Returned test_corrupt_all_block_hash_tree_late to its original semant…

…ics. Added functions to clear the cache in slotreadproxy.

Signed-off-by: Andrew Miller <amiller@dappervision.com>

src/allmydata/mutable/layout.py

@@ -1235,9 +1235,12 @@ def __init__(self,
         # The way callers interact with cache in the filenode returns
         # None if there isn't any cached data, but the way we index the
         # cached data requires a string, so convert None to "".
-        if self._data == None:
+        if self._data is None:
             self._data = ""
 
+    def _clear_cache(self):
+        self._data = ""
+        self._data_is_everything = False
 
     def _maybe_fetch_offsets_and_header(self, force_remote=False):
         """

src/allmydata/mutable/servermap.py

@@ -377,6 +377,13 @@ def set_update_data_for_share_and_verinfo(self, shnum, verinfo, data):
         self.update_data.setdefault(shnum , []).append((verinfo, data))
 
 
+    def _test_clear_cache(self):
+        # Force each of the slotread proxies to clear their data cache.
+        # This is useful for unit tests.
+        for _,proxy in self.proxies.iteritems():
+            proxy._clear_cache()
+
+
 class ServermapUpdater:
     def __init__(self, filenode, storage_broker, monitor, servermap,
                  mode=MODE_READ, add_lease=False, update_range=None):

src/allmydata/test/test_mutable.py

@@ -1377,6 +1377,7 @@ def _test_corrupt_all(self, offset, substring,
             d.addCallback(corrupt, self._storage, offset)
         def _do_retrieve(servermap):
             ver = servermap.best_recoverable_version()
+            servermap._test_clear_cache()
             if ver is None and not should_succeed:
                 # no recoverable versions == not succeeding. The problem
                 # should be noted in the servermap's list of problems.
@@ -1515,7 +1516,7 @@ def _check(res):
             self.failUnless(f.check(NotEnoughSharesError))
         return self._test_corrupt_all("block_hash_tree",
                                       "block hash tree failure",
-                                      corrupt_early=True,
+                                      corrupt_early=False,
                                       failure_checker=_check)
 
 
@@ -1599,7 +1600,7 @@ def test_corrupt_mdmf_block_hash_tree(self):
         d.addCallback(lambda ignored:
             self._test_corrupt_all(("block_hash_tree", 12 * 32),
                                    "block hash tree failure",
-                                   corrupt_early=False,
+                                   corrupt_early=True,
                                    should_succeed=False))
         return d
 
@@ -1609,7 +1610,7 @@ def test_corrupt_mdmf_block_hash_tree_late(self):
         d.addCallback(lambda ignored:
             self._test_corrupt_all(("block_hash_tree", 12 * 32),
                                    "block hash tree failure",
-                                   corrupt_early=True,
+                                   corrupt_early=False,
                                    should_succeed=False))
         return d