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httppeer: remove support for connecting to <0.9.1 servers (BC)...
httppeer: remove support for connecting to <0.9.1 servers (BC) Previously, HTTP wire protocol clients would attempt a "capabilities" wire protocol command. If that failed, they would fall back to issuing a "between" command. The "capabilities" command was added in Mercurial 0.9.1 (released July 2006). The "between" command has been present for as long as the wire protocol has existed. So if the "between" command failed, it was safe to assume that the remote could not speak any version of the Mercurial wire protocol. The "between" fallback was added in 395a84f78736 in 2011. Before that changeset, Mercurial would *always* issue the "between" command and would issue "capabilities" if capabilities were requested. At that time, many connections would issue "capabilities" eventually, so it was decided to issue "capabilities" by default and fall back to "between" if that failed. This saved a round trip when connecting to modern servers while still preserving compatibility with legacy servers. Fast forward ~7 years. Mercurial servers supporting "capabilities" have been around for over a decade. If modern clients are connecting to <0.9.1 servers, they are getting a bad experience. They may even be getting bad data (an old server is vulnerable to numerous security issues and could have been p0wned, leading to a Mercurial repository serving backdoors or other badness). In addition, the fallback can harm experience for modern servers. If a client experiences an intermittent HTTP request failure (due to bad network, etc) and falls back to a "between" that works, it would assume an empty capability set and would attempt to communicate with the repository using a very ancient wire protocol. Auditing HTTP logs for hg.mozilla.org, I did find a handful of requests for the null range of the "between" command. However, requests can be days apart. And when I do see requests, they come in batches. Those batches seem to correlate to spikes of HTTP 500 or other server/network events. So I think these requests are fallbacks from failed "capabilities" requests and not from old clients. If you need even more evidence to discontinue support, apparently we have no test coverage for communicating with servers not supporting "capabilities." I know this because all tests pass with the "between" fallback removed. Finally, server-side support for <0.9.1 pushing (the "addchangegroup" wire protocol command along with locking-related commands) was dropped from the HTTP client in fda0867cfe03 in 2017 and the SSH client in 9f6e0e7ef828 in 2015. I think this all adds up to enough justification for removing client support for communicating with servers not supporting "capabilities." So this commit removes that fallback. Differential Revision: https://phab.mercurial-scm.org/D2001

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error.py
307 lines | 9.7 KiB | text/x-python | PythonLexer
# error.py - Mercurial exceptions
#
# Copyright 2005-2008 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.
"""Mercurial exceptions.
This allows us to catch exceptions at higher levels without forcing
imports.
"""
from __future__ import absolute_import
# Do not import anything but pycompat here, please
from . import pycompat
def _tobytes(exc):
"""Byte-stringify exception in the same way as BaseException_str()"""
if not exc.args:
return b''
if len(exc.args) == 1:
return pycompat.bytestr(exc.args[0])
return b'(%s)' % b', '.join(b"'%s'" % pycompat.bytestr(a) for a in exc.args)
class Hint(object):
"""Mix-in to provide a hint of an error
This should come first in the inheritance list to consume a hint and
pass remaining arguments to the exception class.
"""
def __init__(self, *args, **kw):
self.hint = kw.pop(r'hint', None)
super(Hint, self).__init__(*args, **kw)
class RevlogError(Hint, Exception):
__bytes__ = _tobytes
class FilteredIndexError(IndexError):
__bytes__ = _tobytes
class LookupError(RevlogError, KeyError):
def __init__(self, name, index, message):
self.name = name
self.index = index
# this can't be called 'message' because at least some installs of
# Python 2.6+ complain about the 'message' property being deprecated
self.lookupmessage = message
if isinstance(name, str) and len(name) == 20:
from .node import short
name = short(name)
RevlogError.__init__(self, '%s@%s: %s' % (index, name, message))
def __bytes__(self):
return RevlogError.__bytes__(self)
def __str__(self):
return RevlogError.__str__(self)
class FilteredLookupError(LookupError):
pass
class ManifestLookupError(LookupError):
pass
class CommandError(Exception):
"""Exception raised on errors in parsing the command line."""
__bytes__ = _tobytes
class InterventionRequired(Hint, Exception):
"""Exception raised when a command requires human intervention."""
__bytes__ = _tobytes
class Abort(Hint, Exception):
"""Raised if a command needs to print an error and exit."""
__bytes__ = _tobytes
class HookLoadError(Abort):
"""raised when loading a hook fails, aborting an operation
Exists to allow more specialized catching."""
class HookAbort(Abort):
"""raised when a validation hook fails, aborting an operation
Exists to allow more specialized catching."""
class ConfigError(Abort):
"""Exception raised when parsing config files"""
class UpdateAbort(Abort):
"""Raised when an update is aborted for destination issue"""
class MergeDestAbort(Abort):
"""Raised when an update is aborted for destination issues"""
class NoMergeDestAbort(MergeDestAbort):
"""Raised when an update is aborted because there is nothing to merge"""
class ManyMergeDestAbort(MergeDestAbort):
"""Raised when an update is aborted because destination is ambiguous"""
class ResponseExpected(Abort):
"""Raised when an EOF is received for a prompt"""
def __init__(self):
from .i18n import _
Abort.__init__(self, _('response expected'))
class OutOfBandError(Hint, Exception):
"""Exception raised when a remote repo reports failure"""
__bytes__ = _tobytes
class ParseError(Hint, Exception):
"""Raised when parsing config files and {rev,file}sets (msg[, pos])"""
__bytes__ = _tobytes
class PatchError(Exception):
__bytes__ = _tobytes
class UnknownIdentifier(ParseError):
"""Exception raised when a {rev,file}set references an unknown identifier"""
def __init__(self, function, symbols):
from .i18n import _
ParseError.__init__(self, _("unknown identifier: %s") % function)
self.function = function
self.symbols = symbols
class RepoError(Hint, Exception):
__bytes__ = _tobytes
class RepoLookupError(RepoError):
pass
class FilteredRepoLookupError(RepoLookupError):
pass
class CapabilityError(RepoError):
pass
class RequirementError(RepoError):
"""Exception raised if .hg/requires has an unknown entry."""
class StdioError(IOError):
"""Raised if I/O to stdout or stderr fails"""
def __init__(self, err):
IOError.__init__(self, err.errno, err.strerror)
# no __bytes__() because error message is derived from the standard IOError
class UnsupportedMergeRecords(Abort):
def __init__(self, recordtypes):
from .i18n import _
self.recordtypes = sorted(recordtypes)
s = ' '.join(self.recordtypes)
Abort.__init__(
self, _('unsupported merge state records: %s') % s,
hint=_('see https://mercurial-scm.org/wiki/MergeStateRecords for '
'more information'))
class UnknownVersion(Abort):
"""generic exception for aborting from an encounter with an unknown version
"""
def __init__(self, msg, hint=None, version=None):
self.version = version
super(UnknownVersion, self).__init__(msg, hint=hint)
class LockError(IOError):
def __init__(self, errno, strerror, filename, desc):
IOError.__init__(self, errno, strerror, filename)
self.desc = desc
# no __bytes__() because error message is derived from the standard IOError
class LockHeld(LockError):
def __init__(self, errno, filename, desc, locker):
LockError.__init__(self, errno, 'Lock held', filename, desc)
self.locker = locker
class LockUnavailable(LockError):
pass
# LockError is for errors while acquiring the lock -- this is unrelated
class LockInheritanceContractViolation(RuntimeError):
__bytes__ = _tobytes
class ResponseError(Exception):
"""Raised to print an error with part of output and exit."""
__bytes__ = _tobytes
class UnknownCommand(Exception):
"""Exception raised if command is not in the command table."""
__bytes__ = _tobytes
class AmbiguousCommand(Exception):
"""Exception raised if command shortcut matches more than one command."""
__bytes__ = _tobytes
# derived from KeyboardInterrupt to simplify some breakout code
class SignalInterrupt(KeyboardInterrupt):
"""Exception raised on SIGTERM and SIGHUP."""
class SignatureError(Exception):
__bytes__ = _tobytes
class PushRaced(RuntimeError):
"""An exception raised during unbundling that indicate a push race"""
__bytes__ = _tobytes
class ProgrammingError(Hint, RuntimeError):
"""Raised if a mercurial (core or extension) developer made a mistake"""
__bytes__ = _tobytes
class WdirUnsupported(Exception):
"""An exception which is raised when 'wdir()' is not supported"""
__bytes__ = _tobytes
# bundle2 related errors
class BundleValueError(ValueError):
"""error raised when bundle2 cannot be processed"""
__bytes__ = _tobytes
class BundleUnknownFeatureError(BundleValueError):
def __init__(self, parttype=None, params=(), values=()):
self.parttype = parttype
self.params = params
self.values = values
if self.parttype is None:
msg = 'Stream Parameter'
else:
msg = parttype
entries = self.params
if self.params and self.values:
assert len(self.params) == len(self.values)
entries = []
for idx, par in enumerate(self.params):
val = self.values[idx]
if val is None:
entries.append(val)
else:
entries.append("%s=%r" % (par, val))
if entries:
msg = '%s - %s' % (msg, ', '.join(entries))
ValueError.__init__(self, msg)
class ReadOnlyPartError(RuntimeError):
"""error raised when code tries to alter a part being generated"""
__bytes__ = _tobytes
class PushkeyFailed(Abort):
"""error raised when a pushkey part failed to update a value"""
def __init__(self, partid, namespace=None, key=None, new=None, old=None,
ret=None):
self.partid = partid
self.namespace = namespace
self.key = key
self.new = new
self.old = old
self.ret = ret
# no i18n expected to be processed into a better message
Abort.__init__(self, 'failed to update value for "%s/%s"'
% (namespace, key))
class CensoredNodeError(RevlogError):
"""error raised when content verification fails on a censored node
Also contains the tombstone data substituted for the uncensored data.
"""
def __init__(self, filename, node, tombstone):
from .node import short
RevlogError.__init__(self, '%s:%s' % (filename, short(node)))
self.tombstone = tombstone
class CensoredBaseError(RevlogError):
"""error raised when a delta is rejected because its base is censored
A delta based on a censored revision must be formed as single patch
operation which replaces the entire base with new content. This ensures
the delta may be applied by clones which have not censored the base.
"""
class InvalidBundleSpecification(Exception):
"""error raised when a bundle specification is invalid.
This is used for syntax errors as opposed to support errors.
"""
__bytes__ = _tobytes
class UnsupportedBundleSpecification(Exception):
"""error raised when a bundle specification is not supported."""
__bytes__ = _tobytes
class CorruptedState(Exception):
"""error raised when a command is not able to read its state from file"""
__bytes__ = _tobytes
class PeerTransportError(Abort):
"""Transport-level I/O error when communicating with a peer repo."""
class InMemoryMergeConflictsError(Exception):
"""Exception raised when merge conflicts arose during an in-memory merge."""
__bytes__ = _tobytes