wireproto: compress data from a generator
Currently, the "getbundle" wire protocol command obtains a generator of
data, converts it to a util.chunkbuffer, then converts it back to a
generator via the protocol's groupchunks() implementation. For the SSH
protocol, groupchunks() simply reads 4kb chunks then write()s the
data to a file descriptor. For the HTTP protocol, groupchunks() reads
32kb chunks, feeds those into a zlib compressor, emits compressed data
as it is available, and that is sent to the WSGI layer, where it is
likely turned into HTTP chunked transfer chunks as is or further
buffered and turned into a larger chunk.
For both the SSH and HTTP protocols, there is inefficiency from using
util.chunkbuffer.
For SSH, emitting consistent 4kb chunks sounds nice. However, the file
descriptor it is writing to is almost certainly buffered. That means
that a Python .write() probably doesn't translate into exactly what is
written to the I/O layer.
For HTTP, we're going through an intermediate layer to zlib compress
data. So all util.chunkbuffer is doing is ensuring that the chunks we
feed into the zlib compressor are of uniform size. This means more CPU
time in Python buffering and emitting chunks in util.chunkbuffer but
fewer function calls to zlib.
This patch introduces and implements a new wire protocol abstract
method: compresschunks(). It is like groupchunks() except it operates
on a generator instead of something with a .read(). The SSH
implementation simply proxies chunks. The HTTP implementation uses
zlib compression.
To avoid duplicate code, the HTTP groupchunks() has been reimplemented
in terms of compresschunks().
To prove this all works, the "getbundle" wire protocol command has been
switched to compresschunks(). This removes the util.chunkbuffer from
that command. Now, data essentially streams straight from the
changegroup emitter to the wire, possibly through a zlib compressor.
Generators all the way, baby.
There were slim to no performance changes on the server as measured
with the mozilla-central repository. This is likely because CPU
time is dominated by reading revlogs, producing the changegroup, and
zlib compressing the output stream. Still, this brings us a little
closer to our ideal of using generators everywhere.
# acl.py - changeset access control for mercurial
#
# Copyright 2006 Vadim Gelfer <vadim.gelfer@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.
'''hooks for controlling repository access
This hook makes it possible to allow or deny write access to given
branches and paths of a repository when receiving incoming changesets
via pretxnchangegroup and pretxncommit.
The authorization is matched based on the local user name on the
system where the hook runs, and not the committer of the original
changeset (since the latter is merely informative).
The acl hook is best used along with a restricted shell like hgsh,
preventing authenticating users from doing anything other than pushing
or pulling. The hook is not safe to use if users have interactive
shell access, as they can then disable the hook. Nor is it safe if
remote users share an account, because then there is no way to
distinguish them.
The order in which access checks are performed is:
1) Deny list for branches (section ``acl.deny.branches``)
2) Allow list for branches (section ``acl.allow.branches``)
3) Deny list for paths (section ``acl.deny``)
4) Allow list for paths (section ``acl.allow``)
The allow and deny sections take key-value pairs.
Branch-based Access Control
---------------------------
Use the ``acl.deny.branches`` and ``acl.allow.branches`` sections to
have branch-based access control. Keys in these sections can be
either:
- a branch name, or
- an asterisk, to match any branch;
The corresponding values can be either:
- a comma-separated list containing users and groups, or
- an asterisk, to match anyone;
You can add the "!" prefix to a user or group name to invert the sense
of the match.
Path-based Access Control
-------------------------
Use the ``acl.deny`` and ``acl.allow`` sections to have path-based
access control. Keys in these sections accept a subtree pattern (with
a glob syntax by default). The corresponding values follow the same
syntax as the other sections above.
Groups
------
Group names must be prefixed with an ``@`` symbol. Specifying a group
name has the same effect as specifying all the users in that group.
You can define group members in the ``acl.groups`` section.
If a group name is not defined there, and Mercurial is running under
a Unix-like system, the list of users will be taken from the OS.
Otherwise, an exception will be raised.
Example Configuration
---------------------
::
[hooks]
# Use this if you want to check access restrictions at commit time
pretxncommit.acl = python:hgext.acl.hook
# Use this if you want to check access restrictions for pull, push,
# bundle and serve.
pretxnchangegroup.acl = python:hgext.acl.hook
[acl]
# Allow or deny access for incoming changes only if their source is
# listed here, let them pass otherwise. Source is "serve" for all
# remote access (http or ssh), "push", "pull" or "bundle" when the
# related commands are run locally.
# Default: serve
sources = serve
[acl.deny.branches]
# Everyone is denied to the frozen branch:
frozen-branch = *
# A bad user is denied on all branches:
* = bad-user
[acl.allow.branches]
# A few users are allowed on branch-a:
branch-a = user-1, user-2, user-3
# Only one user is allowed on branch-b:
branch-b = user-1
# The super user is allowed on any branch:
* = super-user
# Everyone is allowed on branch-for-tests:
branch-for-tests = *
[acl.deny]
# This list is checked first. If a match is found, acl.allow is not
# checked. All users are granted access if acl.deny is not present.
# Format for both lists: glob pattern = user, ..., @group, ...
# To match everyone, use an asterisk for the user:
# my/glob/pattern = *
# user6 will not have write access to any file:
** = user6
# Group "hg-denied" will not have write access to any file:
** = @hg-denied
# Nobody will be able to change "DONT-TOUCH-THIS.txt", despite
# everyone being able to change all other files. See below.
src/main/resources/DONT-TOUCH-THIS.txt = *
[acl.allow]
# if acl.allow is not present, all users are allowed by default
# empty acl.allow = no users allowed
# User "doc_writer" has write access to any file under the "docs"
# folder:
docs/** = doc_writer
# User "jack" and group "designers" have write access to any file
# under the "images" folder:
images/** = jack, @designers
# Everyone (except for "user6" and "@hg-denied" - see acl.deny above)
# will have write access to any file under the "resources" folder
# (except for 1 file. See acl.deny):
src/main/resources/** = *
.hgtags = release_engineer
Examples using the "!" prefix
.............................
Suppose there's a branch that only a given user (or group) should be able to
push to, and you don't want to restrict access to any other branch that may
be created.
The "!" prefix allows you to prevent anyone except a given user or group to
push changesets in a given branch or path.
In the examples below, we will:
1) Deny access to branch "ring" to anyone but user "gollum"
2) Deny access to branch "lake" to anyone but members of the group "hobbit"
3) Deny access to a file to anyone but user "gollum"
::
[acl.allow.branches]
# Empty
[acl.deny.branches]
# 1) only 'gollum' can commit to branch 'ring';
# 'gollum' and anyone else can still commit to any other branch.
ring = !gollum
# 2) only members of the group 'hobbit' can commit to branch 'lake';
# 'hobbit' members and anyone else can still commit to any other branch.
lake = !@hobbit
# You can also deny access based on file paths:
[acl.allow]
# Empty
[acl.deny]
# 3) only 'gollum' can change the file below;
# 'gollum' and anyone else can still change any other file.
/misty/mountains/cave/ring = !gollum
'''
from __future__ import absolute_import
import getpass
from mercurial.i18n import _
from mercurial import (
error,
match,
util,
)
urlreq = util.urlreq
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'
def _getusers(ui, group):
# First, try to use group definition from section [acl.groups]
hgrcusers = ui.configlist('acl.groups', group)
if hgrcusers:
return hgrcusers
ui.debug('acl: "%s" not defined in [acl.groups]\n' % group)
# If no users found in group definition, get users from OS-level group
try:
return util.groupmembers(group)
except KeyError:
raise error.Abort(_("group '%s' is undefined") % group)
def _usermatch(ui, user, usersorgroups):
if usersorgroups == '*':
return True
for ug in usersorgroups.replace(',', ' ').split():
if ug.startswith('!'):
# Test for excluded user or group. Format:
# if ug is a user name: !username
# if ug is a group name: !@groupname
ug = ug[1:]
if not ug.startswith('@') and user != ug \
or ug.startswith('@') and user not in _getusers(ui, ug[1:]):
return True
# Test for user or group. Format:
# if ug is a user name: username
# if ug is a group name: @groupname
elif user == ug \
or ug.startswith('@') and user in _getusers(ui, ug[1:]):
return True
return False
def buildmatch(ui, repo, user, key):
'''return tuple of (match function, list enabled).'''
if not ui.has_section(key):
ui.debug('acl: %s not enabled\n' % key)
return None
pats = [pat for pat, users in ui.configitems(key)
if _usermatch(ui, user, users)]
ui.debug('acl: %s enabled, %d entries for user %s\n' %
(key, len(pats), user))
# Branch-based ACL
if not repo:
if pats:
# If there's an asterisk (meaning "any branch"), always return True;
# Otherwise, test if b is in pats
if '*' in pats:
return util.always
return lambda b: b in pats
return util.never
# Path-based ACL
if pats:
return match.match(repo.root, '', pats)
return util.never
def hook(ui, repo, hooktype, node=None, source=None, **kwargs):
if hooktype not in ['pretxnchangegroup', 'pretxncommit']:
raise error.Abort(_('config error - hook type "%s" cannot stop '
'incoming changesets nor commits') % hooktype)
if (hooktype == 'pretxnchangegroup' and
source not in ui.config('acl', 'sources', 'serve').split()):
ui.debug('acl: changes have source "%s" - skipping\n' % source)
return
user = None
if source == 'serve' and 'url' in kwargs:
url = kwargs['url'].split(':')
if url[0] == 'remote' and url[1].startswith('http'):
user = urlreq.unquote(url[3])
if user is None:
user = getpass.getuser()
ui.debug('acl: checking access for user "%s"\n' % user)
# deprecated config: acl.config
cfg = ui.config('acl', 'config')
if cfg:
ui.readconfig(cfg, sections=['acl.groups', 'acl.allow.branches',
'acl.deny.branches', 'acl.allow', 'acl.deny'])
allowbranches = buildmatch(ui, None, user, 'acl.allow.branches')
denybranches = buildmatch(ui, None, user, 'acl.deny.branches')
allow = buildmatch(ui, repo, user, 'acl.allow')
deny = buildmatch(ui, repo, user, 'acl.deny')
for rev in xrange(repo[node], len(repo)):
ctx = repo[rev]
branch = ctx.branch()
if denybranches and denybranches(branch):
raise error.Abort(_('acl: user "%s" denied on branch "%s"'
' (changeset "%s")')
% (user, branch, ctx))
if allowbranches and not allowbranches(branch):
raise error.Abort(_('acl: user "%s" not allowed on branch "%s"'
' (changeset "%s")')
% (user, branch, ctx))
ui.debug('acl: branch access granted: "%s" on branch "%s"\n'
% (ctx, branch))
for f in ctx.files():
if deny and deny(f):
raise error.Abort(_('acl: user "%s" denied on "%s"'
' (changeset "%s")') % (user, f, ctx))
if allow and not allow(f):
raise error.Abort(_('acl: user "%s" not allowed on "%s"'
' (changeset "%s")') % (user, f, ctx))
ui.debug('acl: path access granted: "%s"\n' % ctx)