mercurial/peer.py

rebase: use scmutil.cleanupnodes (issue5606) (BC)

This patch migrates rebase to use scmutil.cleanupnodes API. It simplifies
the code and makes rebase code reusable inside a transaction.

This is a BC because the backup file is no longer strip-backup/*-backup.hg,
but strip-backup/*-rebase.hg. The latter looks more reasonable since the
directory name is "strip-backup" so there is no need to repeat "backup".

I think the backup file name change is probably fine as a BC, since we have
changed it before (aa4a1672583e) and didn't get complains. The end result
of this series will be a much more consistent and unified backup names:

  command  | old backup file suffix       | new backup file suffix
  -------------------------------------------------------------------
  amend    | amend-backup.hg              | amend.hg
  histedit | backup.hg (could be 2 files) | histedit.hg (single file)
  rebase   | backup.hg                    | rebase.hg
  strip    | backup.hg                    | backup.hg

(note: backup files are under .hg/strip-backup)

It also fixes issue5606 as a side effect because the new "delayedstrip" code
path will carefully examine nodes (safestriproots) to make sure orphaned
changesets won't get stripped by accident.

Some warning messages are changed to the new "warning: orphaned descendants
detected, not stripping HASHES", which provides more information about
exactly what changesets are left behind.

Another minor behavior change is when there is an obsoleted changeset with a
successor in the destination branch, bookmarks pointing to that obsoleted
changeset will not be moved. I have commented in test-rebase-obsolete.t
explaining why that is more desirable.

# peer.py - repository base classes for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
# Copyright 2006 Vadim Gelfer <[e-mail]>
#
# 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 .i18n import _
from . import (
    error,
    util,
)

# abstract batching support

class future(object):
    '''placeholder for a value to be set later'''
    def set(self, value):
        if util.safehasattr(self, 'value'):
            raise error.RepoError("future is already set")
        self.value = value

class batcher(object):
    '''base class for batches of commands submittable in a single request

    All methods invoked on instances of this class are simply queued and
    return a a future for the result. Once you call submit(), all the queued
    calls are performed and the results set in their respective futures.
    '''
    def __init__(self):
        self.calls = []
    def __getattr__(self, name):
        def call(*args, **opts):
            resref = future()
            self.calls.append((name, args, opts, resref,))
            return resref
        return call
    def submit(self):
        raise NotImplementedError()

class iterbatcher(batcher):

    def submit(self):
        raise NotImplementedError()

    def results(self):
        raise NotImplementedError()

class localbatch(batcher):
    '''performs the queued calls directly'''
    def __init__(self, local):
        batcher.__init__(self)
        self.local = local
    def submit(self):
        for name, args, opts, resref in self.calls:
            resref.set(getattr(self.local, name)(*args, **opts))

class localiterbatcher(iterbatcher):
    def __init__(self, local):
        super(iterbatcher, self).__init__()
        self.local = local

    def submit(self):
        # submit for a local iter batcher is a noop
        pass

    def results(self):
        for name, args, opts, resref in self.calls:
            yield getattr(self.local, name)(*args, **opts)

def batchable(f):
    '''annotation for batchable methods

    Such methods must implement a coroutine as follows:

    @batchable
    def sample(self, one, two=None):
        # Handle locally computable results first:
        if not one:
            yield "a local result", None
        # Build list of encoded arguments suitable for your wire protocol:
        encargs = [('one', encode(one),), ('two', encode(two),)]
        # Create future for injection of encoded result:
        encresref = future()
        # Return encoded arguments and future:
        yield encargs, encresref
        # Assuming the future to be filled with the result from the batched
        # request now. Decode it:
        yield decode(encresref.value)

    The decorator returns a function which wraps this coroutine as a plain
    method, but adds the original method as an attribute called "batchable",
    which is used by remotebatch to split the call into separate encoding and
    decoding phases.
    '''
    def plain(*args, **opts):
        batchable = f(*args, **opts)
        encargsorres, encresref = next(batchable)
        if not encresref:
            return encargsorres # a local result in this case
        self = args[0]
        encresref.set(self._submitone(f.func_name, encargsorres))
        return next(batchable)
    setattr(plain, 'batchable', f)
    return plain

class peerrepository(object):

    def batch(self):
        return localbatch(self)

    def iterbatch(self):
        """Batch requests but allow iterating over the results.

        This is to allow interleaving responses with things like
        progress updates for clients.
        """
        return localiterbatcher(self)

    def capable(self, name):
        '''tell whether repo supports named capability.
        return False if not supported.
        if boolean capability, return True.
        if string capability, return string.'''
        caps = self._capabilities()
        if name in caps:
            return True
        name_eq = name + '='
        for cap in caps:
            if cap.startswith(name_eq):
                return cap[len(name_eq):]
        return False

    def requirecap(self, name, purpose):
        '''raise an exception if the given capability is not present'''
        if not self.capable(name):
            raise error.CapabilityError(
                _('cannot %s; remote repository does not '
                  'support the %r capability') % (purpose, name))

    def local(self):
        '''return peer as a localrepo, or None'''
        return None

    def peer(self):
        return self

    def canpush(self):
        return True

    def close(self):
        pass