Read from server sometimes fails (Patch included)

[Jeremy Cowles]

The function _expectvalue assumes a value is always returned from the server, which was not true in some cases.

Here is my patch:

--- python-memcached-1.45/memcache.py 2010-09-01 12:53:40.615960000 -0700
+++ local_copy/memcache.py 2010-08-31 11:04:31.517060834 -0700
@@ -870,6 +870,8 @@
     def _expectvalue(self, server, line=None):
         if not line:
             line = server.readline()
+ if not line:
+ return (None, None, None)

         if line[:5] == 'VALUE':
             resp, rkey, flags, len = line.split()

(the same as attachment)

--
Jeremy

[Kirill Zaitsev (k-zaitsev)]

I confirm that.
The bug is pretty easy to reproduce. It happens always when one of the servers in multi-server setup fails.
To reproduce: create a Client with at least two servers (for example two local memcached servers on different ports), then set some values, then shut one of the servers down and try to fetch a value. this will result in a TypeError as specified above.

This happens because readline() of the _Host class returns None if the Host is down(and no data was received). This affects several places actually: _incrdecr, _expectvalue, _expect_cas_value will all fail as they expect line to be a string. There are few other functions, that just check that value returned by readline is true, but that's OK in those functions I guess.
I'll supply a bit better patch here soon.