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repo: Support multiple branches for the same project.

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It is often useful to be able to include the same project more than
once, but with different branches and placed in different paths in the
workspace. Add this feature.

This CL adds the concept of an object directory. The object directory
stores objects that can be shared amongst several working trees. For
newly synced repositories, we set up the git repo now to share its
objects with an object repo.

Each worktree for a given repo shares objects, but has an independent
set of references and branches. This ensures that repo only has to
update the objects once; however the references for each worktree are
updated separately. Storing the references separately is needed to
ensure that commits to a branch on one worktree will not change the
HEAD commits of the others.

One nice side effect of sharing objects between different worktrees is
that you can easily cherry-pick changes between the two worktrees
without needing to fetch them.

Bug: Issue 141
Change-Id: I5e2f4e1a7abb56f9d3f310fa6fd0c17019330ecd
This commit is contained in:
David James 2013-10-11 17:03:19 -07:00
parent b25ea555c3
commit 8d20116038
6 changed files with 191 additions and 80 deletions
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118
project.py
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@ -487,6 +487,7 @@ class Project(object):
name,
remote,
gitdir,
objdir,
worktree,
relpath,
revisionExpr,
@ -507,6 +508,7 @@ class Project(object):
name: The `name` attribute of manifest.xml's project element.
remote: RemoteSpec object specifying its remote's properties.
gitdir: Absolute path of git directory.
objdir: Absolute path of directory to store git objects.
worktree: Absolute path of git working tree.
relpath: Relative path of git working tree to repo's top directory.
revisionExpr: The `revision` attribute of manifest.xml's project element.
@ -525,6 +527,7 @@ class Project(object):
self.name = name
self.remote = remote
self.gitdir = gitdir.replace('\\', '/')
self.objdir = objdir.replace('\\', '/')
if worktree:
self.worktree = worktree.replace('\\', '/')
else:
@ -557,11 +560,12 @@ class Project(object):
defaults = self.manifest.globalConfig)
if self.worktree:
self.work_git = self._GitGetByExec(self, bare=False)
self.work_git = self._GitGetByExec(self, bare=False, gitdir=gitdir)
else:
self.work_git = None
self.bare_git = self._GitGetByExec(self, bare=True)
self.bare_git = self._GitGetByExec(self, bare=True, gitdir=gitdir)
self.bare_ref = GitRefs(gitdir)
self.bare_objdir = self._GitGetByExec(self, bare=True, gitdir=objdir)
self.dest_branch = dest_branch
# This will be filled in if a project is later identified to be the
@ -1069,6 +1073,7 @@ class Project(object):
"""Perform only the local IO portion of the sync process.
Network access is not required.
"""
self._InitWorkTree()
all_refs = self.bare_ref.all
self.CleanPublishedCache(all_refs)
revid = self.GetRevisionId(all_refs)
@ -1077,7 +1082,6 @@ class Project(object):
self._FastForward(revid)
self._CopyFiles()
self._InitWorkTree()
head = self.work_git.GetHead()
if head.startswith(R_HEADS):
branch = head[len(R_HEADS):]
@ -1544,11 +1548,13 @@ class Project(object):
return result
for rev, path, url in self._GetSubmodules():
name = self.manifest.GetSubprojectName(self, path)
project = self.manifest.projects.get(name)
relpath, worktree, gitdir, objdir = \
self.manifest.GetSubprojectPaths(self, name, path)
project = self.manifest.paths.get(relpath)
if project:
result.extend(project.GetDerivedSubprojects())
continue
relpath, worktree, gitdir = self.manifest.GetSubprojectPaths(self, path)
remote = RemoteSpec(self.remote.name,
url = url,
review = self.remote.review)
@ -1556,6 +1562,7 @@ class Project(object):
name = name,
remote = remote,
gitdir = gitdir,
objdir = objdir,
worktree = worktree,
relpath = relpath,
revisionExpr = self.revisionExpr,
@ -1905,8 +1912,17 @@ class Project(object):
def _InitGitDir(self, mirror_git=None):
if not os.path.exists(self.gitdir):
os.makedirs(self.gitdir)
self.bare_git.init()
# Initialize the bare repository, which contains all of the objects.
if not os.path.exists(self.objdir):
os.makedirs(self.objdir)
self.bare_objdir.init()
# If we have a separate directory to hold refs, initialize it as well.
if self.objdir != self.gitdir:
os.makedirs(self.gitdir)
self._ReferenceGitDir(self.objdir, self.gitdir, share_refs=False,
copy_all=True)
mp = self.manifest.manifestProject
ref_dir = mp.config.GetString('repo.reference') or ''
@ -2022,33 +2038,61 @@ class Project(object):
msg = 'manifest set to %s' % self.revisionExpr
self.bare_git.symbolic_ref('-m', msg, ref, dst)
def _ReferenceGitDir(self, gitdir, dotgit, share_refs, copy_all):
"""Update |dotgit| to reference |gitdir|, using symlinks where possible.
Args:
gitdir: The bare git repository. Must already be initialized.
dotgit: The repository you would like to initialize.
share_refs: If true, |dotgit| will store its refs under |gitdir|.
Only one work tree can store refs under a given |gitdir|.
copy_all: If true, copy all remaining files from |gitdir| -> |dotgit|.
This saves you the effort of initializing |dotgit| yourself.
"""
# These objects can be shared between several working trees.
symlink_files = ['description', 'info']
symlink_dirs = ['hooks', 'objects', 'rr-cache', 'svn']
if share_refs:
# These objects can only be used by a single working tree.
symlink_files += ['config', 'packed-refs']
symlink_dirs += ['logs', 'refs']
to_symlink = symlink_files + symlink_dirs
to_copy = []
if copy_all:
to_copy = os.listdir(gitdir)
for name in set(to_copy).union(to_symlink):
try:
src = os.path.realpath(os.path.join(gitdir, name))
dst = os.path.realpath(os.path.join(dotgit, name))
if os.path.lexists(dst) and not os.path.islink(dst):
raise GitError('cannot overwrite a local work tree')
# If the source dir doesn't exist, create an empty dir.
if name in symlink_dirs and not os.path.lexists(src):
os.makedirs(src)
if name in to_symlink:
os.symlink(os.path.relpath(src, os.path.dirname(dst)), dst)
elif copy_all and not os.path.islink(dst):
if os.path.isdir(src):
shutil.copytree(src, dst)
elif os.path.isfile(src):
shutil.copy(src, dst)
except OSError as e:
if e.errno == errno.EPERM:
raise GitError('filesystem must support symlinks')
else:
raise
def _InitWorkTree(self):
dotgit = os.path.join(self.worktree, '.git')
if not os.path.exists(dotgit):
os.makedirs(dotgit)
for name in ['config',
'description',
'hooks',
'info',
'logs',
'objects',
'packed-refs',
'refs',
'rr-cache',
'svn']:
try:
src = os.path.join(self.gitdir, name)
dst = os.path.join(dotgit, name)
if os.path.islink(dst) or not os.path.exists(dst):
os.symlink(os.path.relpath(src, os.path.dirname(dst)), dst)
else:
raise GitError('cannot overwrite a local work tree')
except OSError as e:
if e.errno == errno.EPERM:
raise GitError('filesystem must support symlinks')
else:
raise
self._ReferenceGitDir(self.gitdir, dotgit, share_refs=True,
copy_all=False)
_lwrite(os.path.join(dotgit, HEAD), '%s\n' % self.GetRevisionId())
@ -2058,14 +2102,10 @@ class Project(object):
if GitCommand(self, cmd).Wait() != 0:
raise GitError("cannot initialize work tree")
rr_cache = os.path.join(self.gitdir, 'rr-cache')
if not os.path.exists(rr_cache):
os.makedirs(rr_cache)
self._CopyFiles()
def _gitdir_path(self, path):
return os.path.join(self.gitdir, path)
return os.path.realpath(os.path.join(self.gitdir, path))
def _revlist(self, *args, **kw):
a = []
@ -2078,9 +2118,10 @@ class Project(object):
return self.bare_ref.all
class _GitGetByExec(object):
def __init__(self, project, bare):
def __init__(self, project, bare, gitdir):
self._project = project
self._bare = bare
self._gitdir = gitdir
def LsOthers(self):
p = GitCommand(self._project,
@ -2089,6 +2130,7 @@ class Project(object):
'--others',
'--exclude-standard'],
bare = False,
gitdir=self._gitdir,
capture_stdout = True,
capture_stderr = True)
if p.Wait() == 0:
@ -2104,6 +2146,7 @@ class Project(object):
cmd.extend(args)
p = GitCommand(self._project,
cmd,
gitdir=self._gitdir,
bare = False,
capture_stdout = True,
capture_stderr = True)
@ -2213,6 +2256,7 @@ class Project(object):
p = GitCommand(self._project,
cmdv,
bare = self._bare,
gitdir=self._gitdir,
capture_stdout = True,
capture_stderr = True)
r = []
@ -2265,6 +2309,7 @@ class Project(object):
p = GitCommand(self._project,
cmdv,
bare = self._bare,
gitdir=self._gitdir,
capture_stdout = True,
capture_stderr = True)
if p.Wait() != 0:
@ -2398,6 +2443,7 @@ class MetaProject(Project):
manifest = manifest,
name = name,
gitdir = gitdir,
objdir = gitdir,
worktree = worktree,
remote = RemoteSpec('origin'),
relpath = '.repo/%s' % name,