view mercurial/pycompat.py @ 48687:f8f2ecdde4b5

branchmap: skip obsolete revisions while computing heads

It's time to make this part of core Mercurial obsolescence-aware.

Not considering obsolete revisions when computing heads is clearly what
Mercurial should do. But there are a couple of small issues:

- Let's say tip of the repo is obsolete. There are two ways of finding tiprev
  for branchcache (both are in use): looking at input data for update() and
  looking at computed heads after update(). Previously, repo tip would be
  tiprev of the branchcache. With this patch, an obsolete revision can no
  longer be tiprev. And depending on what way we use for finding tiprev (input
  data vs computed heads) we'll get a different result. This is relevant when
  recomputing cache key from cache contents, and may lead to updating cache for
  obsolete revisions multiple times (not from scratch, because it still would
  be considered valid for a subset of revisions in the repo).

- If all commits on a branch are obsolete, the branchcache will include that
  branch, but the list of heads will be empty (that's why there's now `if not
  heads` when recomputing tiprev/tipnode from cache contents). Having an entry
  for every branch is currently required for notify extension (and
  test-notify.t to pass), because notify doesn't handle revsets in its
  subscription config very well and will throw an error if e.g. a branch
  doesn't exist.

- Cloning static HTTP repos may try to stat() a non-existent obsstore file. The
  issue is that we now care about obsolescence during clone, but statichttpvfs
  doesn't implement a stat method, so a regular vfs.stat() is used, and it
  assumes that file is local and calls os.stat().  During a clone, we're trying
  to stat() .hg/store/obsstore, but in static HTTP case we provide a literal
  URL to the obsstore file on the remote as if it were a local file path. On
  windows it actually results in a failure in test-static-http.t.

The first issue is going to be addressed in a series dedicated to making sure
branchcache is properly and timely written on disk (it wasn't perfect even
before this patch, but there aren't enough tests to demonstrate that). The
second issue will be addressed in a future patch for notify extension that will
make it not raise an exception if a branch doesn't exist. And the third one was
partially addressed in the previous patch in this series and will be properly
fixed in a future patch when this series is accepted.

filteredhash() grows a keyword argument to make sure that branchcache is also
invalidated when there are new obsolete revisions in its repo view. This way
the on-disk cache format is unchanged and compatible between versions (although
it will obviously be recomputed when switching versions before/after this patch
and the repo has obsolete revisions).

There's one test that uses plain `hg up` without arguments while updated to a
pruned commit. To make this test pass, simply return current working directory
parent. Later in this series this code will be replaced by what prune command
does: updating to the closest non-obsolete ancestor.

Test changes:

test-branch-change.t: update branch head and cache update message. The head of
default listed in hg heads is changed because revision 2 was rewritten as 7,
and 1 is the closest ancestor on the same branch, so it's the head of default
now.

The cache invalidation message appears now because of the cache hash change,
since we're now accounting for obsolete revisions. Here's some context:

"served.hidden" repo filter means everything is visible (no filtered
revisions), so before this series branch2-served.hidden file would not contain
any cache hash, only revnum and node. Now it also has a hash when there are
obsolete changesets in the repo. The command that the message appears for is
changing branch of 5 and 6, which are now obsolete, so the cache hash changes.

In general, when cache is simply out-of-date, it can be updated using the old
version as a base. But if cache hash differs, then the cache for that
particular repo filter is recomputed (at least with the current
implementation). This is what happens here.

test-obsmarker-template.t: the pull reports 2 heads changed, but after that the
repo correctly sees only 1. The new message could be better, but it's still an
improvement over the previous one where hg pull suggested merging with an
obsolete revision.

test-obsolete.t: we can see these revisions in hg log --hidden, but they
shouldn't be considered heads even with --hidden.

test-rebase-obsolete{,2}.t: there were new heads created previously after
making new orphan changesets, but they weren't detected. Now we are properly
detecting and reporting them.

test-rebase-obsolete4.t: there's only one head now because the other head is
pruned and was falsely reported before.

test-static-http.t: add obsstore to the list of requested files. This file
doesn't exist on the remotes, but clients want it anyway (they get 404). This
is fine, because there are other nonexistent files that clients request, like
.hg/bookmarks or .hg/cache/tags2-served.

Differential Revision: https://phab.mercurial-scm.org/D12097

# pycompat.py - portability shim for python 3
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

"""Mercurial portability shim for python 3.

This contains aliases to hide python version-specific details from the core.
"""

from __future__ import absolute_import

import getopt
import inspect
import json
import os
import shlex
import sys
import tempfile

ispy3 = sys.version_info[0] >= 3
ispypy = '__pypy__' in sys.builtin_module_names
TYPE_CHECKING = False

if not globals():  # hide this from non-pytype users
    import typing

    TYPE_CHECKING = typing.TYPE_CHECKING

if not ispy3:
    import cookielib
    import cPickle as pickle
    import httplib
    import Queue as queue
    import SocketServer as socketserver
    import xmlrpclib

    from .thirdparty.concurrent import futures

    def future_set_exception_info(f, exc_info):
        f.set_exception_info(*exc_info)

    # this is close enough for our usage
    FileNotFoundError = OSError

else:
    import builtins
    import concurrent.futures as futures
    import http.cookiejar as cookielib
    import http.client as httplib
    import pickle
    import queue as queue
    import socketserver
    import xmlrpc.client as xmlrpclib

    def future_set_exception_info(f, exc_info):
        f.set_exception(exc_info[0])

    FileNotFoundError = builtins.FileNotFoundError


def identity(a):
    return a


def _rapply(f, xs):
    if xs is None:
        # assume None means non-value of optional data
        return xs
    if isinstance(xs, (list, set, tuple)):
        return type(xs)(_rapply(f, x) for x in xs)
    if isinstance(xs, dict):
        return type(xs)((_rapply(f, k), _rapply(f, v)) for k, v in xs.items())
    return f(xs)


def rapply(f, xs):
    """Apply function recursively to every item preserving the data structure

    >>> def f(x):
    ...     return 'f(%s)' % x
    >>> rapply(f, None) is None
    True
    >>> rapply(f, 'a')
    'f(a)'
    >>> rapply(f, {'a'}) == {'f(a)'}
    True
    >>> rapply(f, ['a', 'b', None, {'c': 'd'}, []])
    ['f(a)', 'f(b)', None, {'f(c)': 'f(d)'}, []]

    >>> xs = [object()]
    >>> rapply(identity, xs) is xs
    True
    """
    if f is identity:
        # fast path mainly for py2
        return xs
    return _rapply(f, xs)


if ispy3:
    import builtins
    import codecs
    import functools
    import io
    import struct

    if os.name == r'nt' and sys.version_info >= (3, 6):
        # MBCS (or ANSI) filesystem encoding must be used as before.
        # Otherwise non-ASCII filenames in existing repositories would be
        # corrupted.
        # This must be set once prior to any fsencode/fsdecode calls.
        sys._enablelegacywindowsfsencoding()  # pytype: disable=module-attr

    fsencode = os.fsencode
    fsdecode = os.fsdecode
    oscurdir = os.curdir.encode('ascii')
    oslinesep = os.linesep.encode('ascii')
    osname = os.name.encode('ascii')
    ospathsep = os.pathsep.encode('ascii')
    ospardir = os.pardir.encode('ascii')
    ossep = os.sep.encode('ascii')
    osaltsep = os.altsep
    if osaltsep:
        osaltsep = osaltsep.encode('ascii')
    osdevnull = os.devnull.encode('ascii')

    sysplatform = sys.platform.encode('ascii')
    sysexecutable = sys.executable
    if sysexecutable:
        sysexecutable = os.fsencode(sysexecutable)
    bytesio = io.BytesIO
    # TODO deprecate stringio name, as it is a lie on Python 3.
    stringio = bytesio

    def maplist(*args):
        return list(map(*args))

    def rangelist(*args):
        return list(range(*args))

    def ziplist(*args):
        return list(zip(*args))

    rawinput = input
    getargspec = inspect.getfullargspec

    long = int

    if getattr(sys, 'argv', None) is not None:
        # On POSIX, the char** argv array is converted to Python str using
        # Py_DecodeLocale(). The inverse of this is Py_EncodeLocale(), which
        # isn't directly callable from Python code. In practice, os.fsencode()
        # can be used instead (this is recommended by Python's documentation
        # for sys.argv).
        #
        # On Windows, the wchar_t **argv is passed into the interpreter as-is.
        # Like POSIX, we need to emulate what Py_EncodeLocale() would do. But
        # there's an additional wrinkle. What we really want to access is the
        # ANSI codepage representation of the arguments, as this is what
        # `int main()` would receive if Python 3 didn't define `int wmain()`
        # (this is how Python 2 worked). To get that, we encode with the mbcs
        # encoding, which will pass CP_ACP to the underlying Windows API to
        # produce bytes.
        if os.name == r'nt':
            sysargv = [a.encode("mbcs", "ignore") for a in sys.argv]
        else:
            sysargv = [fsencode(a) for a in sys.argv]

    bytechr = struct.Struct('>B').pack
    byterepr = b'%r'.__mod__

    class bytestr(bytes):
        """A bytes which mostly acts as a Python 2 str

        >>> bytestr(), bytestr(bytearray(b'foo')), bytestr(u'ascii'), bytestr(1)
        ('', 'foo', 'ascii', '1')
        >>> s = bytestr(b'foo')
        >>> assert s is bytestr(s)

        __bytes__() should be called if provided:

        >>> class bytesable(object):
        ...     def __bytes__(self):
        ...         return b'bytes'
        >>> bytestr(bytesable())
        'bytes'

        There's no implicit conversion from non-ascii str as its encoding is
        unknown:

        >>> bytestr(chr(0x80)) # doctest: +ELLIPSIS
        Traceback (most recent call last):
          ...
        UnicodeEncodeError: ...

        Comparison between bytestr and bytes should work:

        >>> assert bytestr(b'foo') == b'foo'
        >>> assert b'foo' == bytestr(b'foo')
        >>> assert b'f' in bytestr(b'foo')
        >>> assert bytestr(b'f') in b'foo'

        Sliced elements should be bytes, not integer:

        >>> s[1], s[:2]
        (b'o', b'fo')
        >>> list(s), list(reversed(s))
        ([b'f', b'o', b'o'], [b'o', b'o', b'f'])

        As bytestr type isn't propagated across operations, you need to cast
        bytes to bytestr explicitly:

        >>> s = bytestr(b'foo').upper()
        >>> t = bytestr(s)
        >>> s[0], t[0]
        (70, b'F')

        Be careful to not pass a bytestr object to a function which expects
        bytearray-like behavior.

        >>> t = bytes(t)  # cast to bytes
        >>> assert type(t) is bytes
        """

        # Trick pytype into not demanding Iterable[int] be passed to __new__(),
        # since the appropriate bytes format is done internally.
        #
        # https://github.com/google/pytype/issues/500
        if TYPE_CHECKING:

            def __init__(self, s=b''):
                pass

        def __new__(cls, s=b''):
            if isinstance(s, bytestr):
                return s
            if not isinstance(
                s, (bytes, bytearray)
            ) and not hasattr(  # hasattr-py3-only
                s, u'__bytes__'
            ):
                s = str(s).encode('ascii')
            return bytes.__new__(cls, s)

        def __getitem__(self, key):
            s = bytes.__getitem__(self, key)
            if not isinstance(s, bytes):
                s = bytechr(s)
            return s

        def __iter__(self):
            return iterbytestr(bytes.__iter__(self))

        def __repr__(self):
            return bytes.__repr__(self)[1:]  # drop b''

    def iterbytestr(s):
        """Iterate bytes as if it were a str object of Python 2"""
        return map(bytechr, s)

    def maybebytestr(s):
        """Promote bytes to bytestr"""
        if isinstance(s, bytes):
            return bytestr(s)
        return s

    def sysbytes(s):
        """Convert an internal str (e.g. keyword, __doc__) back to bytes

        This never raises UnicodeEncodeError, but only ASCII characters
        can be round-trip by sysstr(sysbytes(s)).
        """
        if isinstance(s, bytes):
            return s
        return s.encode('utf-8')

    def sysstr(s):
        """Return a keyword str to be passed to Python functions such as
        getattr() and str.encode()

        This never raises UnicodeDecodeError. Non-ascii characters are
        considered invalid and mapped to arbitrary but unique code points
        such that 'sysstr(a) != sysstr(b)' for all 'a != b'.
        """
        if isinstance(s, builtins.str):
            return s
        return s.decode('latin-1')

    def strurl(url):
        """Converts a bytes url back to str"""
        if isinstance(url, bytes):
            return url.decode('ascii')
        return url

    def bytesurl(url):
        """Converts a str url to bytes by encoding in ascii"""
        if isinstance(url, str):
            return url.encode('ascii')
        return url

    def raisewithtb(exc, tb):
        """Raise exception with the given traceback"""
        raise exc.with_traceback(tb)

    def getdoc(obj):
        """Get docstring as bytes; may be None so gettext() won't confuse it
        with _('')"""
        doc = getattr(obj, '__doc__', None)
        if doc is None:
            return doc
        return sysbytes(doc)

    def _wrapattrfunc(f):
        @functools.wraps(f)
        def w(object, name, *args):
            return f(object, sysstr(name), *args)

        return w

    # these wrappers are automagically imported by hgloader
    delattr = _wrapattrfunc(builtins.delattr)
    getattr = _wrapattrfunc(builtins.getattr)
    hasattr = _wrapattrfunc(builtins.hasattr)
    setattr = _wrapattrfunc(builtins.setattr)
    xrange = builtins.range
    unicode = str

    def open(name, mode=b'r', buffering=-1, encoding=None):
        return builtins.open(name, sysstr(mode), buffering, encoding)

    safehasattr = _wrapattrfunc(builtins.hasattr)

    def _getoptbwrapper(orig, args, shortlist, namelist):
        """
        Takes bytes arguments, converts them to unicode, pass them to
        getopt.getopt(), convert the returned values back to bytes and then
        return them for Python 3 compatibility as getopt.getopt() don't accepts
        bytes on Python 3.
        """
        args = [a.decode('latin-1') for a in args]
        shortlist = shortlist.decode('latin-1')
        namelist = [a.decode('latin-1') for a in namelist]
        opts, args = orig(args, shortlist, namelist)
        opts = [(a[0].encode('latin-1'), a[1].encode('latin-1')) for a in opts]
        args = [a.encode('latin-1') for a in args]
        return opts, args

    def strkwargs(dic):
        """
        Converts the keys of a python dictonary to str i.e. unicodes so that
        they can be passed as keyword arguments as dictionaries with bytes keys
        can't be passed as keyword arguments to functions on Python 3.
        """
        dic = {k.decode('latin-1'): v for k, v in dic.items()}
        return dic

    def byteskwargs(dic):
        """
        Converts keys of python dictionaries to bytes as they were converted to
        str to pass that dictonary as a keyword argument on Python 3.
        """
        dic = {k.encode('latin-1'): v for k, v in dic.items()}
        return dic

    # TODO: handle shlex.shlex().
    def shlexsplit(s, comments=False, posix=True):
        """
        Takes bytes argument, convert it to str i.e. unicodes, pass that into
        shlex.split(), convert the returned value to bytes and return that for
        Python 3 compatibility as shelx.split() don't accept bytes on Python 3.
        """
        ret = shlex.split(s.decode('latin-1'), comments, posix)
        return [a.encode('latin-1') for a in ret]

    iteritems = lambda x: x.items()
    itervalues = lambda x: x.values()

    # Python 3.5's json.load and json.loads require str. We polyfill its
    # code for detecting encoding from bytes.
    if sys.version_info[0:2] < (3, 6):

        def _detect_encoding(b):
            bstartswith = b.startswith
            if bstartswith((codecs.BOM_UTF32_BE, codecs.BOM_UTF32_LE)):
                return 'utf-32'
            if bstartswith((codecs.BOM_UTF16_BE, codecs.BOM_UTF16_LE)):
                return 'utf-16'
            if bstartswith(codecs.BOM_UTF8):
                return 'utf-8-sig'

            if len(b) >= 4:
                if not b[0]:
                    # 00 00 -- -- - utf-32-be
                    # 00 XX -- -- - utf-16-be
                    return 'utf-16-be' if b[1] else 'utf-32-be'
                if not b[1]:
                    # XX 00 00 00 - utf-32-le
                    # XX 00 00 XX - utf-16-le
                    # XX 00 XX -- - utf-16-le
                    return 'utf-16-le' if b[2] or b[3] else 'utf-32-le'
            elif len(b) == 2:
                if not b[0]:
                    # 00 XX - utf-16-be
                    return 'utf-16-be'
                if not b[1]:
                    # XX 00 - utf-16-le
                    return 'utf-16-le'
            # default
            return 'utf-8'

        def json_loads(s, *args, **kwargs):
            if isinstance(s, (bytes, bytearray)):
                s = s.decode(_detect_encoding(s), 'surrogatepass')

            return json.loads(s, *args, **kwargs)

    else:
        json_loads = json.loads

else:
    import cStringIO

    xrange = xrange
    unicode = unicode
    bytechr = chr
    byterepr = repr
    bytestr = str
    iterbytestr = iter
    maybebytestr = identity
    sysbytes = identity
    sysstr = identity
    strurl = identity
    bytesurl = identity
    open = open
    delattr = delattr
    getattr = getattr
    hasattr = hasattr
    setattr = setattr

    # this can't be parsed on Python 3
    exec(b'def raisewithtb(exc, tb):\n    raise exc, None, tb\n')

    def fsencode(filename):
        """
        Partial backport from os.py in Python 3, which only accepts bytes.
        In Python 2, our paths should only ever be bytes, a unicode path
        indicates a bug.
        """
        if isinstance(filename, str):
            return filename
        else:
            raise TypeError("expect str, not %s" % type(filename).__name__)

    # In Python 2, fsdecode() has a very chance to receive bytes. So it's
    # better not to touch Python 2 part as it's already working fine.
    fsdecode = identity

    def getdoc(obj):
        return getattr(obj, '__doc__', None)

    _notset = object()

    def safehasattr(thing, attr):
        return getattr(thing, attr, _notset) is not _notset

    def _getoptbwrapper(orig, args, shortlist, namelist):
        return orig(args, shortlist, namelist)

    strkwargs = identity
    byteskwargs = identity

    oscurdir = os.curdir
    oslinesep = os.linesep
    osname = os.name
    ospathsep = os.pathsep
    ospardir = os.pardir
    ossep = os.sep
    osaltsep = os.altsep
    osdevnull = os.devnull
    long = long
    if getattr(sys, 'argv', None) is not None:
        sysargv = sys.argv
    sysplatform = sys.platform
    sysexecutable = sys.executable
    shlexsplit = shlex.split
    bytesio = cStringIO.StringIO
    stringio = bytesio
    maplist = map
    rangelist = range
    ziplist = zip
    rawinput = raw_input
    getargspec = inspect.getargspec
    iteritems = lambda x: x.iteritems()
    itervalues = lambda x: x.itervalues()
    json_loads = json.loads

isjython = sysplatform.startswith(b'java')

isdarwin = sysplatform.startswith(b'darwin')
islinux = sysplatform.startswith(b'linux')
isposix = osname == b'posix'
iswindows = osname == b'nt'


def getoptb(args, shortlist, namelist):
    return _getoptbwrapper(getopt.getopt, args, shortlist, namelist)


def gnugetoptb(args, shortlist, namelist):
    return _getoptbwrapper(getopt.gnu_getopt, args, shortlist, namelist)


def mkdtemp(suffix=b'', prefix=b'tmp', dir=None):
    return tempfile.mkdtemp(suffix, prefix, dir)


# text=True is not supported; use util.from/tonativeeol() instead
def mkstemp(suffix=b'', prefix=b'tmp', dir=None):
    return tempfile.mkstemp(suffix, prefix, dir)


# TemporaryFile does not support an "encoding=" argument on python2.
# This wrapper file are always open in byte mode.
def unnamedtempfile(mode=None, *args, **kwargs):
    if mode is None:
        mode = 'w+b'
    else:
        mode = sysstr(mode)
    assert 'b' in mode
    return tempfile.TemporaryFile(mode, *args, **kwargs)


# NamedTemporaryFile does not support an "encoding=" argument on python2.
# This wrapper file are always open in byte mode.
def namedtempfile(
    mode=b'w+b', bufsize=-1, suffix=b'', prefix=b'tmp', dir=None, delete=True
):
    mode = sysstr(mode)
    assert 'b' in mode
    return tempfile.NamedTemporaryFile(
        mode, bufsize, suffix=suffix, prefix=prefix, dir=dir, delete=delete
    )