bisect: avoid copying ancestor list for non-merge commits
During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.
To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.
During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:
Setup:
$ cd mozilla-central
$ hg bisect --reset
$ hg bisect --good 0
$ hg log -r tip -T '{rev}\n'
628417
Test:
$ time hg bisect --bad tip --noupdate
Before:
real 3m35.927s
user 3m35.553s
sys 0m0.319s
After:
real 1m41.142s
user 1m40.810s
sys 0m0.285s
$ cat >> fakepager.py <<EOF
> import sys
> for line in sys.stdin:
> sys.stdout.write('paged! %r\n' % line)
> EOF
Enable ui.formatted because pager won't fire without it, and set up
pager and tell it to use our fake pager that lets us see when the
pager was running.
$ cat >> $HGRCPATH <<EOF
> [ui]
> formatted = yes
> color = no
> [extensions]
> pager=
> [pager]
> pager = "$PYTHON" $TESTTMP/fakepager.py
> EOF
$ hg init repo
$ cd repo
$ echo a >> a
$ hg add a
$ hg ci -m 'add a'
$ for x in `"$PYTHON" $TESTDIR/seq.py 1 10`; do
> echo a $x >> a
> hg ci -m "modify a $x"
> done
By default diff and log are paged, but summary is not:
$ hg diff -c 2 --pager=yes
paged! 'diff -r f4be7687d414 -r bce265549556 a\n'
paged! '--- a/a\tThu Jan 01 00:00:00 1970 +0000\n'
paged! '+++ b/a\tThu Jan 01 00:00:00 1970 +0000\n'
paged! '@@ -1,2 +1,3 @@\n'
paged! ' a\n'
paged! ' a 1\n'
paged! '+a 2\n'
$ hg log --limit 2
paged! 'changeset: 10:46106edeeb38\n'
paged! 'tag: tip\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 10\n'
paged! '\n'
paged! 'changeset: 9:6dd8ea7dd621\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 9\n'
paged! '\n'
$ hg summary
parent: 10:46106edeeb38 tip
modify a 10
branch: default
commit: (clean)
update: (current)
phases: 11 draft
We can enable the pager on summary:
$ hg --config pager.attend-summary=yes summary
paged! 'parent: 10:46106edeeb38 tip\n'
paged! ' modify a 10\n'
paged! 'branch: default\n'
paged! 'commit: (clean)\n'
paged! 'update: (current)\n'
paged! 'phases: 11 draft\n'
$ hg --config pager.attend-diff=no diff -c 2
diff -r f4be7687d414 -r bce265549556 a
--- a/a Thu Jan 01 00:00:00 1970 +0000
+++ b/a Thu Jan 01 00:00:00 1970 +0000
@@ -1,2 +1,3 @@
a
a 1
+a 2
If we completely change the attend list that's respected:
$ hg --config pager.attend=summary diff -c 2
diff -r f4be7687d414 -r bce265549556 a
--- a/a Thu Jan 01 00:00:00 1970 +0000
+++ b/a Thu Jan 01 00:00:00 1970 +0000
@@ -1,2 +1,3 @@
a
a 1
+a 2
If 'log' is in attend, then 'history' should also be paged:
$ hg history --limit 2 --config pager.attend=log
paged! 'changeset: 10:46106edeeb38\n'
paged! 'tag: tip\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 10\n'
paged! '\n'
paged! 'changeset: 9:6dd8ea7dd621\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 9\n'
paged! '\n'
Possible bug: history is explicitly ignored in pager config, but
because log is in the attend list it still gets pager treatment.
$ hg history --limit 2 --config pager.attend=log \
> --config pager.ignore=history
paged! 'changeset: 10:46106edeeb38\n'
paged! 'tag: tip\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 10\n'
paged! '\n'
paged! 'changeset: 9:6dd8ea7dd621\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 9\n'
paged! '\n'
Possible bug: history is explicitly marked as attend-history=no, but
it doesn't fail to get paged because log is still in the attend list.
$ hg history --limit 2 --config pager.attend-history=no
paged! 'changeset: 10:46106edeeb38\n'
paged! 'tag: tip\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 10\n'
paged! '\n'
paged! 'changeset: 9:6dd8ea7dd621\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 9\n'
paged! '\n'
Possible bug: disabling pager for log but enabling it for history
doesn't result in history being paged.
$ hg history --limit 2 --config pager.attend-log=no \
> --config pager.attend-history=yes
changeset: 10:46106edeeb38
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: modify a 10
changeset: 9:6dd8ea7dd621
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: modify a 9
Pager should not start if stdout is not a tty.
$ hg log -l1 -q --config ui.formatted=False
10:46106edeeb38
Pager with color enabled allows colors to come through by default,
even though stdout is no longer a tty.
$ cat >> $HGRCPATH <<EOF
> [ui]
> color = always
> [color]
> mode = ansi
> EOF
$ hg log --limit 3
paged! '\x1b[0;33mchangeset: 10:46106edeeb38\x1b[0m\n'
paged! 'tag: tip\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 10\n'
paged! '\n'
paged! '\x1b[0;33mchangeset: 9:6dd8ea7dd621\x1b[0m\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 9\n'
paged! '\n'
paged! '\x1b[0;33mchangeset: 8:cff05a6312fe\x1b[0m\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'summary: modify a 8\n'
paged! '\n'
Pager works with shell aliases.
$ cat >> $HGRCPATH <<EOF
> [alias]
> echoa = !echo a
> EOF
$ hg echoa
a
$ hg --config pager.attend-echoa=yes echoa
paged! 'a\n'
Pager attributes should be copied to mq repo. Otherwise pager would be started
twice and color mode would be lost.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> mq =
> EOF
$ hg init --mq
$ hg qnew foo.patch
$ hg qpop
popping foo.patch
patch queue now empty
$ hg ci --mq -m 'commit patches'
$ hg log --mq --debug
starting pager for command 'extension-via-attend-log'
paged! '\x1b[0;33mchangeset: 0:6cc2ded15503e368aaf76b6cc3d12f320c9e3b87\x1b[0m\n'
paged! 'tag: tip\n'
paged! 'phase: draft\n'
paged! 'parent: -1:0000000000000000000000000000000000000000\n'
paged! 'parent: -1:0000000000000000000000000000000000000000\n'
paged! 'manifest: 0:4980de1ae1b612014d5bcfa9507da84ce8891daa\n'
paged! 'user: test\n'
paged! 'date: Thu Jan 01 00:00:00 1970 +0000\n'
paged! 'files+: .hgignore foo.patch series\n'
paged! 'extra: branch=default\n'
paged! 'description:\n'
paged! 'commit patches\n'
paged! '\n'
paged! '\n'
Pager works with hg aliases including environment variables.
$ cat >> $HGRCPATH <<'EOF'
> [alias]
> printa = log -T "$A\n" -r 0
> EOF
$ A=1 hg --config pager.attend-printa=yes printa
paged! '1\n'
$ A=2 hg --config pager.attend-printa=yes printa
paged! '2\n'
Something that's explicitly attended is still not paginated if the
pager is globally set to off using a flag:
$ A=2 hg --config pager.attend-printa=yes printa --pager=no
2
Pager should not override the exit code of other commands
$ cat >> $TESTTMP/fortytwo.py <<'EOF'
> from mercurial import commands, registrar
> cmdtable = {}
> command = registrar.command(cmdtable)
> @command(b'fortytwo', [], b'fortytwo', norepo=True)
> def fortytwo(ui, *opts):
> ui.write(b'42\n')
> return 42
> EOF
$ cat >> $HGRCPATH <<'EOF'
> [extensions]
> fortytwo = $TESTTMP/fortytwo.py
> EOF
$ hg fortytwo --pager=on
paged! '42\n'
[42]