mercurial/peer.py

branchmap: Save changectx creation during update

The newly introduced `branchmap` function allows us to skip the
creation of changectx objects. This speeds up the construction of
the branchmap.

On the mozilla repository (117293 changesets, 15490 mutable)

Before:
  ! impactable 19.9
  ! mutable 0.576
  ! unserved 3.16

After:
  ! impactable 7.03 (2.8x faster)
  ! mutable 0.352 (1.6x)
  ! unserved 1.15 (2.7x)

On the cpython repository (81418 changesets, 6418 mutable)

Before:
  ! impactable 15.9
  ! mutable 0.451
  ! unserved 0.861

After:
  ! impactable 6.55 (2.4x faster)
  ! mutable 0.170 (2.6x faster)
  ! unserved 0.289 (2.9x faster)

On the pypy repository (58852 changesets)

Before:
  ! impactable 13.6

After:
  ! impactable 6.17 (2.2x faster)

On my Mercurial repository (18295 changesets, 2210 mutable)

Before:
  ! impactable 23.9
  ! mutable 0.368
  ! unserved 0.057

After:
  ! impactable 1.31 (18x faster)
  ! mutable 0.042 (8.7x)
  ! unserved 0.025 (2.2x)

# 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 i18n import _
import error

class peerrepository(object):

    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