view mercurial/txnutil.py @ 42278:8dc22a209420

automation: wait for instance profiles and roles

Otherwise there is a race condition between creating the resources
and us attempting to use them / them becoming available.

The role waiter API was recently introduced, so we had to upgrade
the boto3 package to get it. Other packages were also updated
to latest versions just because.

Even with this change, I still run into issues with the IAM instance
profile not being available when we attempt to create an EC2 instance
using a just-created profile. I'm not sure what's going on. Possibly
a bug on Amazon's end. But the new behavior is "more correct."

Differential Revision: https://phab.mercurial-scm.org/D6286

# 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)