[PATCH 2/4] test/atomicity: guard chert-only optimization

[David Bremner]

This should potentially be updated to have an equivalent optimization
for the glass backend, but it in my unscientific tests, the glass backend
without the optimization is faster then the chert backend with.
---
 test/atomicity.py | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/test/atomicity.py b/test/atomicity.py
index 01a4205..1ca52b9 100644
--- a/test/atomicity.py
+++ b/test/atomicity.py
@@ -29,16 +29,19 @@ class RenameBreakpoint(gdb.Breakpoint):
         self.n = 0
 
     def stop(self):
-        # As an optimization, only consider snapshots after a Xapian
-        # has really committed.  Xapian overwrites record.base? as the
-        # last step in the commit, so keep an eye on their inumbers.
-        inodes = {}
-        for path in glob.glob('%s/.notmuch/xapian/record.base*' % maildir):
-            inodes[path] = os.stat(path).st_ino
-        if inodes == self.last_inodes:
-            # Continue
-            return False
-        self.last_inodes = inodes
+        xapiandir = '%s/.notmuch/xapian' % maildir
+        if os.path.isfile('%s/iamchert' % xapiandir):
+            # As an optimization, only consider snapshots after a
+            # Xapian has really committed.  The chert backend
+            # overwrites record.base? as the last step in the commit,
+            # so keep an eye on their inumbers.
+            inodes = {}
+            for path in glob.glob('%s/record.base*' % xapiandir):
+                inodes[path] = os.stat(path).st_ino
+            if inodes == self.last_inodes:
+                # Continue
+                return False
+            self.last_inodes = inodes
 
         # Save a backtrace in case the test does fail
         backtrace = gdb.execute('backtrace', to_string=True)
-- 
2.8.0.rc3