Mercurial > hg
view tests/test-convert-clonebranches.t @ 39496:2f9f7889549b
snapshot: introduce an intermediate `_refinedgroups` generator
This method will be used to improve the search for a good snapshot base. To
keep things simpler, we introduce the necessary function before doing any
delta base logic change. The next handful of commits will focus on refactoring
the code to let that new logic land as clearly as possible.
# General Idea
Right now, the search for a good delta base stop whenever we found a good one.
However, when using sparse-revlog, we should probably try a bit harder.
We do significant effort to increase delta re-use by jumping on "unrelated"
delta chains that provide better results. Moving to another chain for a better
result is good, but we have no guarantee we jump at a reasonable point in that
new chain. When we consider over the chains related to the parents, we start
from the higher-level snapshots. This is a way to consider the snapshot closer
to the current revision that has the best chance to produce a small delta. We
do benefit from this walk order when jumping to a better "unrelated" stack.
To counter-balance this, we'll introduce a way to "refine" the result. After a
good delta have been found, we'll keep searching for a better delta, using the
current best one as a starting point.
# Target Setup
The `finddeltainfo` method is responsible for the general search for a good
delta. It requests candidates base from `_candidategroups` and decides which
one are usable.
The `_candidategroups` generator act as a top-level filter, it does not care
about how we pick candidates, it just does basic filtering, excluding
revisions that have been tested already or that are an obvious misfit.
The `_rawgroups` generator is the one with the actual ancestors walking logic,
It does not care about what would do a good delta and what was already tested,
it just issues the initial candidates.
We introduce a new `_refinedgroup` function to bridge the gap between
`_candidategroups` and `_rawgroups`. It delegates the initial iteration logic
and then performing relevant refining of the valid base once found. (This
logic is yet to be added to function)
All these logics are fairly independent and easier to understand when standing
alone, not mixed with each other. It also makes it easy to test and try
different approaches for one of those four layers without affecting the other
ones.
# Technical details
To communicate `finddeltainfo` choice of "current best delta base" to the
`_refinegroup` logic, we plan to use python co-routine feature. The
`_candidategroups` and `_refinegroup` generators will become co-routine. This
will allow `_refinegroup` to detect when a good delta have been found and
triggers various refining steps.
For now, `_candidategroups` will just pass the value down the stack.
After poking at various option, the co-routine appears the best to keep each
layers focus on its duty, without the need to spread implementation details
across layers.
author | Boris Feld <boris.feld@octobus.net> |
---|---|
date | Fri, 07 Sep 2018 11:17:32 -0400 |
parents | 794f7bb739be |
children | 5abc47d4ca6b |
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$ cat <<EOF >> $HGRCPATH > [extensions] > convert = > [convert] > hg.tagsbranch = 0 > EOF $ hg init source $ cd source $ echo a > a $ hg ci -qAm adda Add a merge with one parent in the same branch $ echo a >> a $ hg ci -qAm changea $ hg up -qC 0 $ hg branch branch0 marked working directory as branch branch0 (branches are permanent and global, did you want a bookmark?) $ echo b > b $ hg ci -qAm addb $ hg up -qC $ hg merge default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -qm mergeab $ hg tag -ql mergeab $ cd .. Miss perl... sometimes $ cat > filter.py <<EOF > from __future__ import absolute_import > import re > import sys > > r = re.compile(r'^(?:\d+|pulling from)') > sys.stdout.writelines([l for l in sys.stdin if r.search(l)]) > EOF convert $ hg convert -v --config convert.hg.clonebranches=1 source dest | > $PYTHON filter.py 3 adda 2 changea 1 addb pulling from default into branch0 1 changesets found 0 mergeab pulling from default into branch0 1 changesets found Add a merge with both parents and child in different branches $ cd source $ hg branch branch1 marked working directory as branch branch1 $ echo a > file1 $ hg ci -qAm c1 $ hg up -qC mergeab $ hg branch branch2 marked working directory as branch branch2 $ echo a > file2 $ hg ci -qAm c2 $ hg merge branch1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg branch branch3 marked working directory as branch branch3 $ hg ci -qAm c3 $ cd .. incremental conversion $ hg convert -v --config convert.hg.clonebranches=1 source dest | > $PYTHON filter.py 2 c1 pulling from branch0 into branch1 4 changesets found 1 c2 pulling from branch0 into branch2 4 changesets found 0 c3 pulling from branch1 into branch3 5 changesets found pulling from branch2 into branch3 1 changesets found