Mercurial > hg
view mercurial/diffutil.py @ 50316:87f0155d68aa stable
revlog: improve the robustness of the splitting process
The previous "in-place" splitting, preserving the splitting on transaction
failure had a couple of issue in case of transaction rollback:
- a race windows that could still lead to a crash and data loss
- it corrupted the `fncache`.
So instead, we use a new approach that we summarized as "we do a backup of the
inline revlog pre-split, and we restore this in case of failure".
To make readers live easier, we don't overwrite the inline index file until
transaction finalization. (once the transaction get into its finalization phase,
it is not expected to rollback, unless some crash happens).
To do so, we write the index of the split index in a temporary file that we use
until transaction finalization. We also keep a backup of the initial inline file
to be able to rollback the split if needed.
As a result, transaction rollback cancel the split and no longer corrupt
fncache. We also no longer have a small inconsistency windows where the
transaction could be unrecoverable.
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Mon, 20 Mar 2023 11:52:17 +0100 |
parents | a6b8b1ab9116 |
children | d6e5bec550f1 |
line wrap: on
line source
# diffutil.py - utility functions related to diff and patch # # Copyright 2006 Brendan Cully <brendan@kublai.com> # Copyright 2007 Chris Mason <chris.mason@oracle.com> # Copyright 2018 Octobus <octobus@octobus.net> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. import typing from typing import ( Any, Dict, Optional, ) from .i18n import _ from . import ( mdiff, pycompat, ) if typing.TYPE_CHECKING: from . import ui as uimod # TODO: narrow the value after the config module is typed _Opts = Dict[bytes, Any] def diffallopts( ui: "uimod.ui", opts: Optional[_Opts] = None, untrusted: bool = False, section: bytes = b'diff', configprefix: bytes = b'', ) -> mdiff.diffopts: '''return diffopts with all features supported and parsed''' return difffeatureopts( ui, opts=opts, untrusted=untrusted, section=section, git=True, whitespace=True, formatchanging=True, configprefix=configprefix, ) def difffeatureopts( ui: "uimod.ui", opts: Optional[_Opts] = None, untrusted: bool = False, section: bytes = b'diff', git: bool = False, whitespace: bool = False, formatchanging: bool = False, configprefix: bytes = b'', ) -> mdiff.diffopts: """return diffopts with only opted-in features parsed Features: - git: git-style diffs - whitespace: whitespace options like ignoreblanklines and ignorews - formatchanging: options that will likely break or cause correctness issues with most diff parsers """ def get( key: bytes, name: Optional[bytes] = None, getter=ui.configbool, forceplain: Optional[bool] = None, ) -> Any: if opts: v = opts.get(key) # diffopts flags are either None-default (which is passed # through unchanged, so we can identify unset values), or # some other falsey default (eg --unified, which defaults # to an empty string). We only want to override the config # entries from hgrc with command line values if they # appear to have been set, which is any truthy value, # True, or False. if v or isinstance(v, bool): return v if forceplain is not None and ui.plain(): return forceplain return getter( section, configprefix + (name or key), untrusted=untrusted ) # core options, expected to be understood by every diff parser buildopts = { b'nodates': get(b'nodates'), b'showfunc': get(b'show_function', b'showfunc'), b'context': get(b'unified', getter=ui.config), } buildopts[b'xdiff'] = ui.configbool(b'experimental', b'xdiff') if git: buildopts[b'git'] = get(b'git') # since this is in the experimental section, we need to call # ui.configbool directory buildopts[b'showsimilarity'] = ui.configbool( b'experimental', b'extendedheader.similarity' ) # need to inspect the ui object instead of using get() since we want to # test for an int hconf = ui.config(b'experimental', b'extendedheader.index') if hconf is not None: hlen = None try: # the hash config could be an integer (for length of hash) or a # word (e.g. short, full, none) hlen = int(hconf) if hlen < 0 or hlen > 40: msg = _(b"invalid length for extendedheader.index: '%d'\n") ui.warn(msg % hlen) except ValueError: # default value if hconf == b'short' or hconf == b'': hlen = 12 elif hconf == b'full': hlen = 40 elif hconf != b'none': msg = _(b"invalid value for extendedheader.index: '%s'\n") ui.warn(msg % hconf) finally: buildopts[b'index'] = hlen if whitespace: buildopts[b'ignorews'] = get(b'ignore_all_space', b'ignorews') buildopts[b'ignorewsamount'] = get( b'ignore_space_change', b'ignorewsamount' ) buildopts[b'ignoreblanklines'] = get( b'ignore_blank_lines', b'ignoreblanklines' ) buildopts[b'ignorewseol'] = get(b'ignore_space_at_eol', b'ignorewseol') if formatchanging: buildopts[b'text'] = None if opts is None else opts.get(b'text') binary = None if opts is None else opts.get(b'binary') buildopts[b'nobinary'] = ( not binary if binary is not None else get(b'nobinary', forceplain=False) ) buildopts[b'noprefix'] = get(b'noprefix', forceplain=False) buildopts[b'worddiff'] = get( b'word_diff', b'word-diff', forceplain=False ) return mdiff.diffopts(**pycompat.strkwargs(buildopts))