Implement git-drover.

git_common.py

 # Copyright 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.
 
 # Monkeypatch IMapIterator so that Ctrl-C can kill everything properly.
 # Derived from https://gist.github.com/aljungberg/626518
 import multiprocessing.pool
 from multiprocessing.pool import IMapIterator
 def wrapper(func):
   def wrap(self, timeout=None):
@@ skipping 12 matching lines @@
 import os
 import re
 import signal
 import sys
 import tempfile
 import textwrap
 import threading
 
 import subprocess2
 
+import git_cache
+
 
 GIT_EXE = 'git.bat' if sys.platform.startswith('win') else 'git'
 TEST_MODE = False
 
 FREEZE = 'FREEZE'
 FREEZE_SECTIONS = {
   'indexed': 'soft',
   'unindexed': 'mixed'
 }
 FREEZE_MATCHER = re.compile(r'%s.(%s)' % (FREEZE, '|'.join(FREEZE_SECTIONS)))
@@ skipping 165 matching lines @@
     with self._dead_cond:
       self._dead_cond.notifyAll()
     self._thread.join()
     del self._thread
 
 
 def once(function):
   """@Decorates |function| so that it only performs its action once, no matter
   how many times the decorated |function| is called."""
   def _inner_gen():
-    yield function()
+    ret = function()
+    yield ret
     while True:
-      yield
+      yield ret
   return _inner_gen().next
 
 
 ## Git functions
 
 
 def branch_config(branch, option, default=None):
   return config('branch.%s.%s' % (branch, option), default=default)
 
 
@@ skipping 37 matching lines @@
 
 def run_with_retcode(*cmd, **kwargs):
   """Run a command but only return the status code."""
   try:
     run(*cmd, **kwargs)
     return 0
   except subprocess2.CalledProcessError as cpe:
     return cpe.returncode
 
 
+def cached_fetch(commits):
+  m = git_cache.Mirror.from_repo('.')
+  if m:
+    m.populate(fetch_specs=commits)
+  else:
+    for commit in commits:
+      run('fetch', 'origin', commit)
+
+
+def check(*args, **kwargs):
+  try:
+    run(*args, **kwargs)
+    return True
+  except subprocess2.CalledProcessError:
+    return False
+
+
 def config(option, default=None):
   try:
     return run('config', '--get', option) or default
   except subprocess2.CalledProcessError:
     return default
 
 
 def config_list(option):
   try:
     return run('config', '--get-all', option).split()
@@ skipping 80 matching lines @@
     else:
       logging.debug('Found pre-set merge-base for %s: %s', branch, base)
 
   if not base:
     base = actual_merge_base
     manual_merge_base(branch, base)
 
   return base
 
 
+def get_remote_url(remote):
+  m = git_cache.Mirror.from_repo('.')
+  if m:
+    return m.url
+
+  return config('remote.%s.url' % remote)
+
+
 def hash_multi(*reflike):
   return run('rev-parse', *reflike).splitlines()
 
 
 def hash_one(reflike):
   return run('rev-parse', reflike)
 
 
 def in_rebase():
   git_dir = run('rev-parse', '--git-dir')
@@ skipping 117 matching lines @@
   Returns (stdout, stderr) as a pair of strings.
 
   kwargs
     autostrip (bool) - Strip the output. Defaults to True.
     indata (str) - Specifies stdin data for the process.
   """
   kwargs.setdefault('stdin', subprocess2.PIPE)
   kwargs.setdefault('stdout', subprocess2.PIPE)
   kwargs.setdefault('stderr', subprocess2.PIPE)
   autostrip = kwargs.pop('autostrip', True)
+  verbose = kwargs.pop('verbose', False)
   indata = kwargs.pop('indata', None)
 
   cmd = (GIT_EXE, '-c', 'color.ui=never') + cmd
+  if verbose:
+    print "running `%s`" % (cmd,)
   proc = subprocess2.Popen(cmd, **kwargs)
   ret, err = proc.communicate(indata)
   retcode = proc.wait()
   if retcode != 0:
     raise subprocess2.CalledProcessError(retcode, cmd, os.getcwd(), ret, err)
 
   if autostrip:
     ret = (ret or '').strip()
     err = (err or '').strip()
 
@@ skipping 122 matching lines @@
     return None
   return ret
 
 
 def upstream(branch):
   try:
     return run('rev-parse', '--abbrev-ref', '--symbolic-full-name',
                branch+'@{upstream}')
   except subprocess2.CalledProcessError:
     return None
+
+
+def verify_commit(commit):
+  return check('rev-parse', '--quiet', '--verify', '%s^{commit}' % commit)