Mercurial > hg
view mercurial/wireprotov2peer.py @ 47072:4c041c71ec01
revlog: introduce an explicit tracking of what the revlog is about
Since the dawn of time, people have been forced to rely to lossy introspection
of the index filename to determine what the purpose and role of the revlog they
encounter is. This is hacky, error prone, inflexible, abstraction-leaky,
<insert-your-own-complaints-here>.
In f63299ee7e4d Raphaël introduced a new attribute to track this information:
`revlog_kind`. However it is initialized in an odd place and various instances
end up not having it set. In addition is only tracking some of the information
we end up having to introspect in various pieces of code.
So we add a new attribute that holds more data and is more strictly enforced.
This work is done in collaboration with Raphaël.
The `revlog_kind` one will be removed/adapted in the next changeset. We expect
to be able to clean up various existing piece of code and to simplify coming
work around the newer revlog format.
Differential Revision: https://phab.mercurial-scm.org/D10352
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Tue, 06 Apr 2021 05:20:24 +0200 |
parents | 9f70512ae2cf |
children |
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# wireprotov2peer.py - client side code for wire protocol version 2 # # Copyright 2018 Gregory Szorc <gregory.szorc@gmail.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 threading from .i18n import _ from . import ( encoding, error, pycompat, sslutil, url as urlmod, util, wireprotoframing, wireprototypes, ) from .utils import cborutil def formatrichmessage(atoms): """Format an encoded message from the framing protocol.""" chunks = [] for atom in atoms: msg = _(atom[b'msg']) if b'args' in atom: msg = msg % tuple(atom[b'args']) chunks.append(msg) return b''.join(chunks) SUPPORTED_REDIRECT_PROTOCOLS = { b'http', b'https', } SUPPORTED_CONTENT_HASHES = { b'sha1', b'sha256', } def redirecttargetsupported(ui, target): """Determine whether a redirect target entry is supported. ``target`` should come from the capabilities data structure emitted by the server. """ if target.get(b'protocol') not in SUPPORTED_REDIRECT_PROTOCOLS: ui.note( _(b'(remote redirect target %s uses unsupported protocol: %s)\n') % (target[b'name'], target.get(b'protocol', b'')) ) return False if target.get(b'snirequired') and not sslutil.hassni: ui.note( _(b'(redirect target %s requires SNI, which is unsupported)\n') % target[b'name'] ) return False if b'tlsversions' in target: tlsversions = set(target[b'tlsversions']) supported = set() for v in sslutil.supportedprotocols: assert v.startswith(b'tls') supported.add(v[3:]) if not tlsversions & supported: ui.note( _( b'(remote redirect target %s requires unsupported TLS ' b'versions: %s)\n' ) % (target[b'name'], b', '.join(sorted(tlsversions))) ) return False ui.note(_(b'(remote redirect target %s is compatible)\n') % target[b'name']) return True def supportedredirects(ui, apidescriptor): """Resolve the "redirect" command request key given an API descriptor. Given an API descriptor returned by the server, returns a data structure that can be used in hte "redirect" field of command requests to advertise support for compatible redirect targets. Returns None if no redirect targets are remotely advertised or if none are supported. """ if not apidescriptor or b'redirect' not in apidescriptor: return None targets = [ t[b'name'] for t in apidescriptor[b'redirect'][b'targets'] if redirecttargetsupported(ui, t) ] hashes = [ h for h in apidescriptor[b'redirect'][b'hashes'] if h in SUPPORTED_CONTENT_HASHES ] return { b'targets': targets, b'hashes': hashes, } class commandresponse(object): """Represents the response to a command request. Instances track the state of the command and hold its results. An external entity is required to update the state of the object when events occur. """ def __init__(self, requestid, command, fromredirect=False): self.requestid = requestid self.command = command self.fromredirect = fromredirect # Whether all remote input related to this command has been # received. self._inputcomplete = False # We have a lock that is acquired when important object state is # mutated. This is to prevent race conditions between 1 thread # sending us new data and another consuming it. self._lock = threading.RLock() # An event is set when state of the object changes. This event # is waited on by the generator emitting objects. self._serviceable = threading.Event() self._pendingevents = [] self._pendingerror = None self._decoder = cborutil.bufferingdecoder() self._seeninitial = False self._redirect = None def _oninputcomplete(self): with self._lock: self._inputcomplete = True self._serviceable.set() def _onresponsedata(self, data): available, readcount, wanted = self._decoder.decode(data) if not available: return with self._lock: for o in self._decoder.getavailable(): if not self._seeninitial and not self.fromredirect: self._handleinitial(o) continue # We should never see an object after a content redirect, # as the spec says the main status object containing the # content redirect is the only object in the stream. Fail # if we see a misbehaving server. if self._redirect: raise error.Abort( _( b'received unexpected response data ' b'after content redirect; the remote is ' b'buggy' ) ) self._pendingevents.append(o) self._serviceable.set() def _onerror(self, e): self._pendingerror = e with self._lock: self._serviceable.set() def _handleinitial(self, o): self._seeninitial = True if o[b'status'] == b'ok': return elif o[b'status'] == b'redirect': l = o[b'location'] self._redirect = wireprototypes.alternatelocationresponse( url=l[b'url'], mediatype=l[b'mediatype'], size=l.get(b'size'), fullhashes=l.get(b'fullhashes'), fullhashseed=l.get(b'fullhashseed'), serverdercerts=l.get(b'serverdercerts'), servercadercerts=l.get(b'servercadercerts'), ) return atoms = [{b'msg': o[b'error'][b'message']}] if b'args' in o[b'error']: atoms[0][b'args'] = o[b'error'][b'args'] raise error.RepoError(formatrichmessage(atoms)) def objects(self): """Obtained decoded objects from this response. This is a generator of data structures that were decoded from the command response. Obtaining the next member of the generator may block due to waiting on external data to become available. If the server encountered an error in the middle of serving the data or if another error occurred, an exception may be raised when advancing the generator. """ while True: # TODO this can infinite loop if self._inputcomplete is never # set. We likely want to tie the lifetime of this object/state # to that of the background thread receiving frames and updating # our state. self._serviceable.wait(1.0) if self._pendingerror: raise self._pendingerror with self._lock: self._serviceable.clear() # Make copies because objects could be mutated during # iteration. stop = self._inputcomplete pending = list(self._pendingevents) self._pendingevents[:] = [] for o in pending: yield o if stop: break class clienthandler(object): """Object to handle higher-level client activities. The ``clientreactor`` is used to hold low-level state about the frame-based protocol, such as which requests and streams are active. This type is used for higher-level operations, such as reading frames from a socket, exposing and managing a higher-level primitive for representing command responses, etc. This class is what peers should probably use to bridge wire activity with the higher-level peer API. """ def __init__( self, ui, clientreactor, opener=None, requestbuilder=util.urlreq.request ): self._ui = ui self._reactor = clientreactor self._requests = {} self._futures = {} self._responses = {} self._redirects = [] self._frameseof = False self._opener = opener or urlmod.opener(ui) self._requestbuilder = requestbuilder def callcommand(self, command, args, f, redirect=None): """Register a request to call a command. Returns an iterable of frames that should be sent over the wire. """ request, action, meta = self._reactor.callcommand( command, args, redirect=redirect ) if action != b'noop': raise error.ProgrammingError(b'%s not yet supported' % action) rid = request.requestid self._requests[rid] = request self._futures[rid] = f # TODO we need some kind of lifetime on response instances otherwise # objects() may deadlock. self._responses[rid] = commandresponse(rid, command) return iter(()) def flushcommands(self): """Flush all queued commands. Returns an iterable of frames that should be sent over the wire. """ action, meta = self._reactor.flushcommands() if action != b'sendframes': raise error.ProgrammingError(b'%s not yet supported' % action) return meta[b'framegen'] def readdata(self, framefh): """Attempt to read data and do work. Returns None if no data was read. Presumably this means we're done with all read I/O. """ if not self._frameseof: frame = wireprotoframing.readframe(framefh) if frame is None: # TODO tell reactor? self._frameseof = True else: self._ui.debug(b'received %r\n' % frame) self._processframe(frame) # Also try to read the first redirect. if self._redirects: if not self._processredirect(*self._redirects[0]): self._redirects.pop(0) if self._frameseof and not self._redirects: return None return True def _processframe(self, frame): """Process a single read frame.""" action, meta = self._reactor.onframerecv(frame) if action == b'error': e = error.RepoError(meta[b'message']) if frame.requestid in self._responses: self._responses[frame.requestid]._oninputcomplete() if frame.requestid in self._futures: self._futures[frame.requestid].set_exception(e) del self._futures[frame.requestid] else: raise e return elif action == b'noop': return elif action == b'responsedata': # Handled below. pass else: raise error.ProgrammingError(b'action not handled: %s' % action) if frame.requestid not in self._requests: raise error.ProgrammingError( b'received frame for unknown request; this is either a bug in ' b'the clientreactor not screening for this or this instance was ' b'never told about this request: %r' % frame ) response = self._responses[frame.requestid] if action == b'responsedata': # Any failures processing this frame should bubble up to the # future tracking the request. try: self._processresponsedata(frame, meta, response) except BaseException as e: # If an exception occurs before the future is resolved, # fail the future. Otherwise, we stuff the exception on # the response object so it can be raised during objects() # iteration. If nothing is consuming objects(), we could # silently swallow this exception. That's a risk we'll have to # take. if frame.requestid in self._futures: self._futures[frame.requestid].set_exception(e) del self._futures[frame.requestid] response._oninputcomplete() else: response._onerror(e) else: raise error.ProgrammingError( b'unhandled action from clientreactor: %s' % action ) def _processresponsedata(self, frame, meta, response): # This can raise. The caller can handle it. response._onresponsedata(meta[b'data']) # We need to be careful about resolving futures prematurely. If a # response is a redirect response, resolving the future before the # redirect is processed would result in the consumer seeing an # empty stream of objects, since they'd be consuming our # response.objects() instead of the redirect's response.objects(). # # Our strategy is to not resolve/finish the request until either # EOS occurs or until the initial response object is fully received. # Always react to eos. if meta[b'eos']: response._oninputcomplete() del self._requests[frame.requestid] # Not EOS but we haven't decoded the initial response object yet. # Return and wait for more data. elif not response._seeninitial: return # The specification says no objects should follow the initial/redirect # object. So it should be safe to handle the redirect object if one is # decoded, without having to wait for EOS. if response._redirect: self._followredirect(frame.requestid, response._redirect) return # If the command has a decoder, we wait until all input has been # received before resolving the future. Otherwise we resolve the # future immediately. if frame.requestid not in self._futures: return if response.command not in COMMAND_DECODERS: self._futures[frame.requestid].set_result(response.objects()) del self._futures[frame.requestid] elif response._inputcomplete: decoded = COMMAND_DECODERS[response.command](response.objects()) self._futures[frame.requestid].set_result(decoded) del self._futures[frame.requestid] def _followredirect(self, requestid, redirect): """Called to initiate redirect following for a request.""" self._ui.note(_(b'(following redirect to %s)\n') % redirect.url) # TODO handle framed responses. if redirect.mediatype != b'application/mercurial-cbor': raise error.Abort( _(b'cannot handle redirects for the %s media type') % redirect.mediatype ) if redirect.fullhashes: self._ui.warn( _( b'(support for validating hashes on content ' b'redirects not supported)\n' ) ) if redirect.serverdercerts or redirect.servercadercerts: self._ui.warn( _( b'(support for pinning server certificates on ' b'content redirects not supported)\n' ) ) headers = { 'Accept': redirect.mediatype, } req = self._requestbuilder(pycompat.strurl(redirect.url), None, headers) try: res = self._opener.open(req) except util.urlerr.httperror as e: if e.code == 401: raise error.Abort(_(b'authorization failed')) raise except util.httplib.HTTPException as e: self._ui.debug(b'http error requesting %s\n' % req.get_full_url()) self._ui.traceback() raise IOError(None, e) urlmod.wrapresponse(res) # The existing response object is associated with frame data. Rather # than try to normalize its state, just create a new object. oldresponse = self._responses[requestid] self._responses[requestid] = commandresponse( requestid, oldresponse.command, fromredirect=True ) self._redirects.append((requestid, res)) def _processredirect(self, rid, res): """Called to continue processing a response from a redirect. Returns a bool indicating if the redirect is still serviceable. """ response = self._responses[rid] try: data = res.read(32768) response._onresponsedata(data) # We're at end of stream. if not data: response._oninputcomplete() if rid not in self._futures: return bool(data) if response.command not in COMMAND_DECODERS: self._futures[rid].set_result(response.objects()) del self._futures[rid] elif response._inputcomplete: decoded = COMMAND_DECODERS[response.command](response.objects()) self._futures[rid].set_result(decoded) del self._futures[rid] return bool(data) except BaseException as e: self._futures[rid].set_exception(e) del self._futures[rid] response._oninputcomplete() return False def decodebranchmap(objs): # Response should be a single CBOR map of branch name to array of nodes. bm = next(objs) return {encoding.tolocal(k): v for k, v in bm.items()} def decodeheads(objs): # Array of node bytestrings. return next(objs) def decodeknown(objs): # Bytestring where each byte is a 0 or 1. raw = next(objs) return [True if raw[i : i + 1] == b'1' else False for i in range(len(raw))] def decodelistkeys(objs): # Map with bytestring keys and values. return next(objs) def decodelookup(objs): return next(objs) def decodepushkey(objs): return next(objs) COMMAND_DECODERS = { b'branchmap': decodebranchmap, b'heads': decodeheads, b'known': decodeknown, b'listkeys': decodelistkeys, b'lookup': decodelookup, b'pushkey': decodepushkey, }