Mercurial > hg-stable
view mercurial/vfs.py @ 39646:9c2c77c73f23
wireprotov2: define and implement "changesetdata" command
This commit introduces the "changesetdata" wire protocol command.
The role of the command is to expose data associated with changelog
revisions, including the raw revision data itself.
This command is the first piece of a new clone/pull strategy that
is built on top of domain-specific commands for data retrieval.
Instead of a monolithic "getbundle" command that transfers all of the
things, we'll be introducing commands for fetching specific pieces
of data.
Since the changeset is the fundamental unit from which we derive
pointers to other data (manifests, file nodes, etc), it makes sense
to start reimplementing pull with this data.
The command accepts as arguments a set of root and head revisions
defining the changesets that should be fetched as well as an explicit
list of nodes. By default, the command returns only the node values:
the client must explicitly request additional fields be added to the
response. Current supported fields are the list of parent nodes and
the revision fulltext.
My plan is to eventually add support for transferring other data
associated with changesets, including phases, bookmarks, obsolescence
markers, etc. Since the response format is CBOR, we'll be able to add
this data into the response object relatively easily (it should be
as simple as adding a key in a map).
The documentation captures a number of TODO items. Some of these may
require BC breaking changes. That's fine: wire protocol v2 is still
highly experimental.
Differential Revision: https://phab.mercurial-scm.org/D4481
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 12 Sep 2018 10:01:16 -0700 |
parents | 3dd34b401bc2 |
children | 5fe0b880200e |
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# vfs.py - Mercurial 'vfs' classes # # Copyright Matt Mackall <mpm@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 . 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""" def __init__(self, *args, **kwargs): '''Prevent instantiation; don't call this from subclasses.''' raise NotImplementedError('attempted instantiating ' + str(type(self))) 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 "" def tryreadlines(self, path, mode='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, 'rb') as fp: return fp.read() def readlines(self, path, mode='rb'): with self(path, mode=mode) as fp: return fp.readlines() def write(self, path, data, backgroundclose=False, **kwargs): with self(path, 'wb', backgroundclose=backgroundclose, **kwargs) as fp: return fp.write(data) def writelines(self, path, data, mode='wb', notindexed=False): with self(path, mode=mode, notindexed=notindexed) as fp: return fp.writelines(data) def append(self, path, data): with self(path, '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 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 os.path.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='', prefix='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). """ 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 os.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.currentThread(), threading._MainThread): yield return vfs = getattr(self, 'vfs', self) if getattr(vfs, '_backgroundfilecloser', None): raise error.Abort( _('can only have 1 active background file closer')) with backgroundfilecloser(ui, expectedcount=expectedcount) as bfc: try: vfs._backgroundfilecloser = bfc yield bfc finally: vfs._backgroundfilecloser = None 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 @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 __call__(self, path, mode="r", atomictemp=False, notindexed=False, backgroundclose=False, checkambig=False, auditpath=True): '''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. 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 atomictemplfile (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: if self._audit: r = util.checkosfilename(path) if r: raise error.Abort("%s: %r" % (r, path)) self.audit(path, mode=mode) f = self.join(path) if "b" not in mode: mode += "b" # for that other OS nlink = -1 if mode not in ('r', '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: util.makedirs(dirname, self.createmode, notindexed) return util.atomictempfile(f, mode, self.createmode, checkambig=checkambig) try: if '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 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 ('r', 'rb'): raise error.Abort(_('implementation error: mode %s is not' ' valid for checkambig=True') % mode) fp = checkambigatclosing(fp) if (backgroundclose and isinstance(threading.currentThread(), threading._MainThread)): if not self._backgroundfilecloser: raise error.Abort(_('backgroundclose can only be used when a ' 'backgroundclosing context manager is active') ) fp = delayclosedfile(fp, self._backgroundfilecloser) 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, _('could not symlink to %r: %s') % (src, encoding.strtolocal(err.strerror)), linkname) else: self.write(dst, src) def join(self, path, *insidef): if path: return os.path.join(self.base, path, *insidef) else: return self.base opener = vfs class proxyvfs(object): def __init__(self, vfs): self.vfs = vfs @property def options(self): return self.vfs.options @options.setter def options(self, value): self.vfs.options = value class filtervfs(abstractvfs, proxyvfs): '''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(abstractvfs, proxyvfs): '''Wrapper vfs preventing any writing.''' def __init__(self, vfs): proxyvfs.__init__(self, vfs) def __call__(self, path, mode='r', *args, **kw): if mode not in ('r', 'rb'): raise error.Abort(_('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, r'_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): return self._origfh.__enter__() 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, r'_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('worker', '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('worker', '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('worker', 'backgroundclosemaxqueue') threadcount = ui.configint('worker', 'backgroundclosethreadcount') ui.debug('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(_('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, r'_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()