Drive asyncore during cache verification in synchronous mode.

If asyncore is not running in a separate thread, the client needs to
call poll() to perform the IO necessary for cache verification to
finish.

This allows us to eliminate several calls to sync() in the test suite.

src/ZEO/ClientStorage.py

@@ -293,6 +293,9 @@ class ClientStorage:
                     break
                 log2(INFO, "Wait for cache verification to finish")
         else:
+            self._wait_sync()
+
+    def _wait_sync(self):
         # If there is no mainloop running, this code needs
         # to call poll() to cause asyncore to handle events.
         while 1:
@@ -414,6 +417,9 @@ class ClientStorage:
         self._oids = []
         self._info.update(stub.get_info())
         self.verify_cache(stub)
+        if not conn.is_async():
+            log2(INFO, "Waiting for cache verification to finish")
+            self._wait_sync()
 
     def set_server_addr(self, addr):
         # Normalize server address and convert to string

src/ZEO/tests/ConnectionTests.py

@@ -205,7 +205,6 @@ class ConnectionTests(CommonSetupTearDown):
                 self._dostore()
                 break
             except ClientDisconnected:
-                self._storage.sync()
                 time.sleep(0.5)
 
     def checkReadOnlyClient(self):
@@ -392,7 +391,6 @@ class ConnectionTests(CommonSetupTearDown):
                          "Error after server restart; retrying.",
                          error=sys.exc_info())
                 get_transaction().abort()
-                self._storage.sync()
             # XXX This is a bloody pain.  We're placing a heavy burden
             # on users to catch a plethora of exceptions in order to
             # write robust code.  Need to think about implementing
@@ -645,7 +643,6 @@ class ReconnectionTests(CommonSetupTearDown):
                 # quickly and the test fails because it doesn't wait
                 # long enough for the client.
                 time.sleep(0.1)
-                self._storage.sync()
         else:
             self.fail("Couldn't store after starting a read-write server")