Re: [PATCH 2/3] git-p4: Search for parent commit on branch creation
From: Pete Wyckoff <hidden>
Date: 2016-06-15 22:52:48
vitor.hda@gmail.com wrote on Mon, 16 Jan 2012 00:39 +0000:
To find out which is its parent the commit of the new branch is applied sequentially to each blob of the parent branch from the newest to the oldest. The first blob which results in a zero diff is considered the parent commit. If none is found, then the commit is applied to the top of the parent branch. A fast-import "checkpoint" call is required for each comparison because diff-tree is only able to work with blobs on disk. But most of these commits will not be part of the final imported tree, making fast-import fail. To avoid this, the temporary branches are tracked and then removed at the end of the import process.
This looks much better without the need for "--force". It'll be great to fix this major branch detection problem. Can you make a couple of further minor changes?
quoted hunk ↗ jump to hunk
diff --git a/contrib/fast-import/git-p4 b/contrib/fast-import/git-p4@@ -2012,7 +2014,28 @@ class P4Sync(Command, P4UserMap): - self.commit(description, filesForCommit, branch, [branchPrefix], parent) + parentFound = 0 + if len(parent) > 0: + self.checkpoint() + for blob in read_pipe_lines("git rev-list --reverse --no-merges %s" % parent): + blob = blob.strip() + tempBranch = self.tempBranchLocation + os.sep + "%d-%s" % (change, blob) + if self.verbose: + print "Creating temporary branch: " + tempBranch + self.commit(description, filesForCommit, tempBranch, [branchPrefix], blob) + self.tempBranches.append(tempBranch) + self.checkpoint() + if len( read_pipe("git diff-tree %s %s" % (blob, tempBranch)) ) == 0: + parentFound = 1 + if self.verbose: + print "Found parent of %s in commit %s" % (branch, blob) + break + if parentFound: + self.commit(description, filesForCommit, branch, [branchPrefix], blob) + else: + if self.verbose: + print "Parent of %s not found. Committing into head of %s" % (branch, parent) + self.commit(description, filesForCommit, branch, [branchPrefix], parent)
1. Move the tempBranch commit outside of the "for blob" loop.
It can have no parent, and the diff-tree will still tell you
if you found the same contents. Instead of a ref for
each blob inspected for each change, you'll just have one ref
per change. Only one checkpoint() after the tempBranch
commit should be needed.
2. Nit. parentFound is boolean, use True/False, not 1/0.
quoted hunk ↗ jump to hunk
@@ -2347,6 +2370,12 @@ class P4Sync(Command, P4UserMap): + # Cleanup temporary branches created during import + if self.tempBranches != []: + for branch in self.tempBranches: + os.remove(".git" + os.sep + branch) + os.rmdir(".git" + os.sep + self.tempBranchLocation) +
3. Deleting refs should probably use "git update-ref -d"
just in case GIT_DIR is not ".git". I think you could just
leave the "git-p4-tmp" directory around, but use
os.environ["GIT_DIR"] instead of ".git" if you want to
delete it.
4. Paths are best manipulated with os.path.join(dir, file), to handle
weirdnesses like drive letters.
Eventually if the fast-import protocol learns to delete the refs
it creates, we can clean up a bit more nicely. I think there was
agreement this was a good idea, just needs someone to do it
sometime.
-- Pete