##// END OF EJS Templates
localrepo: experimental support for non-zlib revlog compression...
localrepo: experimental support for non-zlib revlog compression The final part of integrating the compression manager APIs into revlog storage is the plumbing for repositories to advertise they are using non-zlib storage and for revlogs to instantiate a non-zlib compression engine. The main intent of the compression manager work was to zstd all of the things. Adding zstd to revlogs has proved to be more involved than other places because revlogs are... special. Very small inputs and the use of delta chains (which are themselves a form of compression) are a completely different use case from streaming compression, which bundles and the wire protocol employ. I've conducted numerous experiments with zstd in revlogs and have yet to formalize compression settings and a storage architecture that I'm confident I won't regret later. In other words, I'm not yet ready to commit to a new mechanism for using zstd - or any other compression format - in revlogs. That being said, having some support for zstd (and other compression formats) in revlogs in core is beneficial. It can allow others to conduct experiments. This patch introduces *highly experimental* support for non-zlib compression formats in revlogs. Introduced is a config option to control which compression engine to use. Also introduced is a namespace of "exp-compression-*" requirements to denote support for non-zlib compression in revlogs. I've prefixed the namespace with "exp-" (short for "experimental") because I'm not confident of the requirements "schema" and in no way want to give the illusion of supporting these requirements in the future. I fully intend to drop support for these requirements once we figure out what we're doing with zstd in revlogs. A good portion of the patch is teaching the requirements system about registered compression engines and passing the requested compression engine as an opener option so revlogs can instantiate the proper compression engine for new operations. That's a verbose way of saying "we can now use zstd in revlogs!" On an `hg pull` conversion of the mozilla-unified repo with no extra redelta settings (like aggressivemergedeltas), we can see the impact of zstd vs zlib in revlogs: $ hg perfrevlogchunks -c ! chunk ! wall 2.032052 comb 2.040000 user 1.990000 sys 0.050000 (best of 5) ! wall 1.866360 comb 1.860000 user 1.820000 sys 0.040000 (best of 6) ! chunk batch ! wall 1.877261 comb 1.870000 user 1.860000 sys 0.010000 (best of 6) ! wall 1.705410 comb 1.710000 user 1.690000 sys 0.020000 (best of 6) $ hg perfrevlogchunks -m ! chunk ! wall 2.721427 comb 2.720000 user 2.640000 sys 0.080000 (best of 4) ! wall 2.035076 comb 2.030000 user 1.950000 sys 0.080000 (best of 5) ! chunk batch ! wall 2.614561 comb 2.620000 user 2.580000 sys 0.040000 (best of 4) ! wall 1.910252 comb 1.910000 user 1.880000 sys 0.030000 (best of 6) $ hg perfrevlog -c -d 1 ! wall 4.812885 comb 4.820000 user 4.800000 sys 0.020000 (best of 3) ! wall 4.699621 comb 4.710000 user 4.700000 sys 0.010000 (best of 3) $ hg perfrevlog -m -d 1000 ! wall 34.252800 comb 34.250000 user 33.730000 sys 0.520000 (best of 3) ! wall 24.094999 comb 24.090000 user 23.320000 sys 0.770000 (best of 3) Only modest wins for the changelog. But manifest reading is significantly faster. What's going on? One reason might be data volume. zstd decompresses faster. So given more bytes, it will put more distance between it and zlib. Another reason is size. In the current design, zstd revlogs are *larger*: debugcreatestreamclonebundle (size in bytes) zlib: 1,638,852,492 zstd: 1,680,601,332 I haven't investigated this fully, but I reckon a significant cause of larger revlogs is that the zstd frame/header has more bytes than zlib's. For very small inputs or data that doesn't compress well, we'll tend to store more uncompressed chunks than with zlib (because the compressed size isn't smaller than original). This will make revlog reading faster because it is doing less decompression. Moving on to bundle performance: $ hg bundle -a -t none-v2 (total CPU time) zlib: 102.79s zstd: 97.75s So, marginal CPU decrease for reading all chunks in all revlogs (this is somewhat disappointing). $ hg bundle -a -t <engine>-v2 (total CPU time) zlib: 191.59s zstd: 115.36s This last test effectively measures the difference between zlib->zlib and zstd->zstd for revlogs to bundle. This is a rough approximation of what a server does during `hg clone`. There are some promising results for zstd. But not enough for me to feel comfortable advertising it to users. We'll get there...

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request.py
152 lines | 5.3 KiB | text/x-python | PythonLexer
# hgweb/request.py - An http request from either CGI or the standalone server.
#
# Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net>
# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
#
# 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 cgi
import errno
import socket
from .common import (
ErrorResponse,
HTTP_NOT_MODIFIED,
statusmessage,
)
from .. import (
util,
)
shortcuts = {
'cl': [('cmd', ['changelog']), ('rev', None)],
'sl': [('cmd', ['shortlog']), ('rev', None)],
'cs': [('cmd', ['changeset']), ('node', None)],
'f': [('cmd', ['file']), ('filenode', None)],
'fl': [('cmd', ['filelog']), ('filenode', None)],
'fd': [('cmd', ['filediff']), ('node', None)],
'fa': [('cmd', ['annotate']), ('filenode', None)],
'mf': [('cmd', ['manifest']), ('manifest', None)],
'ca': [('cmd', ['archive']), ('node', None)],
'tags': [('cmd', ['tags'])],
'tip': [('cmd', ['changeset']), ('node', ['tip'])],
'static': [('cmd', ['static']), ('file', None)]
}
def normalize(form):
# first expand the shortcuts
for k in shortcuts.iterkeys():
if k in form:
for name, value in shortcuts[k]:
if value is None:
value = form[k]
form[name] = value
del form[k]
# And strip the values
for k, v in form.iteritems():
form[k] = [i.strip() for i in v]
return form
class wsgirequest(object):
"""Higher-level API for a WSGI request.
WSGI applications are invoked with 2 arguments. They are used to
instantiate instances of this class, which provides higher-level APIs
for obtaining request parameters, writing HTTP output, etc.
"""
def __init__(self, wsgienv, start_response):
version = wsgienv['wsgi.version']
if (version < (1, 0)) or (version >= (2, 0)):
raise RuntimeError("Unknown and unsupported WSGI version %d.%d"
% version)
self.inp = wsgienv['wsgi.input']
self.err = wsgienv['wsgi.errors']
self.threaded = wsgienv['wsgi.multithread']
self.multiprocess = wsgienv['wsgi.multiprocess']
self.run_once = wsgienv['wsgi.run_once']
self.env = wsgienv
self.form = normalize(cgi.parse(self.inp,
self.env,
keep_blank_values=1))
self._start_response = start_response
self.server_write = None
self.headers = []
def __iter__(self):
return iter([])
def read(self, count=-1):
return self.inp.read(count)
def drain(self):
'''need to read all data from request, httplib is half-duplex'''
length = int(self.env.get('CONTENT_LENGTH') or 0)
for s in util.filechunkiter(self.inp, limit=length):
pass
def respond(self, status, type, filename=None, body=None):
if self._start_response is not None:
self.headers.append(('Content-Type', type))
if filename:
filename = (filename.rpartition('/')[-1]
.replace('\\', '\\\\').replace('"', '\\"'))
self.headers.append(('Content-Disposition',
'inline; filename="%s"' % filename))
if body is not None:
self.headers.append(('Content-Length', str(len(body))))
for k, v in self.headers:
if not isinstance(v, str):
raise TypeError('header value must be string: %r' % (v,))
if isinstance(status, ErrorResponse):
self.headers.extend(status.headers)
if status.code == HTTP_NOT_MODIFIED:
# RFC 2616 Section 10.3.5: 304 Not Modified has cases where
# it MUST NOT include any headers other than these and no
# body
self.headers = [(k, v) for (k, v) in self.headers if
k in ('Date', 'ETag', 'Expires',
'Cache-Control', 'Vary')]
status = statusmessage(status.code, str(status))
elif status == 200:
status = '200 Script output follows'
elif isinstance(status, int):
status = statusmessage(status)
self.server_write = self._start_response(status, self.headers)
self._start_response = None
self.headers = []
if body is not None:
self.write(body)
self.server_write = None
def write(self, thing):
if thing:
try:
self.server_write(thing)
except socket.error as inst:
if inst[0] != errno.ECONNRESET:
raise
def writelines(self, lines):
for line in lines:
self.write(line)
def flush(self):
return None
def close(self):
return None
def wsgiapplication(app_maker):
'''For compatibility with old CGI scripts. A plain hgweb() or hgwebdir()
can and should now be used as a WSGI application.'''
application = app_maker()
def run_wsgi(env, respond):
return application(env, respond)
return run_wsgi