Fix error handling logic for pickling errors.

If an exception occurs while decoding a message, there is really
nothing the server can do to recover.  If the message was a
synchronous call, the client will wait for ever for the reply.  The
server can't send the reply, because it couldn't unpickle the message
id.  Instead of trying to recover, just let the exception propogate up
to asyncore where the connection will be closed.

As a result, eliminate DecodingError and special case in
handle_error() that handled flags == None.

src/ZEO/zrpc/connection.py

@@ -20,7 +20,7 @@ import types
 
 import ThreadedAsync
 from ZEO.zrpc import smac
-from ZEO.zrpc.error import ZRPCError, DisconnectedError, DecodingError
+from ZEO.zrpc.error import ZRPCError, DisconnectedError
 from ZEO.zrpc.log import log, short_repr
 from ZEO.zrpc.marshal import Marshaller
 from ZEO.zrpc.trigger import trigger
@@ -188,13 +188,11 @@ class Connection(smac.SizedMessageAsyncConnection):
 
     def message_input(self, message):
         """Decoding an incoming message and dispatch it"""
-        # XXX Not sure what to do with errors that reach this level.
-        # Need to catch ZRPCErrors in handle_reply() and
-        # handle_request() so that they get back to the client.
-        try:
+        # If something goes wrong during decoding, the marshaller
+        # will raise an exception.  The exception will ultimately
+        # result in asycnore calling handle_error(), which will
+        # close the connection.
         msgid, flags, name, args = self.marshal.decode(message)
-        except DecodingError, msg:
-            return self.return_error(None, None, DecodingError, msg)
 
         if __debug__:
             log("recv msg: %s, %s, %s, %s" % (msgid, flags, name,
@@ -276,9 +274,6 @@ class Connection(smac.SizedMessageAsyncConnection):
         self.poll()
 
     def return_error(self, msgid, flags, err_type, err_value):
-        if flags is None:
-            self.log_error("Exception raised during decoding")
-            return
         if flags & ASYNC:
             self.log_error("Asynchronous call raised exception: %s" % self)
             return

src/ZEO/zrpc/error.py

@@ -17,8 +17,5 @@ from ZEO.Exceptions import Disconnected
 class ZRPCError(POSException.StorageError):
     pass
 
-class DecodingError(ZRPCError):
-    """A ZRPC message could not be decoded."""
-
 class DisconnectedError(ZRPCError, Disconnected):
     """The database storage is disconnected from the storage server."""

src/ZEO/zrpc/marshal.py

@@ -18,7 +18,7 @@ import types
 
 import zLOG
 
-from ZEO.zrpc.error import ZRPCError, DecodingError
+from ZEO.zrpc.error import ZRPCError
 from ZEO.zrpc.log import log
 
 class Marshaller:
@@ -50,8 +50,8 @@ class Marshaller:
         try:
             return unpickler.load() # msgid, flags, name, args
         except (self.errors, IndexError), err_msg:
-            log("can't decode %s" % repr(msg), level=zLOG.ERROR)
-            raise DecodingError(msg)
+            log("can't decode message: %s" % repr(msg), level=zLOG.ERROR)
+            raise
 
 _globals = globals()
 _silly = ('__doc__',)