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.
Make sure that the internal merge tools (internal:fail, internal:local,
internal:union and internal:other) are used when matched by a
merge-pattern in hgrc
Make sure HGMERGE doesn't interfere with the test:
$ unset HGMERGE
$ hg init
Initial file contents:
$ echo "line 1" > f
$ echo "line 2" >> f
$ echo "line 3" >> f
$ hg ci -Am "revision 0"
adding f
$ cat f
line 1
line 2
line 3
Branch 1: editing line 1:
$ sed 's/line 1/first line/' f > f.new
$ mv f.new f
$ hg ci -Am "edited first line"
Branch 2: editing line 3:
$ hg update 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/line 3/third line/' f > f.new
$ mv f.new f
$ hg ci -Am "edited third line"
created new head
Merge using internal:fail tool:
$ echo "[merge-patterns]" > .hg/hgrc
$ echo "* = internal:fail" >> .hg/hgrc
$ hg merge
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
$ cat f
line 1
line 2
third line
$ hg stat
M f
Merge using internal:local tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/internal:fail/internal:local/' .hg/hgrc > .hg/hgrc.new
$ mv .hg/hgrc.new .hg/hgrc
$ hg merge
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
line 1
line 2
third line
$ hg stat
M f
Merge using internal:other tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/internal:local/internal:other/' .hg/hgrc > .hg/hgrc.new
$ mv .hg/hgrc.new .hg/hgrc
$ hg merge
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
first line
line 2
line 3
$ hg stat
M f
Merge using default tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm .hg/hgrc
$ hg merge
merging f
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
first line
line 2
third line
$ hg stat
M f
Merge using internal:union tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "line 4a" >>f
$ hg ci -Am "Adding fourth line (commit 4)"
$ hg update 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "line 4b" >>f
$ hg ci -Am "Adding fourth line v2 (commit 5)"
created new head
$ echo "[merge-patterns]" > .hg/hgrc
$ echo "* = internal:union" >> .hg/hgrc
$ hg merge 3
merging f
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
line 1
line 2
third line
line 4b
line 4a