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
$ hg init repo
$ cd repo
$ echo a > a
$ hg add a
$ hg commit -m test
Do we ever miss a sub-second change?:
$ for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
> hg update -qC 0
> echo b > a
> hg st
> done
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
M a
$ echo test > b
$ mkdir dir1
$ echo test > dir1/c
$ echo test > d
$ echo test > e
#if execbit
A directory will typically have the execute bit -- make sure it doesn't get
confused with a file with the exec bit set
$ chmod +x e
#endif
$ hg add b dir1 d e
adding dir1/c
$ hg commit -m test2
$ cat >> $TESTTMP/dirstaterace.py << EOF
> from mercurial import (
> context,
> extensions,
> )
> def extsetup(ui):
> extensions.wrapfunction(context.workingctx, '_checklookup', overridechecklookup)
> def overridechecklookup(orig, self, *args, **kwargs):
> # make an update that changes the dirstate from underneath
> self._repo.ui.system(br"sh '$TESTTMP/dirstaterace.sh'",
> cwd=self._repo.root)
> return orig(self, *args, **kwargs)
> EOF
$ hg debugrebuilddirstate
$ hg debugdirstate
n 0 -1 unset a
n 0 -1 unset b
n 0 -1 unset d
n 0 -1 unset dir1/c
n 0 -1 unset e
XXX Note that this returns M for files that got replaced by directories. This is
definitely a bug, but the fix for that is hard and the next status run is fine
anyway.
$ cat > $TESTTMP/dirstaterace.sh <<EOF
> rm b && rm -r dir1 && rm d && mkdir d && rm e && mkdir e
> EOF
$ sleep 1 # ensure non-ambiguous mtime
$ hg status --config extensions.dirstaterace=$TESTTMP/dirstaterace.py
M d
M e
! b
! dir1/c
$ hg debugdirstate
n 644 2 * a (glob)
n 0 -1 unset b
n 0 -1 unset d
n 0 -1 unset dir1/c
n 0 -1 unset e
$ hg status
! b
! d
! dir1/c
! e
$ rmdir d e
$ hg update -C -q .
Test that dirstate changes aren't written out at the end of "hg
status", if .hg/dirstate is already changed simultaneously before
acquisition of wlock in workingctx._poststatusfixup().
This avoidance is important to keep consistency of dirstate in race
condition (see issue5584 for detail).
$ hg parents -q
1:* (glob)
$ hg debugrebuilddirstate
$ hg debugdirstate
n 0 -1 unset a
n 0 -1 unset b
n 0 -1 unset d
n 0 -1 unset dir1/c
n 0 -1 unset e
$ cat > $TESTTMP/dirstaterace.sh <<EOF
> # This script assumes timetable of typical issue5584 case below:
> #
> # 1. "hg status" loads .hg/dirstate
> # 2. "hg status" confirms clean-ness of FILE
> # 3. "hg update -C 0" updates the working directory simultaneously
> # (FILE is removed, and FILE is dropped from .hg/dirstate)
> # 4. "hg status" acquires wlock
> # (.hg/dirstate is re-loaded = no FILE entry in dirstate)
> # 5. "hg status" marks FILE in dirstate as clean
> # (FILE entry is added to in-memory dirstate)
> # 6. "hg status" writes dirstate changes into .hg/dirstate
> # (FILE entry is written into .hg/dirstate)
> #
> # To reproduce similar situation easily and certainly, #2 and #3
> # are swapped. "hg cat" below ensures #2 on "hg status" side.
>
> hg update -q -C 0
> hg cat -r 1 b > b
> # make sure the timestamps is not ambiguous and a write will be issued
> touch -t 198606251012 b
> EOF
"hg status" below should excludes "e", of which exec flag is set, for
portability of test scenario, because unsure but missing "e" is
treated differently in _checklookup() according to runtime platform.
- "missing(!)" on POSIX, "pctx[f].cmp(self[f])" raises ENOENT
- "modified(M)" on Windows, "self.flags(f) != pctx.flags(f)" is True
$ hg status --config extensions.dirstaterace=$TESTTMP/dirstaterace.py --debug -X path:e
skip updating dirstate: identity mismatch
M a
! d
! dir1/c
$ hg parents -q
0:* (glob)
$ hg files
a
$ hg debugdirstate
n * * * a (glob)
$ rm b
#if fsmonitor
Create fsmonitor state.
$ hg status
$ f --type .hg/fsmonitor.state
.hg/fsmonitor.state: file
Test that invalidating fsmonitor state in the middle (which doesn't require the
wlock) causes the fsmonitor update to be skipped.
hg debugrebuilddirstate ensures that the dirstaterace hook will be called, but
it also invalidates the fsmonitor state. So back it up and restore it.
$ mv .hg/fsmonitor.state .hg/fsmonitor.state.tmp
$ hg debugrebuilddirstate
$ mv .hg/fsmonitor.state.tmp .hg/fsmonitor.state
$ cat > $TESTTMP/dirstaterace.sh <<EOF
> rm .hg/fsmonitor.state
> EOF
$ hg status --config extensions.dirstaterace=$TESTTMP/dirstaterace.py --debug
skip updating fsmonitor.state: identity mismatch
$ f .hg/fsmonitor.state
.hg/fsmonitor.state: file not found
#endif
Set up a rebase situation for issue5581.
$ echo c2 > a
$ echo c2 > b
$ hg add b
$ hg commit -m c2
created new head
$ echo c3 >> a
$ hg commit -m c3
$ hg update 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo c4 >> a
$ echo c4 >> b
$ hg commit -m c4
created new head
Configure a merge tool that runs status in the middle of the rebase. The goal of
the status call is to trigger a potential bug if fsmonitor's state is written
even though the wlock is held by another process. The output of 'hg status' in
the merge tool goes to /dev/null because we're more interested in the results of
'hg status' run after the rebase.
$ cat >> $TESTTMP/mergetool-race.sh << EOF
> echo "custom merge tool"
> printf "c2\nc3\nc4\n" > \$1
> hg --cwd "$TESTTMP/repo" status > /dev/null
> echo "custom merge tool end"
> EOF
$ cat >> $HGRCPATH << EOF
> [extensions]
> rebase =
> [merge-tools]
> test.executable=sh
> test.args=$TESTTMP/mergetool-race.sh \$output
> EOF
$ hg rebase -s . -d 3 --tool test
rebasing 4:b08445fd6b2a tip "c4"
merging a
custom merge tool
custom merge tool end
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/* (glob)
This hg status should be empty, whether or not fsmonitor is enabled (issue5581).
$ hg status