Add git-reup and friends

git_rebase_update.py

Index: git_rebase_update.py
diff --git a/git_rebase_update.py b/git_rebase_update.py
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index 0000000000000000000000000000000000000000..3646498f628e89945ae4cfa4ae036bcc37a41ea0
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+++ b/git_rebase_update.py
@@ -0,0 +1,227 @@
+#!/usr/bin/python
+# Copyright (c) 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+

[agable, 2014/03/21 01:14:21]

docstrong

+import argparse
+import collections
+import logging
+import sys
+
+from pprint import pformat
+
+from git_common import run, root, tags, topo_iter, once, hash_one, rebase

[agable, 2014/03/21 01:14:21]

Honestly might be more reasonable to do
import git_common as git
at this point

+from git_common import get_or_create_merge_base, squash_current_branch, run_both
+from git_common import get_branch_tree, branches, remove_merge_base
+from git_common import current_branch, set_config, config
+
+from git_freezer import freeze, thaw
+
+
+def find_return_branch():
+  """Finds the branch which we should return to after rebase-update completes
+  its entire action without any conflicts.
+  """
+  STARTING_BRANCH_KEY = 'depot-tools.rebase-update.starting-branch'
+  return_branch = config(STARTING_BRANCH_KEY)
+  if return_branch is None:
+    return_branch = current_branch()
+    if return_branch != 'HEAD':
+      set_config(STARTING_BRANCH_KEY, return_branch)
+
+  return return_branch
+
+
+def check_for_rebase():
+  from git_common import in_rebase
+
+  if in_rebase():
+    # TODO(iannucci): Be able to resume rebase with flags like --continue,
+    # etc.
+    print (
+      'Rebase in progress. Please complete the rebase before running '
+      '`git rebase-update`.'
+    )
+    sys.exit(1)
+
+
+def fetch_remotes(branch_tree):
+  """Fetches all remotes which are needed to update |branch_tree|."""
+
+  fetch_tags = False
+  remotes = set()
+  tag_set = tags()
+  for parent in branch_tree.itervalues():
+    if parent in tag_set:
+      fetch_tags = True
+    else:
+      full_ref = run('rev-parse', '--symbolic-full-name', parent)
+      if full_ref.startswith('refs/remotes'):
+        parts = full_ref.split('/')
+        remote_name = parts[2]
+        remotes.add(remote_name)
+
+  fetch_args = []
+  if fetch_tags:
+    fetch_args.append('--tags')
+  fetch_args.append('--multiple')
+  fetch_args.extend(remotes)
+  # TODO(iannucci): Should we fetch git-svn?
+
+  if not fetch_args:  # pragma: no cover
+    print 'Nothing to fetch.'
+  else:
+    out, err = run_both('fetch', *fetch_args)
+    for data, stream in zip((out, err), (sys.stdout, sys.stderr)):
+      if data:
+        print >> stream, data
+
+
+def remove_empty_branches(branch_tree):
+  tag_set = tags()
+  ensure_root_checkout = once(lambda: run('checkout', root()))
+
+  downstreams = collections.defaultdict(list)
+  for branch, parent in topo_iter(branch_tree, top_down=False):
+    downstreams[parent].append(branch)
+
+    if hash_one(branch) == hash_one(parent):
+      ensure_root_checkout()
+
+      logging.debug('branch %s merged to %s', branch, parent)
+
+      for down in downstreams[branch]:
+        if parent in tag_set:
+          set_config('branch.%s.remote', '.')
+          set_config('branch.%s.merge', 'refs/tags/parent')
+          print ('Reparented %s to track %s [tag] (was tracking %s)'
+                 % (down, parent, branch))
+        else:
+          run('branch', '--set-upstream-to', parent, down)
+          print ('Reparented %s to track %s (was tracking %s)'
+                 % (down, parent, branch))
+
+      print run('branch', '-d', branch)
+
+
+def rebase_branch(branch, parent, start_hash):
+  logging.debug('considering %s(%s) -> %s(%s) : %s',
+                branch, hash_one(branch), parent, hash_one(parent), start_hash)
+
+  # If parent has FROZEN commits, don't base branch on top of them. Instead,
+  # base branch on top of whatever commit is before them.
+  back_ups = 0
+  orig_parent = parent
+  while run('log', '-n1', '--format=%s', parent).startswith('FREEZE'):
+    back_ups += 1
+    parent = run('rev-parse', parent+'~')
+
+  if back_ups:
+    logging.debug('Backed parent up by %d from %s to %s',
+                  back_ups, orig_parent, parent)
+
+  if hash_one(parent) != start_hash:
+    # Try a plain rebase first
+    print 'Rebasing:', branch
+    if not rebase(parent, start_hash, branch, abort=True).success:
+      # TODO(iannucci): Find collapsible branches in a smarter way?
+      # Maybe squashing will help?
+      print "Failed! Attempting to squash", branch, "...",
+      squash_branch = branch+"_squash_attempt"
+      run('checkout', '-b', squash_branch)
+      squash_current_branch(merge_base=start_hash)
+
+      # Try to rebase the branch_squash_attempt branch to see if it's empty.
+      squash_ret = rebase(parent, start_hash, squash_branch, abort=True)
+      empty_rebase = hash_one(squash_branch) == hash_one(parent)
+      run('checkout', branch)
+      run('branch', '-D', squash_branch)
+      if squash_ret.success and empty_rebase:
+        print 'Success!'
+        squash_current_branch(merge_base=start_hash)
+        rebase(parent, start_hash, branch)
+      else:
+        # rebase and leave in mid-rebase state.
+
+        # TODO(iannucci): Allow user to mark branch as 'dormant' so that
+        # rebase-update can skip it.
+        rebase(parent, start_hash, branch)
+        print squash_ret.message
+        print 'Failure :('
+        print 'Your working copy is in mid-rebase. Please completely resolve '
+        print 'and run `git rebase-update` again.'
+        sys.exit(1)
+  else:
+    print '%s up-to-date' % branch
+
+  remove_merge_base(branch)
+  get_or_create_merge_base(branch)
+
+
+def main(args=None):
+  try:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--verbose', '-v', action='store_true')
+    opts = parser.parse_args(args)
+
+    if opts.verbose:  # pragma: no cover
+      logging.getLogger().setLevel(logging.DEBUG)
+
+    # TODO(iannucci): snapshot all branches somehow, so we can implement
+    #                 `git rebase-update --undo`.
+    #   * Perhaps just copy packed-refs + refs/ + logs/ to the side?
+    #     * commit them to a secret ref?
+    #       * Then we could view a summary of each run as a
+    #         `diff --stat` on that secret ref.
+
+    check_for_rebase()
+
+    return_branch = find_return_branch()
+
+    if current_branch() == 'HEAD':
+      if run('status', '--porcelain'):
+        print 'Cannot rebase-update with detached head + uncommitted changes.'
+        return 1
+    else:
+      freeze()  # just in case there are any local changes.
+
+    skipped, branch_tree = get_branch_tree()
+    for branch in skipped:
+      print 'Skipping %s: No upstream specified' % branch
+
+    fetch_remotes(branch_tree)
+
+    branch_to_merge_base = {}
+    for branch, parent in branch_tree.iteritems():
+      branch_to_merge_base[branch] = get_or_create_merge_base(branch, parent)
+
+    print 'branch_tree: %s' % pformat(branch_tree)
+    print 'branch_to_merge_base: %s' % pformat(branch_to_merge_base)
+
+    # Rebase each branch starting with the root-most branches and working
+    # towards the leaves.
+    for branch, parent in topo_iter(branch_tree):
+      rebase_branch(branch, parent, branch_to_merge_base[branch])
+
+    remove_empty_branches(branch_tree)
+
+    # return_branch may not be there any more.
+    if return_branch in branches():
+      run('checkout', return_branch)
+      thaw()
+    else:
+      root_branch = root()
+      if return_branch != 'HEAD':
+        print (
+          "%r was merged with its parent, checking out %r instead."
+          % (return_branch, root_branch)
+        )
+      run('checkout', root_branch)
+  except SystemExit as se:
+    return se.code
+
+  return 0
+
+
+if __name__ == '__main__':  # pragma: no cover
+  sys.exit(main(sys.argv[1:]))