revisionbranchcache: fall back to slow path if starting readonly (issue4531)
Transitioning to Mercurial versions with revision branch cache could be slow as
long as all operations were readonly (revset queries) and the cache would be
populated but not written back.
Instead, fall back to using the consistently slow path when readonly and the
cache doesn't exist yet. That avoids the overhead of populating the cache
without writing it back.
If not readonly, it will still populate all missing entries initially. That
avoids repeated writing of the cache file with small updates, and it also makes
sure a fully populated cache available for the readonly operations.
"""Extension to verify locks are obtained in the required places.
This works by wrapping functions that should be surrounded by a lock
and asserting the lock is held. Missing locks are called out with a
traceback printed to stderr.
This currently only checks store locks, not working copy locks.
"""
import os
from mercurial import util
def _checklock(repo):
l = repo._lockref and repo._lockref()
if l is None or not l.held:
util.debugstacktrace('missing lock', skip=1)
def reposetup(ui, repo):
orig = repo.__class__
class lockcheckrepo(repo.__class__):
def _writejournal(self, *args, **kwargs):
_checklock(self)
return orig._writejournal(self, *args, **kwargs)
def transaction(self, *args, **kwargs):
_checklock(self)
return orig.transaction(self, *args, **kwargs)
# TODO(durin42): kiilerix had a commented-out lock check in
# _writebranchcache and _writerequirements
def _tag(self, *args, **kwargs):
_checklock(self)
return orig._tag(self, *args, **kwargs)
def write(self, *args, **kwargs):
assert os.path.lexists(self._join('.hg/wlock'))
return orig.write(self, *args, **kwargs)
repo.__class__ = lockcheckrepo