context: optimize linkrev adjustment in blockancestors() (issue5538)
We set parent._descendantrev = child.rev() when walking parents in
blockancestors() so that, when linkrev adjustment is perform for these, it
starts from a close descendant instead of possibly topmost introrev. (See
`self._adjustlinkrev(self._descendantrev)` in filectx._changeid().)
This is similar to changeset c82d88dfaf59, which added a "f._changeid"
instruction in annotate() for the same purpose.
However, here, we set _descendantrev explicitly instead of relying on the
'_changeid' cached property being accessed (with effect to set _changeid
attribute) so that, in _parentfilectx() (called from parents()), we go through
`if '_changeid' in vars(self) [...]` branch in which instruction
`fctx._descendantrev = self.rev()` finally appears and does what we want.
With this, we can roughly get a 3x speedup (including in example of issue5538
from mozilla-central repository) on usage of followlines revset (and
equivalent hgweb request).
# txnutil.py - transaction related utilities
#
# Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import errno
from . import (
encoding,
)
def mayhavepending(root):
'''return whether 'root' may have pending changes, which are
visible to this process.
'''
return root == encoding.environ.get('HG_PENDING')
def trypending(root, vfs, filename, **kwargs):
'''Open file to be read according to HG_PENDING environment variable
This opens '.pending' of specified 'filename' only when HG_PENDING
is equal to 'root'.
This returns '(fp, is_pending_opened)' tuple.
'''
if mayhavepending(root):
try:
return (vfs('%s.pending' % filename, **kwargs), True)
except IOError as inst:
if inst.errno != errno.ENOENT:
raise
return (vfs(filename, **kwargs), False)