annotate mercurial/cacheutil.py @ 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.

# scmutil.py - Mercurial core utility functions
#
#  Copyright Matt Mackall <[e-mail]> and other
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import

from . import repoview


def cachetocopy(srcrepo):
    """return the list of cache file valuable to copy during a clone"""
    # In local clones we're copying all nodes, not just served
    # ones. Therefore copy all branch caches over.
    cachefiles = [b'branch2']
    cachefiles += [b'branch2-%s' % f for f in repoview.filtertable]
    cachefiles += [b'rbc-names-v1', b'rbc-revs-v1']
    cachefiles += [b'tags2']
    cachefiles += [b'tags2-%s' % f for f in repoview.filtertable]
    cachefiles += [b'hgtagsfnodes1']
    return cachefiles