Refactor infra git libs and testing.

infra/services/gnumbd/support/git.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.
-import collections
-import fnmatch
-import logging
-import os
-import subprocess
-import sys
-import tempfile
-import urlparse
-
-from infra.services.gnumbd.support.util import (
-    cached_property, CalledProcessError)
-
-from infra.services.gnumbd.support.data import CommitData
-
-LOGGER = logging.getLogger(__name__)
-
-
-class _Invalid(object):
-  def __call__(self, *_args, **_kwargs):
-    return self
-
-  def __getattr__(self, _key):
-    return self
-
-  def __eq__(self, _other):
-    return False
-
-  def __ne__(self, _other):  # pylint: disable=R0201
-    return True
-
-INVALID = _Invalid()
-
-
-class Repo(object):
-  """Represents a remote git repo.
-
-  Manages the (bare) on-disk mirror of the remote repo.
-  """
-  MAX_CACHE_SIZE = 1024
-
-  def __init__(self, url):
-    self.dry_run = False
-    self.repos_dir = None
-
-    self._url = url
-    self._repo_path = None
-    self._commit_cache = collections.OrderedDict()
-    self._log = LOGGER.getChild('Repo')
-
-  def reify(self):
-    """Ensures the local mirror of this Repo exists."""
-    assert self.repos_dir is not None
-    parsed = urlparse.urlparse(self._url)
-    norm_url = parsed.netloc + parsed.path
-    if norm_url.endswith('.git'):
-      norm_url = norm_url[:-len('.git')]
-    folder = norm_url.replace('-', '--').replace('/', '-').lower()
-
-    rpath = os.path.abspath(os.path.join(self.repos_dir, folder))
-    if not os.path.isdir(rpath):
-      self._log.debug('initializing %r -> %r', self, rpath)
-      name = tempfile.mkdtemp(dir=self.repos_dir)
-      self.run('clone', '--mirror', self._url, os.path.basename(name),
-               stdout=sys.stdout, stderr=sys.stderr, cwd=self.repos_dir)
-      os.rename(os.path.join(self.repos_dir, name),
-                os.path.join(self.repos_dir, folder))
-    else:
-      self._log.debug('%r already initialized', self)
-    self._repo_path = rpath
-
-    # This causes pushes to fail, so unset it.
-    self.run('config', '--unset', 'remote.origin.mirror', ok_ret={0, 5})
-
-  # Representation
-  def __repr__(self):
-    return 'Repo({_url!r})'.format(**self.__dict__)
-
-  # Methods
-  def get_commit(self, hsh):
-    """Creates a new |Commit| object for this |Repo|.
-
-    Uses a very basic LRU cache for commit objects, keeping up to
-    |MAX_CACHE_SIZE| before eviction. This cuts down on the number of redundant
-    git commands by > 50%, and allows expensive cached_property's to remain
-    for the life of the process.
-    """
-    if hsh in self._commit_cache:
-      self._log.debug('Hit %s', hsh)
-      r = self._commit_cache.pop(hsh)
-    else:
-      self._log.debug('Miss %s', hsh)
-      if len(self._commit_cache) >= self.MAX_CACHE_SIZE:
-        self._commit_cache.popitem(last=False)
-      r = Commit(self, hsh)
-
-    self._commit_cache[hsh] = r
-    return r
-
-  def refglob(self, globstring):
-    """Yield every Ref in this repo which matches |globstring|."""
-    for _, ref in (l.split() for l in self.run('show-ref').splitlines()):
-      if fnmatch.fnmatch(ref, globstring):
-        yield Ref(self, ref)
-
-  def run(self, *args, **kwargs):
-    """Yet-another-git-subprocess-wrapper.
-
-    Args: argv tokens. 'git' is always argv[0]
-
-    Kwargs:
-      indata - String data to feed to communicate()
-      ok_ret - A set() of valid return codes. Defaults to {0}.
-      ...    - passes through to subprocess.Popen()
-    """
-    if args[0] == 'push' and self.dry_run:
-      self._log.warn('DRY-RUN: Would have pushed %r', args[1:])
-      return
-
-    if not 'cwd' in kwargs:
-      assert self._repo_path is not None
-      kwargs.setdefault('cwd', self._repo_path)
-
-    kwargs.setdefault('stderr', subprocess.PIPE)
-    kwargs.setdefault('stdout', subprocess.PIPE)
-    indata = kwargs.pop('indata', None)
-    if indata:
-      assert 'stdin' not in kwargs
-      kwargs['stdin'] = subprocess.PIPE
-    ok_ret = kwargs.pop('ok_ret', {0})
-    cmd = ('git',) + args
-
-    self._log.debug('Running %r', cmd)
-    process = subprocess.Popen(cmd, **kwargs)
-    output, errout = process.communicate(indata)
-    retcode = process.poll()
-    if retcode not in ok_ret:
-      raise CalledProcessError(retcode, cmd, output, errout)
-
-    if errout:
-      sys.stderr.write(errout)
-    return output
-
-  def intern(self, data, typ='blob'):
-    return self.run(
-        'hash-object', '-w', '-t', typ, '--stdin', indata=str(data)).strip()
-
-
-class Commit(object):
-  """Represents the identity of a commit in a git repo."""
-
-  def __init__(self, repo, hsh):
-    """
-    @type repo: Repo
-    """
-    assert CommitData.HASH_RE.match(hsh)
-    self._repo = repo
-    self._hsh = hsh
-
-  # Comparison & Representation
-  def __eq__(self, other):
-    return (self is other) or (
-        isinstance(other, Commit) and (
-            self.hsh == other.hsh
-        )
-    )
-
-  def __ne__(self, other):
-    return not (self == other)
-
-  def __repr__(self):
-    return 'Commit({_repo!r}, {_hsh!r})'.format(**self.__dict__)
-
-  # Accessors
-  # pylint: disable=W0212
-  repo = property(lambda self: self._repo)
-  hsh = property(lambda self: self._hsh)
-
-  # Properties
-  @cached_property
-  def data(self):
-    """Get a structured data representation of this commit."""
-    try:
-      raw_data = self.repo.run('cat-file', 'commit', self.hsh)
-    except CalledProcessError:
-      return INVALID
-    return CommitData.from_raw(raw_data)
-
-  @cached_property
-  def parent(self):
-    """Get the corresponding parent Commit() for this Commit(), or None.
-
-    If self has more than one parent, this raises an Exception.
-    """
-    parents = self.data.parents
-    if len(parents) > 1:
-      LOGGER.error('Commit %r has more than one parent!', self.hsh)
-      return INVALID
-    return self.repo.get_commit(parents[0]) if parents else None
-
-  # Methods
-  def alter(self, **kwargs):
-    """Get a new Commit which is the same as this one, except for alterations
-    specified by kwargs.
-
-    This will intern the new Commit object into the Repo.
-    """
-    return self.repo.get_commit(
-        self.repo.intern(self.data.alter(**kwargs), 'commit'))
-
-
-class Ref(object):
-  """Represents a single simple ref in a git Repo."""
-  def __init__(self, repo, ref_str):
-    """
-    @type repo: Repo
-    @type ref_str: str
-    """
-    self._repo = repo
-    self._ref = ref_str
-
-  # Comparison & Representation
-  def __eq__(self, other):
-    return (self is other) or (
-        isinstance(other, Ref) and (
-            self.ref == other.ref and
-            self.repo is other.repo
-        )
-    )
-
-  def __ne__(self, other):
-    return not (self == other)
-
-  def __repr__(self):
-    return 'Ref({_repo!r}, {_ref!r})'.format(**self.__dict__)
-
-  # Accessors
-  # pylint: disable=W0212
-  repo = property(lambda self: self._repo)
-  ref = property(lambda self: self._ref)
-
-  # Properties
-  @property
-  def commit(self):
-    """Get the Commit at the tip of this Ref."""
-    try:
-      val = self._repo.run('show-ref', '--verify', self._ref)
-    except CalledProcessError:
-      return INVALID
-    return self._repo.get_commit(val.split()[0])
-
-  # Methods
-  def to(self, other):
-    """Generate Commit()'s which occur from `self..other`."""
-    assert self.commit is not INVALID
-    arg = '%s..%s' % (self.ref, other.ref)
-    for hsh in self.repo.run('rev-list', '--reverse', arg).splitlines():
-      yield self.repo.get_commit(hsh)
-
-  def fast_forward_push(self, commit):
-    """Push |commit| to this ref on the remote, and update the local copy of the
-    ref to |commit|."""
-    self.repo.run('push', 'origin', '%s:%s' % (commit.hsh, self.ref))
-    self.update_to(commit)
-
-  def update_to(self, commit):
-    """Update the local copy of the ref to |commit|."""
-    self.repo.run('update-ref', self.ref, commit.hsh)