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 serve
$ hgserve()
> {
> hg serve -a localhost -d --pid-file=hg.pid -E errors.log -v $@ \
> | sed -e "s/:$HGPORT1\\([^0-9]\\)/:HGPORT1\1/g" \
> -e "s/:$HGPORT2\\([^0-9]\\)/:HGPORT2\1/g" \
> -e 's/http:\/\/[^/]*\//http:\/\/localhost\//'
> if [ -f hg.pid ]; then
> killdaemons.py hg.pid
> fi
> echo % errors
> cat errors.log
> }
$ hg init test
$ cd test
$ echo '[web]' > .hg/hgrc
$ echo 'accesslog = access.log' >> .hg/hgrc
$ echo "port = $HGPORT1" >> .hg/hgrc
Without -v
$ hg serve -a localhost -p $HGPORT -d --pid-file=hg.pid -E errors.log
$ cat hg.pid >> "$DAEMON_PIDS"
$ if [ -f access.log ]; then
> echo 'access log created - .hg/hgrc respected'
> fi
access log created - .hg/hgrc respected
errors
$ cat errors.log
With -v
$ hgserve
listening at http://localhost/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With -v and -p HGPORT2
$ hgserve -p "$HGPORT2"
listening at http://localhost/ (bound to *$LOCALIP*:HGPORT2) (glob) (?)
% errors
With -v and -p daytime
# On some system this will fails because port < 1024 are not bindable by normal
# users.
#
# On some others the kernel is configured to allow any user to bind them and
# this will work fine
#if no-windows
$ KILLQUIETLY=Y
$ hgserve -p daytime
abort: cannot start server at 'localhost:13': Permission denied (?)
abort: child process failed to start (?)
abort: no port number associated with service 'daytime' (?)
listening at http://localhost/ (bound to $LOCALIP:13) (?)
% errors
$ KILLQUIETLY=N
#endif
With --prefix foo
$ hgserve --prefix foo
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With --prefix /foo
$ hgserve --prefix /foo
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With --prefix foo/
$ hgserve --prefix foo/
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With --prefix /foo/
$ hgserve --prefix /foo/
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
$ "$PYTHON" $RUNTESTDIR/killdaemons.py $DAEMON_PIDS
With out of bounds accesses
$ rm access.log
$ hg serve -a localhost -p $HGPORT -d --prefix some/dir \
> --pid-file=hg.pid -E errors.log
$ cat hg.pid >> "$DAEMON_PIDS"
$ hg id http://localhost:$HGPORT/some/dir7
abort: HTTP Error 404: Not Found
[100]
$ hg id http://localhost:$HGPORT/some
abort: HTTP Error 404: Not Found
[100]
$ cat access.log errors.log
$LOCALIP - - [$LOGDATE$] "GET /some/dir7?cmd=capabilities HTTP/1.1" 404 - (glob)
$LOCALIP - - [$LOGDATE$] "GET /some?cmd=capabilities HTTP/1.1" 404 - (glob)
$ "$PYTHON" $RUNTESTDIR/killdaemons.py $DAEMON_PIDS
issue6362: Previously, this crashed on Python 3
$ hg serve -a 0.0.0.0 -d --pid-file=hg.pid
listening at http://*:$HGPORT1/ (bound to *:$HGPORT1) (glob) (?)
$ cat hg.pid > "$DAEMON_PIDS"
$ "$PYTHON" $RUNTESTDIR/killdaemons.py $DAEMON_PIDS
$ cd ..