snapshot: consider all snapshots in the parents' chains
There are no reasons to only consider full snapshot as a possible base for an
intermediate snapshot. Now that the basic principles have been set, we can
start adding more levels of snapshots.
We now consider all snapshots in the parent's chains (full or intermediate).
This creates a chain of intermediate snapshots, each smaller than the previous
one.
# Effect On The Test Repository
In the test repository, we can see a decrease in the revlog size and slightly
shorter delta chain.
However, that approach creates snapshots more frequently, increasing the risk
of ending into problematic cases in very branchy repositories (not triggered
by the test repository). The next changesets will remove that risk by adding
logic that increases deltas reuse.
# narrowrevlog.py - revlog storing irrelevant nodes as "ellipsis" nodes
#
# Copyright 2017 Google, Inc.
#
# 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 mercurial import (
revlog,
util,
)
def readtransform(self, text):
return text, False
def writetransform(self, text):
return text, False
def rawtransform(self, text):
return False
revlog.addflagprocessor(revlog.REVIDX_ELLIPSIS,
(readtransform, writetransform, rawtransform))
def setup():
# We just wanted to add the flag processor, which is done at module
# load time.
pass
def makenarrowfilelog(fl, narrowmatch):
class narrowfilelog(fl.__class__):
def renamed(self, node):
# Renames that come from outside the narrowspec are
# problematic at least for git-diffs, because we lack the
# base text for the rename. This logic was introduced in
# 3cd72b1 of narrowhg (authored by martinvonz, reviewed by
# adgar), but that revision doesn't have any additional
# commentary on what problems we can encounter.
m = super(narrowfilelog, self).renamed(node)
if m and not narrowmatch(m[0]):
return None
return m
def size(self, rev):
# We take advantage of the fact that remotefilelog
# lacks a node() method to just skip the
# rename-checking logic when on remotefilelog. This
# might be incorrect on other non-revlog-based storage
# engines, but for now this seems to be fine.
#
# TODO: when remotefilelog is in core, improve this to
# explicitly look for remotefilelog instead of cheating
# with a hasattr check.
if util.safehasattr(self, 'node'):
node = self.node(rev)
# Because renamed() is overridden above to
# sometimes return None even if there is metadata
# in the revlog, size can be incorrect for
# copies/renames, so we need to make sure we call
# the super class's implementation of renamed()
# for the purpose of size calculation.
if super(narrowfilelog, self).renamed(node):
return len(self.read(node))
return super(narrowfilelog, self).size(rev)
def cmp(self, node, text):
different = super(narrowfilelog, self).cmp(node, text)
if different:
# Similar to size() above, if the file was copied from
# a file outside the narrowspec, the super class's
# would have returned True because we tricked it into
# thinking that the file was not renamed.
if super(narrowfilelog, self).renamed(node):
t2 = self.read(node)
return t2 != text
return different
fl.__class__ = narrowfilelog