revlog: add a C implementation of `headrevsdiff`
Python implementation of `headrevsdiff` can be very slow in the worst
case compared with the `heads` computation it replaces, since the
latter is done in C.
Even the average case of this Python implementation is still
noticeable in the profiles.
This patch makes the computation much much faster by doing it in C.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Ama
adding a
$ hg qnew a.patch
$ echo a >> a
$ hg qrefresh
$ hg qnew b.patch
$ echo b > b
$ hg add b
$ hg qrefresh
$ hg qnew c.patch
$ echo c > c
$ hg add c
$ hg qrefresh
$ hg qgoto a.patch
popping c.patch
popping b.patch
now at: a.patch
$ hg qgoto c.patch
applying b.patch
applying c.patch
now at: c.patch
$ hg qgoto b.patch
popping c.patch
now at: b.patch
Using index:
$ hg qgoto 0
popping b.patch
now at: a.patch
$ hg qgoto 2
applying b.patch
applying c.patch
now at: c.patch
No warnings when using index ... and update from non-qtip and with pending
changes in unrelated files:
$ hg qnew bug314159
$ echo d >> c
$ hg qrefresh
$ hg qnew bug141421
$ echo e >> b
$ hg qrefresh
$ hg up -r bug314159
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo f >> a
$ echo f >> b
$ echo f >> c
$ hg qgoto 1
abort: local changes found, qrefresh first
[255]
$ hg qgoto 1 -f
popping bug141421
popping bug314159
popping c.patch
now at: b.patch
$ hg st
M a
M b
? c.orig
$ hg up -qCr.
$ hg qgoto 3
applying c.patch
applying bug314159
now at: bug314159
Detect ambiguous non-index:
$ hg qgoto 14
patch name "14" is ambiguous:
bug314159
bug141421
abort: patch 14 not in series
[255]
$ cd ..