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.
$ echo "[extensions]" >> $HGRCPATH
$ echo "rebase=" >> $HGRCPATH
initialize repository
$ hg init
$ echo 'a' > a
$ hg ci -A -m "0"
adding a
$ echo 'b' > b
$ hg ci -A -m "1"
adding b
$ hg up 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo 'c' > c
$ hg ci -A -m "2"
adding c
created new head
$ echo 'd' > d
$ hg ci -A -m "3"
adding d
$ hg bookmark -r 1 one
$ hg bookmark -r 3 two
$ hg up -q two
bookmark list
$ hg bookmark
one 1:925d80f479bb
* two 3:2ae46b1d99a7
rebase
$ hg rebase -s two -d one
rebasing 3:2ae46b1d99a7 two tip "3"
saved backup bundle to $TESTTMP/.hg/strip-backup/2ae46b1d99a7-e6b057bc-rebase.hg
$ hg log
changeset: 3:42e5ed2cdcf4
bookmark: two
tag: tip
parent: 1:925d80f479bb
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 2:db815d6d32e6
parent: 0:f7b1eb17ad24
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 1:925d80f479bb
bookmark: one
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 0:f7b1eb17ad24
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
aborted rebase should restore active bookmark.
$ hg up 1
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
(leaving bookmark two)
$ echo 'e' > d
$ hg ci -A -m "4"
adding d
created new head
$ hg bookmark three
$ hg rebase -s three -d two
rebasing 4:dd7c838e8362 three tip "4"
merging d
warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
[240]
$ hg rebase --abort
rebase aborted
$ hg bookmark
one 1:925d80f479bb
* three 4:dd7c838e8362
two 3:42e5ed2cdcf4
after aborted rebase, restoring a bookmark that has been removed should not fail
$ hg rebase -s three -d two
rebasing 4:dd7c838e8362 three tip "4"
merging d
warning: conflicts while merging d! (edit, then use 'hg resolve --mark')
unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
[240]
$ hg bookmark -d three
$ hg rebase --abort
rebase aborted
$ hg bookmark
one 1:925d80f479bb
two 3:42e5ed2cdcf4