Mercurial > hg
view mercurial/scmposix.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 | 7a4143428db7 |
children | 18c8c18993f0 |
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import array import errno import fcntl import os import sys from typing import ( List, Tuple, ) from .pycompat import getattr from . import ( encoding, pycompat, util, ) if pycompat.TYPE_CHECKING: from . import ui as uimod # BSD 'more' escapes ANSI color sequences by default. This can be disabled by # $MORE variable, but there's no compatible option with Linux 'more'. Given # OS X is widely used and most modern Unix systems would have 'less', setting # 'less' as the default seems reasonable. fallbackpager = b'less' def _rcfiles(path: bytes) -> List[bytes]: rcs = [os.path.join(path, b'hgrc')] rcdir = os.path.join(path, b'hgrc.d') try: rcs.extend( [ os.path.join(rcdir, f) for f, kind in sorted(util.listdir(rcdir)) if f.endswith(b".rc") ] ) except OSError: pass return rcs def systemrcpath() -> List[bytes]: path = [] if pycompat.sysplatform == b'plan9': root = b'lib/mercurial' else: root = b'etc/mercurial' # old mod_python does not set sys.argv if len(getattr(sys, 'argv', [])) > 0: p = os.path.dirname(os.path.dirname(pycompat.sysargv[0])) if p != b'/': path.extend(_rcfiles(os.path.join(p, root))) path.extend(_rcfiles(b'/' + root)) return path def userrcpath() -> List[bytes]: if pycompat.sysplatform == b'plan9': return [encoding.environ[b'home'] + b'/lib/hgrc'] elif pycompat.isdarwin: return [os.path.expanduser(b'~/.hgrc')] else: confighome = encoding.environ.get(b'XDG_CONFIG_HOME') if confighome is None or not os.path.isabs(confighome): confighome = os.path.expanduser(b'~/.config') return [ os.path.expanduser(b'~/.hgrc'), os.path.join(confighome, b'hg', b'hgrc'), ] def termsize(ui: "uimod.ui") -> Tuple[int, int]: try: import termios TIOCGWINSZ = termios.TIOCGWINSZ # unavailable on IRIX (issue3449) except (AttributeError, ImportError): return 80, 24 for dev in (ui.ferr, ui.fout, ui.fin): try: try: fd = dev.fileno() except AttributeError: continue if not os.isatty(fd): continue arri = fcntl.ioctl(fd, TIOCGWINSZ, b'\0' * 8) height, width = array.array('h', arri)[:2] if width > 0 and height > 0: return width, height except ValueError: pass except IOError as e: if e.errno == errno.EINVAL: pass else: raise return 80, 24