[Zodb-checkins] CVS: StandaloneZODB/ZEO - ClientStorage.py:1.26.4.29

[Jeremy Hylton]

Update of /cvs-repository/StandaloneZODB/ZEO
In directory cvs.zope.org:/tmp/cvs-serv11395

Modified Files:
      Tag: ZEO-ZRPC-Dev
	ClientStorage.py 
Log Message:
Use ClientDisconnectedStub for _server attribute of ClientStorage.

The CDS always raises a ClientDisconnected() error.  This is simpler
than testing for _server == None and raising the error in every place
where _server is used.


=== StandaloneZODB/ZEO/ClientStorage.py 1.26.4.28 => 1.26.4.29 ===
     return t
 
-class ClientStorage:
+class DisconnectedServerStub:
+    """Raise ClientDisconnected on all attribute access."""
+
+    def __getattr__(self, attr):
+        raise ClientDisconnected()
 
-    _server = None
+disconnected_stub = DisconnectedServerStub()
+
+class ClientStorage:
 
     def __init__(self, addr, storage='1', cache_size=20000000,
                  name='', client='', debug=0, var=None,
@@ -148,6 +154,7 @@
         # Decide whether to use non-temporary files
         client = client or os.environ.get('ZEO_CLIENT','')
 
+        self._server = disconnected_stub
         self._connection = addr
         self._storage = storage
         self._debug = debug
@@ -174,7 +181,6 @@
                                                 #debug=debug,
                                                 tmin=min_disconnect_poll,
                                                 tmax=max_disconnect_poll)
-        self._server = None
         if wait_for_server_on_startup:
             self._rpc_mgr.connect(sync=1)
         else:
@@ -213,10 +219,10 @@
         self._db = db
 
     def is_connected(self):
-        if self._server:
-            return 1
-        else:
+        if self._server is disconnected_stub:
             return 0
+        else:
+            return 1
 
     def notifyConnected(self, c):
         log2(INFO, "Connected to storage")
@@ -224,6 +230,8 @@
 
         self._oids = []
 
+        # XXX Why is this synchronous?  If it were async, verification
+        # would start faster.
         stub.register(str(self._storage))
         self.verify_cache(stub)
 
@@ -250,7 +258,7 @@
 
     def notifyDisconnected(self, ignored):
         log2(PROBLEM, "Disconnected from storage")
-        self._server = None
+        self._server = disconnected_stub
         if self._transaction:
             self._transaction = None
             self.tpc_cond.notifyAll()
@@ -326,7 +334,8 @@
         # Close the manager first, so that it doesn't attempt to
         # re-open the connection. 
         self._rpc_mgr.close()
-        if self._server:
+        if self._server is not disconnected_stub:
+            # XXX why doesn't the manager close this for us?
             self._server.rpc.close()
         if self._cache is not None:
             self._cache.close()
@@ -452,7 +461,7 @@
             # If _server is None, then the client disconnected during
             # the tpc_begin() and notifyDisconnected() will have
             # released the lock.
-            if self._server is not None:
+            if self._server is not disconnected_stub:
                 self.tpc_cond.release()
             raise