sync: superproject performance changes.

After updating all project’s revsionIds with the SHAs from superproject,
write the updated manifest into superproject_override.xml file. Reload
that file for future Reloads. This file is created in exp-superproject
directory.

Moved most of the code that is superproject specific into
git_superproject.py and wrote test code.

If git pull fails, did a git clone of the superproject.

We saw performance gains for consecutive repo sync's. The time to sync
went down from around 120 secs to 40 secs when repo sync is executed
consecutively.

Tested the code with the following commands.

$ ./run_tests -v tests/test_git_superproject.py
$ ./run_tests -v

Tested the sync code by copying all the repo changes into my Android
AOSP checkout and doing a repo sync --use-superproject twice.

First run
$ time repo sync --use-superproject
...
real	21m3.745s
user	97m59.380s
sys	19m11.286s

After two consecutive sync runs
$ time repo sync -c -j8 --use-superproject
real	0m39.626s
user	0m29.937s
sys	0m38.155s

Bug: https://crbug.com/gerrit/13709
Bug: https://crbug.com/gerrit/13707
Tested-by: Raman Tenneti <rtenneti@google.com>

Change-Id: Id79a0d7c4d20babd65e9bd485196c6f8fbe9de5e
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/296082
Reviewed-by: Ian Kasprzak <iankaz@google.com>
Tested-by: Raman Tenneti <rtenneti@google.com>
diff --git a/git_superproject.py b/git_superproject.py
index e2045cf..465d1f8 100644
--- a/git_superproject.py
+++ b/git_superproject.py
@@ -25,8 +25,9 @@
 import os
 import sys
 
-from error import GitError
+from error import BUG_REPORT_URL, GitError
 from git_command import GitCommand
+import platform_utils
 
 
 class Superproject(object):
@@ -46,6 +47,9 @@
     self._repodir = os.path.abspath(repodir)
     self._superproject_dir = superproject_dir
     self._superproject_path = os.path.join(self._repodir, superproject_dir)
+    self._manifest_path = os.path.join(self._superproject_path,
+                                       'superproject_override.xml')
+    self._work_git = os.path.join(self._superproject_path, 'superproject')
 
   @property
   def project_shas(self):
@@ -57,7 +61,7 @@
 
     Args:
       url: superproject's url to be passed to git clone.
-      branch: the branchname to be passed as argument to git clone.
+      branch: The branchname to be passed as argument to git clone.
 
     Returns:
       True if 'git clone <url> <branch>' is successful, or False.
@@ -86,13 +90,12 @@
     Returns:
       True if 'git pull <branch>' is successful, or False.
     """
-    git_dir = os.path.join(self._superproject_path, 'superproject')
-    if not os.path.exists(git_dir):
-      raise GitError('git pull. Missing drectory: %s' % git_dir)
+    if not os.path.exists(self._work_git):
+      raise GitError('git pull missing drectory: %s' % self._work_git)
     cmd = ['pull']
     p = GitCommand(None,
                    cmd,
-                   cwd=git_dir,
+                   cwd=self._work_git,
                    capture_stdout=True,
                    capture_stderr=True)
     retval = p.Wait()
@@ -110,14 +113,13 @@
     Returns:
       data: data returned from 'git ls-tree -r HEAD' instead of None.
     """
-    git_dir = os.path.join(self._superproject_path, 'superproject')
-    if not os.path.exists(git_dir):
-      raise GitError('git ls-tree. Missing drectory: %s' % git_dir)
+    if not os.path.exists(self._work_git):
+      raise GitError('git ls-tree. Missing drectory: %s' % self._work_git)
     data = None
     cmd = ['ls-tree', '-z', '-r', 'HEAD']
     p = GitCommand(None,
                    cmd,
-                   cwd=git_dir,
+                   cwd=self._work_git,
                    capture_stdout=True,
                    capture_stderr=True)
     retval = p.Wait()
@@ -130,22 +132,26 @@
           retval, p.stderr), file=sys.stderr)
     return data
 
-  def GetAllProjectsSHAs(self, url, branch=None):
+  def _GetAllProjectsSHAs(self, url, branch=None):
     """Get SHAs for all projects from superproject and save them in _project_shas.
 
     Args:
-      url: superproject's url to be passed to git clone.
-      branch: the branchname to be passed as argument to git clone.
+      url: superproject's url to be passed to git clone or pull.
+      branch: The branchname to be passed as argument to git clone or pull.
 
     Returns:
       A dictionary with the projects/SHAs instead of None.
     """
     if not url:
       raise ValueError('url argument is not supplied.')
+    do_clone = True
     if os.path.exists(self._superproject_path):
       if not self._Pull():
-        raise GitError('git pull failed for url: %s' % url)
-    else:
+        # If pull fails due to a corrupted git directory, then do a git clone.
+        platform_utils.rmtree(self._superproject_path)
+      else:
+        do_clone = False
+    if do_clone:
       if not self._Clone(url, branch):
         raise GitError('git clone failed for url: %s' % url)
 
@@ -168,3 +174,67 @@
 
     self._project_shas = shas
     return shas
+
+  def _WriteManfiestFile(self, manifest):
+    """Writes manifest to a file.
+
+    Args:
+      manifest: A Manifest object that is to be written to a file.
+
+    Returns:
+      manifest_path: Path name of the file into which manifest is written instead of None.
+    """
+    if not os.path.exists(self._superproject_path):
+      print('error: missing superproject directory %s' %
+            self._superproject_path,
+            file=sys.stderr)
+      return None
+    manifest_str = manifest.ToXml().toxml()
+    manifest_path = self._manifest_path
+    try:
+      with open(manifest_path, 'w', encoding='utf-8') as fp:
+        fp.write(manifest_str)
+    except IOError as e:
+      print('error: cannot write manifest to %s:\n%s'
+            % (manifest_path, e),
+            file=sys.stderr)
+      return None
+    return manifest_path
+
+  def UpdateProjectsRevisionId(self, manifest, projects, url, branch=None):
+    """Update revisionId of every project in projects with the SHA.
+
+    Args:
+      manifest: A Manifest object that is to be written to a file.
+      projects: List of projects whose revisionId needs to be updated.
+      url: superproject's url to be passed to git clone or fetch.
+      branch: The branchname to be passed as argument to git clone or pull.
+
+    Returns:
+      manifest_path: Path name of the overriding manfiest file instead of None.
+    """
+    try:
+      shas = self._GetAllProjectsSHAs(url=url, branch=branch)
+    except Exception as e:
+      print('error: Cannot get project SHAs for %s: %s: %s' %
+            (url, type(e).__name__, str(e)),
+            file=sys.stderr)
+      return None
+
+    projects_missing_shas = []
+    for project in projects:
+      path = project.relpath
+      if not path:
+        continue
+      sha = shas.get(path)
+      if sha:
+        project.SetRevisionId(sha)
+      else:
+        projects_missing_shas.append(path)
+    if projects_missing_shas:
+      print('error: please file a bug using %s to report missing shas for: %s' %
+            (BUG_REPORT_URL, projects_missing_shas), file=sys.stderr)
+      return None
+
+    manifest_path = self._WriteManfiestFile(manifest)
+    return manifest_path
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 225e565..c0f605a 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -56,7 +56,7 @@
 from project import Project
 from project import RemoteSpec
 from command import Command, MirrorSafeCommand
-from error import BUG_REPORT_URL, RepoChangedException, GitError, ManifestParseError
+from error import RepoChangedException, GitError, ManifestParseError
 import platform_utils
 from project import SyncBuffer
 from progress import Progress
@@ -271,6 +271,47 @@
                  dest='repo_upgraded', action='store_true',
                  help=SUPPRESS_HELP)
 
+  def _UpdateProjectsRevisionId(self, opt, args):
+    """Update revisionId of every project with the SHA from superproject.
+
+    This function updates each project's revisionId with SHA from superproject.
+    It writes the updated manifest into a file and reloads the manifest from it.
+
+    Args:
+      opt: Program options returned from optparse.  See _Options().
+      args: Arguments to pass to GetProjects. See the GetProjects
+          docstring for details.
+
+    Returns:
+      Returns path to the overriding manifest file.
+    """
+    if not self.manifest.superproject:
+      print('error: superproject tag is not defined in manifest.xml',
+            file=sys.stderr)
+      sys.exit(1)
+    print('WARNING: --use-superproject is experimental and not '
+          'for general use', file=sys.stderr)
+
+    superproject_url = self.manifest.superproject['remote'].url
+    if not superproject_url:
+      print('error: superproject URL is not defined in manifest.xml',
+            file=sys.stderr)
+      sys.exit(1)
+
+    superproject = git_superproject.Superproject(self.manifest.repodir)
+    all_projects = self.GetProjects(args,
+                                    missing_ok=True,
+                                    submodules_ok=opt.fetch_submodules)
+    manifest_path = superproject.UpdateProjectsRevisionId(self.manifest,
+                                                          all_projects,
+                                                          url=superproject_url)
+    if not manifest_path:
+      print('error: Update of revsionId from superproject has failed',
+            file=sys.stderr)
+      sys.exit(1)
+    self._ReloadManifest(manifest_path)
+    return manifest_path
+
   def _FetchProjectList(self, opt, projects, sem, *args, **kwargs):
     """Main function of the fetch threads.
 
@@ -859,6 +900,9 @@
     else:
       self._UpdateManifestProject(opt, mp, manifest_name)
 
+    if opt.use_superproject:
+      manifest_name = self._UpdateProjectsRevisionId(opt, args)
+
     if self.gitc_manifest:
       gitc_manifest_projects = self.GetProjects(args,
                                                 missing_ok=True)
@@ -898,41 +942,6 @@
                                     missing_ok=True,
                                     submodules_ok=opt.fetch_submodules)
 
-    if opt.use_superproject:
-      if not self.manifest.superproject:
-        print('error: superproject tag is not defined in manifest.xml',
-              file=sys.stderr)
-        sys.exit(1)
-      print('WARNING: --use-superproject is experimental and not '
-            'for general use', file=sys.stderr)
-      superproject_url = self.manifest.superproject['remote'].url
-      if not superproject_url:
-        print('error: superproject URL is not defined in manifest.xml',
-              file=sys.stderr)
-        sys.exit(1)
-      superproject = git_superproject.Superproject(self.manifest.repodir)
-      try:
-        superproject_shas = superproject.GetAllProjectsSHAs(url=superproject_url)
-      except Exception as e:
-        print('error: Cannot get project SHAs for %s: %s: %s' %
-              (superproject_url, type(e).__name__, str(e)),
-              file=sys.stderr)
-        sys.exit(1)
-      projects_missing_shas = []
-      for project in all_projects:
-        path = project.relpath
-        if not path:
-          continue
-        sha = superproject_shas.get(path)
-        if sha:
-          project.SetRevisionId(sha)
-        else:
-          projects_missing_shas.append(path)
-      if projects_missing_shas:
-        print('error: please file a bug using %s to report missing shas for: %s' %
-              (BUG_REPORT_URL, projects_missing_shas), file=sys.stderr)
-        sys.exit(1)
-
     err_network_sync = False
     err_update_projects = False
     err_checkout = False
diff --git a/tests/test_git_superproject.py b/tests/test_git_superproject.py
index 4012ec2..d2c2f50 100644
--- a/tests/test_git_superproject.py
+++ b/tests/test_git_superproject.py
@@ -21,6 +21,7 @@
 
 from error import GitError
 import git_superproject
+import manifest_xml
 import platform_utils
 
 
@@ -31,27 +32,43 @@
     """Set up superproject every time."""
     self.tempdir = tempfile.mkdtemp(prefix='repo_tests')
     self.repodir = os.path.join(self.tempdir, '.repo')
-    os.mkdir(self.repodir)
     self._superproject = git_superproject.Superproject(self.repodir)
+    self.manifest_file = os.path.join(
+        self.repodir, manifest_xml.MANIFEST_FILE_NAME)
+    os.mkdir(self.repodir)
+
+    # The manifest parsing really wants a git repo currently.
+    gitdir = os.path.join(self.repodir, 'manifests.git')
+    os.mkdir(gitdir)
+    with open(os.path.join(gitdir, 'config'), 'w') as fp:
+      fp.write("""[remote "origin"]
+        url = https://localhost:0/manifest
+""")
 
   def tearDown(self):
     """Tear down superproject every time."""
     platform_utils.rmtree(self.tempdir)
 
+  def getXmlManifest(self, data):
+    """Helper to initialize a manifest for testing."""
+    with open(self.manifest_file, 'w') as fp:
+      fp.write(data)
+    return manifest_xml.XmlManifest(self.repodir, self.manifest_file)
+
   def test_superproject_get_project_shas_no_url(self):
     """Test with no url."""
     with self.assertRaises(ValueError):
-      self._superproject.GetAllProjectsSHAs(url=None)
+      self._superproject._GetAllProjectsSHAs(url=None)
 
   def test_superproject_get_project_shas_invalid_url(self):
     """Test with an invalid url."""
     with self.assertRaises(GitError):
-      self._superproject.GetAllProjectsSHAs(url='localhost')
+      self._superproject._GetAllProjectsSHAs(url='localhost')
 
   def test_superproject_get_project_shas_invalid_branch(self):
     """Test with an invalid branch."""
     with self.assertRaises(GitError):
-      self._superproject.GetAllProjectsSHAs(
+      self._superproject._GetAllProjectsSHAs(
           url='sso://android/platform/superproject',
           branch='junk')
 
@@ -59,14 +76,14 @@
     """Test with _Clone failing."""
     with self.assertRaises(GitError):
       with mock.patch.object(self._superproject, '_Clone', return_value=False):
-        self._superproject.GetAllProjectsSHAs(url='localhost')
+        self._superproject._GetAllProjectsSHAs(url='localhost')
 
   def test_superproject_get_project_shas_mock_pull(self):
     """Test with _Pull failing."""
     with self.assertRaises(GitError):
       with mock.patch.object(self._superproject, '_Clone', return_value=True):
         with mock.patch.object(self._superproject, '_Pull', return_value=False):
-          self._superproject.GetAllProjectsSHAs(url='localhost')
+          self._superproject._GetAllProjectsSHAs(url='localhost')
 
   def test_superproject_get_project_shas_mock_ls_tree(self):
     """Test with LsTree being a mock."""
@@ -77,13 +94,71 @@
             '160000 commit ade9b7a0d874e25fff4bf2552488825c6f111928\tbuild/bazel\x00')
     with mock.patch.object(self._superproject, '_Clone', return_value=True):
       with mock.patch.object(self._superproject, '_LsTree', return_value=data):
-        shas = self._superproject.GetAllProjectsSHAs(url='localhost', branch='junk')
+        shas = self._superproject._GetAllProjectsSHAs(url='localhost', branch='junk')
         self.assertEqual(shas, {
             'art': '2c2724cb36cd5a9cec6c852c681efc3b7c6b86ea',
             'bootable/recovery': 'e9d25da64d8d365dbba7c8ee00fe8c4473fe9a06',
             'build/bazel': 'ade9b7a0d874e25fff4bf2552488825c6f111928'
         })
 
+  def test_superproject_write_manifest_file(self):
+    """Test with writing manifest to a file after setting revisionId."""
+    manifest = self.getXmlManifest("""
+<manifest>
+  <remote name="default-remote" fetch="http://localhost" />
+  <default remote="default-remote" revision="refs/heads/main" />
+  <project name="test-name"/>
+</manifest>
+""")
+    self.assertEqual(len(manifest.projects), 1)
+    project = manifest.projects[0]
+    project.SetRevisionId('ABCDEF')
+    # Create temporary directory so that it can write the file.
+    os.mkdir(self._superproject._superproject_path)
+    manifest_path = self._superproject._WriteManfiestFile(manifest)
+    self.assertIsNotNone(manifest_path)
+    with open(manifest_path, 'r') as fp:
+      manifest_xml = fp.read()
+    self.assertEqual(
+        manifest_xml,
+        '<?xml version="1.0" ?><manifest>' +
+        '<remote name="default-remote" fetch="http://localhost"/>' +
+        '<default remote="default-remote" revision="refs/heads/main"/>' +
+        '<project name="test-name" revision="ABCDEF"/>' +
+        '</manifest>')
+
+  def test_superproject_update_project_revision_id(self):
+    """Test with LsTree being a mock."""
+    manifest = self.getXmlManifest("""
+<manifest>
+  <remote name="default-remote" fetch="http://localhost" />
+  <default remote="default-remote" revision="refs/heads/main" />
+  <project path="art" name="platform/art" />
+</manifest>
+""")
+    self.assertEqual(len(manifest.projects), 1)
+    projects = manifest.projects
+    data = ('160000 commit 2c2724cb36cd5a9cec6c852c681efc3b7c6b86ea\tart\x00'
+            '160000 commit e9d25da64d8d365dbba7c8ee00fe8c4473fe9a06\tbootable/recovery\x00')
+    with mock.patch.object(self._superproject, '_Clone', return_value=True):
+      with mock.patch.object(self._superproject, '_Pull', return_value=True):
+        with mock.patch.object(self._superproject, '_LsTree', return_value=data):
+          # Create temporary directory so that it can write the file.
+          os.mkdir(self._superproject._superproject_path)
+          manifest_path = self._superproject.UpdateProjectsRevisionId(
+              manifest, projects, url='localhost')
+          self.assertIsNotNone(manifest_path)
+          with open(manifest_path, 'r') as fp:
+            manifest_xml = fp.read()
+          self.assertEqual(
+              manifest_xml,
+              '<?xml version="1.0" ?><manifest>' +
+              '<remote name="default-remote" fetch="http://localhost"/>' +
+              '<default remote="default-remote" revision="refs/heads/main"/>' +
+              '<project name="platform/art" path="art" ' +
+              'revision="2c2724cb36cd5a9cec6c852c681efc3b7c6b86ea"/>' +
+              '</manifest>')
+
 
 if __name__ == '__main__':
   unittest.main()