annotate hgext/narrow/TODO.rst @ 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.

Address commentary in manifest.excludedmanifestrevlog.add -
specifically we should improve the collaboration with core so that
add() never gets called on an excluded directory and we can improve
the stand-in to raise a ProgrammingError.

Reason more completely about rename-filtering logic in
narrowfilelog. There could be some surprises lurking there.

Formally document the narrowspec format. For bonus points, unify with the
server-specified narrowspec format.

narrowrepo.setnarrowpats() or narrowspec.save() need to make sure
they're holding the wlock.

The follinwg places do an unrestricted dirstate walk (including files outside the
narrowspec). Some of them should perhaps not do that.

 * debugfileset
 * perfwalk
 * sparse (but restricted to sparse config)
 * largefiles