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Differential D2483

wireproto: allow wire protocol commands to declare transport support
ClosedPublic

Authored by indygreg on Feb 27 2018, 6:49 PM.

Details

Reviewers
durin42
Group Reviewers
hg-reviewers
Commits
rHGabc3b9801563: wireproto: allow wire protocol commands to declare transport support
Summary

Currently, wire protocol commands are exposed on all transports.
Some wire protocol commands are only supported or sensical on some
transports. In the future, new wire protocol commands may only be
available on new transports and legacy wire protocol commands may
not be available to newer transports.

This commit introduces a mechanism to allow @wireprotocommand to
declare transports for which they should not be available. The
mechanism for determining if a wire protocol command is available
for a given transport instance has been taught to take this knowledge
into account.

To help implement this feature, we add a dict to wireprototypes
declaring all wire transports and their metadata. There's probably
room to refactor the constants used to identify the wire protocols.
But that can be in another commit.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

indygreg created this revision.Feb 27 2018, 6:49 PM
durin42 added a subscriber: durin42.Mar 1 2018, 4:49 PM
durin42 added inline comments.
mercurial/wireproto.py
669–673

These feel vaguely orthogonal? Some are proto versions (that only apply to ssh?)

indygreg updated this revision to Diff 6332.Mar 2 2018, 9:50 AM
durin42 accepted this revision.Mar 2 2018, 7:04 PM
This revision is now accepted and ready to land.Mar 2 2018, 7:04 PM
Closed by commit rHGabc3b9801563: wireproto: allow wire protocol commands to declare transport support (authored by indygreg). · Explain WhyMar 2 2018, 7:13 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mmercurial/wireproto.py (49 lines)
Mmercurial/wireprototypes.py (16 lines)

Diff 6408

mercurial/wireproto.py

'compression engines') % config, 'compression engines') % config,
hint=_('usable compression engines: %s') % hint=_('usable compression engines: %s') %
', '.sorted(validnames)) ', '.sorted(validnames))
return compengines return compengines
class commandentry(object): class commandentry(object):
"""Represents a declared wire protocol command.""" """Represents a declared wire protocol command."""
def __init__(self, func, args=''): def __init__(self, func, args='', transports=None):
self.func = func self.func = func
self.args = args self.args = args
self.transports = transports or set()
def _merge(self, func, args): def _merge(self, func, args):
"""Merge this instance with an incoming 2-tuple. """Merge this instance with an incoming 2-tuple.
This is called when a caller using the old 2-tuple API attempts This is called when a caller using the old 2-tuple API attempts
to replace an instance. The incoming values are merged with to replace an instance. The incoming values are merged with
data not captured by the 2-tuple and a new instance containing data not captured by the 2-tuple and a new instance containing
the union of the two objects is returned. the union of the two objects is returned.
""" """
return commandentry(func, args=args) return commandentry(func, args=args, transports=set(self.transports))
# Old code treats instances as 2-tuples. So expose that interface. # Old code treats instances as 2-tuples. So expose that interface.
def __iter__(self): def __iter__(self):
yield self.func yield self.func
yield self.args yield self.args
def __getitem__(self, i): def __getitem__(self, i):
if i == 0: if i == 0:
# It is common for extensions to wrap wire protocol commands via # It is common for extensions to wrap wire protocol commands via
# e.g. ``wireproto.commands[x] = (newfn, args)``. Because callers # e.g. ``wireproto.commands[x] = (newfn, args)``. Because callers
# doing this aren't aware of the new API that uses objects to store # doing this aren't aware of the new API that uses objects to store
# command entries, we automatically merge old state with new. # command entries, we automatically merge old state with new.
if k in self: if k in self:
v = self[k]._merge(v[0], v[1]) v = self[k]._merge(v[0], v[1])
else: else:
v = commandentry(v[0], args=v[1]) # Use default values from @wireprotocommand.
v = commandentry(v[0], args=v[1],
transports=set(wireprototypes.TRANSPORTS))
else: else:
raise ValueError('command entries must be commandentry instances ' raise ValueError('command entries must be commandentry instances '
'or 2-tuples') 'or 2-tuples')
return super(commanddict, self).__setitem__(k, v) return super(commanddict, self).__setitem__(k, v)
def commandavailable(self, command, proto): def commandavailable(self, command, proto):
"""Determine if a command is available for the requested protocol.""" """Determine if a command is available for the requested protocol."""
# For now, commands are available for all protocols. So do a simple assert proto.name in wireprototypes.TRANSPORTS
# membership test.
return command in self entry = self.get(command)
if not entry:
return False
if proto.name not in entry.transports:
return False
return True
# Constants specifying which transports a wire protocol command should be
# available on. For use with @wireprotocommand.
POLICY_ALL = 'all'
POLICY_V1_ONLY = 'v1-only'
POLICY_V2_ONLY = 'v2-only'
commands = commanddict() commands = commanddict()
durin42Unsubmitted
Not Done

These feel vaguely orthogonal? Some are proto versions (that only apply to ssh?)

durin42: These feel vaguely orthogonal? Some are proto versions (that only apply to ssh?)
def wireprotocommand(name, args=''): def wireprotocommand(name, args='', transportpolicy=POLICY_ALL):
"""Decorator to declare a wire protocol command. """Decorator to declare a wire protocol command.
``name`` is the name of the wire protocol command being provided. ``name`` is the name of the wire protocol command being provided.
``args`` is a space-delimited list of named arguments that the command ``args`` is a space-delimited list of named arguments that the command
accepts. ``*`` is a special value that says to accept all arguments. accepts. ``*`` is a special value that says to accept all arguments.
``transportpolicy`` is a POLICY_* constant denoting which transports
this wire protocol command should be exposed to. By default, commands
are exposed to all wire protocol transports.
""" """
if transportpolicy == POLICY_ALL:
transports = set(wireprototypes.TRANSPORTS)
elif transportpolicy == POLICY_V1_ONLY:
transports = {k for k, v in wireprototypes.TRANSPORTS.items()
if v['version'] == 1}
elif transportpolicy == POLICY_V2_ONLY:
transports = {k for k, v in wireprototypes.TRANSPORTS.items()
if v['version'] == 2}
else:
raise error.Abort(_('invalid transport policy value: %s') %
transportpolicy)
def register(func): def register(func):
commands[name] = commandentry(func, args=args) commands[name] = commandentry(func, args=args, transports=transports)
return func return func
return register return register
@wireprotocommand('batch', 'cmds *') @wireprotocommand('batch', 'cmds *')
def batch(repo, proto, cmds, others): def batch(repo, proto, cmds, others):
repo = repo.filtered("served") repo = repo.filtered("served")
res = [] res = []
for pair in cmds.split(';'): for pair in cmds.split(';'):

mercurial/wireprototypes.py

# Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com> # Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com>
# #
# This software may be used and distributed according to the terms of the # This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version. # GNU General Public License version 2 or any later version.
from __future__ import absolute_import from __future__ import absolute_import
import abc import abc
# Names of the SSH protocol implementations. # Names of the SSH protocol implementations.
SSHV1 = 'ssh-v1' SSHV1 = 'ssh-v1'
# This is advertised over the wire. Incremental the counter at the end # This is advertised over the wire. Incremental the counter at the end
# to reflect BC breakages. # to reflect BC breakages.
SSHV2 = 'exp-ssh-v2-0001' SSHV2 = 'exp-ssh-v2-0001'
# All available wire protocol transports.
TRANSPORTS = {
SSHV1: {
'transport': 'ssh',
'version': 1,
},
SSHV2: {
'transport': 'ssh',
'version': 2,
},
'http-v1': {
'transport': 'http',
'version': 1,
}
}
class bytesresponse(object): class bytesresponse(object):
"""A wire protocol response consisting of raw bytes.""" """A wire protocol response consisting of raw bytes."""
def __init__(self, data): def __init__(self, data):
self.data = data self.data = data
class ooberror(object): class ooberror(object):
"""wireproto reply: failure of a batch of operation """wireproto reply: failure of a batch of operation