Mercurial > hg
view mercurial/logexchange.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 | 5bceea1a8234 |
children | f4733654f144 |
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# logexchange.py # # Copyright 2017 Augie Fackler <raf@durin42.com> # Copyright 2017 Sean Farley <sean@farley.io> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from .node import hex from . import ( util, vfs as vfsmod, ) from .utils import ( urlutil, ) # directory name in .hg/ in which remotenames files will be present remotenamedir = b'logexchange' def readremotenamefile(repo, filename): """ reads a file from .hg/logexchange/ directory and yields it's content filename: the file to be read yield a tuple (node, remotepath, name) """ vfs = vfsmod.vfs(repo.vfs.join(remotenamedir)) if not vfs.exists(filename): return f = vfs(filename) lineno = 0 for line in f: line = line.strip() if not line: continue # contains the version number if lineno == 0: lineno += 1 try: node, remote, rname = line.split(b'\0') yield node, remote, rname except ValueError: pass f.close() def readremotenames(repo): """ read the details about the remotenames stored in .hg/logexchange/ and yields a tuple (node, remotepath, name). It does not yields information about whether an entry yielded is branch or bookmark. To get that information, call the respective functions. """ for bmentry in readremotenamefile(repo, b'bookmarks'): yield bmentry for branchentry in readremotenamefile(repo, b'branches'): yield branchentry def writeremotenamefile(repo, remotepath, names, nametype): vfs = vfsmod.vfs(repo.vfs.join(remotenamedir)) f = vfs(nametype, b'w', atomictemp=True) # write the storage version info on top of file # version '0' represents the very initial version of the storage format f.write(b'0\n\n') olddata = set(readremotenamefile(repo, nametype)) # re-save the data from a different remote than this one. for node, oldpath, rname in sorted(olddata): if oldpath != remotepath: f.write(b'%s\0%s\0%s\n' % (node, oldpath, rname)) for name, node in sorted(names.items()): if nametype == b"branches": for n in node: f.write(b'%s\0%s\0%s\n' % (n, remotepath, name)) elif nametype == b"bookmarks": if node: f.write(b'%s\0%s\0%s\n' % (node, remotepath, name)) f.close() def saveremotenames(repo, remotepath, branches=None, bookmarks=None): """ save remotenames i.e. remotebookmarks and remotebranches in their respective files under ".hg/logexchange/" directory. """ wlock = repo.wlock() try: if bookmarks: writeremotenamefile(repo, remotepath, bookmarks, b'bookmarks') if branches: writeremotenamefile(repo, remotepath, branches, b'branches') finally: wlock.release() def activepath(repo, remote): """returns remote path""" # is the remote a local peer local = remote.local() # determine the remote path from the repo, if possible; else just # use the string given to us rpath = remote if local: rpath = util.pconvert(remote._repo.root) elif not isinstance(remote, bytes): rpath = remote.url() # represent the remotepath with user defined path name if exists for path, url in repo.ui.configitems(b'paths'): # remove auth info from user defined url noauthurl = urlutil.removeauth(url) # Standardize on unix style paths, otherwise some {remotenames} end up # being an absolute path on Windows. url = util.pconvert(bytes(url)) noauthurl = util.pconvert(noauthurl) if url == rpath or noauthurl == rpath: rpath = path break return rpath def pullremotenames(localrepo, remoterepo): """ pulls bookmarks and branches information of the remote repo during a pull or clone operation. localrepo is our local repository remoterepo is the peer instance """ remotepath = activepath(localrepo, remoterepo) with remoterepo.commandexecutor() as e: bookmarks = e.callcommand( b'listkeys', { b'namespace': b'bookmarks', }, ).result() # on a push, we don't want to keep obsolete heads since # they won't show up as heads on the next pull, so we # remove them here otherwise we would require the user # to issue a pull to refresh the storage bmap = {} repo = localrepo.unfiltered() with remoterepo.commandexecutor() as e: branchmap = e.callcommand(b'branchmap', {}).result() for branch, nodes in branchmap.items(): bmap[branch] = [] for node in nodes: if node in repo and not repo[node].obsolete(): bmap[branch].append(hex(node)) saveremotenames(localrepo, remotepath, bmap, bookmarks)