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.
$ cat <<EOF >> $HGRCPATH
> [extensions]
> convert =
> [convert]
> hg.tagsbranch = 0
> EOF
$ hg init source
$ cd source
$ echo a > a
$ hg ci -qAm adda
Add a merge with one parent in the same branch
$ echo a >> a
$ hg ci -qAm changea
$ hg up -qC 0
$ hg branch branch0
marked working directory as branch branch0
(branches are permanent and global, did you want a bookmark?)
$ echo b > b
$ hg ci -qAm addb
$ hg up -qC
$ hg merge default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg ci -qm mergeab
$ hg tag -ql mergeab
$ cd ..
Miss perl... sometimes
$ cat > filter.py <<EOF
> import re
> import sys
>
> r = re.compile(r'^(?:\d+|pulling from)')
> sys.stdout.writelines([l for l in sys.stdin if r.search(l)])
> EOF
convert
$ hg convert -v --config convert.hg.clonebranches=1 source dest |
> "$PYTHON" filter.py
3 adda
2 changea
1 addb
pulling from default into branch0
1 changesets found
0 mergeab
pulling from default into branch0
1 changesets found
Add a merge with both parents and child in different branches
$ cd source
$ hg branch branch1
marked working directory as branch branch1
$ echo a > file1
$ hg ci -qAm c1
$ hg up -qC mergeab
$ hg branch branch2
marked working directory as branch branch2
$ echo a > file2
$ hg ci -qAm c2
$ hg merge branch1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg branch branch3
marked working directory as branch branch3
$ hg ci -qAm c3
$ cd ..
incremental conversion
$ hg convert -v --config convert.hg.clonebranches=1 source dest |
> "$PYTHON" filter.py
2 c1
pulling from branch0 into branch1
4 changesets found
1 c2
pulling from branch0 into branch2
4 changesets found
0 c3
pulling from branch1 into branch3
5 changesets found
pulling from branch2 into branch3
1 changesets found