the result isn't a promise, then the next promise
-        is completed with it by calling set_result. If the success
-        callback fails, then it's exception is passed to
-        next.set_exception.
-
-        If the promise completes with an error and the error callback
-        isn't set, then the exception is passed to the next promises
-        set_exception.  If an error handler is provided, it's called
-        and if it doesn't error, then the original exception is passed
-        to the next promise's set_exception. If there error handler
-        errors, then that exception is passed to the next promise's
-        set_exception.
-        """
-        self.next = self.__class__()
-        self.success_callback = success_callback
-        self.error_callback = error_callback
-        return self.next
-
-    def cancel(self):
-        self.set_exception(concurrent.futures.CancelledError)
-
-    def catch(self, error_callback):
-        self.error_callback = error_callback
+    def add_done_callback(self, cb):
+        self.cb = cb
 
+    exc = None
     def set_exception(self, exc):
-        self._notify(None, exc)
+        self.exc = exc
+        self.cb(self)
 
     def set_result(self, result):
-        self._notify(result, None)
+        self._result = result
+        self.cb(self)
 
-    def _notify(self, result, exc):
-        next = self.next
-        if exc is not None:
-            if self.error_callback is not None:
-                try:
-                    result = self.error_callback(exc)
-                except Exception:
-                    logger.exception("Exception handling error %s", exc)
-                    if next is not None:
-                        next.set_exception(exc)
-                else:
-                    if next is not None:
-                        next.set_result(result)
-            elif next is not None:
-                next.set_exception(exc)
-        else:
-            if self.success_callback is not None:
-                try:
-                    result = self.success_callback(result)
-                except Exception as exc:
-                    logger.exception("Exception in success callback")
-                    if next is not None:
-                        next.set_exception(exc)
-                else:
-                    if next is not None:
-                        if isinstance(result, Promise):
-                            result(next.set_result, next.set_exception)
+    def result(self):
+        if self.exc:
+            raise self.exc
         else:
-                            next.set_result(result)
-            elif next is not None:
-                next.set_result(result)
+            return self._result

src/ZEO/asyncio/tests.py

@@ -12,7 +12,6 @@ from ZODB.POSException import ReadOnlyError
 
 import collections
 import logging
-import pdb
 import struct
 import unittest
 
@@ -71,6 +70,12 @@ class Base(object):
 
 class ClientTests(Base, setupstack.TestCase, ClientRunner):
 
+    maxDiff = None
+
+    def tearDown(self):
+        self.client.close()
+        super(ClientTests, self)
+
     def start(self,
               addrs=(('127.0.0.1', 8200), ), loop_addrs=None,
               read_only=False,
@@ -95,12 +100,9 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         if finish_start:
             protocol.data_received(sized(b'Z3101'))
             self.assertEqual(self.pop(2, False), b'Z3101')
-            self.assertEqual(self.pop(),
-                             [(1, False, 'register', ('TEST', False)),
-                              (2, False, 'lastTransaction', ()),
-                              ])
             self.respond(1, None)
             self.respond(2, 'a'*8)
+            self.pop(4)
             self.assertEqual(self.pop(), (3, False, 'get_info', ()))
             self.respond(3, dict(length=42))
 
@@ -134,12 +136,9 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         # The client sends back a handshake, and registers the
         # storage, and requests the last transaction.
         self.assertEqual(self.pop(2, False), b'Z5')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
+        self.assertEqual(self.pop(), (1, False, 'register', ('TEST', False)))
 
-        # Actually, the client isn't connected until it initializes it's cache:
+        # The client isn't connected until it initializes it's cache:
         self.assertFalse(client.connected.done() or transport.data)
 
         # If we try to make calls while the client is *initially*
@@ -162,9 +161,13 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         # The wrapper object (ClientStorage) hasn't been notified:
         self.assertFalse(wrapper.notify_connected.called)
 
-        # Let's respond to those first 2 calls:
-
+        # Let's respond to the register call:
         self.respond(1, None)
+
+        # The client requests the last transaction:
+        self.assertEqual(self.pop(), (2, False, 'lastTransaction', ()))
+
+        # We respond
         self.respond(2, 'a'*8)
 
         # After verification, the client requests info:
@@ -191,9 +194,11 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         # Loading objects gets special handling to leverage the cache.
         loaded = self.load_before(b'1'*8, m64)
 
-        # The data wasn't in the cache, so we make a server call:
-        self.assertEqual(self.pop(), (5, False, 'loadBefore', (b'1'*8, m64)))
-        self.respond(5, (b'data', b'a'*8, None))
+        # The data wasn't in the cache, so we made a server call:
+        self.assertEqual(self.pop(),
+                         ((b'1'*8, m64), False, 'loadBefore', (b'1'*8, m64)))
+        # Note load_before uses the oid as the message id.
+        self.respond((b'1'*8, m64), (b'data', b'a'*8, None))
         self.assertEqual(loaded.result(), (b'data', b'a'*8, None))
 
         # If we make another request, it will be satisfied from the cache:
@@ -206,9 +211,16 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
 
         # Now, if we try to load current again, we'll make a server request.
         loaded = self.load_before(b'1'*8, m64)
-        self.assertEqual(self.pop(), (6, False, 'loadBefore', (b'1'*8, m64)))
-        self.respond(6, (b'data2', b'b'*8, None))
+
+        # Note that if we make another request for the same object,
+        # the requests will be collapsed:
+        loaded2 = self.load_before(b'1'*8, m64)
+
+        self.assertEqual(self.pop(),
+                         ((b'1'*8, m64), False, 'loadBefore', (b'1'*8, m64)))
+        self.respond((b'1'*8, m64), (b'data2', b'b'*8, None))
         self.assertEqual(loaded.result(), (b'data2', b'b'*8, None))
+        self.assertEqual(loaded2.result(), (b'data2', b'b'*8, None))
 
         # Loading non-current data may also be satisfied from cache
         loaded = self.load_before(b'1'*8, b'b'*8)
@@ -219,9 +231,10 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         self.assertFalse(transport.data)
         loaded = self.load_before(b'1'*8, b'_'*8)
 
-        self.assertEqual(self.pop(),
-                         (7, False, 'loadBefore', (b'1'*8, b'_'*8)))
-        self.respond(7, (b'data0', b'^'*8, b'_'*8))
+        self.assertEqual(
+            self.pop(),
+            ((b'1'*8, b'_'*8), False, 'loadBefore', (b'1'*8, b'_'*8)))
+        self.respond((b'1'*8, b'_'*8), (b'data0', b'^'*8, b'_'*8))
         self.assertEqual(loaded.result(), (b'data0', b'^'*8, b'_'*8))
 
         # When committing transactions, we need to update the cache
@@ -244,8 +257,8 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
                          cache.load(b'4'*8))
         self.assertEqual(cache.load(b'1'*8), (b'data2', b'b'*8))
         self.assertEqual(self.pop(),
-                         (8, False, 'tpc_finish', (b'd'*8,)))
-        self.respond(8, b'e'*8)
+                         (5, False, 'tpc_finish', (b'd'*8,)))
+        self.respond(5, b'e'*8)
         self.assertEqual(committed.result(), b'e'*8)
         self.assertEqual(cache.load(b'1'*8), None)
         self.assertEqual(cache.load(b'2'*8), ('committed 2', b'e'*8))
@@ -257,8 +270,9 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         loaded = self.load_before(b'1'*8, m64)
         f1 = self.call('foo', 1, 2)
         self.assertFalse(loaded.done() or f1.done())
-        self.assertEqual(self.pop(), [(9, False, 'loadBefore', (b'1'*8, m64)),
-                                      (10, False, 'foo', (1, 2))],
+        self.assertEqual(self.pop(),
+                         [((b'1'*8, m64), False, 'loadBefore', (b'1'*8, m64)),
+                          (6, False, 'foo', (1, 2))],
                          )
         exc = TypeError(43)
 
@@ -286,15 +300,14 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         # protocol:
         protocol.data_received(sized(b'Z310'))
         self.assertEqual(self.unsized(transport.pop(2)), b'Z310')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
+        self.assertEqual(self.pop(), (1, False, 'register', ('TEST', False)))
         self.assertFalse(wrapper.notify_connected.called)
-        self.respond(1, None)
-        self.respond(2, b'e'*8)
-        self.assertEqual(self.pop(), (3, False, 'get_info', ()))
-        self.respond(3, dict(length=42))
+
+        # If the register response is a tid, then the client won't
+        # request lastTransaction
+        self.respond(1, b'e'*8)
+        self.assertEqual(self.pop(), (2, False, 'get_info', ()))
+        self.respond(2, dict(length=42))
 
         # Because the server tid matches the cache tid, we're done connecting
         wrapper.notify_connected.assert_called_with(client, {'length': 42})
@@ -323,12 +336,9 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         self.assertFalse(client.connected.done() or transport.data)
         protocol.data_received(sized(b'Z3101'))
         self.assertEqual(self.unsized(transport.pop(2)), b'Z3101')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
         self.respond(1, None)
         self.respond(2, b'e'*8)
+        self.pop(4)
 
         # We have to verify the cache, so we're not done connecting:
         self.assertFalse(client.connected.done())
@@ -361,12 +371,9 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         self.assertFalse(client.connected.done() or transport.data)
         protocol.data_received(sized(b'Z3101'))
         self.assertEqual(self.unsized(transport.pop(2)), b'Z3101')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
         self.respond(1, None)
         self.respond(2, b'e'*8)
+        self.pop(4)
 
         # We have to verify the cache, so we're not done connecting:
         self.assertFalse(client.connected.done())
@@ -433,12 +440,9 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         cache.setLastTid('b'*8)
         protocol.data_received(sized(b'Z3101'))
         self.assertEqual(self.unsized(transport.pop(2)), b'Z3101')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
         self.respond(1, None)
         self.respond(2, 'a'*8)
+        self.pop()
         self.assertFalse(client.connected.done() or transport.data)
         delay, func, args, _ = loop.later.pop(1) # first in later is heartbeat
         self.assert_(8 < delay < 10)
@@ -450,12 +454,9 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         transport = loop.transport
         protocol.data_received(sized(b'Z3101'))
         self.assertEqual(self.unsized(transport.pop(2)), b'Z3101')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
         self.respond(1, None)
         self.respond(2, 'b'*8)
+        self.pop(4)
         self.assertEqual(self.pop(), (3, False, 'get_info', ()))
         self.respond(3, dict(length=42))
         self.assert_(client.connected.done() and not transport.data)
@@ -481,12 +482,10 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         self.assertTrue(self.is_read_only())
 
         # The client tries for a read-only connection:
-        self.assertEqual(self.pop(),
-                         [(2, False, 'register', ('TEST', True)),
-                          (3, False, 'lastTransaction', ()),
-                          ])
+        self.assertEqual(self.pop(), (2, False, 'register', ('TEST', True)))
         # We respond with successfully:
         self.respond(2, None)
+        self.pop(2)
         self.respond(3, 'b'*8)
         self.assertTrue(self.is_read_only())
 
@@ -513,12 +512,12 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
 
         # We respond and the writable connection succeeds:
         self.respond(1, None)
-        self.assertFalse(self.is_read_only())
 
         # at this point, a lastTransaction request is emitted:
 
         self.assertEqual(self.parse(loop.transport.pop()),
                          (2, False, 'lastTransaction', ()))
+        self.assertFalse(self.is_read_only())
 
         # Now, the original protocol is closed, and the client is
         # no-longer ready:
@@ -542,11 +541,8 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
         wrapper, cache, loop, client, protocol, transport = self.start()
         protocol.data_received(sized(b'Z3101'))
         self.assertEqual(self.unsized(transport.pop(2)), b'Z3101')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
         self.respond(1, None)
+        self.pop(4)
         self.send('invalidateTransaction', b'b'*8, [b'1'*8], called=False)
         self.respond(2, b'a'*8)
         self.send('invalidateTransaction', b'c'*8, [b'1'*8], no_output=False)
@@ -563,11 +559,8 @@ class ClientTests(Base, setupstack.TestCase, ClientRunner):
 
         protocol.data_received(sized(b'Z3101'))
         self.assertEqual(self.unsized(transport.pop(2)), b'Z3101')
-        self.assertEqual(self.pop(),
-                         [(1, False, 'register', ('TEST', False)),
-                          (2, False, 'lastTransaction', ()),
-                          ])
         self.respond(1, None)
+        self.pop(4)
         self.send('invalidateTransaction', b'd'*8, [b'1'*8], called=False)
         self.respond(2, b'c'*8)
         self.send('invalidateTransaction', b'e'*8, [b'1'*8], no_output=False)
@@ -720,7 +713,9 @@ class MemoryCache(object):
     def store(self, oid, start_tid, end_tid, data):
         assert start_tid is not None
         revisions = self.data[oid]
-        revisions.append((start_tid, end_tid, data))
+        data = (start_tid, end_tid, data)
+        if not revisions or data != revisions[-1]:
+            revisions.append(data)
         revisions.sort()
 
     def loadBefore(self, oid, tid):

src/ZEO/interfaces.py

@@ -90,14 +90,6 @@ class IServeable(zope.interface.Interface):
     """Interface provided by storages that can be served by ZEO
     """
 
-    def getTid(oid):
-        """The last transaction to change an object
-
-        Return the transaction id of the last transaction that committed a
-        change to an object with the given object id.
-
-        """
-
     def tpc_transaction():
         """The current transaction being committed.
 

src/ZEO/tests/forker.py

@@ -110,6 +110,7 @@ def runner(config, qin, qout, timeout=None,
         options = ZEO.runzeo.ZEOOptions()
         options.realize(['-C', config])
         server = ZEO.runzeo.ZEOServer(options)
+        globals()[(name if name else 'last') + '_server'] = server
         server.open_storages()
         server.clear_socket()
         server.create_server()

src/ZEO/tests/testZEO2.py

@@ -492,6 +492,50 @@ ZEOStorage as closed and see if trying to get a lock cleans it up:
     >>> logging.getLogger('ZEO').removeHandler(handler)
     """
 
+def test_prefetch(self):
+    """The client storage prefetch method pre-fetches from the server
+
+    >>> count = 999
+
+    >>> import ZEO
+    >>> addr, stop = ZEO.server()
+    >>> conn = ZEO.connection(addr)
+    >>> root = conn.root()
+    >>> cls = root.__class__
+    >>> for i in range(count):
+    ...     root[i] = cls()
+    >>> conn.transaction_manager.commit()
+    >>> oids = [root[i]._p_oid for i in range(count)]
+    >>> conn.close()
+    >>> conn = ZEO.connection(addr)
+    >>> storage = conn.db().storage
+    >>> len(storage._cache)
+    1
+    >>> storage.prefetch(oids, conn._storage._start)
+
+    The prefetch returns before the cache is filled:
+
+    >>> len(storage._cache) < count
+    True
+
+    But it is filled eventually:
+
+    >>> from zope.testing.wait import wait
+    >>> wait(lambda : len(storage._cache) > count)
+
+    >>> loads = storage.server_status()['loads']
+
+    Now if we reload the data, it will be satisfied from the cache:
+
+    >>> for oid in oids:
+    ...     _ = conn._storage.load(oid)
+
+    >>> storage.server_status()['loads'] == loads
+    True
+
+    >>> conn.close()
+    >>> stop()
+    """
 
 def test_suite():
     return unittest.TestSuite((

src/ZEO/tests/testssl.py

@@ -195,6 +195,8 @@ class SSLConfigTestMockiavellian(ZEOConfigTestBase):
             factory, context, (client_cert, client_key, None),
             check_hostname=True)
 
+        context.load_default_certs.assert_called_with()
+
     @mock.patch('ssl.create_default_context')
     @mock.patch('ZEO.ClientStorage.ClientStorage')
     def test_ssl_mockiavellian_client_auth_dir(
@@ -210,6 +212,7 @@ class SSLConfigTestMockiavellian(ZEOConfigTestBase):
             capath=here,
             check_hostname=True,
             )
+        context.load_default_certs.assert_not_called()
 
     @mock.patch('ssl.create_default_context')
     @mock.patch('ZEO.ClientStorage.ClientStorage')
@@ -226,6 +229,7 @@ class SSLConfigTestMockiavellian(ZEOConfigTestBase):
             cafile=server_cert,
             check_hostname=True,
             )
+        context.load_default_certs.assert_not_called()
 
     @mock.patch('ssl.create_default_context')
     @mock.patch('ZEO.ClientStorage.ClientStorage')
@@ -345,7 +349,10 @@ server_config = """
     </zeo>
     """.format(server_cert, server_key, client_cert)
 
-def client_ssl():
+def client_ssl(cafile=server_key,
+               client_cert=client_cert,
+               client_key=client_key,
+               ):
     context = ssl.create_default_context(
         ssl.Purpose.CLIENT_AUTH, cafile=server_cert)
 
@@ -353,3 +360,7 @@ def client_ssl():
     context.verify_mode = ssl.CERT_REQUIRED
     context.check_hostname = False
     return context
+
+# Here's a command to create a cert/key pair:
+# openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem \
+#             -days 999999 -nodes -batch

src/ZEO/zconfig.py

@@ -11,12 +11,16 @@ def ssl_config(section, server):
     if auth:
         if os.path.isdir(auth):
             capath=auth
-        else:
+        elif auth != 'DYNAMIC':
             cafile=auth
 
     context = ssl.create_default_context(
         ssl.Purpose.CLIENT_AUTH, cafile=cafile, capath=capath)
 
+    if not auth:
+        assert not server
+        context.load_default_certs()
+
     if section.certificate:
         password = section.password_function
         if password: