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add experimental git worktree support

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This provides initial support for using git worktrees internally
instead of our own ad-hoc symlink tree.  It's been lightly tested
which is why it's not currently exposed via --help.

When people opt-in to worktrees in an existing repo client checkout,
no projects are migrated.  Instead, only new projects will use the
worktree method.  This allows for limited testing/opting in without
having to completely blow things away or get a second checkout.

Bug: https://crbug.com/gerrit/11486
Change-Id: Ic3ff891b30940a6ba497b406b2a387e0a8517ed8
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/254075
Tested-by: Mike Frysinger <vapier@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
This commit is contained in:
Mike Frysinger 2020-02-09 02:28:34 -05:00
parent 56ce3468b4
commit 979d5bdc3e
6 changed files with 138 additions and 23 deletions
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70
project.py
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@ -866,6 +866,7 @@ class Project(object):
clone_depth=None,
upstream=None,
parent=None,
use_git_worktrees=False,
is_derived=False,
dest_branch=None,
optimized_fetch=False,
@ -889,6 +890,7 @@ class Project(object):
sync_tags: The `sync-tags` attribute of manifest.xml's project element.
upstream: The `upstream` attribute of manifest.xml's project element.
parent: The parent Project object.
use_git_worktrees: Whether to use `git worktree` for this project.
is_derived: False if the project was explicitly defined in the manifest;
True if the project is a discovered submodule.
dest_branch: The branch to which to push changes for review by default.
@ -923,6 +925,10 @@ class Project(object):
self.clone_depth = clone_depth
self.upstream = upstream
self.parent = parent
# NB: Do not use this setting in __init__ to change behavior so that the
# manifest.git checkout can inspect & change it after instantiating. See
# the XmlManifest init code for more info.
self.use_git_worktrees = use_git_worktrees
self.is_derived = is_derived
self.optimized_fetch = optimized_fetch
self.subprojects = []
@ -1872,15 +1878,19 @@ class Project(object):
except KeyError:
head = None
if revid and head and revid == head:
ref = os.path.join(self.gitdir, R_HEADS + name)
try:
os.makedirs(os.path.dirname(ref))
except OSError:
pass
_lwrite(ref, '%s\n' % revid)
_lwrite(self.GetHeadPath(), 'ref: %s%s\n' % (R_HEADS, name))
branch.Save()
return True
if self.use_git_worktrees:
self.work_git.update_ref(HEAD, revid)
branch.Save()
else:
ref = os.path.join(self.gitdir, R_HEADS + name)
try:
os.makedirs(os.path.dirname(ref))
except OSError:
pass
_lwrite(ref, '%s\n' % revid)
_lwrite(self.GetHeadPath(), 'ref: %s%s\n' % (R_HEADS, name))
branch.Save()
return True
if GitCommand(self,
['checkout', '-b', branch.name, revid],
@ -2617,6 +2627,11 @@ class Project(object):
os.makedirs(self.objdir)
self.bare_objdir.init()
# Enable per-worktree config file support if possible. This is more a
# nice-to-have feature for users rather than a hard requirement.
if self.use_git_worktrees and git_require((2, 19, 0)):
self.config.SetString('extensions.worktreeConfig', 'true')
# If we have a separate directory to hold refs, initialize it as well.
if self.objdir != self.gitdir:
if init_git_dir:
@ -2651,13 +2666,15 @@ class Project(object):
mirror_git = os.path.join(ref_dir, self.name + '.git')
repo_git = os.path.join(ref_dir, '.repo', 'projects',
self.relpath + '.git')
worktrees_git = os.path.join(ref_dir, '.repo', 'worktrees',
self.name + '.git')
if os.path.exists(mirror_git):
ref_dir = mirror_git
elif os.path.exists(repo_git):
ref_dir = repo_git
elif os.path.exists(worktrees_git):
ref_dir = worktrees_git
else:
ref_dir = None
@ -2765,6 +2782,10 @@ class Project(object):
self.bare_git.symbolic_ref('-m', msg, ref, dst)
def _CheckDirReference(self, srcdir, destdir, share_refs):
# Git worktrees don't use symlinks to share at all.
if self.use_git_worktrees:
return
symlink_files = self.shareable_files[:]
symlink_dirs = self.shareable_dirs[:]
if share_refs:
@ -2864,11 +2885,38 @@ class Project(object):
else:
raise
def _InitGitWorktree(self):
"""Init the project using git worktrees."""
self.bare_git.worktree('prune')
self.bare_git.worktree('add', '-ff', '--checkout', '--detach', '--lock',
self.worktree, self.GetRevisionId())
# Rewrite the internal state files to use relative paths between the
# checkouts & worktrees.
dotgit = os.path.join(self.worktree, '.git')
with open(dotgit, 'r') as fp:
# Figure out the checkout->worktree path.
setting = fp.read()
assert setting.startswith('gitdir:')
git_worktree_path = setting.split(':', 1)[1].strip()
# Use relative path from checkout->worktree.
with open(dotgit, 'w') as fp:
print('gitdir:', os.path.relpath(git_worktree_path, self.worktree),
file=fp)
# Use relative path from worktree->checkout.
with open(os.path.join(git_worktree_path, 'gitdir'), 'w') as fp:
print(os.path.relpath(dotgit, git_worktree_path), file=fp)
def _InitWorkTree(self, force_sync=False, submodules=False):
realdotgit = os.path.join(self.worktree, '.git')
tmpdotgit = realdotgit + '.tmp'
init_dotgit = not os.path.exists(realdotgit)
if init_dotgit:
if self.use_git_worktrees:
self._InitGitWorktree()
self._CopyAndLinkFiles()
return
dotgit = tmpdotgit
platform_utils.rmtree(tmpdotgit, ignore_errors=True)
os.makedirs(tmpdotgit)