branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
#require no-windows no-rhg
XXX-RHG this test hangs if `hg` is really `rhg`. This was hidden by the use of
`alias hg=rhg` by run-tests.py. With such alias removed, this test is revealed
buggy. This need to be resolved sooner than later.
Dummy extension simulating unsafe long running command
$ SYNC_FILE="$TESTTMP/sync-file"
$ export SYNC_FILE
$ DONE_FILE="$TESTTMP/done-file"
$ export DONE_FILE
$
$ cat > wait_ext.py <<EOF
> import os
> import time
>
> from mercurial.i18n import _
> from mercurial import registrar
> from mercurial import testing
>
> cmdtable = {}
> command = registrar.command(cmdtable)
>
> @command(b'wait-signal', [], _(b'SYNC_FILE DONE_FILE'), norepo=True)
> def sleep(ui, sync_file=b"$SYNC_FILE", done_file=b"$DONE_FILE", **opts):
> start = time.time()
> with ui.uninterruptible():
> testing.write_file(sync_file, b'%d' % os.getpid())
> testing.wait_file(done_file)
> ui.warn(b"end of unsafe operation\n")
> ui.warn(b"%d second(s) passed\n" % int(time.time() - start))
> EOF
$ cat > send-signal.sh << EOF
> #!/bin/sh
> SIG=\$1
> if [ -z "\$SIG" ]; then
> echo "send-signal.sh requires one argument" >&2
> exit 1
> fi
> "$RUNTESTDIR/testlib/wait-on-file" 10 "$SYNC_FILE" || exit 2
> kill -s \$SIG \`cat "$SYNC_FILE"\`
> EOF
#if no-windows
$ chmod +x send-signal.sh
#endif
$ cat > wait-signal.sh << 'EOF'
> #!/bin/sh
> (hg wait-signal 2>&1; echo [$?]) | {
> read line
> touch "$DONE_FILE"
> echo "$line"
> cat
> }
> EOF
#if no-windows
$ chmod +x wait-signal.sh
#endif
Kludge to emulate timeout(1) which is not generally available.
Set up repository
$ hg init repo
$ cd repo
$ cat >> $HGRCPATH << EOF
> [extensions]
> wait_ext = $TESTTMP/wait_ext.py
> EOF
Test ctrl-c
$ rm -f $SYNC_FILE $DONE_FILE
$ sh -c "../send-signal.sh INT" &
$ ../wait-signal.sh
interrupted!
[255]
$ cat >> $HGRCPATH << EOF
> [experimental]
> nointerrupt = yes
> EOF
$ rm -f $SYNC_FILE $DONE_FILE
$ sh -c "../send-signal.sh INT" &
$ ../wait-signal.sh
interrupted!
[255]
$ cat >> $HGRCPATH << EOF
> [experimental]
> nointerrupt-interactiveonly = False
> EOF
$ rm -f $SYNC_FILE $DONE_FILE
$ sh -c "../send-signal.sh INT" &
$ ../wait-signal.sh
shutting down cleanly
press ^C again to terminate immediately (dangerous)
end of unsafe operation
interrupted!
[255]