git: implement basic bookmark activation

This is very limited, but it allows 'hg update foo' when already on foo.

The caching is based on bmstore's caching.

hgext/git/__init__.py

@@ -1,305 +1,318 b''
 """grant Mercurial the ability to operate on Git repositories. (EXPERIMENTAL)
 
 This is currently super experimental. It probably will consume your
 firstborn a la Rumpelstiltskin, etc.
 """
 
 from __future__ import absolute_import
 
 import os
 
 from mercurial.i18n import _
 
 from mercurial import (
     commands,
     error,
     extensions,
     localrepo,
     pycompat,
     scmutil,
     store,
     util,
 )
 
 from . import (
     dirstate,
     gitlog,
     gitutil,
     index,
 )
 
 # TODO: extract an interface for this in core
 class gitstore(object):  # store.basicstore):
     def __init__(self, path, vfstype):
         self.vfs = vfstype(path)
         self.path = self.vfs.base
         self.createmode = store._calcmode(self.vfs)
         # above lines should go away in favor of:
         # super(gitstore, self).__init__(path, vfstype)
 
         self.git = gitutil.get_pygit2().Repository(
             os.path.normpath(os.path.join(path, b'..', b'.git'))
         )
         self._progress_factory = lambda *args, **kwargs: None
 
     @util.propertycache
     def _db(self):
         # We lazy-create the database because we want to thread a
         # progress callback down to the indexing process if it's
         # required, and we don't have a ui handle in makestore().
         return index.get_index(self.git, self._progress_factory)
 
     def join(self, f):
         """Fake store.join method for git repositories.
 
         For the most part, store.join is used for @storecache
         decorators to invalidate caches when various files
         change. We'll map the ones we care about, and ignore the rest.
         """
         if f in (b'00changelog.i', b'00manifest.i'):
             # This is close enough: in order for the changelog cache
             # to be invalidated, HEAD will have to change.
             return os.path.join(self.path, b'HEAD')
         elif f == b'lock':
             # TODO: we probably want to map this to a git lock, I
             # suspect index.lock. We should figure out what the
             # most-alike file is in git-land. For now we're risking
             # bad concurrency errors if another git client is used.
             return os.path.join(self.path, b'hgit-bogus-lock')
         elif f in (b'obsstore', b'phaseroots', b'narrowspec', b'bookmarks'):
             return os.path.join(self.path, b'..', b'.hg', f)
         raise NotImplementedError(b'Need to pick file for %s.' % f)
 
     def changelog(self, trypending):
         # TODO we don't have a plan for trypending in hg's git support yet
         return gitlog.changelog(self.git, self._db)
 
     def manifestlog(self, repo, storenarrowmatch):
         # TODO handle storenarrowmatch and figure out if we need the repo arg
         return gitlog.manifestlog(self.git, self._db)
 
     def invalidatecaches(self):
         pass
 
     def write(self, tr=None):
         # normally this handles things like fncache writes, which we don't have
         pass
 
 
 def _makestore(orig, requirements, storebasepath, vfstype):
     if b'git' in requirements:
         if not os.path.exists(os.path.join(storebasepath, b'..', b'.git')):
             raise error.Abort(
                 _(
                     b'repository specified git format in '
                     b'.hg/requires but has no .git directory'
                 )
             )
         # Check for presence of pygit2 only here. The assumption is that we'll
         # run this code iff we'll later need pygit2.
         if gitutil.get_pygit2() is None:
             raise error.Abort(
                 _(
                     b'the git extension requires the Python '
                     b'pygit2 library to be installed'
                 )
             )
 
         return gitstore(storebasepath, vfstype)
     return orig(requirements, storebasepath, vfstype)
 
 
 class gitfilestorage(object):
     def file(self, path):
         if path[0:1] == b'/':
             path = path[1:]
         return gitlog.filelog(self.store.git, self.store._db, path)
 
 
 def _makefilestorage(orig, requirements, features, **kwargs):
     store = kwargs['store']
     if isinstance(store, gitstore):
         return gitfilestorage
     return orig(requirements, features, **kwargs)
 
 
 def _setupdothg(ui, path):
     dothg = os.path.join(path, b'.hg')
     if os.path.exists(dothg):
         ui.warn(_(b'git repo already initialized for hg\n'))
     else:
         os.mkdir(os.path.join(path, b'.hg'))
         # TODO is it ok to extend .git/info/exclude like this?
         with open(
             os.path.join(path, b'.git', b'info', b'exclude'), 'ab'
         ) as exclude:
             exclude.write(b'\n.hg\n')
     with open(os.path.join(dothg, b'requires'), 'wb') as f:
         f.write(b'git\n')
 
 
 _BMS_PREFIX = 'refs/heads/'
 
 
 class gitbmstore(object):
     def __init__(self, gitrepo):
         self.gitrepo = gitrepo
+        self._aclean = True
+        self._active = gitrepo.references['HEAD']  # git head, not mark
 
     def __contains__(self, name):
         return (
             _BMS_PREFIX + pycompat.fsdecode(name)
         ) in self.gitrepo.references
 
     def __iter__(self):
         for r in self.gitrepo.listall_references():
             if r.startswith(_BMS_PREFIX):
                 yield pycompat.fsencode(r[len(_BMS_PREFIX) :])
 
     def __getitem__(self, k):
         return (
             self.gitrepo.references[_BMS_PREFIX + pycompat.fsdecode(k)]
             .peel()
             .id.raw
         )
 
     def get(self, k, default=None):
         try:
             if k in self:
                 return self[k]
             return default
         except gitutil.get_pygit2().InvalidSpecError:
             return default
 
     @property
     def active(self):
         h = self.gitrepo.references['HEAD']
         if not isinstance(h.target, str) or not h.target.startswith(
             _BMS_PREFIX
         ):
             return None
         return pycompat.fsencode(h.target[len(_BMS_PREFIX) :])
 
     @active.setter
     def active(self, mark):
-        raise NotImplementedError
+        githead = mark is not None and (_BMS_PREFIX + mark) or None
+        if githead is not None and githead not in self.gitrepo.references:
+            raise AssertionError(b'bookmark %s does not exist!' % mark)
+
+        self._active = githead
+        self._aclean = False
+
+    def _writeactive(self):
+        if self._aclean:
+            return
+        self.gitrepo.references.create('HEAD', self._active, True)
+        self._aclean = True
 
     def names(self, node):
         r = []
         for ref in self.gitrepo.listall_references():
             if not ref.startswith(_BMS_PREFIX):
                 continue
             if self.gitrepo.references[ref].peel().id.raw != node:
                 continue
             r.append(pycompat.fsencode(ref[len(_BMS_PREFIX) :]))
         return r
 
     # Cleanup opportunity: this is *identical* to core's bookmarks store.
     def expandname(self, bname):
         if bname == b'.':
             if self.active:
                 return self.active
             raise error.RepoLookupError(_(b"no active bookmark"))
         return bname
 
     def applychanges(self, repo, tr, changes):
         """Apply a list of changes to bookmarks
         """
         # TODO: this should respect transactions, but that's going to
         # require enlarging the gitbmstore to know how to do in-memory
         # temporary writes and read those back prior to transaction
         # finalization.
         for name, node in changes:
             if node is None:
                 self.gitrepo.references.delete(
                     _BMS_PREFIX + pycompat.fsdecode(name)
                 )
             else:
                 self.gitrepo.references.create(
                     _BMS_PREFIX + pycompat.fsdecode(name),
                     gitutil.togitnode(node),
                     force=True,
                 )
 
     def checkconflict(self, mark, force=False, target=None):
         githead = _BMS_PREFIX + mark
         cur = self.gitrepo.references['HEAD']
         if githead in self.gitrepo.references and not force:
             if target:
                 if self.gitrepo.references[githead] == target and target == cur:
                     # re-activating a bookmark
                     return []
                 # moving a bookmark - forward?
                 raise NotImplementedError
             raise error.Abort(
                 _(b"bookmark '%s' already exists (use -f to force)") % mark
             )
         if len(mark) > 3 and not force:
             try:
                 shadowhash = scmutil.isrevsymbol(self._repo, mark)
             except error.LookupError:  # ambiguous identifier
                 shadowhash = False
             if shadowhash:
                 self._repo.ui.warn(
                     _(
                         b"bookmark %s matches a changeset hash\n"
                         b"(did you leave a -r out of an 'hg bookmark' "
                         b"command?)\n"
                     )
                     % mark
                 )
         return []
 
 
 def init(orig, ui, dest=b'.', **opts):
     if opts.get('git', False):
         path = os.path.abspath(dest)
         # TODO: walk up looking for the git repo
         _setupdothg(ui, path)
         return 0
     return orig(ui, dest=dest, **opts)
 
 
 def reposetup(ui, repo):
     if repo.local() and isinstance(repo.store, gitstore):
         orig = repo.__class__
         repo.store._progress_factory = repo.ui.makeprogress
 
         class gitlocalrepo(orig):
             def _makedirstate(self):
                 # TODO narrow support here
                 return dirstate.gitdirstate(
                     self.ui, self.vfs.base, self.store.git
                 )
 
             def commit(self, *args, **kwargs):
                 ret = orig.commit(self, *args, **kwargs)
                 tid = self.store.git[gitutil.togitnode(ret)].tree.id
                 # DANGER! This will flush any writes staged to the
                 # index in Git, but we're sidestepping the index in a
                 # way that confuses git when we commit. Alas.
                 self.store.git.index.read_tree(tid)
                 self.store.git.index.write()
                 return ret
 
             @property
             def _bookmarks(self):
                 return gitbmstore(self.store.git)
 
         repo.__class__ = gitlocalrepo
     return repo
 
 
 def _featuresetup(ui, supported):
     # don't die on seeing a repo with the git requirement
     supported |= {b'git'}
 
 
 def extsetup(ui):
     extensions.wrapfunction(localrepo, b'makestore', _makestore)
     extensions.wrapfunction(localrepo, b'makefilestorage', _makefilestorage)
     # Inject --git flag for `hg init`
     entry = extensions.wrapcommand(commands.table, b'init', init)
     entry[1].extend(
         [(b'', b'git', None, b'setup up a git repository instead of hg')]
     )
     localrepo.featuresetupfuncs.add(_featuresetup)