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
#require no-windows
ATTENTION: logtoprocess runs commands asynchronously. Be sure to append "| cat"
to hg commands, to wait for the output, if you want to test its output.
Otherwise the test will be flaky.
Test if logtoprocess correctly captures command-related log calls.
$ hg init
$ cat > $TESTTMP/foocommand.py << EOF
> from mercurial import registrar
> cmdtable = {}
> command = registrar.command(cmdtable)
> configtable = {}
> configitem = registrar.configitem(configtable)
> configitem(b'logtoprocess', b'foo',
> default=None,
> )
> @command(b'foobar', [])
> def foo(ui, repo):
> ui.log(b'foo', b'a message: %s\n', b'spam')
> EOF
$ cp $HGRCPATH $HGRCPATH.bak
$ cat >> $HGRCPATH << EOF
> [extensions]
> logtoprocess=
> foocommand=$TESTTMP/foocommand.py
> [logtoprocess]
> command=(echo 'logtoprocess command output:';
> echo "\$EVENT";
> echo "\$MSG1") > $TESTTMP/command.log
> commandfinish=(echo 'logtoprocess commandfinish output:';
> echo "\$EVENT";
> echo "\$MSG1";
> echo "canonical: \$OPT_CANONICAL_COMMAND") > $TESTTMP/commandfinish.log
> foo=(echo 'logtoprocess foo output:';
> echo "\$EVENT";
> echo "\$MSG1") > $TESTTMP/foo.log
> EOF
Running a command triggers both a ui.log('command') and a
ui.log('commandfinish') call. The foo command also uses ui.log.
Use sort to avoid ordering issues between the various processes we spawn:
$ hg fooba
$ sleep 1
$ cat $TESTTMP/command.log | sort
command
fooba
logtoprocess command output:
#if no-chg
$ cat $TESTTMP/commandfinish.log | sort
canonical: foobar
commandfinish
fooba exited 0 after * seconds (glob)
logtoprocess commandfinish output:
$ cat $TESTTMP/foo.log | sort
a message: spam
foo
logtoprocess foo output:
#endif
Confirm that logging blocked time catches stdio properly:
$ cp $HGRCPATH.bak $HGRCPATH
$ cat >> $HGRCPATH << EOF
> [extensions]
> logtoprocess=
> pager=
> [logtoprocess]
> uiblocked=echo "\$EVENT stdio \$OPT_STDIO_BLOCKED ms command \$OPT_COMMAND_DURATION ms" > $TESTTMP/uiblocked.log
> [ui]
> logblockedtimes=True
> EOF
$ hg log
$ sleep 1
$ cat $TESTTMP/uiblocked.log
uiblocked stdio [0-9]+.[0-9]* ms command [0-9]+.[0-9]* ms (re)
Try to confirm that pager wait on logtoprocess:
Add a script that wait on a file to appears for 5 seconds, if it sees it touch
another file or die after 5 seconds. If the scripts is awaited by hg, the
script will die after the timeout before we could touch the file and the
resulting file will not exists. If not, we will touch the file and see it.
$ cat >> fakepager.py <<EOF
> import sys
> printed = False
> for line in sys.stdin:
> sys.stdout.write(line)
> printed = True
> if not printed:
> sys.stdout.write('paged empty output!\n')
> EOF
$ cat > $TESTTMP/wait-output.sh << EOF
> #!/bin/sh
> for i in \`$TESTDIR/seq.py 50\`; do
> if [ -f "$TESTTMP/wait-for-touched" ];
> then
> touch "$TESTTMP/touched";
> break;
> else
> sleep 0.1;
> fi
> done
> EOF
$ chmod +x $TESTTMP/wait-output.sh
$ cat >> $HGRCPATH << EOF
> [extensions]
> logtoprocess=
> pager=
> [pager]
> pager = "$PYTHON" $TESTTMP/fakepager.py
> [logtoprocess]
> commandfinish=$TESTTMP/wait-output.sh
> EOF
$ hg version -q --pager=always
Mercurial Distributed SCM (version *) (glob)
$ touch $TESTTMP/wait-for-touched
$ sleep 0.2
$ test -f $TESTTMP/touched && echo "SUCCESS Pager is not waiting on ltp" || echo "FAIL Pager is waiting on ltp"
SUCCESS Pager is not waiting on ltp