mercurial/stack.py

exchangev2: use filesdata

filesdata is a more efficient mechanism for bulk fetching files data for a
range of changesets. Let's use it in exchangev2.

With this change, a client performing a full clone of mozilla-unified
transmits substantially fewer bytes across the wire:

before: 139,124,863 bytes sent
after:   20,522,499 bytes sent

The bulk of the remaining bytes is likely the transfer of ~1M nodes for
changesets and manifests. We can eliminate this by making requests in
terms of node ranges instead of explicit node lists...

Differential Revision: https://phab.mercurial-scm.org/D4982

# stack.py - Mercurial functions for stack definition
#
#  Copyright Matt Mackall <[e-mail]> and other
#
# 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

from . import (
    revsetlang,
    scmutil,
)

def getstack(repo, rev=None):
    """return a sorted smartrev of the stack containing either rev if it is
    not None or the current working directory parent.

    The stack will always contain all drafts changesets which are ancestors to
    the revision and are not merges.
    """
    if rev is None:
        rev = '.'

    revspec = 'reverse(only(%s) and not public() and not ::merge())'
    revset = revsetlang.formatspec(revspec, rev)
    revisions = scmutil.revrange(repo, [revset])
    revisions.sort()
    return revisions