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.
$ . "$TESTDIR/narrow-library.sh"
create full repo
$ hg init master
$ cd master
$ echo init > init
$ hg ci -Aqm 'initial'
$ mkdir inside
$ echo inside > inside/f1
$ mkdir outside
$ echo outside > outside/f1
$ hg ci -Aqm 'add inside and outside'
$ echo modified > inside/f1
$ hg ci -qm 'modify inside'
$ echo modified > outside/f1
$ hg ci -qm 'modify outside'
$ cd ..
$ hg clone --narrow ssh://user@dummy/master narrow --include inside
requesting all changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 2 changes to 1 files
new changesets *:* (glob)
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd narrow
$ hg debugindex -c
rev linkrev nodeid p1-nodeid p2-nodeid
0 0 9958b1af2add 000000000000 000000000000
1 1 2db4ce2a3bfe 9958b1af2add 000000000000
2 2 0980ee31a742 2db4ce2a3bfe 000000000000
3 3 4410145019b7 0980ee31a742 000000000000
$ hg update -q 0
Can update to revision with changes inside
$ hg update -q 'desc("add inside and outside")'
$ hg update -q 'desc("modify inside")'
$ find *
inside
inside/f1
$ cat inside/f1
modified
Can update to revision with changes outside
$ hg update -q 'desc("modify outside")'
$ find *
inside
inside/f1
$ cat inside/f1
modified
Can update with a deleted file inside
$ hg rm inside/f1
$ hg update -q 'desc("modify inside")'
$ hg update -q 'desc("modify outside")'
$ hg update -q 'desc("initial")'
$ hg update -q 'desc("modify inside")'
Can update with a moved file inside
$ hg mv inside/f1 inside/f2
$ hg update -q 'desc("modify outside")'
$ hg update -q 'desc("add inside and outside")'
$ hg update -q 'desc("modify inside")'