contrib/simplemerge

discovery-helper: use reflink copy if available

A reflink copy will copy the files "as usual" but keep using the same data block
underneath. This is only supported by "copy on write" file system like btrfs or
zfs.

This will achieve similar performance that the existing hardlink clone that
Mercurial performs with the same initial space saving. However, it will behave
better on revlogs start being touch by strip. Instead of duplicating all data in
the touched revlogs, only the block actually affected by the strip will be
duplicated. This save a lot of space when building many variants of large
repositories.

The --reflink=always flag make sure the `cp` call fails if reflink copies are
not supported. Falling back to local clone.

#!/usr/bin/env python
from __future__ import absolute_import

import getopt
import sys

import hgdemandimport
hgdemandimport.enable()

from mercurial.i18n import _
from mercurial import (
    context,
    error,
    fancyopts,
    pycompat,
    simplemerge,
    ui as uimod,
)
from mercurial.utils import (
    procutil,
)

options = [(b'L', b'label', [], _(b'labels to use on conflict markers')),
           (b'a', b'text', None, _(b'treat all files as text')),
           (b'p', b'print', None,
            _(b'print results instead of overwriting LOCAL')),
           (b'', b'no-minimal', None, _(b'no effect (DEPRECATED)')),
           (b'h', b'help', None, _(b'display help and exit')),
           (b'q', b'quiet', None, _(b'suppress output'))]

usage = _(b'''simplemerge [OPTS] LOCAL BASE OTHER

    Simple three-way file merge utility with a minimal feature set.

    Apply to LOCAL the changes necessary to go from BASE to OTHER.

    By default, LOCAL is overwritten with the results of this operation.
''')

class ParseError(Exception):
    """Exception raised on errors in parsing the command line."""

def showhelp():
    pycompat.stdout.write(usage)
    pycompat.stdout.write(b'\noptions:\n')

    out_opts = []
    for shortopt, longopt, default, desc in options:
        out_opts.append((b'%2s%s' % (shortopt and b'-%s' % shortopt,
                                     longopt and b' --%s' % longopt),
                         b'%s' % desc))
    opts_len = max([len(opt[0]) for opt in out_opts])
    for first, second in out_opts:
        pycompat.stdout.write(b' %-*s  %s\n' % (opts_len, first, second))

try:
    for fp in (sys.stdin, pycompat.stdout, sys.stderr):
        procutil.setbinary(fp)

    opts = {}
    try:
        bargv = [a.encode('utf8') for a in sys.argv[1:]]
        args = fancyopts.fancyopts(bargv, options, opts)
    except getopt.GetoptError as e:
        raise ParseError(e)
    if opts[b'help']:
        showhelp()
        sys.exit(0)
    if len(args) != 3:
            raise ParseError(_(b'wrong number of arguments').decode('utf8'))
    local, base, other = args
    sys.exit(simplemerge.simplemerge(uimod.ui.load(),
                                     context.arbitraryfilectx(local),
                                     context.arbitraryfilectx(base),
                                     context.arbitraryfilectx(other),
                                     **pycompat.strkwargs(opts)))
except ParseError as e:
    if pycompat.ispy3:
        e = str(e).encode('utf8')
    pycompat.stdout.write(b"%s: %s\n" % (sys.argv[0].encode('utf8'), e))
    showhelp()
    sys.exit(1)
except error.Abort as e:
    pycompat.stderr.write(b"abort: %s\n" % e)
    sys.exit(255)
except KeyboardInterrupt:
    sys.exit(255)