view mercurial/helptext/deprecated.txt @ 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.

Mercurial evolves over time, some features, options, commands may be replaced by
better and more secure alternatives. This topic will help you migrating your
existing usage and/or configuration to newer features.

Commands
========

The following commands are still available but their use are not recommended:

``locate``

This command has been replaced by `hg files`.

``parents``

This command can be replaced by `hg summary` or `hg log` with appropriate
revsets. See `hg help revsets` for more information.

``tip``

The recommended alternative is `hg heads`.

Options
=======

``web.allowpull``
    Renamed to `allow-pull`.

``web.allow_push``
    Renamed to `allow-push`.