upstream/mercurial-mirror Files · mercurial/dicthelpers.py

obsolete: order of magnitude speedup in _computebumpedset...

obsolete: order of magnitude speedup in _computebumpedset Reminder: a changeset is said "bumped" if it tries to obsolete a immutable changeset. The previous algorithm for computing bumped changeset was: 1) Get all public changesets 2) Find all they successors 3) Search for stuff that are eligible for being "bumped" (mutable and non obsolete) The entry size of this algorithm is `O(len(public))` which is mostly the same as `O(len(repo))`. Even this this approach mean fewer obsolescence marker are traveled, this is not very scalable. The new algorithm is: 1) For each potential bumped changesets (non obsolete mutable) 2) iterate over precursors 3) if a precursors is public. changeset is bumped We travel more obsolescence marker, but the entry size is much smaller since the amount of potential bumped should remains mostly stable with time `O(1)`. On some confidential gigantic repo this move bumped computation from 15.19s to 0.46s (×33 speedup…). On "smaller" repo (mercurial, cubicweb's review) no significant gain were seen. The additional traversal of obsolescence marker is probably probably counter balance the advantage of it. Other optimisation could be done in the future (eg: sharing precursors cache for divergence detection)

Siddharth Agarwal - - Load All Authors

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      # dicthelpers.py - helper routines for Python dicts

      #

      # Copyright 2013 Facebook

      #

      # This software may be used and distributed according to the terms of the

      # GNU General Public License version 2 or any later version.

      def diff(d1, d2, default=None):

          '''Return all key-value pairs that are different between d1 and d2.

          This includes keys that are present in one dict but not the other, and

          keys whose values are different. The return value is a dict with values

          being pairs of values from d1 and d2 respectively, and missing values

          treated as default, so if a value is missing from one dict and the same as

          default in the other, it will not be returned.'''

          res = {}

          if d1 is d2:

              # same dict, so diff is empty

              return res

          for k1, v1 in d1.iteritems():

              v2 = d2.get(k1, default)

              if v1 != v2:

                  res[k1] = (v1, v2)

          for k2 in d2:

              if k2 not in d1:

                  v2 = d2[k2]

                  if v2 != default:

                      res[k2] = (default, v2)

          return res

      def join(d1, d2, default=None):

          '''Return all key-value pairs from both d1 and d2.

          This is akin to an outer join in relational algebra. The return value is a

          dict with values being pairs of values from d1 and d2 respectively, and

          missing values represented as default.'''

          res = {}

          for k1, v1 in d1.iteritems():

              if k1 in d2:

                  res[k1] = (v1, d2[k1])

              else:

                  res[k1] = (v1, default)

          if d1 is d2:

              return res

          for k2 in d2:

              if k2 not in d1:

                  res[k2] = (default, d2[k2])

          return res

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				# dicthelpers.py - helper routines for Python dicts
				#
				# Copyright 2013 Facebook
				#
				# This software may be used and distributed according to the terms of the
				# GNU General Public License version 2 or any later version.

				def diff(d1, d2, default=None):
				'''Return all key-value pairs that are different between d1 and d2.

				This includes keys that are present in one dict but not the other, and
				keys whose values are different. The return value is a dict with values
				being pairs of values from d1 and d2 respectively, and missing values
				treated as default, so if a value is missing from one dict and the same as
				default in the other, it will not be returned.'''
				res = {}
				if d1 is d2:
				# same dict, so diff is empty
				return res

				for k1, v1 in d1.iteritems():
				v2 = d2.get(k1, default)
				if v1 != v2:
				res[k1] = (v1, v2)

				for k2 in d2:
				if k2 not in d1:
				v2 = d2[k2]
				if v2 != default:
				res[k2] = (default, v2)

				return res

				def join(d1, d2, default=None):
				'''Return all key-value pairs from both d1 and d2.

				This is akin to an outer join in relational algebra. The return value is a
				dict with values being pairs of values from d1 and d2 respectively, and
				missing values represented as default.'''
				res = {}

				for k1, v1 in d1.iteritems():
				if k1 in d2:
				res[k1] = (v1, d2[k1])
				else:
				res[k1] = (v1, default)

				if d1 is d2:
				return res

				for k2 in d2:
				if k2 not in d1:
				res[k2] = (default, d2[k2])

				return res