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.
#testcases dirstate-v1 dirstate-v2
#if dirstate-v2
$ cat >> $HGRCPATH << EOF
> [format]
> use-dirstate-v2=1
> [storage]
> dirstate-v2.slow-path=allow
> EOF
#endif
Checking the size/permissions/file-type of files stored in the
dirstate after an update where the files are changed concurrently
outside of hg's control.
$ hg init repo
$ cd repo
$ echo a > a
$ hg commit -qAm _
$ echo aa > a
$ hg commit -m _
# this sleep is there to ensure current time has -at-least- one second away
# from the current time. It ensure the mtime is not ambiguous. If the test
# "sleep" longer this will be fine.
# It is not used to synchronise parallele operation so it is "fine" to use it.
$ sleep 1
$ hg status
$ hg debugdirstate --no-dates
n 644 3 (set |unset) a (re)
$ cat >> $TESTTMP/dirstaterace.py << EOF
> import time
> from mercurial import (
> commit,
> extensions,
> merge,
> )
> def extsetup(ui):
> extensions.wrapfunction(merge, 'applyupdates', wrap(0))
> extensions.wrapfunction(commit, 'commitctx', wrap(1))
> def wrap(duration):
> def new(orig, *args, **kwargs):
> res = orig(*args, **kwargs)
> with open("a", "w"):
> pass # just truncate the file
> time.sleep(duration)
> return res
> return new
> EOF
Do an update where file 'a' is changed between hg writing it to disk
and hg writing the dirstate. The dirstate is correct nonetheless, and
so hg status correctly shows a as clean.
$ hg up -r 0 --config extensions.race=$TESTTMP/dirstaterace.py
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg debugdirstate --no-dates
n 644 2 (set |unset) a (re)
$ echo a > a; hg status; hg diff
Do a commit where file 'a' is changed between hg committing its new
revision into the repository, and the writing of the dirstate.
This used to results in a corrupted dirstate (size did not match committed size).
$ echo aaa > a; hg commit -qm _
$ hg merge -qr 1; hg resolve -m; rm a.orig
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
(no more unresolved files)
$ cat a
<<<<<<< working copy: be46f74ce38d - test: _
aaa
=======
aa
>>>>>>> merge rev: eb3fc6c17aa3 - test: _
$ hg debugdirstate --no-dates
m 0 -2 (set |unset) a (re)
$ hg commit -m _ --config extensions.race=$TESTTMP/dirstaterace.py
$ hg debugdirstate --no-dates
n 0 -1 unset a
$ cat a | wc -c
*0 (re)
$ hg cat -r . a | wc -c
*105 (re)
$ hg status; hg diff --stat
M a
a | 5 -----
1 files changed, 0 insertions(+), 5 deletions(-)