mercurial/hgweb/__init__.py

changegroup: capture revision delta in a data structure

The current changegroup generation code is tightly coupled to
the revlog API. This tight coupling makes it difficult to implement
alternate storage backends without requiring a large surface area
of the revlog API to be exposed. This is not desirable.

In order to support changegroup generation with non-revlog storage,
we'll need to abstract the concept of delta generation.

This commit is the first step down that road. We introduce a
data structure for representing a delta in a changegroup.

The API still leaves a lot to be desired. But at least we now
have separation between data and actions performed on it.

As part of this, we tweak behavior slightly: we no longer
concatenate the delta prefix with the metadata header. Instead,
we track and emit the prefix as a separate chunk. This shouldn't
have any meaningful impact since all the chunks just get sent to
the wire, the compressor, etc.

Because we're introducing a new object, this does add some
overhead to changegroup execution. `hg perfchangegroupchangelog`
on my clone of the Mercurial repo (~40,000 visible revisions in
the changelog) slows down a bit:

! wall 1.268600 comb 1.270000 user 1.270000 sys 0.000000 (best of 8)
! wall 1.419479 comb 1.410000 user 1.410000 sys 0.000000 (best of 8)

With for `hg bundle -t none-v2 -a /dev/null`:

before: real 6.610 secs (user 6.460+0.000 sys 0.140+0.000)
after:  real 7.210 secs (user 7.060+0.000 sys 0.140+0.000)

I plan to claw back this regression in future commits. And I may
even do away with this data structure once the refactor is complete.
For now, it makes things easier to comprehend.

Differential Revision: https://phab.mercurial-scm.org/D4075

# hgweb/__init__.py - web interface to a mercurial repository
#
# Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
# Copyright 2005 Matt Mackall <[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 __future__ import absolute_import

import os

from ..i18n import _

from .. import (
    error,
    pycompat,
)

from ..utils import (
    procutil,
)

from . import (
    hgweb_mod,
    hgwebdir_mod,
    server,
)

def hgweb(config, name=None, baseui=None):
    '''create an hgweb wsgi object

    config can be one of:
    - repo object (single repo view)
    - path to repo (single repo view)
    - path to config file (multi-repo view)
    - dict of virtual:real pairs (multi-repo view)
    - list of virtual:real tuples (multi-repo view)
    '''

    if ((isinstance(config, bytes) and not os.path.isdir(config)) or
        isinstance(config, dict) or isinstance(config, list)):
        # create a multi-dir interface
        return hgwebdir_mod.hgwebdir(config, baseui=baseui)
    return hgweb_mod.hgweb(config, name=name, baseui=baseui)

def hgwebdir(config, baseui=None):
    return hgwebdir_mod.hgwebdir(config, baseui=baseui)

class httpservice(object):
    def __init__(self, ui, app, opts):
        self.ui = ui
        self.app = app
        self.opts = opts

    def init(self):
        procutil.setsignalhandler()
        self.httpd = server.create_server(self.ui, self.app)

        if (self.opts['port'] and
            not self.ui.verbose and
            not self.opts['print_url']):
            return

        if self.httpd.prefix:
            prefix = self.httpd.prefix.strip('/') + '/'
        else:
            prefix = ''

        port = r':%d' % self.httpd.port
        if port == r':80':
            port = r''

        bindaddr = self.httpd.addr
        if bindaddr == r'0.0.0.0':
            bindaddr = r'*'
        elif r':' in bindaddr: # IPv6
            bindaddr = r'[%s]' % bindaddr

        fqaddr = self.httpd.fqaddr
        if r':' in fqaddr:
            fqaddr = r'[%s]' % fqaddr

        url = 'http://%s%s/%s' % (
            pycompat.sysbytes(fqaddr), pycompat.sysbytes(port), prefix)
        if self.opts['print_url']:
            self.ui.write('%s\n' % url)
        else:
            if self.opts['port']:
                write = self.ui.status
            else:
                write = self.ui.write
            write(_('listening at %s (bound to %s:%d)\n') %
                  (url, pycompat.sysbytes(bindaddr), self.httpd.port))
        self.ui.flush()  # avoid buffering of status message

    def run(self):
        self.httpd.serve_forever()

def createapp(baseui, repo, webconf):
    if webconf:
        return hgwebdir_mod.hgwebdir(webconf, baseui=baseui)
    else:
        if not repo:
            raise error.RepoError(_("there is no Mercurial repository"
                                    " here (.hg not found)"))
        return hgweb_mod.hgweb(repo, baseui=baseui)