git_cl: add GitNumbererState in preparation to stop gnumbd service.

The new class is unused and doesn't change any existing functionality.

BUG=chromium:642493
R=machenbach@chromium.org,iannucci@chromium.org

Change-Id: Id3fe71b07b694339f0a620b427816e52560069d8
Reviewed-on: https://chromium-review.googlesource.com/416430Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>

git_cl.py

@@ -13,6 +13,7 @@ from distutils.version import LooseVersion
 from multiprocessing.pool import ThreadPool
 import base64
 import collections
+import fnmatch
 import httplib
 import json
 import logging
@@ -22,6 +23,7 @@ import os
 import re
 import stat
 import sys
+import tempfile
 import textwrap
 import traceback
 import urllib
@@ -1039,6 +1041,129 @@ def ShouldGenerateGitNumberFooters():
   return keyvals.get('GENERATE_GIT_NUMBER_FOOTERS', '').lower() == 'true'
 
 
+class _GitNumbererState(object):
+  KNOWN_PROJECTS_WHITELIST = [
+      'chromium/src',
+      'external/webrtc',
+      'v8/v8',
+  ]
+
+  @classmethod
+  def load(cls, remote_url, remote_ref):
+    """Figures out the state by fetching special refs from remote repo.
+    """
+    assert remote_ref and remote_ref.startswith('refs/'), remote_ref
+    url_parts = urlparse.urlparse(remote_url)
+    project_name = url_parts.path.lstrip('/').rstrip('git./')
+    for known in cls.KNOWN_PROJECTS_WHITELIST:
+      if project_name.endswith(known):
+        break
+    else:
+      # Early exit to avoid extra fetches for repos that aren't using gnumbd.
+      return cls(cls._get_pending_prefix_fallback(), None)
+
+    # This pollutes local ref space, but the amount of objects is neglible.
+    error, _ = cls._run_git_with_code([
+        'fetch', remote_url,
+        '+refs/meta/config:refs/git_cl/meta/config',
+        '+refs/gnumbd-config/main:refs/git_cl/gnumbd-config/main'])
+    if error:
+      # Some ref doesn't exist or isn't accessible to current user.
+      # This shouldn't happen on production KNOWN_PROJECTS_WHITELIST
+      # with git-numberer.
+      cls._warn('failed to fetch gnumbd and project config for %s: %s',
+                remote_url, error)
+      return cls(cls._get_pending_prefix_fallback(), None)
+    return cls(cls._get_pending_prefix(remote_ref),
+               cls._is_validator_enabled(remote_ref))
+
+  @classmethod
+  def _get_pending_prefix(cls, ref):
+    error, gnumbd_config_data = cls._run_git_with_code(
+        ['show', 'refs/git_cl/gnumbd-config/main:config.json'])
+    if error:
+      cls._warn('gnumbd config file not found')
+      return cls._get_pending_prefix_fallback()
+
+    try:
+      config = json.loads(gnumbd_config_data)
+      if cls.match_refglobs(ref, config['enabled_refglobs']):
+        return config['pending_ref_prefix']
+      return None
+    except KeyboardInterrupt:
+      raise
+    except Exception as e:
+      cls._warn('failed to parse gnumbd config: %s', e)
+      return cls._get_pending_prefix_fallback()
+
+  @staticmethod
+  def _get_pending_prefix_fallback():
+    global settings
+    if not settings:
+      settings = Settings()
+    return settings.GetPendingRefPrefix()
+
+  @classmethod
+  def _is_validator_enabled(cls, ref):
+    error, project_config_data = cls._run_git_with_code(
+        ['show', 'refs/git_cl/meta/config:project.config'])
+    if error:
+      cls._warn('project.config file not found')
+      return False
+    # Gerrit's project.config is really a git config file.
+    # So, parse it as such.
+    with tempfile.NamedTemporaryFile(prefix='git_cl_proj_config') as f:
+      f.write(project_config_data)
+      # Make sure OS sees this, but don't close the file just yet,
+      # as NamedTemporaryFile deletes it on closing.
+      f.flush()
+
+      def get_opts(x):
+        code, out = cls._run_git_with_code(
+            ['config', '-f', f.name, '--get-all',
+             'plugin.git-numberer.validate-%s-refglob' % x])
+        if code == 0:
+          return out.strip().splitlines()
+        return []
+      enabled, disabled = map(get_opts, ['enabled', 'disabled'])
+
+    if cls.match_refglobs(ref, disabled):
+      return False
+    return cls.match_refglobs(ref, enabled)
+
+  @staticmethod
+  def match_refglobs(ref, refglobs):
+    for refglob in refglobs:
+      if ref == refglob or fnmatch.fnmatch(ref, refglob):
+        return True
+    return False
+
+  @staticmethod
+  def _run_git_with_code(*args, **kwargs):
+    # The only reason for this wrapper is easy porting of this code to CQ
+    # codebase, which forked git_cl.py and checkouts.py long time ago.
+    return RunGitWithCode(*args, **kwargs)
+
+  @staticmethod
+  def _warn(msg, *args):
+    if args:
+      msg = msg % args
+    print('WARNING: %s' % msg)
+
+  def __init__(self, pending_prefix, validator_enabled):
+    # TODO(tandrii): remove pending_prefix after gnumbd is no more.
+    self._pending_prefix = pending_prefix or None
+    self._validator_enabled = validator_enabled or False
+
+  @property
+  def pending_prefix(self):
+    return self._pending_prefix
+
+  @property
+  def should_git_number(self):
+    return self._validator_enabled and self._pending_prefix is None
+
+
 def ShortBranchName(branch):
   """Convert a name like 'refs/heads/foo' to just 'foo'."""
   return branch.replace('refs/heads/', '', 1)

tests/git_cl_test.py

@@ -5,6 +5,7 @@
 
 """Unit tests for git_cl.py."""
 
+import contextlib
 import json
 import os
 import StringIO
@@ -1165,6 +1166,108 @@ class TestGitCl(TestCase):
     self.mock(git_cl, 'FindCodereviewSettingsFile', lambda: None)
     self.assertFalse(git_cl.ShouldGenerateGitNumberFooters())
 
+  def test_GitNumbererState_not_whitelisted_repo(self):
+    self.calls = [
+        ((['git', 'config', 'rietveld.autoupdate'],), CERR1),
+        ((['git', 'config', 'rietveld.pending-ref-prefix'],), CERR1),
+    ]
+    res = git_cl._GitNumbererState.load(
+        remote_url='https://chromium.googlesource.com/chromium/tools/build',
+        remote_ref='refs/whatever')
+    self.assertEqual(res.pending_prefix, None)
+    self.assertEqual(res.should_git_number, False)
+
+  def test_GitNumbererState_fail_fetch(self):
+    self.mock(git_cl.sys, 'stdout', StringIO.StringIO())
+    self.calls = [
+        ((['git', 'fetch', 'https://chromium.googlesource.com/chromium/src',
+           '+refs/meta/config:refs/git_cl/meta/config',
+           '+refs/gnumbd-config/main:refs/git_cl/gnumbd-config/main'],), CERR1),
+        ((['git', 'config', 'rietveld.autoupdate'],), CERR1),
+        ((['git', 'config', 'rietveld.pending-ref-prefix'],),
+         'refs/pending-prefix'),
+    ]
+    res = git_cl._GitNumbererState.load(
+        remote_url='https://chromium.googlesource.com/chromium/src',
+        remote_ref='refs/whatever')
+    self.assertEqual(res.pending_prefix, 'refs/pending-prefix')
+    self.assertEqual(res.should_git_number, False)
+
+  def test_GitNumbererState_fail_gnumbd_and_validator(self):
+    self.mock(git_cl.sys, 'stdout', StringIO.StringIO())
+    self.calls = [
+        ((['git', 'fetch', 'https://chromium.googlesource.com/chromium/src',
+           '+refs/meta/config:refs/git_cl/meta/config',
+           '+refs/gnumbd-config/main:refs/git_cl/gnumbd-config/main'],), ''),
+        ((['git', 'show', 'refs/git_cl/gnumbd-config/main:config.json'],),
+         'ba d conig'),
+        ((['git', 'config', 'rietveld.autoupdate'],), CERR1),
+        ((['git', 'config', 'rietveld.pending-ref-prefix'],), CERR1),
+        ((['git', 'show', 'refs/git_cl/meta/config:project.config'],), CERR1),
+    ]
+    res = git_cl._GitNumbererState.load(
+        remote_url='https://chromium.googlesource.com/chromium/src',
+        remote_ref='refs/whatever')
+    self.assertEqual(res.pending_prefix, None)
+    self.assertEqual(res.should_git_number, False)
+
+  def test_GitNumbererState_valid_configs(self):
+    class NamedTempFileStab(StringIO.StringIO):
+      @classmethod
+      @contextlib.contextmanager
+      def create(cls, *_, **__):
+        yield cls()
+      name = 'tempfile'
+    self.mock(git_cl.tempfile, 'NamedTemporaryFile', NamedTempFileStab.create)
+    self.calls = [
+        ((['git', 'fetch', 'https://chromium.googlesource.com/chromium/src',
+           '+refs/meta/config:refs/git_cl/meta/config',
+           '+refs/gnumbd-config/main:refs/git_cl/gnumbd-config/main'],), ''),
+        ((['git', 'show', 'refs/git_cl/gnumbd-config/main:config.json'],),
+         '''{
+              "pending_tag_prefix": "refs/pending-tags",
+              "pending_ref_prefix": "refs/pending",
+              "enabled_refglobs": [
+                "refs/heads/m*"
+              ]
+            }
+         '''),
+        ((['git', 'show', 'refs/git_cl/meta/config:project.config'],),
+         '''
+          [plugin "git-numberer"]
+            validate-enabled-refglob = refs/else/*
+            validate-enabled-refglob = refs/heads/*
+            validate-disabled-refglob = refs/heads/disabled
+            validate-disabled-refglob = refs/branch-heads/*
+         '''),
+        ((['git', 'config', '-f', 'tempfile', '--get-all',
+           'plugin.git-numberer.validate-enabled-refglob'],),
+         'refs/else/*\n'
+         'refs/heads/*\n'),
+        ((['git', 'config', '-f', 'tempfile', '--get-all',
+           'plugin.git-numberer.validate-disabled-refglob'],),
+         'refs/heads/disabled\n'
+         'refs/branch-heads/*\n'),
+    ] * 3  # 3 tests below have exactly same IO.
+
+    res = git_cl._GitNumbererState.load(
+        remote_url='https://chromium.googlesource.com/chromium/src',
+        remote_ref='refs/heads/master')
+    self.assertEqual(res.pending_prefix, 'refs/pending')
+    self.assertEqual(res.should_git_number, False)
+
+    res = git_cl._GitNumbererState.load(
+        remote_url='https://chromium.googlesource.com/chromium/src',
+        remote_ref='refs/heads/test')
+    self.assertEqual(res.pending_prefix, None)
+    self.assertEqual(res.should_git_number, True)
+
+    res = git_cl._GitNumbererState.load(
+        remote_url='https://chromium.googlesource.com/chromium/src',
+        remote_ref='refs/heads/disabled')
+    self.assertEqual(res.pending_prefix, None)
+    self.assertEqual(res.should_git_number, False)
+
   @classmethod
   def _gerrit_ensure_auth_calls(cls, issue=None, skip_auth_check=False):
     cmd = ['git', 'config', '--bool', 'gerrit.skip-ensure-authenticated']