[Zodb-checkins] SVN: ZODB/trunk/src/ZEO/zrpc/smac.py fix for https://bugs.launchpad.net/zodb/+bug/182833 (Severe ZEO protocol error)

[Dieter Maurer]

Log message for revision 86902:
  fix for https://bugs.launchpad.net/zodb/+bug/182833 (Severe ZEO protocol error)
  Notes:
   I had to exclude 'kill_does_not_cause_cache_corruption (ZEO.tests.test_cache.__test__)' from the test as it deterministically hung on my platform (with or without my fix)
   Running the remaining test suite caused Ran 3279 tests with 5 failures and 0 errors in 17 minutes 31.116 seconds and one import problem -- all failures and problems in zope.testing-3.5.1-py2.4.egg, i.e. unrelated to my fix:
  Tests with failures:
     /home/dieter/ZopeSVN/W/ZODB/eggs/zope.testing-3.5.1-py2.4.egg/zope/testing/testrunner-coverage.txt
     /home/dieter/ZopeSVN/W/ZODB/eggs/zope.testing-3.5.1-py2.4.egg/zope/testing/testrunner-debugging.txt
     /home/dieter/ZopeSVN/W/ZODB/eggs/zope.testing-3.5.1-py2.4.egg/zope/testing/testrunner-edge-cases.txt
     /home/dieter/ZopeSVN/W/ZODB/eggs/zope.testing-3.5.1-py2.4.egg/zope/testing/testrunner-layers-ntd.txt
     /home/dieter/ZopeSVN/W/ZODB/eggs/zope.testing-3.5.1-py2.4.egg/zope/testing/testrunner-colors.txt
  
  Test-modules with import problems:
    zope.testing.testrunner.tests
  

Changed:
  U   ZODB/trunk/src/ZEO/zrpc/smac.py

-=-
Modified: ZODB/trunk/src/ZEO/zrpc/smac.py
===================================================================
--- ZODB/trunk/src/ZEO/zrpc/smac.py	2008-05-21 22:49:29 UTC (rev 86901)
+++ ZODB/trunk/src/ZEO/zrpc/smac.py	2008-05-22 08:08:22 UTC (rev 86902)
@@ -298,11 +298,17 @@
             i += 1
             # It is very unlikely that i will be 1.
             v = "".join(output[:i])
+            # Note: "output" usually contains the output not yet sent
+            #  The "del" below breaks this invariant temporarily.
+            #  We must ensure its satisfaction again when we leave the loop
             del output[:i]
 
             try:
                 n = self.send(v)
             except socket.error, err:
+                # Fix for https://bugs.launchpad.net/zodb/+bug/182833
+                #  ensure the above mentioned "output" invariant
+                output.insert(0, v)
                 if err[0] in expected_socket_write_errors:
                     break # we couldn't write anything
                 raise