mercurial/cffi/mpatch.py

revset: use phasecache.getrevset to calculate public()

Other revsets like secret(), draft(), _nonpublic() are using
phasescache.getrevset already. The latter is more efficient after D1606.
So let's migrate the public() revset function too.

Tested using:

  $ hg debugshell --hidden --cwd hg-committed`
  In [1]: %timeit len(repo.revs('public()'))

* Before D1606: 10 loops, best of 3: 22.5 ms per loop
* Before this change, after D1606: 10 loops, best of 3: 28.6 ms per loop
* After this change: 10 loops, best of 3: 20.2 ms per loop

Therefore `public()` revset becomes even slightly faster after the data
structure change by D1606. A similar performance win could also be observed
on a large repo.

A side effect is `phasecache.getrevset` needs to take a `subset` parameter.
That was added with a default value so it won't cause BC issues.

Differential Revision: https://phab.mercurial-scm.org/D1620

# mpatch.py - CFFI implementation of mpatch.c
#
# Copyright 2016 Maciej Fijalkowski <[e-mail]>
#
# 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 ..pure.mpatch import *
from ..pure.mpatch import mpatchError  # silence pyflakes
from . import _mpatch

ffi = _mpatch.ffi
lib = _mpatch.lib

@ffi.def_extern()
def cffi_get_next_item(arg, pos):
    all, bins = ffi.from_handle(arg)
    container = ffi.new("struct mpatch_flist*[1]")
    to_pass = ffi.new("char[]", str(bins[pos]))
    all.append(to_pass)
    r = lib.mpatch_decode(to_pass, len(to_pass) - 1, container)
    if r < 0:
        return ffi.NULL
    return container[0]

def patches(text, bins):
    lgt = len(bins)
    all = []
    if not lgt:
        return text
    arg = (all, bins)
    patch = lib.mpatch_fold(ffi.new_handle(arg),
                            lib.cffi_get_next_item, 0, lgt)
    if not patch:
        raise mpatchError("cannot decode chunk")
    outlen = lib.mpatch_calcsize(len(text), patch)
    if outlen < 0:
        lib.mpatch_lfree(patch)
        raise mpatchError("inconsistency detected")
    buf = ffi.new("char[]", outlen)
    if lib.mpatch_apply(buf, text, len(text), patch) < 0:
        lib.mpatch_lfree(patch)
        raise mpatchError("error applying patches")
    res = ffi.buffer(buf, outlen)[:]
    lib.mpatch_lfree(patch)
    return res