If the destination directory doesn't contain the desired repo, delete it

gclient.py

Index: gclient.py
diff --git a/gclient.py b/gclient.py
index c3e295c42e1dca0fff893a61352cfa7deee4fe36..6117ecafcad7fa86560de953f083edecbc2c5e61 100755
--- a/gclient.py
+++ b/gclient.py
@@ -641,6 +641,19 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
             command, options, parsed_url, self.parent.name, revision_overrides)
         self._used_scm = gclient_scm.CreateSCM(
             parsed_url, self.root.root_dir, self.name)
+

[borenet, 2013/11/12 19:33:37]

This may not be in the right place.  Any alternative suggestions?

I kept things simple for now, but this could also be placed behind a flag so
that this only happens on the bots.

[iannucci, 2013/11/13 06:26:30]

the 'force' flag would probably be sufficient

[borenet, 2013/11/13 19:12:24]

Done.

+        # When updating, determine whether the destination directory contains a
+        # checkout of the desired repository. If not, avoid conflicts by
+        # deleting the directory before running the update.
+        if command == 'update':
+          actual_remote_url = self._used_scm.GetRemoteURL(options)
+          url, _ = gclient_utils.SplitUrlRevision(parsed_url)
+          if actual_remote_url != url:
+            dest_dir = os.path.join(self.root.root_dir, self.name)
+            logging.debug('%s does not contain a checkout of %s. Removing.' %

[iannucci, 2013/11/13 06:26:30]

I think this should actually be at least a warn, since it's destructive.

[if we don't end up placing behind --force] We should probably also prompt if
stdout is not closed or --force is not supplied, to avoid nuking developer
changes.

[borenet, 2013/11/13 19:12:24]

Done.

+                          dest_dir)
+            gclient_utils.rmtree(dest_dir)

[borenet, 2013/11/12 19:33:37]

Alternatively, we could move into a temporary directory to avoid clobbering
things.  I think ilevy@ mentioned using such a temporary directory and swapping
out the contents of the directory as appropriate.  For example, when syncing
Skia forward across the DEPS change, third_party/skia gets moved into
".deleteme".  If, at some later time, we sync backward across the DEPS change,
we swap the current contents of third_party/skia with those that we previously
moved into ".deleteme" before syncing.  This strikes me as tricky to pull off
correctly, and I'm not sure that it will save us all that much for a small
(<50M) repo.

[iannucci, 2013/11/13 06:26:30]

This sounds like a lot of complexity to me with very minimal upside (aka
premature optimization). I think git_cache would obviate the need for this,
since the new clone/checkout would be relatively lightweight. Since skia is
already a git repo (right?) it would get this for free just by setting git_cache
(which I believe all the bots do already).

Of course, this will not be true for non-git repos. But IMO the solution there
should be to switch the bots to git checkouts, not to add complexity to gclient.

[borenet, 2013/11/13 19:12:24]

Agreed.  I think the most I'd want to do is move into some ".deleteme"
directory.

[Isaac (away), 2013/12/03 18:25:05]

Other than bots, I don't think it's OK for gclient to delete folders
unfortunately.  You can use tempfile library to create a unique temp directory
with prefix like "skia_deleteme_" and move things there..

[Isaac (away), 2013/12/03 18:25:49]

Ignore this comment, it's stale.

[borenet, 2013/12/03 21:12:02]

Confirming that you're okay with the deletion approach, guarded by the "prompt
if not --force"?

[Isaac (away), 2013/12/04 03:29:19]

Yes.  With a prompt this is fine.

+
         self._got_revision = self._used_scm.RunCommand(command, options, args,
                                                        file_list)
         if file_list: