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wireprotov2: implement commands as a generator of objects...
wireprotov2: implement commands as a generator of objects Previously, wire protocol version 2 inherited version 1's model of having separate types to represent the results of different wire protocol commands. As I implemented more powerful commands in future commits, I found I was using a common pattern of returning a special type to hold a generator. This meant the command function required a closure to do most of the work. That made logic flow more difficult to follow. I also noticed that many commands were effectively a sequence of objects to be CBOR encoded. I think it makes sense to define version 2 commands as generators. This way, commands can simply emit the data structures they wish to send to the client. This eliminates the need for a closure in command functions and removes encoding from the bodies of commands. As part of this commit, the handling of response objects has been moved into the serverreactor class. This puts the reactor in the driver's seat with regards to CBOR encoding and error handling. Having error handling in the function that emits frames is particularly important because exceptions in that function can lead to things getting in a bad state: I'm fairly certain that uncaught exceptions in the frame generator were causing deadlocks. I also introduced a dedicated error type for explicit error reporting in command handlers. This will be used in subsequent commits. There's still a bit of work to be done here, especially around formalizing the error handling "protocol." I've added yet another TODO to track this so we don't forget. Test output changed because we're using generators and no longer know we are at the end of the data until we hit the end of the generator. This means we can't emit the end-of-stream flag until we've exhausted the generator. Hence the introduction of 0-sized end-of-stream frames. Differential Revision: https://phab.mercurial-scm.org/D4472
Gregory Szorc - - Load All Authors

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interfaceutil.py
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Gregory Szorc
interfaceutil: module to stub out zope.interface...
 r37828 # interfaceutil.py - Utilities for declaring interfaces.
#
# 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.
# zope.interface imposes a run-time cost due to module import overhead and
# bookkeeping for declaring interfaces. So, we use stubs for various
# zope.interface primitives unless instructed otherwise.
from __future__ import absolute_import
from .. import (
encoding,
)
if encoding.environ.get('HGREALINTERFACES'):
from ..thirdparty.zope import (
interface as zi,
)
Attribute = zi.Attribute
Interface = zi.Interface
implementer = zi.implementer
else:
class Attribute(object):
def __init__(self, __name__, __doc__=''):
pass
class Interface(object):
def __init__(self, name, bases=(), attrs=None, __doc__=None,
__module__=None):
pass
def implementer(*ifaces):
def wrapper(cls):
return cls
return wrapper