procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
# test-batching.py - tests for transparent command batching
#
# Copyright 2011 Peter Arrenbrecht <peter@arrenbrecht.ch>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import contextlib
from mercurial import (
localrepo,
pycompat,
wireprotov1peer,
)
def bprint(*bs):
print(*[pycompat.sysstr(b) for b in bs])
# equivalent of repo.repository
class thing:
def hello(self):
return b"Ready."
# equivalent of localrepo.localrepository
class localthing(thing):
def foo(self, one, two=None):
if one:
return b"%s and %s" % (
one,
two,
)
return b"Nope"
def bar(self, b, a):
return b"%s und %s" % (
b,
a,
)
def greet(self, name=None):
return b"Hello, %s" % name
@contextlib.contextmanager
def commandexecutor(self):
e = localrepo.localcommandexecutor(self)
try:
yield e
finally:
e.close()
# usage of "thing" interface
def use(it):
# Direct call to base method shared between client and server.
bprint(it.hello())
# Direct calls to proxied methods. They cause individual roundtrips.
bprint(it.foo(b"Un", two=b"Deux"))
bprint(it.bar(b"Eins", b"Zwei"))
# Batched call to a couple of proxied methods.
with it.commandexecutor() as e:
ffoo = e.callcommand(b'foo', {b'one': b'One', b'two': b'Two'})
fbar = e.callcommand(b'bar', {b'b': b'Eins', b'a': b'Zwei'})
fbar2 = e.callcommand(b'bar', {b'b': b'Uno', b'a': b'Due'})
bprint(ffoo.result())
bprint(fbar.result())
bprint(fbar2.result())
# local usage
mylocal = localthing()
print()
bprint(b"== Local")
use(mylocal)
# demo remoting; mimicks what wireproto and HTTP/SSH do
# shared
def escapearg(plain):
return (
plain.replace(b':', b'::')
.replace(b',', b':,')
.replace(b';', b':;')
.replace(b'=', b':=')
)
def unescapearg(escaped):
return (
escaped.replace(b':=', b'=')
.replace(b':;', b';')
.replace(b':,', b',')
.replace(b'::', b':')
)
# server side
# equivalent of wireproto's global functions
class server:
def __init__(self, local):
self.local = local
def _call(self, name, args):
args = dict(arg.split(b'=', 1) for arg in args)
return getattr(self, name)(**args)
def perform(self, req):
bprint(b"REQ:", req)
name, args = req.split(b'?', 1)
args = args.split(b'&')
vals = dict(arg.split(b'=', 1) for arg in args)
res = getattr(self, pycompat.sysstr(name))(**pycompat.strkwargs(vals))
bprint(b" ->", res)
return res
def batch(self, cmds):
res = []
for pair in cmds.split(b';'):
name, args = pair.split(b':', 1)
vals = {}
for a in args.split(b','):
if a:
n, v = a.split(b'=')
vals[n] = unescapearg(v)
res.append(
escapearg(
getattr(self, pycompat.sysstr(name))(
**pycompat.strkwargs(vals)
)
)
)
return b';'.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 b''.join(pycompat.bytechr(ord(c) + 1) for c in pycompat.bytestr(s))
def unmangle(s):
return b''.join(pycompat.bytechr(ord(c) - 1) for c in pycompat.bytestr(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 + b'?' + b'&'.join([b'%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 = b','.join(n + b'=' + escapearg(v) for n, v in args)
req.append(name + b':' + args)
req = b';'.join(req)
res = self._submitone(
b'batch',
[
(
b'cmds',
req,
)
],
)
for r in res.split(b';'):
yield r
@contextlib.contextmanager
def commandexecutor(self):
e = wireprotov1peer.peerexecutor(self)
try:
yield e
finally:
e.close()
@wireprotov1peer.batchable
def foo(self, one, two=None):
encoded_args = [
(
b'one',
mangle(one),
),
(
b'two',
mangle(two),
),
]
return encoded_args, unmangle
@wireprotov1peer.batchable
def bar(self, b, a):
return [
(
b'b',
mangle(b),
),
(
b'a',
mangle(a),
),
], unmangle
# 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(
b'greet',
[
(
b'name',
mangle(name),
)
],
)
)
# demo remote usage
myproxy = remotething(myserver)
print()
bprint(b"== Remote")
use(myproxy)