Add a --squash option to Gerrit uploads.

This makes uploading to Gerrit with `git cl` more similar to uploading to Rietveld, by uploading a squashed commit containing the diff to the newest common ancestor.

Uploaded commits are stored in refs/heads/git_cl_uploads/<branch> (and their commit message is used for the squash commit), which allows amending the commit message to change it on the uploaded CL, and looking through the reflog to find old uploaded versions.

BUG=none

Review URL: https://codereview.chromium.org/200023004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@294077 0039d316-1c4b-4281-b951-d872f2087c98

git_cl.py

@@ -18,6 +18,7 @@ import Queue
 import re
 import stat
 import sys
+import tempfile
 import textwrap
 import threading
 import urllib2
@@ -113,6 +114,11 @@ def RunGitWithCode(args, suppress_stderr=False):
     return 1, ''
 
 
+def RunGitSilent(args):
+  """Returns stdout, suppresses stderr and ingores the return code."""
+  return RunGitWithCode(args, suppress_stderr=True)[1]
+
+
 def IsGitVersionAtLeast(min_version):
   prefix = 'git version '
   version = RunGit(['--version']).strip()
@@ -1633,7 +1639,7 @@ def GerritUpload(options, args, cl, change):
   """upload the current branch to gerrit."""
   # We assume the remote called "origin" is the one we want.
   # It is probably not worthwhile to support different workflows.
-  remote = 'origin'
+  gerrit_remote = 'origin'
   branch = 'master'
   if options.target_branch:
     branch = options.target_branch
@@ -1643,15 +1649,72 @@ def GerritUpload(options, args, cl, change):
   if not change_desc.description:
     print "Description is empty; aborting."
     return 1
-  if CHANGE_ID not in change_desc.description:
-    AddChangeIdToCommitMessage(options, args)
 
-  commits = RunGit(['rev-list', '%s/%s..' % (remote, branch)]).splitlines()
+  if options.squash:
+    # Try to get the message from a previous upload.
+    shadow_branch = 'refs/heads/git_cl_uploads/' + cl.GetBranch()
+    message = RunGitSilent(['show', '--format=%s\n\n%b', '-s', shadow_branch])
+    if not message:
+      if not options.force:
+        change_desc.prompt()
+
+      if CHANGE_ID not in change_desc.description:
+        # Run the commit-msg hook without modifying the head commit by writing
+        # the commit message to a temporary file and running the hook over it,
+        # then reading the file back in.
+        commit_msg_hook = os.path.join(settings.GetRoot(), '.git', 'hooks',
+                                       'commit-msg')
+        file_handle, msg_file = tempfile.mkstemp(text=True,
+                                                 prefix='commit_msg')
+        try:
+          try:
+            with os.fdopen(file_handle, 'w') as fileobj:
+              fileobj.write(change_desc.description)
+          finally:
+            os.close(file_handle)
+            RunCommand([commit_msg_hook, msg_file])
+            change_desc.set_description(gclient_utils.FileRead(msg_file))
+        finally:
+          os.remove(msg_file)
+
+      if not change_desc.description:
+        print "Description is empty; aborting."
+        return 1
+
+      message = change_desc.description
+
+    remote, upstream_branch = cl.FetchUpstreamTuple(cl.GetBranch())
+    if remote is '.':
+      # If our upstream branch is local, we base our squashed commit on its
+      # squashed version.
+      parent = ('refs/heads/git_cl_uploads/' +
+                scm.GIT.ShortBranchName(upstream_branch))
+
+      # Verify that the upstream branch has been uploaded too, otherwise Gerrit
+      # will create additional CLs when uploading.
+      if (RunGitSilent(['rev-parse', upstream_branch + ':']) !=
+          RunGitSilent(['rev-parse', parent + ':'])):
+        print 'Upload upstream branch ' + upstream_branch + ' first.'
+        return 1
+    else:
+      parent = cl.GetCommonAncestorWithUpstream()
+
+    tree = RunGit(['rev-parse', 'HEAD:']).strip()
+    ref_to_push = RunGit(['commit-tree', tree, '-p', parent,
+                          '-m', message]).strip()
+  else:
+    if CHANGE_ID not in change_desc.description:
+      AddChangeIdToCommitMessage(options, args)
+    ref_to_push = 'HEAD'
+    parent = '%s/%s' % (gerrit_remote, branch)
+
+  commits = RunGitSilent(['rev-list', '%s..%s' % (parent,
+                                                  ref_to_push)]).splitlines()
   if len(commits) > 1:
     print('WARNING: This will upload %d commits. Run the following command '
           'to see which commits will be uploaded: ' % len(commits))
-    print('git log %s/%s..' % (remote, branch))
+    print('git log %s..%s' % (parent, ref_to_push))
-    print('You can also use `git squash-branch` to squash these into a single'
+    print('You can also use `git squash-branch` to squash these into a single '
           'commit.')
     ask_for_data('About to upload; enter to confirm.')
 
@@ -1673,8 +1736,13 @@ def GerritUpload(options, args, cl, change):
   if receive_options:
     git_command.append('--receive-pack=git receive-pack %s' %
                        ' '.join(receive_options))
-  git_command += [remote, 'HEAD:refs/for/' + branch]
+  git_command += [gerrit_remote, ref_to_push + ':refs/for/' + branch]
   RunGit(git_command)
+
+  if options.squash:
+    head = RunGit(['rev-parse', 'HEAD']).strip()
+    RunGit(['update-ref', '-m', 'Uploaded ' + head, shadow_branch, ref_to_push])
+
   # TODO(ukai): parse Change-Id: and set issue number?
   return 0
 
@@ -1896,6 +1964,8 @@ def CMDupload(parser, args):
                     metavar='TARGET',
                     help='Apply CL to remote ref TARGET.  ' +
                          'Default: remote branch head, or master')
+  parser.add_option('--squash', action='store_true',
+                    help='Squash multiple commits into one (Gerrit only)')
   parser.add_option('--email', default=None,
                     help='email address to use to connect to Rietveld')
   parser.add_option('--tbr-owners', dest='tbr_owners', action='store_true',

tests/git_cl_test.py

@@ -571,7 +571,7 @@ class TestGitCl(TestCase):
         ]
 
   @staticmethod
-  def _gerrit_upload_calls(description, reviewers):
+  def _gerrit_upload_calls(description, reviewers, squash):
     calls = [
         ((['git', 'config', 'gerrit.host'],),
          'gerrit.example.com'),
@@ -590,8 +590,29 @@ class TestGitCl(TestCase):
              'fake_ancestor_sha..HEAD'],),
            description)
           ]
+    if squash:
+      ref_to_push = 'abcdef0123456789'
+      calls += [
+          ((['git', 'show', '--format=%s\n\n%b', '-s',
+            'refs/heads/git_cl_uploads/master'],),
+           (description, 0)),
+          ((['git', 'config', 'branch.master.merge'],),
+           'refs/heads/master'),
+          ((['git', 'config', 'branch.master.remote'],),
+           'origin'),
+          ((['get_or_create_merge_base', 'master', 'master'],),
+           'origin/master'),
+          ((['git', 'rev-parse', 'HEAD:'],),
+           '0123456789abcdef'),
+          ((['git', 'commit-tree', '0123456789abcdef', '-p',
+             'origin/master', '-m', 'd'],),
+           ref_to_push),
+          ]
+    else:
+      ref_to_push = 'HEAD'
+
     calls += [
-        ((['git', 'rev-list', 'origin/master..'],), ''),
+        ((['git', 'rev-list', 'origin/master..' + ref_to_push],), ''),
         ((['git', 'config', 'rietveld.cc'],), '')
         ]
     receive_pack = '--receive-pack=git receive-pack '
@@ -603,19 +624,28 @@ class TestGitCl(TestCase):
     receive_pack += ''
     calls += [
         ((['git',
-           'push', receive_pack, 'origin', 'HEAD:refs/for/master'],),
+           'push', receive_pack, 'origin', ref_to_push + ':refs/for/master'],),
          '')
         ]
+    if squash:
+      calls += [
+          ((['git', 'rev-parse', 'HEAD'],), 'abcdef0123456789'),
+          ((['git', 'update-ref', '-m', 'Uploaded abcdef0123456789',
+            'refs/heads/git_cl_uploads/master', 'abcdef0123456789'],),
+           '')
+          ]
+
     return calls
 
   def _run_gerrit_upload_test(
       self,
       upload_args,
       description,
-      reviewers):
+      reviewers,
+      squash=False):
     """Generic gerrit upload test framework."""
     self.calls = self._gerrit_base_calls()
-    self.calls += self._gerrit_upload_calls(description, reviewers)
+    self.calls += self._gerrit_upload_calls(description, reviewers, squash)
     git_cl.main(['upload'] + upload_args)
 
   def test_gerrit_upload_without_change_id(self):
@@ -643,6 +673,12 @@ class TestGitCl(TestCase):
         'Change-Id:123456789\n',
         ['reviewer@example.com', 'another@example.com'])
 
+  def test_gerrit_upload_squash(self):
+    self._run_gerrit_upload_test(
+        ['--squash'],
+        'desc\n\nBUG=\nChange-Id:123456789\n',
+        [],
+        squash=True)
 
   def test_config_gerrit_download_hook(self):
     self.mock(git_cl, 'FindCodereviewSettingsFile', CodereviewSettingsFileMock)