Mercurial > hg
view mercurial/vfs.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- Let's say tip of the repo is obsolete.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
author | Anton Shestakov <av6@dwimlabs.net> |
---|---|
date | Fri, 07 Jan 2022 11:53:23 +0300 |
parents | 98c3fa6a3ac2 |
children | 6000f5b25c9b |
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# vfs.py - Mercurial 'vfs' classes # # Copyright Olivia Mackall <olivia@selenic.com> # # 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 import contextlib import errno import os import shutil import stat import threading from .i18n import _ from .pycompat import ( delattr, getattr, setattr, ) from . import ( encoding, error, pathutil, pycompat, util, ) def _avoidambig(path, oldstat): """Avoid file stat ambiguity forcibly This function causes copying ``path`` file, if it is owned by another (see issue5418 and issue5584 for detail). """ def checkandavoid(): newstat = util.filestat.frompath(path) # return whether file stat ambiguity is (already) avoided return not newstat.isambig(oldstat) or newstat.avoidambig(path, oldstat) if not checkandavoid(): # simply copy to change owner of path to get privilege to # advance mtime (see issue5418) util.rename(util.mktempcopy(path), path) checkandavoid() class abstractvfs(object): """Abstract base class; cannot be instantiated""" # default directory separator for vfs # # Other vfs code always use `/` and this works fine because python file API # abstract the use of `/` and make it work transparently. For consistency # vfs will always use `/` when joining. This avoid some confusion in # encoded vfs (see issue6546) _dir_sep = b'/' def __init__(self, *args, **kwargs): '''Prevent instantiation; don't call this from subclasses.''' raise NotImplementedError('attempted instantiating ' + str(type(self))) def __call__(self, path, mode=b'rb', **kwargs): raise NotImplementedError def _auditpath(self, path, mode): raise NotImplementedError def join(self, path, *insidef): raise NotImplementedError def tryread(self, path): '''gracefully return an empty string for missing files''' try: return self.read(path) except IOError as inst: if inst.errno != errno.ENOENT: raise return b"" def tryreadlines(self, path, mode=b'rb'): '''gracefully return an empty array for missing files''' try: return self.readlines(path, mode=mode) except IOError as inst: if inst.errno != errno.ENOENT: raise return [] @util.propertycache def open(self): """Open ``path`` file, which is relative to vfs root. Newly created directories are marked as "not to be indexed by the content indexing service", if ``notindexed`` is specified for "write" mode access. """ return self.__call__ def read(self, path): with self(path, b'rb') as fp: return fp.read() def readlines(self, path, mode=b'rb'): with self(path, mode=mode) as fp: return fp.readlines() def write(self, path, data, backgroundclose=False, **kwargs): with self(path, b'wb', backgroundclose=backgroundclose, **kwargs) as fp: return fp.write(data) def writelines(self, path, data, mode=b'wb', notindexed=False): with self(path, mode=mode, notindexed=notindexed) as fp: return fp.writelines(data) def append(self, path, data): with self(path, b'ab') as fp: return fp.write(data) def basename(self, path): """return base element of a path (as os.path.basename would do) This exists to allow handling of strange encoding if needed.""" return os.path.basename(path) def chmod(self, path, mode): return os.chmod(self.join(path), mode) def dirname(self, path): """return dirname element of a path (as os.path.dirname would do) This exists to allow handling of strange encoding if needed.""" return os.path.dirname(path) def exists(self, path=None): return os.path.exists(self.join(path)) def fstat(self, fp): return util.fstat(fp) def isdir(self, path=None): return os.path.isdir(self.join(path)) def isfile(self, path=None): return os.path.isfile(self.join(path)) def islink(self, path=None): return os.path.islink(self.join(path)) def isfileorlink(self, path=None): """return whether path is a regular file or a symlink Unlike isfile, this doesn't follow symlinks.""" try: st = self.lstat(path) except OSError: return False mode = st.st_mode return stat.S_ISREG(mode) or stat.S_ISLNK(mode) def _join(self, *paths): root_idx = 0 for idx, p in enumerate(paths): if os.path.isabs(p) or p.startswith(self._dir_sep): root_idx = idx if root_idx != 0: paths = paths[root_idx:] paths = [p for p in paths if p] return self._dir_sep.join(paths) def reljoin(self, *paths): """join various elements of a path together (as os.path.join would do) The vfs base is not injected so that path stay relative. This exists to allow handling of strange encoding if needed.""" return self._join(*paths) def split(self, path): """split top-most element of a path (as os.path.split would do) This exists to allow handling of strange encoding if needed.""" return os.path.split(path) def lexists(self, path=None): return os.path.lexists(self.join(path)) def lstat(self, path=None): return os.lstat(self.join(path)) def listdir(self, path=None): return os.listdir(self.join(path)) def makedir(self, path=None, notindexed=True): return util.makedir(self.join(path), notindexed) def makedirs(self, path=None, mode=None): return util.makedirs(self.join(path), mode) def makelock(self, info, path): return util.makelock(info, self.join(path)) def mkdir(self, path=None): return os.mkdir(self.join(path)) def mkstemp(self, suffix=b'', prefix=b'tmp', dir=None): fd, name = pycompat.mkstemp( suffix=suffix, prefix=prefix, dir=self.join(dir) ) dname, fname = util.split(name) if dir: return fd, os.path.join(dir, fname) else: return fd, fname def readdir(self, path=None, stat=None, skip=None): return util.listdir(self.join(path), stat, skip) def readlock(self, path): return util.readlock(self.join(path)) def rename(self, src, dst, checkambig=False): """Rename from src to dst checkambig argument is used with util.filestat, and is useful only if destination file is guarded by any lock (e.g. repo.lock or repo.wlock). To avoid file stat ambiguity forcibly, checkambig=True involves copying ``src`` file, if it is owned by another. Therefore, use checkambig=True only in limited cases (see also issue5418 and issue5584 for detail). """ self._auditpath(dst, b'w') srcpath = self.join(src) dstpath = self.join(dst) oldstat = checkambig and util.filestat.frompath(dstpath) if oldstat and oldstat.stat: ret = util.rename(srcpath, dstpath) _avoidambig(dstpath, oldstat) return ret return util.rename(srcpath, dstpath) def readlink(self, path): return util.readlink(self.join(path)) def removedirs(self, path=None): """Remove a leaf directory and all empty intermediate ones""" return util.removedirs(self.join(path)) def rmdir(self, path=None): """Remove an empty directory.""" return os.rmdir(self.join(path)) def rmtree(self, path=None, ignore_errors=False, forcibly=False): """Remove a directory tree recursively If ``forcibly``, this tries to remove READ-ONLY files, too. """ if forcibly: def onerror(function, path, excinfo): if function is not os.remove: raise # read-only files cannot be unlinked under Windows s = os.stat(path) if (s.st_mode & stat.S_IWRITE) != 0: raise os.chmod(path, stat.S_IMODE(s.st_mode) | stat.S_IWRITE) os.remove(path) else: onerror = None return shutil.rmtree( self.join(path), ignore_errors=ignore_errors, onerror=onerror ) def setflags(self, path, l, x): return util.setflags(self.join(path), l, x) def stat(self, path=None): return os.stat(self.join(path)) def unlink(self, path=None): return util.unlink(self.join(path)) def tryunlink(self, path=None): """Attempt to remove a file, ignoring missing file errors.""" util.tryunlink(self.join(path)) def unlinkpath(self, path=None, ignoremissing=False, rmdir=True): return util.unlinkpath( self.join(path), ignoremissing=ignoremissing, rmdir=rmdir ) def utime(self, path=None, t=None): return os.utime(self.join(path), t) def walk(self, path=None, onerror=None): """Yield (dirpath, dirs, files) tuple for each directories under path ``dirpath`` is relative one from the root of this vfs. This uses ``os.sep`` as path separator, even you specify POSIX style ``path``. "The root of this vfs" is represented as empty ``dirpath``. """ root = os.path.normpath(self.join(None)) # when dirpath == root, dirpath[prefixlen:] becomes empty # because len(dirpath) < prefixlen. prefixlen = len(pathutil.normasprefix(root)) for dirpath, dirs, files in os.walk(self.join(path), onerror=onerror): yield (dirpath[prefixlen:], dirs, files) @contextlib.contextmanager def backgroundclosing(self, ui, expectedcount=-1): """Allow files to be closed asynchronously. When this context manager is active, ``backgroundclose`` can be passed to ``__call__``/``open`` to result in the file possibly being closed asynchronously, on a background thread. """ # Sharing backgroundfilecloser between threads is complex and using # multiple instances puts us at risk of running out of file descriptors # only allow to use backgroundfilecloser when in main thread. if not isinstance( threading.current_thread(), threading._MainThread, # pytype: disable=module-attr ): yield return vfs = getattr(self, 'vfs', self) if getattr(vfs, '_backgroundfilecloser', None): raise error.Abort( _(b'can only have 1 active background file closer') ) with backgroundfilecloser(ui, expectedcount=expectedcount) as bfc: try: vfs._backgroundfilecloser = ( bfc # pytype: disable=attribute-error ) yield bfc finally: vfs._backgroundfilecloser = ( None # pytype: disable=attribute-error ) def register_file(self, path): """generic hook point to lets fncache steer its stew""" class vfs(abstractvfs): """Operate files relative to a base directory This class is used to hide the details of COW semantics and remote file access from higher level code. 'cacheaudited' should be enabled only if (a) vfs object is short-lived, or (b) the base directory is managed by hg and considered sort-of append-only. See pathutil.pathauditor() for details. """ def __init__( self, base, audit=True, cacheaudited=False, expandpath=False, realpath=False, ): if expandpath: base = util.expandpath(base) if realpath: base = os.path.realpath(base) self.base = base self._audit = audit if audit: self.audit = pathutil.pathauditor(self.base, cached=cacheaudited) else: self.audit = lambda path, mode=None: True self.createmode = None self._trustnlink = None self.options = {} @util.propertycache def _cansymlink(self): return util.checklink(self.base) @util.propertycache def _chmod(self): return util.checkexec(self.base) def _fixfilemode(self, name): if self.createmode is None or not self._chmod: return os.chmod(name, self.createmode & 0o666) def _auditpath(self, path, mode): if self._audit: if os.path.isabs(path) and path.startswith(self.base): path = os.path.relpath(path, self.base) r = util.checkosfilename(path) if r: raise error.Abort(b"%s: %r" % (r, path)) self.audit(path, mode=mode) def __call__( self, path, mode=b"r", atomictemp=False, notindexed=False, backgroundclose=False, checkambig=False, auditpath=True, makeparentdirs=True, ): """Open ``path`` file, which is relative to vfs root. By default, parent directories are created as needed. Newly created directories are marked as "not to be indexed by the content indexing service", if ``notindexed`` is specified for "write" mode access. Set ``makeparentdirs=False`` to not create directories implicitly. If ``backgroundclose`` is passed, the file may be closed asynchronously. It can only be used if the ``self.backgroundclosing()`` context manager is active. This should only be specified if the following criteria hold: 1. There is a potential for writing thousands of files. Unless you are writing thousands of files, the performance benefits of asynchronously closing files is not realized. 2. Files are opened exactly once for the ``backgroundclosing`` active duration and are therefore free of race conditions between closing a file on a background thread and reopening it. (If the file were opened multiple times, there could be unflushed data because the original file handle hasn't been flushed/closed yet.) ``checkambig`` argument is passed to atomictempfile (valid only for writing), and is useful only if target file is guarded by any lock (e.g. repo.lock or repo.wlock). To avoid file stat ambiguity forcibly, checkambig=True involves copying ``path`` file opened in "append" mode (e.g. for truncation), if it is owned by another. Therefore, use combination of append mode and checkambig=True only in limited cases (see also issue5418 and issue5584 for detail). """ if auditpath: self._auditpath(path, mode) f = self.join(path) if b"b" not in mode: mode += b"b" # for that other OS nlink = -1 if mode not in (b'r', b'rb'): dirname, basename = util.split(f) # If basename is empty, then the path is malformed because it points # to a directory. Let the posixfile() call below raise IOError. if basename: if atomictemp: if makeparentdirs: util.makedirs(dirname, self.createmode, notindexed) return util.atomictempfile( f, mode, self.createmode, checkambig=checkambig ) try: if b'w' in mode: util.unlink(f) nlink = 0 else: # nlinks() may behave differently for files on Windows # shares if the file is open. with util.posixfile(f): nlink = util.nlinks(f) if nlink < 1: nlink = 2 # force mktempcopy (issue1922) except (OSError, IOError) as e: if e.errno != errno.ENOENT: raise nlink = 0 if makeparentdirs: util.makedirs(dirname, self.createmode, notindexed) if nlink > 0: if self._trustnlink is None: self._trustnlink = nlink > 1 or util.checknlink(f) if nlink > 1 or not self._trustnlink: util.rename(util.mktempcopy(f), f) fp = util.posixfile(f, mode) if nlink == 0: self._fixfilemode(f) if checkambig: if mode in (b'r', b'rb'): raise error.Abort( _( b'implementation error: mode %s is not' b' valid for checkambig=True' ) % mode ) fp = checkambigatclosing(fp) if backgroundclose and isinstance( threading.current_thread(), threading._MainThread, # pytype: disable=module-attr ): if ( not self._backgroundfilecloser # pytype: disable=attribute-error ): raise error.Abort( _( b'backgroundclose can only be used when a ' b'backgroundclosing context manager is active' ) ) fp = delayclosedfile( fp, self._backgroundfilecloser, # pytype: disable=attribute-error ) return fp def symlink(self, src, dst): self.audit(dst) linkname = self.join(dst) util.tryunlink(linkname) util.makedirs(os.path.dirname(linkname), self.createmode) if self._cansymlink: try: os.symlink(src, linkname) except OSError as err: raise OSError( err.errno, _(b'could not symlink to %r: %s') % (src, encoding.strtolocal(err.strerror)), linkname, ) else: self.write(dst, src) def join(self, path, *insidef): if path: parts = [self.base, path] parts.extend(insidef) return self._join(*parts) else: return self.base opener = vfs class proxyvfs(abstractvfs): def __init__(self, vfs): self.vfs = vfs def _auditpath(self, path, mode): return self.vfs._auditpath(path, mode) @property def options(self): return self.vfs.options @options.setter def options(self, value): self.vfs.options = value class filtervfs(proxyvfs, abstractvfs): '''Wrapper vfs for filtering filenames with a function.''' def __init__(self, vfs, filter): proxyvfs.__init__(self, vfs) self._filter = filter def __call__(self, path, *args, **kwargs): return self.vfs(self._filter(path), *args, **kwargs) def join(self, path, *insidef): if path: return self.vfs.join(self._filter(self.vfs.reljoin(path, *insidef))) else: return self.vfs.join(path) filteropener = filtervfs class readonlyvfs(proxyvfs): '''Wrapper vfs preventing any writing.''' def __init__(self, vfs): proxyvfs.__init__(self, vfs) def __call__(self, path, mode=b'r', *args, **kw): if mode not in (b'r', b'rb'): raise error.Abort(_(b'this vfs is read only')) return self.vfs(path, mode, *args, **kw) def join(self, path, *insidef): return self.vfs.join(path, *insidef) class closewrapbase(object): """Base class of wrapper, which hooks closing Do not instantiate outside of the vfs layer. """ def __init__(self, fh): object.__setattr__(self, '_origfh', fh) def __getattr__(self, attr): return getattr(self._origfh, attr) def __setattr__(self, attr, value): return setattr(self._origfh, attr, value) def __delattr__(self, attr): return delattr(self._origfh, attr) def __enter__(self): self._origfh.__enter__() return self def __exit__(self, exc_type, exc_value, exc_tb): raise NotImplementedError('attempted instantiating ' + str(type(self))) def close(self): raise NotImplementedError('attempted instantiating ' + str(type(self))) class delayclosedfile(closewrapbase): """Proxy for a file object whose close is delayed. Do not instantiate outside of the vfs layer. """ def __init__(self, fh, closer): super(delayclosedfile, self).__init__(fh) object.__setattr__(self, '_closer', closer) def __exit__(self, exc_type, exc_value, exc_tb): self._closer.close(self._origfh) def close(self): self._closer.close(self._origfh) class backgroundfilecloser(object): """Coordinates background closing of file handles on multiple threads.""" def __init__(self, ui, expectedcount=-1): self._running = False self._entered = False self._threads = [] self._threadexception = None # Only Windows/NTFS has slow file closing. So only enable by default # on that platform. But allow to be enabled elsewhere for testing. defaultenabled = pycompat.iswindows enabled = ui.configbool(b'worker', b'backgroundclose', defaultenabled) if not enabled: return # There is overhead to starting and stopping the background threads. # Don't do background processing unless the file count is large enough # to justify it. minfilecount = ui.configint(b'worker', b'backgroundcloseminfilecount') # FUTURE dynamically start background threads after minfilecount closes. # (We don't currently have any callers that don't know their file count) if expectedcount > 0 and expectedcount < minfilecount: return maxqueue = ui.configint(b'worker', b'backgroundclosemaxqueue') threadcount = ui.configint(b'worker', b'backgroundclosethreadcount') ui.debug( b'starting %d threads for background file closing\n' % threadcount ) self._queue = pycompat.queue.Queue(maxsize=maxqueue) self._running = True for i in range(threadcount): t = threading.Thread(target=self._worker, name='backgroundcloser') self._threads.append(t) t.start() def __enter__(self): self._entered = True return self def __exit__(self, exc_type, exc_value, exc_tb): self._running = False # Wait for threads to finish closing so open files don't linger for # longer than lifetime of context manager. for t in self._threads: t.join() def _worker(self): """Main routine for worker thread.""" while True: try: fh = self._queue.get(block=True, timeout=0.100) # Need to catch or the thread will terminate and # we could orphan file descriptors. try: fh.close() except Exception as e: # Stash so can re-raise from main thread later. self._threadexception = e except pycompat.queue.Empty: if not self._running: break def close(self, fh): """Schedule a file for closing.""" if not self._entered: raise error.Abort( _(b'can only call close() when context manager active') ) # If a background thread encountered an exception, raise now so we fail # fast. Otherwise we may potentially go on for minutes until the error # is acted on. if self._threadexception: e = self._threadexception self._threadexception = None raise e # If we're not actively running, close synchronously. if not self._running: fh.close() return self._queue.put(fh, block=True, timeout=None) class checkambigatclosing(closewrapbase): """Proxy for a file object, to avoid ambiguity of file stat See also util.filestat for detail about "ambiguity of file stat". This proxy is useful only if the target file is guarded by any lock (e.g. repo.lock or repo.wlock) Do not instantiate outside of the vfs layer. """ def __init__(self, fh): super(checkambigatclosing, self).__init__(fh) object.__setattr__(self, '_oldstat', util.filestat.frompath(fh.name)) def _checkambig(self): oldstat = self._oldstat if oldstat.stat: _avoidambig(self._origfh.name, oldstat) def __exit__(self, exc_type, exc_value, exc_tb): self._origfh.__exit__(exc_type, exc_value, exc_tb) self._checkambig() def close(self): self._origfh.close() self._checkambig()