view mercurial/destutil.py @ 26577:8f2ff40fe9c9

localrepo: execute appropriate actions for dirstate at releasing transaction

Before this patch, in-memory dirstate changes are still kept over a
transaction scope boundary regardless of the result of it.

For "all or nothing" policy of the transaction, in-memory dirstate
changes should be:

  - written out at successful closing a transaction, because
    subsequent 'dirstate.invalidate()' can lose them

  - discarded at failure of a transaction, because outer
    'wlock.release()' or so may write them out

To discard all changes in a transaction completely, this patch also
restores '.hg/dirstate' by '.hg/journal.dirstate' at failure, because
'transaction' itself does nothing for files related to '.hg/journal.*'
in such case (therefore, renaming in this patch is safe enough).

This is a part of preparations for "transactional dirstate". See also
the wiki page below for detail about it.

    https://mercurial.selenic.com/wiki/DirstateTransactionPlan

This patch also removes redundant 'dirstate.invalidate()' just before
aborting a transaction for shelve/unshelve.

# destutil.py - Mercurial utility function for command destination
#
#  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 .i18n import _
from . import (
    error,
    util,
    obsolete,
)

def destupdate(repo):
    """destination for bare update operation
    """
    # Here is where we should consider bookmarks, divergent bookmarks, and tip
    # of current branch; but currently we are only checking the branch tips.
    node = None
    wc = repo[None]
    p1 = wc.p1()
    try:
        node = repo.branchtip(wc.branch())
    except error.RepoLookupError:
        if wc.branch() == 'default': # no default branch!
            node = repo.lookup('tip') # update to tip
        else:
            raise util.Abort(_("branch %s not found") % wc.branch())

    if p1.obsolete() and not p1.children():
        # allow updating to successors
        successors = obsolete.successorssets(repo, p1.node())

        # behavior of certain cases is as follows,
        #
        # divergent changesets: update to highest rev, similar to what
        #     is currently done when there are more than one head
        #     (i.e. 'tip')
        #
        # replaced changesets: same as divergent except we know there
        # is no conflict
        #
        # pruned changeset: no update is done; though, we could
        #     consider updating to the first non-obsolete parent,
        #     similar to what is current done for 'hg prune'

        if successors:
            # flatten the list here handles both divergent (len > 1)
            # and the usual case (len = 1)
            successors = [n for sub in successors for n in sub]

            # get the max revision for the given successors set,
            # i.e. the 'tip' of a set
            node = repo.revs('max(%ln)', successors).first()
    return repo[node].rev()