Mercurial > hg
view mercurial/httpconnection.py @ 44950:f9734b2d59cc
py3: make stdout line-buffered if connected to a TTY
Status messages that are to be shown on the terminal should be written to the
file descriptor before anything further is done, to keep the user updated.
One common way to achieve this is to make stdout line-buffered if it is
connected to a TTY. This is done on Python 2 (except on Windows, where libc,
which the CPython 2 streams depend on, does not properly support this).
Python 3 rolls it own I/O streams. On Python 3, buffered binary streams can't be
set line-buffered. The previous code (added in 227ba1afcb65) incorrectly
assumed that on Python 3, pycompat.stdout (sys.stdout.buffer) is already
line-buffered. However the interpreter initializes it with a block-buffered
stream or an unbuffered stream (when the -u option or the PYTHONUNBUFFERED
environment variable is set), never with a line-buffered stream.
One example where the current behavior is unacceptable is when running
`hg pull https://www.mercurial-scm.org/repo/hg` on Python 3, where the line
"pulling from https://www.mercurial-scm.org/repo/hg" does not appear on the
terminal before the hg process blocks while waiting for the server.
Various approaches to fix this problem are possible, including:
1. Weaken the contract of procutil.stdout to not give any guarantees about
buffering behavior. In this case, users of procutil.stdout need to be
changed to do enough flushes. In particular,
1. either ui must insert enough flushes for ui.write() and friends, or
2. ui.write() and friends get split into flushing and fully buffered
methods, or
3. users of ui.write() and friends must flush explicitly.
2. Make stdout unbuffered.
3. Make stdout line-buffered. Since Python 3 does not natively support that for
binary streams, we must implement it ourselves.
(2.) is problematic because using unbuffered I/O changes the performance
characteristics significantly compared to line-buffered (which is used on
Python 2) and this would be a regression.
(1.2.) and (1.3) are a substantial amount of work. It’s unclear whether the
added complexity would be justified, given that raw performance doesn’t matter
that much when writing to a terminal much faster than the user could read it.
(1.1.) pushes complexity into the ui class instead of separating the concern of
how stdout is buffered. Other users of procutil.stdout would still need to take
care of the flushes.
This patch implements (3.). The general performance considerations are very
similar to (1.1.). The extra method invocation and method forwarding add a
little more overhead if the class is used. In exchange, it doesn’t add overhead
if not used.
For the benchmarks, I compared the previous implementation (incorrect on Python
3), (1.1.), (3.) and (2.). The command was chosen so that the streams were
configured as if they were writing to a TTY, but actually write to a pager,
which is also the default:
HGRCPATH=/dev/null python3 ./hg --cwd ~/vcs/mozilla-central --time --pager yes --config pager.pager='cat > /dev/null' status --all
previous:
time: real 7.880 secs (user 7.290+0.050 sys 0.580+0.170)
time: real 7.830 secs (user 7.220+0.070 sys 0.590+0.140)
time: real 7.800 secs (user 7.210+0.050 sys 0.570+0.170)
(1.1.) using Yuya Nishihara’s patch:
time: real 9.860 secs (user 8.670+0.350 sys 1.160+0.830)
time: real 9.540 secs (user 8.430+0.370 sys 1.100+0.770)
time: real 9.830 secs (user 8.630+0.370 sys 1.180+0.840)
(3.) using this patch:
time: real 9.580 secs (user 8.480+0.350 sys 1.090+0.770)
time: real 9.670 secs (user 8.480+0.330 sys 1.170+0.860)
time: real 9.640 secs (user 8.500+0.350 sys 1.130+0.810)
(2.) using a previous patch by me:
time: real 10.480 secs (user 8.850+0.720 sys 1.590+1.500)
time: real 10.490 secs (user 8.750+0.750 sys 1.710+1.470)
time: real 10.240 secs (user 8.600+0.700 sys 1.590+1.510)
As expected, there’s no difference on Python 2, as exactly the same code paths
are used:
previous:
time: real 6.950 secs (user 5.870+0.330 sys 1.070+0.770)
time: real 7.040 secs (user 6.040+0.360 sys 0.980+0.750)
time: real 7.070 secs (user 5.950+0.360 sys 1.100+0.760)
this patch:
time: real 7.010 secs (user 5.900+0.390 sys 1.070+0.730)
time: real 7.000 secs (user 5.850+0.350 sys 1.120+0.760)
time: real 7.000 secs (user 5.790+0.380 sys 1.170+0.710)
author | Manuel Jacob <me@manueljacob.de> |
---|---|
date | Wed, 10 Jun 2020 13:02:39 +0200 |
parents | 0e8b28fb751b |
children | d4ba4d51f85f |
line wrap: on
line source
# httpconnection.py - urllib2 handler for new http support # # Copyright 2005, 2006, 2007, 2008 Matt Mackall <mpm@selenic.com> # Copyright 2006, 2007 Alexis S. L. Carvalho <alexis@cecm.usp.br> # Copyright 2006 Vadim Gelfer <vadim.gelfer@gmail.com> # Copyright 2011 Google, Inc. # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import os from .i18n import _ from .pycompat import open from . import ( pycompat, util, ) urlerr = util.urlerr urlreq = util.urlreq # moved here from url.py to avoid a cycle class httpsendfile(object): """This is a wrapper around the objects returned by python's "open". Its purpose is to send file-like objects via HTTP. It do however not define a __len__ attribute because the length might be more than Py_ssize_t can handle. """ def __init__(self, ui, *args, **kwargs): self.ui = ui self._data = open(*args, **kwargs) self.seek = self._data.seek self.close = self._data.close self.write = self._data.write self.length = os.fstat(self._data.fileno()).st_size self._pos = 0 self._progress = self._makeprogress() def _makeprogress(self): # We pass double the max for total because we currently have # to send the bundle twice in the case of a server that # requires authentication. Since we can't know until we try # once whether authentication will be required, just lie to # the user and maybe the push succeeds suddenly at 50%. return self.ui.makeprogress( _(b'sending'), unit=_(b'kb'), total=(self.length // 1024 * 2) ) def read(self, *args, **kwargs): ret = self._data.read(*args, **kwargs) if not ret: self._progress.complete() return ret self._pos += len(ret) self._progress.update(self._pos // 1024) return ret def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.close() # moved here from url.py to avoid a cycle def readauthforuri(ui, uri, user): uri = pycompat.bytesurl(uri) # Read configuration groups = {} for key, val in ui.configitems(b'auth'): if key in (b'cookiefile',): continue if b'.' not in key: ui.warn(_(b"ignoring invalid [auth] key '%s'\n") % key) continue group, setting = key.rsplit(b'.', 1) gdict = groups.setdefault(group, {}) if setting in (b'username', b'cert', b'key'): val = util.expandpath(val) gdict[setting] = val # Find the best match scheme, hostpath = uri.split(b'://', 1) bestuser = None bestlen = 0 bestauth = None for group, auth in pycompat.iteritems(groups): if user and user != auth.get(b'username', user): # If a username was set in the URI, the entry username # must either match it or be unset continue prefix = auth.get(b'prefix') if not prefix: continue prefixurl = util.url(prefix) if prefixurl.user and prefixurl.user != user: # If a username was set in the prefix, it must match the username in # the URI. continue # The URI passed in has been stripped of credentials, so erase the user # here to allow simpler matching. prefixurl.user = None prefix = bytes(prefixurl) p = prefix.split(b'://', 1) if len(p) > 1: schemes, prefix = [p[0]], p[1] else: schemes = (auth.get(b'schemes') or b'https').split() if ( (prefix == b'*' or hostpath.startswith(prefix)) and ( len(prefix) > bestlen or ( len(prefix) == bestlen and not bestuser and b'username' in auth ) ) and scheme in schemes ): bestlen = len(prefix) bestauth = group, auth bestuser = auth.get(b'username') if user and not bestuser: auth[b'username'] = user return bestauth