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.
test children command
$ cat <<EOF >> $HGRCPATH
> [extensions]
> children =
> EOF
init
$ hg init t
$ cd t
no working directory
$ hg children
setup
$ echo 0 > file0
$ hg ci -qAm 0 -d '0 0'
$ echo 1 > file1
$ hg ci -qAm 1 -d '1 0'
$ echo 2 >> file0
$ hg ci -qAm 2 -d '2 0'
$ hg co null
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo 3 > file3
$ hg ci -qAm 3 -d '3 0'
hg children at revision 3 (tip)
$ hg children
$ hg co null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
hg children at nullrev (should be 0 and 3)
$ hg children
changeset: 0:4df8521a7374
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 3:e2962852269d
tag: tip
parent: -1:000000000000
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: 3
$ hg co 1
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
hg children at revision 1 (should be 2)
$ hg children
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
$ hg co 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
hg children at revision 2 (other head)
$ hg children
$ for i in null 0 1 2 3 '2^'; do
> echo "hg children -r '$i'"
> hg children -r $i
> done
hg children -r 'null'
changeset: 0:4df8521a7374
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 3:e2962852269d
tag: tip
parent: -1:000000000000
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: 3
hg children -r '0'
changeset: 1:708c093edef0
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: 1
hg children -r '1'
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
hg children -r '2'
hg children -r '3'
hg children -r '2^'
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
hg children -r 0 file0 (should be 2)
$ hg children -r 0 file0
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
hg children -r 1 file0 (should be 2)
$ hg children -r 1 file0
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
$ hg co 0
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
hg children file0 at revision 0 (should be 2)
$ hg children file0
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
should be compatible with templater (don't pass fctx to displayer)
$ hg children file0 -Tdefault
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
$ cd ..