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 file dedicated to checking side-data related behavior
==========================================================
Check data can be written/read from sidedata
============================================
$ cat << EOF >> $HGRCPATH
> [extensions]
> testsidedata=$TESTDIR/testlib/ext-sidedata.py
> EOF
$ hg init test-sidedata --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
$ cd test-sidedata
$ echo aaa > a
$ hg add a
$ hg commit -m a --traceback
$ echo aaa > b
$ hg add b
$ hg commit -m b
$ echo xxx >> a
$ hg commit -m aa
$ hg debugsidedata -c 0
2 sidedata entries
entry-0001 size 4
entry-0002 size 32
$ hg debugsidedata -c 1 -v
2 sidedata entries
entry-0001 size 4
'\x00\x00\x006'
entry-0002 size 32
'\x98\t\xf9\xc4v\xf0\xc5P\x90\xf7wRf\xe8\xe27e\xfc\xc1\x93\xa4\x96\xd0\x1d\x97\xaaG\x1d\xd7t\xfa\xde'
$ hg debugsidedata -m 2
2 sidedata entries
entry-0001 size 4
entry-0002 size 32
$ hg debugsidedata a 1
2 sidedata entries
entry-0001 size 4
entry-0002 size 32
$ hg debug-revlog-index --verbose -c
rev rank linkrev nodeid p1-rev p1-nodeid p2-rev p2-nodeid full-size delta-base flags comp-mode data-offset chunk-size sd-comp-mode sidedata-offset sd-chunk-size
0 -1 0 7049e48789d7 -1 000000000000 -1 000000000000 54 0 0 0 0 54 plain 0 90
1 -1 1 2707720c6597 0 7049e48789d7 -1 000000000000 54 1 0 0 54 54 plain 90 90
2 -1 2 40f977031323 1 2707720c6597 -1 000000000000 55 2 0 0 108 55 plain 180 90
$ hg debug-revlog-index --verbose -m
rev rank linkrev nodeid p1-rev p1-nodeid p2-rev p2-nodeid full-size delta-base flags comp-mode data-offset chunk-size sd-comp-mode sidedata-offset sd-chunk-size
0 -1 0 b85d294330e3 -1 000000000000 -1 000000000000 43 0 0 0 0 43 plain 0 90
1 -1 1 1a0aec305c63 0 b85d294330e3 -1 000000000000 86 0 0 0 43 55 plain 90 90
2 -1 2 104258a4f75f 1 1a0aec305c63 -1 000000000000 86 1 0 0 98 55 plain 180 90
Check upgrade behavior
======================
Right now, sidedata has not upgrade support
Check that we can upgrade to sidedata
-------------------------------------
$ hg init up-no-side-data --config experimental.revlogv2=no
$ hg debugformat -v -R up-no-side-data | egrep 'changelog-v2|revlog-v2'
revlog-v2: no no no
changelog-v2: no no no
$ hg debugformat -v -R up-no-side-data --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data | egrep 'changelog-v2|revlog-v2'
revlog-v2: no yes no
changelog-v2: no no no
$ hg debugupgraderepo -R up-no-side-data --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data > /dev/null
Check that we can downgrade from sidedata
-----------------------------------------
$ hg init up-side-data --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
$ hg debugformat -v -R up-side-data | egrep 'changelog-v2|revlog-v2'
revlog-v2: yes no no
changelog-v2: no no no
$ hg debugformat -v -R up-side-data --config experimental.revlogv2=no | egrep 'changelog-v2|revlog-v2'
revlog-v2: yes no no
changelog-v2: no no no
$ hg debugupgraderepo -R up-side-data --config experimental.revlogv2=no > /dev/null