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view tests/test-diff-antipatience.t @ 45095:8e04607023e5
procutil: ensure that procutil.std{out,err}.write() writes all bytes
Python 3 offers different kind of streams and it’s not guaranteed for all of
them that calling write() writes all bytes.
When Python is started in unbuffered mode, sys.std{out,err}.buffer are
instances of io.FileIO, whose write() can write less bytes for
platform-specific reasons (e.g. Linux has a 0x7ffff000 bytes maximum and could
write less if interrupted by a signal; when writing to Windows consoles, it’s
limited to 32767 bytes to avoid the "not enough space" error). This can lead to
silent loss of data, both when using sys.std{out,err}.buffer (which may in fact
not be a buffered stream) and when using the text streams sys.std{out,err}
(I’ve created a CPython bug report for that:
https://bugs.python.org/issue41221).
Python may fix the problem at some point. For now, we implement our own wrapper
for procutil.std{out,err} that calls the raw stream’s write() method until all
bytes have been written. We don’t use sys.std{out,err} for larger writes, so I
think it’s not worth the effort to patch them.
author | Manuel Jacob <me@manueljacob.de> |
---|---|
date | Fri, 10 Jul 2020 12:27:58 +0200 |
parents | 9ef9884e5d50 |
children |
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#testcases bdiff xdiff #if xdiff #require xdiff $ cat >> $HGRCPATH <<EOF > [experimental] > xdiff = true > EOF #endif Test case that makes use of the weakness of patience diff algorithm $ hg init >>> open('a', 'wb').write(('\n'.join(list('a' + 'x' * 10 + 'u' + 'x' * 30 + 'a\n'))).encode('ascii')) and None $ hg commit -m 1 -A a >>> open('a', 'wb').write(('\n'.join(list('b' + 'x' * 30 + 'u' + 'x' * 10 + 'b\n'))).encode('ascii')) and None #if xdiff $ hg diff diff -r f0aeecb49805 a --- a/a Thu Jan 01 00:00:00 1970 +0000 +++ b/a Thu Jan 01 00:00:00 1970 +0000 @@ -1,4 +1,4 @@ -a +b x x x @@ -9,7 +9,6 @@ x x x -u x x x @@ -30,6 +29,7 @@ x x x +u x x x @@ -40,5 +40,5 @@ x x x -a +b #else $ hg diff diff -r f0aeecb49805 a --- a/a Thu Jan 01 00:00:00 1970 +0000 +++ b/a Thu Jan 01 00:00:00 1970 +0000 @@ -1,15 +1,4 @@ -a -x -x -x -x -x -x -x -x -x -x -u +b x x x @@ -40,5 +29,16 @@ x x x -a +u +x +x +x +x +x +x +x +x +x +x +b #endif