tests/test-batching.py

bundle2: don't try to recover from a GeneratorExit (issue4785)

GeneratorExit means the other end of the conversation has already
stopped listening, so don't try and yield out error
information. Instead, just let the GeneratorExit propagate normally.

This should resolve esoteric issues observed with servers that have
aggressive timeouts waiting for data to send to clients logging
internal Python errors[0]. This has been observed with both gunicorn's
gevent worker model and with scm-manager's built-in webserver (which
itself is something sitting inside jetty.)


0: Exception RuntimeError: 'generator ignored GeneratorExit' in <generator object getchunks at 0x7fd2f6c586e0> ignored

# test-batching.py - tests for transparent command batching
#
# Copyright 2011 Peter Arrenbrecht <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from mercurial.peer import localbatch, batchable, future
from mercurial.wireproto import remotebatch

# equivalent of repo.repository
class thing(object):
    def hello(self):
        return "Ready."

# equivalent of localrepo.localrepository
class localthing(thing):
    def foo(self, one, two=None):
        if one:
            return "%s and %s" % (one, two,)
        return "Nope"
    def bar(self, b, a):
        return "%s und %s" % (b, a,)
    def greet(self, name=None):
        return "Hello, %s" % name
    def batch(self):
        '''Support for local batching.'''
        return localbatch(self)

# usage of "thing" interface
def use(it):

    # Direct call to base method shared between client and server.
    print it.hello()

    # Direct calls to proxied methods. They cause individual roundtrips.
    print it.foo("Un", two="Deux")
    print it.bar("Eins", "Zwei")

    # Batched call to a couple of (possibly proxied) methods.
    batch = it.batch()
    # The calls return futures to eventually hold results.
    foo = batch.foo(one="One", two="Two")
    foo2 = batch.foo(None)
    bar = batch.bar("Eins", "Zwei")
    # We can call non-batchable proxy methods, but the break the current batch
    # request and cause additional roundtrips.
    greet = batch.greet(name="John Smith")
    # We can also add local methods into the mix, but they break the batch too.
    hello = batch.hello()
    bar2 = batch.bar(b="Uno", a="Due")
    # Only now are all the calls executed in sequence, with as few roundtrips
    # as possible.
    batch.submit()
    # After the call to submit, the futures actually contain values.
    print foo.value
    print foo2.value
    print bar.value
    print greet.value
    print hello.value
    print bar2.value

# local usage
mylocal = localthing()
print
print "== Local"
use(mylocal)

# demo remoting; mimicks what wireproto and HTTP/SSH do

# shared

def escapearg(plain):
    return (plain
            .replace(':', '::')
            .replace(',', ':,')
            .replace(';', ':;')
            .replace('=', ':='))
def unescapearg(escaped):
    return (escaped
            .replace(':=', '=')
            .replace(':;', ';')
            .replace(':,', ',')
            .replace('::', ':'))

# server side

# equivalent of wireproto's global functions
class server(object):
    def __init__(self, local):
        self.local = local
    def _call(self, name, args):
        args = dict(arg.split('=', 1) for arg in args)
        return getattr(self, name)(**args)
    def perform(self, req):
        print "REQ:", req
        name, args = req.split('?', 1)
        args = args.split('&')
        vals = dict(arg.split('=', 1) for arg in args)
        res = getattr(self, name)(**vals)
        print "  ->", res
        return res
    def batch(self, cmds):
        res = []
        for pair in cmds.split(';'):
            name, args = pair.split(':', 1)
            vals = {}
            for a in args.split(','):
                if a:
                    n, v = a.split('=')
                    vals[n] = unescapearg(v)
            res.append(escapearg(getattr(self, name)(**vals)))
        return ';'.join(res)
    def foo(self, one, two):
        return mangle(self.local.foo(unmangle(one), unmangle(two)))
    def bar(self, b, a):
        return mangle(self.local.bar(unmangle(b), unmangle(a)))
    def greet(self, name):
        return mangle(self.local.greet(unmangle(name)))
myserver = server(mylocal)

# local side

# equivalent of wireproto.encode/decodelist, that is, type-specific marshalling
# here we just transform the strings a bit to check we're properly en-/decoding
def mangle(s):
    return ''.join(chr(ord(c) + 1) for c in s)
def unmangle(s):
    return ''.join(chr(ord(c) - 1) for c in s)

# equivalent of wireproto.wirerepository and something like http's wire format
class remotething(thing):
    def __init__(self, server):
        self.server = server
    def _submitone(self, name, args):
        req = name + '?' + '&'.join(['%s=%s' % (n, v) for n, v in args])
        return self.server.perform(req)
    def _submitbatch(self, cmds):
        req = []
        for name, args in cmds:
            args = ','.join(n + '=' + escapearg(v) for n, v in args)
            req.append(name + ':' + args)
        req = ';'.join(req)
        res = self._submitone('batch', [('cmds', req,)])
        return res.split(';')

    def batch(self):
        return remotebatch(self)

    @batchable
    def foo(self, one, two=None):
        if not one:
            yield "Nope", None
        encargs = [('one', mangle(one),), ('two', mangle(two),)]
        encresref = future()
        yield encargs, encresref
        yield unmangle(encresref.value)

    @batchable
    def bar(self, b, a):
        encresref = future()
        yield [('b', mangle(b),), ('a', mangle(a),)], encresref
        yield unmangle(encresref.value)

    # greet is coded directly. It therefore does not support batching. If it
    # does appear in a batch, the batch is split around greet, and the call to
    # greet is done in its own roundtrip.
    def greet(self, name=None):
        return unmangle(self._submitone('greet', [('name', mangle(name),)]))

# demo remote usage

myproxy = remotething(myserver)
print
print "== Remote"
use(myproxy)