Address another race condition running tests on Windows

[amccarth]

Summary

Another case where sleep-and-retry avoids file access errors on Windows.

[zturner]

packages/Python/lldbsuite/test/lldbtest.py

1823–1830

I have a patch pending to create an lldbsuite.support package. I wonder if it would be worth sinking this "rename with retry" (and similar for delete-with-retry) into this library. Then you could call this as:

lldbsuite.support.filesystem.rename_with_retry(src, dst, 1)  # Retry up to 1 time

I only mention this because this is now the second time we've had to do this (other time right below), so perhaps we might need this again in the future too.

I don't feel too strongly, so up to you. If you think it's a good idea though, you'll probably need to wait until my CL goes in first so that you can add this method to the package (which doesn't exist yet)

[amccarth]

packages/Python/lldbsuite/test/lldbtest.py

1823–1830

I'm happy to wait. I just glad I found the root cause.

[zturner]

Feel free to get this in. Maybe put it in file lldbsuite/support/filesystem.py

[amccarth]

I'm not seeing this problem now that many of the other changes are in. I'm going to hold off until I see it again.

packages/Python/lldbsuite/test/lldbtest.py

def dumpSessionInfo(self):
                     dst = src.replace(self.log_basename, dst_log_basename)
                     if os.name == "nt" and os.path.isfile(dst):
                         # On Windows, renaming a -> b will throw an exception if b exists.  On non-Windows platforms
                         # it silently replaces the destination.  Ultimately this means that atomic renames are not
                         # guaranteed to be possible on Windows, but we need this to work anyway, so just remove the
                         # destination first if it already exists.
                         os.remove(dst)
 
+                    try:
+                        os.rename(src, dst)
+                    except:
+                        # We've seen consistent rename failures on Windows, perhaps because the
+                        # just-created log file is being scanned by anti-virus.  Empirically, this
+                        # sleep-and-retry approach allows tests to succeed much more reliably.
+                        time.sleep(0.5)
                         os.rename(src, dst)
         else:
             # success!  (and we don't want log files) delete log files
             for log_file in log_files_for_this_test:
                 try:
                     os.unlink(log_file)
                 except:
                     # We've seen consistent unlink failures on Windows, perhaps because the
                     # just-created log file is being scanned by anti-virus.  Empirically, this