mercurial/txnutil.py

infinitepush: introduce server option to route every push to bundlestore

This patch introduces a new config option for server
`infinitepush.pushtobundlestore` which if sets to True, the server will route
each incoming push to the bundlestore and store all the parts i.e. changegroups,
phases, obsmarkers in the bundlestore and won't be applied to the revlog.

This config option does not need any client side wrapping and does not need any
custom bundle2 part or stream level parameter to decide where the push should
go.

This is very useful for Mozilla CI use case where they have a central server
that recieves pushes to trigger code-reviews, trigger a test run of CI, run
static analysis etc. The server using the new config option can stash standalone
bundles to the bundlestore and server can get access to individual revisions on
demand.

A new test file which has related tests are added for the config option.

Differential Revision: https://phab.mercurial-scm.org/D2958

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# 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 errno

from . import (
    encoding,
)

def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get('HG_PENDING')

def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs('%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)