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.
Test correctness of revlog inline -> non-inline transition
----------------------------------------------------------
Helper extension to intercept renames.
$ cat > $TESTTMP/intercept_rename.py << EOF
> import os
> import sys
> from mercurial import extensions, util
>
> def extsetup(ui):
> def close(orig, *args, **kwargs):
> path = util.normpath(args[0]._atomictempfile__name)
> if path.endswith(b'/.hg/store/data/file.i'):
> os._exit(80)
> return orig(*args, **kwargs)
> extensions.wrapfunction(util.atomictempfile, 'close', close)
> EOF
Test offset computation to correctly factor in the index entries themselves.
Also test that the new data size has the correct size if the transaction is aborted
after the index has been replaced.
Test repo has commits a, b, c, D, where D is large (grows the revlog enough that it
transitions to non-inline storage). The clone initially has changes a, b
and will transition to non-inline storage when adding c, D.
If the transaction adding c, D is rolled back, then we don't undo the revlog split,
but truncate the index and the data to remove both c and D.
$ hg init troffset-computation --config format.revlog-compression=none
$ cd troffset-computation
$ printf '%20d' '1' > file
$ hg commit -Aqma
$ printf '%1024d' '1' > file
$ hg commit -Aqmb
$ printf '%20d' '1' > file
$ hg commit -Aqmc
$ dd if=/dev/zero of=file bs=1k count=128 > /dev/null 2>&1
$ hg commit -AqmD
$ cd ..
$ hg clone -r 1 troffset-computation troffset-computation-copy --config format.revlog-compression=none -q
$ cd troffset-computation-copy
Reference size:
$ f -s .hg/store/data/file*
.hg/store/data/file.i: size=1174
$ cat > .hg/hgrc <<EOF
> [hooks]
> pretxnchangegroup = python:$TESTDIR/helper-killhook.py:killme
> EOF
#if chg
$ hg pull ../troffset-computation
pulling from ../troffset-computation
[255]
#else
$ hg pull ../troffset-computation
pulling from ../troffset-computation
[80]
#endif
$ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file | tail -1
data/file.i 128
The first file.i entry should match the "Reference size" above.
The first file.d entry is the temporary record during the split,
the second entry after the split happened. The sum of the second file.d
and the second file.i entry should match the first file.i entry.
$ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file
data/file.i 1174
data/file.d 0
data/file.d 1046
data/file.i 128
$ hg recover
rolling back interrupted transaction
(verify step skipped, run `hg verify` to check your repository content)
$ f -s .hg/store/data/file*
.hg/store/data/file.d: size=1046
.hg/store/data/file.i: size=128
$ hg tip
changeset: 1:cfa8d6e60429
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
$ hg verify -q
warning: revlog 'data/file.d' not in fncache!
1 warnings encountered!
hint: run "hg debugrebuildfncache" to recover from corrupt fncache
$ hg debugrebuildfncache --only-data
adding data/file.d
1 items added, 0 removed from fncache
$ hg verify -q
$ cd ..
Now retry the procedure but intercept the rename of the index and check that
the journal does not contain the new index size. This demonstrates the edge case
where the data file is left as garbage.
$ hg clone -r 1 troffset-computation troffset-computation-copy2 --config format.revlog-compression=none -q
$ cd troffset-computation-copy2
$ cat > .hg/hgrc <<EOF
> [extensions]
> intercept_rename = $TESTTMP/intercept_rename.py
> [hooks]
> pretxnchangegroup = python:$TESTDIR/helper-killhook.py:killme
> EOF
#if chg
$ hg pull ../troffset-computation
pulling from ../troffset-computation
[255]
#else
$ hg pull ../troffset-computation
pulling from ../troffset-computation
[80]
#endif
$ cat .hg/store/journal | tr -s '\000' ' ' | grep data/file
data/file.i 1174
data/file.d 0
data/file.d 1046
$ hg recover
rolling back interrupted transaction
(verify step skipped, run `hg verify` to check your repository content)
$ f -s .hg/store/data/file*
.hg/store/data/file.d: size=1046
.hg/store/data/file.i: size=1174
$ hg tip
changeset: 1:cfa8d6e60429
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
$ hg verify -q
$ cd ..
Repeat the original test but let hg rollback the transaction.
$ hg clone -r 1 troffset-computation troffset-computation-copy-rb --config format.revlog-compression=none -q
$ cd troffset-computation-copy-rb
$ cat > .hg/hgrc <<EOF
> [hooks]
> pretxnchangegroup = false
> EOF
$ hg pull ../troffset-computation
pulling from ../troffset-computation
searching for changes
adding changesets
adding manifests
adding file changes
transaction abort!
rollback completed
abort: pretxnchangegroup hook exited with status 1
[40]
$ f -s .hg/store/data/file*
.hg/store/data/file.d: size=1046
.hg/store/data/file.i: size=128
$ hg tip
changeset: 1:cfa8d6e60429
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
$ hg verify -q
warning: revlog 'data/file.d' not in fncache!
1 warnings encountered!
hint: run "hg debugrebuildfncache" to recover from corrupt fncache
$ cd ..