branchmap: add a cache validation cache, avoid expensive re-hash on every use
In a pathological `hg log` case, we end up executing the branchmap validity
checking twice per commit displayed. Or maybe we always do, and I just noticed
because it's really slow in this repo for some reason.
Before:
```
Time (mean ± σ): 9.816 s ± 0.071 s [User: 9.435 s, System: 0.392 s]
Range (min … max): 9.709 s … 9.920 s
```
After:
```
Time (mean ± σ): 8.671 s ± 0.078 s [User: 8.309 s, System: 0.392 s]
Range (min … max): 8.594 s … 8.816 s
```
Differential Revision: https://phab.mercurial-scm.org/D9023
# stack.py - Mercurial functions for stack definition
#
# Copyright Matt Mackall <mpm@selenic.com> and other
#
# 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
def getstack(repo, rev=None):
"""return a sorted smartrev of the stack containing either rev if it is
not None or the current working directory parent.
The stack will always contain all drafts changesets which are ancestors to
the revision and are not merges.
"""
if rev is None:
rev = b'.'
revspec = b'only(%s) and not public() and not ::merge()'
revisions = repo.revs(revspec, rev)
revisions.sort()
return revisions