Mercurial > hg
view mercurial/statichttprepo.py @ 37716:dfc51a482031
registrar: replace "cmdtype" with an intent-based mechanism (API)
Commands perform varied actions and repositories vary in their
capabilities.
Historically, the .hg/requires file has been used to lock out clients
lacking a requirement. But this is a very heavy-handed approach and
is typically reserved for cases where the on-disk storage format
changes and we want to prevent incompatible clients from operating on
a repo.
Outside of the .hg/requires file, we tend to deal with things like
optional, extension-provided features via checking at call sites.
We'll either have checks in core or extensions will monkeypatch
functions in core disabling incompatible features, enabling new
features, etc.
Things are somewhat tolerable today. But once we introduce alternate
storage backends with varying support for repository features and
vastly different modes of behavior, the current model will quickly
grow unwieldy. For example, the implementation of the "simple store"
required a lot of hacks to deal with stripping and verify because
various parts of core assume things are implemented a certain way.
Partial clone will require new ways of modeling file data retrieval,
because we can no longer assume that all file data is already local.
In this new world, some commands might not make any sense for certain
types of repositories.
What we need is a mechanism to affect the construction of repository
(and eventually peer) instances so the requirements/capabilities
needed for the current operation can be taken into account. "Current
operation" can almost certainly be defined by a command. So it makes
sense for commands to declare their intended actions.
This commit introduces the "intents" concept on the command registrar.
"intents" captures a set of strings that declare actions that are
anticipated to be taken, requirements the repository must possess, etc.
These intents will be passed into hg.repo(), which will pass them into
localrepository, where they can be used to influence the object being
created. Some use cases for this include:
* For read-only intents, constructing a repository object that doesn't
expose methods that can mutate the repository. Its VFS instances
don't even allow opening a file with write access.
* For read-only intents, constructing a repository object without
cache invalidation logic. If the repo never changes during its lifetime,
nothing ever needs to be invalidated and we don't need to do expensive
things like verify the changelog's hidden revisions state is accurate
every time we access repo.changelog.
* We can automatically hide commands from `hg help` when the current
repository doesn't provide that command. For example, an alternate
storage backend may not support `hg commit`, so we can hide that
command or anything else that would perform local commits.
We already kind of had an "intents" mechanism on the registrar in the
form of "cmdtype." However, it was never used. And it was limited to
a single value. We really need something that supports multiple
intents. And because intents may be defined by extensions and at this
point are advisory, I think it is best to define them in a set rather
than as separate arguments/attributes on the command.
Differential Revision: https://phab.mercurial-scm.org/D3376
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sat, 14 Apr 2018 09:23:48 -0700 |
parents | 214f61abd865 |
children | 0664be4f0c1f |
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# statichttprepo.py - simple http repository class for mercurial # # This provides read-only repo access to repositories exported via static http # # Copyright 2005-2007 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 errno from .i18n import _ from . import ( changelog, error, localrepo, manifest, namespaces, pathutil, scmutil, store, url, util, vfs as vfsmod, ) urlerr = util.urlerr urlreq = util.urlreq class httprangereader(object): def __init__(self, url, opener): # we assume opener has HTTPRangeHandler self.url = url self.pos = 0 self.opener = opener self.name = url def __enter__(self): return self def __exit__(self, exc_type, exc_value, traceback): self.close() def seek(self, pos): self.pos = pos def read(self, bytes=None): req = urlreq.request(self.url) end = '' if bytes: end = self.pos + bytes - 1 if self.pos or end: req.add_header('Range', 'bytes=%d-%s' % (self.pos, end)) try: f = self.opener.open(req) data = f.read() code = f.code except urlerr.httperror as inst: num = inst.code == 404 and errno.ENOENT or None raise IOError(num, inst) except urlerr.urlerror as inst: raise IOError(None, inst.reason[1]) if code == 200: # HTTPRangeHandler does nothing if remote does not support # Range headers and returns the full entity. Let's slice it. if bytes: data = data[self.pos:self.pos + bytes] else: data = data[self.pos:] elif bytes: data = data[:bytes] self.pos += len(data) return data def readlines(self): return self.read().splitlines(True) def __iter__(self): return iter(self.readlines()) def close(self): pass # _RangeError and _HTTPRangeHandler were originally in byterange.py, # which was itself extracted from urlgrabber. See the last version of # byterange.py from history if you need more information. class _RangeError(IOError): """Error raised when an unsatisfiable range is requested.""" class _HTTPRangeHandler(urlreq.basehandler): """Handler that enables HTTP Range headers. This was extremely simple. The Range header is a HTTP feature to begin with so all this class does is tell urllib2 that the "206 Partial Content" response from the HTTP server is what we expected. """ def http_error_206(self, req, fp, code, msg, hdrs): # 206 Partial Content Response r = urlreq.addinfourl(fp, hdrs, req.get_full_url()) r.code = code r.msg = msg return r def http_error_416(self, req, fp, code, msg, hdrs): # HTTP's Range Not Satisfiable error raise _RangeError('Requested Range Not Satisfiable') def build_opener(ui, authinfo): # urllib cannot handle URLs with embedded user or passwd urlopener = url.opener(ui, authinfo) urlopener.add_handler(_HTTPRangeHandler()) class statichttpvfs(vfsmod.abstractvfs): def __init__(self, base): self.base = base def __call__(self, path, mode='r', *args, **kw): if mode not in ('r', 'rb'): raise IOError('Permission denied') f = "/".join((self.base, urlreq.quote(path))) return httprangereader(f, urlopener) def join(self, path): if path: return pathutil.join(self.base, path) else: return self.base return statichttpvfs class statichttppeer(localrepo.localpeer): def local(self): return None def canpush(self): return False class statichttprepository(localrepo.localrepository): supported = localrepo.localrepository._basesupported def __init__(self, ui, path): self._url = path self.ui = ui self.root = path u = util.url(path.rstrip('/') + "/.hg") self.path, authinfo = u.authinfo() vfsclass = build_opener(ui, authinfo) self.vfs = vfsclass(self.path) self.cachevfs = vfsclass(self.vfs.join('cache')) self._phasedefaults = [] self.names = namespaces.namespaces() self.filtername = None try: requirements = scmutil.readrequires(self.vfs, self.supported) except IOError as inst: if inst.errno != errno.ENOENT: raise requirements = set() # check if it is a non-empty old-style repository try: fp = self.vfs("00changelog.i") fp.read(1) fp.close() except IOError as inst: if inst.errno != errno.ENOENT: raise # we do not care about empty old-style repositories here msg = _("'%s' does not appear to be an hg repository") % path raise error.RepoError(msg) # setup store self.store = store.store(requirements, self.path, vfsclass) self.spath = self.store.path self.svfs = self.store.opener self.sjoin = self.store.join self._filecache = {} self.requirements = requirements self.manifestlog = manifest.manifestlog(self.svfs, self) self.changelog = changelog.changelog(self.svfs) self._tags = None self.nodetagscache = None self._branchcaches = {} self._revbranchcache = None self.encodepats = None self.decodepats = None self._transref = None def _restrictcapabilities(self, caps): caps = super(statichttprepository, self)._restrictcapabilities(caps) return caps.difference(["pushkey"]) def url(self): return self._url def local(self): return False def peer(self): return statichttppeer(self) def wlock(self, wait=True): raise error.LockUnavailable(0, _('lock not available'), 'lock', _('cannot lock static-http repository')) def lock(self, wait=True): raise error.Abort(_('cannot lock static-http repository')) def _writecaches(self): pass # statichttprepository are read only def instance(ui, path, create): if create: raise error.Abort(_('cannot create new static-http repository')) return statichttprepository(ui, path[7:])