procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
#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)
> # make sure we get rescheduled and the signal get a chance to be handled
> time.sleep(0.1)
> 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 "$SYNC_FILE"\`
> sleep 1
> touch "$DONE_FILE"
> EOF
#if no-windows
$ chmod +x send-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" &
$ hg wait-signal
interrupted!
[255]
$ cat >> $HGRCPATH << EOF
> [experimental]
> nointerrupt = yes
> EOF
$ rm -f $SYNC_FILE $DONE_FILE
$ sh -c "../send-signal.sh INT" &
$ hg wait-signal
interrupted!
[255]
$ cat >> $HGRCPATH << EOF
> [experimental]
> nointerrupt-interactiveonly = False
> EOF
$ rm -f $SYNC_FILE $DONE_FILE
$ sh -c "../send-signal.sh INT" &
$ hg wait-signal
shutting down cleanly
press ^C again to terminate immediately (dangerous)
end of unsafe operation
interrupted!
[255]