hgweb.cgi

localrepo: extract resolving of opener options to standalone functions

Requirements and config options are converted into a dict which is
available to the store vfs to consult. This is how storage options
are communicated from the repo layer to the storage layer.

Currently, we do that option resolution in a private method on the
repo instance. And there is a single method doing that resolution.

Opener options are logically specific to the storage backend they
apply to. And, opener options may wish to influence how the repo
object/type is constructed. So it makes sense to have more granular
storage option resolution that occurs before the repo object is
instantiated.

This commit extracts the code for resolving opener options into new
module-level functions. These functions are run before the repo
instance is constructed.

As part of the code move, we split the option resolution into
generic and revlog-specific options. After this commit, we no longer
add revlog-specific options to repos that don't have a revlog
requirement.

Some of these opener options and associated config options might make
sense on alternate storage backends. We can always reuse config
options and opener option names for other backends. But we shouldn't
be passing opener options to storage backends that won't recognize
them. I haven't done it here, but after this commit it should be
possible for store backends to validate the set of opener options
it receives.

Because localrepository.openerreqs is no longer used after this commit,
it has been removed.

I'm not super thrilled about the code outside of localrepo that is
adding requirements and updating opener options. We'll probably want
to create a more formal API for that use case that constructs a new
repo instance and poisons the old repo object. But this was a
pre-existing issue and can be dealt with later. I have little doubt
it will cause me troubles as I continue to refactor how repository
objects are instantiated.

.. api::

   ``localrepository.openerreqs`` has been removed. Override
   ``localrepo.resolvestorevfsoptions()`` to add custom opener options.

.. api::

   ``localrepository._applyopenerreqs()`` has been removed. Use
   ``localrepo.resolvestorevfsoptions()`` to add custom opener options.

Differential Revision: https://phab.mercurial-scm.org/D4576

#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also https://mercurial-scm.org/wiki/PublishingRepositories

# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "/path/to/repo/or/config"

# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")

# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()

from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb, wsgicgi
application = hgweb(config)
wsgicgi.launch(application)