Improve checkout performance for the common unmodified case
Most projects will have their branch heads matching in all branches,
so switching between them should be just a matter of updating the
work tree's HEAD symref. This can be done in pure Python, saving
quite a bit of time over forking 'git checkout'.
Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/project.py b/project.py
index 10a9b25..029a80f 100644
--- a/project.py
+++ b/project.py
@@ -779,9 +779,8 @@
all = self.bare_ref.all
if (R_HEADS + name) in all:
- cmd = ['checkout', name, '--']
return GitCommand(self,
- cmd,
+ ['checkout', name, '--'],
capture_stdout = True,
capture_stderr = True).Wait() == 0
@@ -815,9 +814,8 @@
branch.Save()
return True
- cmd = ['checkout', '-b', branch.name, rev]
if GitCommand(self,
- cmd,
+ ['checkout', '-b', branch.name, rev],
capture_stdout = True,
capture_stderr = True).Wait() == 0:
branch.Save()
@@ -827,16 +825,39 @@
def CheckoutBranch(self, name):
"""Checkout a local topic branch.
"""
+ rev = R_HEADS + name
+ head = self.work_git.GetHead()
+ if head == rev:
+ # Already on the branch
+ #
+ return True
- # Be sure the branch exists
+ all = self.bare_ref.all
try:
- tip_rev = self.bare_git.rev_parse(R_HEADS + name)
- except GitError:
- return False;
+ revid = all[rev]
+ except KeyError:
+ # Branch does not exist in this project
+ #
+ return False
- # Do the checkout
- cmd = ['checkout', name, '--']
- return GitCommand(self, cmd).Wait() == 0
+ if head.startswith(R_HEADS):
+ try:
+ head = all[head]
+ except KeyError:
+ head = None
+
+ if head == revid:
+ # Same revision; just update HEAD to point to the new
+ # target branch, but otherwise take no other action.
+ #
+ _lwrite(os.path.join(self.worktree, '.git', HEAD),
+ 'ref: %s%s\n' % (R_HEADS, name))
+ return True
+
+ return GitCommand(self,
+ ['checkout', name, '--'],
+ capture_stdout = True,
+ capture_stderr = True).Wait() == 0
def AbandonBranch(self, name):
"""Destroy a local topic branch.