tests/test-revlog-delta-find.t

phases: large rewrite on retract boundary

The new code is still pure Python, so we still have room to going significantly
faster. However its complexity of the complex part is `O(|[min_new_draft, tip]|)` instead of
`O(|[min_draft, tip]|` which should help tremendously one repository with old
draft (like mercurial-devel or mozilla-try).

This is especially useful as the most common "retract boundary" operation
happens when we commit/rewrite new drafts or when we push new draft to a
non-publishing server. In this case, the smallest new_revs is very close to the
tip and there is very few work to do.

A few smaller optimisation could be done for these cases and will be introduced in
later changesets.

We still have iterate over large sets of roots, but this is already a great
improvement for a very small amount of work. We gather information on the
affected changeset as we go as we can put it to use in the next changesets.
This extra data collection might slowdown the `register_new` case a bit, however
for register_new, it should not really matters. The set of new nodes is either
small, so the impact is negligible, or the set of new nodes is large, and the
amount of work to do to had them will dominate the overhead the collecting
information in `changed_revs`.

As this new code compute the changes on the fly, it unlock other interesting
improvement to be done in later changeset.

==========================================================
Test various things around delta computation within revlog
==========================================================


basic setup
-----------

  $ cat << EOF >> $HGRCPATH
  > [debug]
  > revlog.debug-delta=yes
  > EOF

  $ hg init base-repo
  $ cd base-repo

create a "large" file

  $ $TESTDIR/seq.py 1000 | $TESTDIR/sha256line.py > my-file.txt
  $ hg add my-file.txt
  $ hg commit -m initial-commit
  DBG-DELTAS: FILELOG:my-file.txt: rev=0: delta-base=0 * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)

Add more change at the end of the file

  $ $TESTDIR/seq.py 1001 1200 | $TESTDIR/sha256line.py >> my-file.txt
  $ hg commit -m "large-change"
  DBG-DELTAS: FILELOG:my-file.txt: rev=1: delta-base=0 * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)

Add small change at the start

  $ hg up 'desc("initial-commit")' --quiet
  $ mv my-file.txt foo
  $ echo "small change at the start" > my-file.txt
  $ cat foo >> my-file.txt
  $ rm foo
  $ hg commit -m "small-change"
  DBG-DELTAS: FILELOG:my-file.txt: rev=2: delta-base=0 * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  created new head


  $ hg log -r 'head()' -T '{node}\n' >> ../base-heads.nodes
  $ hg log -r 'desc("initial-commit")' -T '{node}\n' >> ../initial.node
  $ hg log -r 'desc("small-change")' -T '{node}\n' >> ../small.node
  $ hg log -r 'desc("large-change")' -T '{node}\n' >> ../large.node
  $ cd ..

Check delta find policy and result for merge on commit
======================================================

Check that delta of merge pick best of the two parents
------------------------------------------------------

As we check against both parents, the one with the largest change should
produce the smallest delta and be picked.

  $ hg clone base-repo test-parents --quiet
  $ hg -R test-parents update 'nodefromfile("small.node")' --quiet
  $ hg -R test-parents merge 'nodefromfile("large.node")' --quiet

The delta base is the "large" revision as it produce a smaller delta.

  $ hg -R test-parents commit -m "merge from small change"
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=1 * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)

Check that the behavior tested above can we disabled
----------------------------------------------------

We disable the checking of both parent at the same time. The `small` change,
that produce a less optimal delta, should be picked first as it is "closer" to
the new commit.

  $ hg clone base-repo test-no-parents --quiet
  $ hg -R test-no-parents update 'nodefromfile("small.node")' --quiet
  $ hg -R test-no-parents merge 'nodefromfile("large.node")' --quiet

The delta base is the "large" revision as it produce a smaller delta.

  $ hg -R test-no-parents commit -m "merge from small change" \
  > --config storage.revlog.optimize-delta-parent-choice=no
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)


Check delta-find policy and result when unbundling
==================================================

Build a bundle with all delta built against p1

  $ hg bundle -R test-parents --all --config devel.bundle.delta=p1 all-p1.hg
  4 changesets found

Default policy of trusting delta from the bundle
------------------------------------------------

Keeping the `p1` delta used in the bundle is sub-optimal for storage, but
strusting in-bundle delta is faster to apply.

  $ hg init bundle-default
  $ hg -R bundle-default unbundle all-p1.hg --quiet
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=0: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=1: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=2: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)

(confirm the file revision are in the same order, 2 should be smaller than 1)

  $ hg -R bundle-default debugdata my-file.txt 2 | wc -l
  \s*1001 (re)
  $ hg -R bundle-default debugdata my-file.txt 1 | wc -l
  \s*1200 (re)

explicitly enabled
------------------

Keeping the `p1` delta used in the bundle is sub-optimal for storage, but
strusting in-bundle delta is faster to apply.

  $ hg init bundle-reuse-enabled
  $ hg -R bundle-reuse-enabled unbundle all-p1.hg --quiet \
  > --config storage.revlog.reuse-external-delta-parent=yes
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=0: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=1: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=2: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)

(confirm the file revision are in the same order, 2 should be smaller than 1)

  $ hg -R bundle-reuse-enabled debugdata my-file.txt 2 | wc -l
  \s*1001 (re)
  $ hg -R bundle-reuse-enabled debugdata my-file.txt 1 | wc -l
  \s*1200 (re)

explicitly disabled
-------------------

Not reusing the delta-base from the parent means we the delta will be made
against the "best" parent. (so not the same as the previous two)

  $ hg init bundle-reuse-disabled
  $ hg -R bundle-reuse-disabled unbundle all-p1.hg --quiet \
  > --config storage.revlog.reuse-external-delta-parent=no
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=0: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=1: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=2: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=1 * (glob)

(confirm the file revision are in the same order, 2 should be smaller than 1)

  $ hg -R bundle-reuse-disabled debugdata my-file.txt 2 | wc -l
  \s*1001 (re)
  $ hg -R bundle-reuse-disabled debugdata my-file.txt 1 | wc -l
  \s*1200 (re)


Check the path.*:pulled-delta-reuse-policy option
==========================================

Get a repository with the bad parent picked and a clone ready to pull the merge

  $ cp -aR bundle-reuse-enabled peer-bad-delta
  $ hg clone peer-bad-delta local-pre-pull --rev `cat large.node` --rev `cat small.node` --quiet
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=0: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=1: delta-base=0 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=2: delta-base=0 * (glob)

Check the parent order for the file

  $ hg -R local-pre-pull debugdata my-file.txt 2 | wc -l
  \s*1001 (re)
  $ hg -R local-pre-pull debugdata my-file.txt 1 | wc -l
  \s*1200 (re)

Pull with no value (so the default)
-----------------------------------

default is to reuse the (bad) delta

  $ cp -aR local-pre-pull local-no-value
  $ hg -R local-no-value pull --quiet
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)

Pull with explicitly the default
--------------------------------

default is to reuse the (bad) delta

  $ cp -aR local-pre-pull local-default
  $ hg -R local-default pull --quiet --config 'paths.default:pulled-delta-reuse-policy=default'
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)

Pull with no-reuse
------------------

We don't reuse the base, so we get a better delta

  $ cp -aR local-pre-pull local-no-reuse
  $ hg -R local-no-reuse pull --quiet --config 'paths.default:pulled-delta-reuse-policy=no-reuse'
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=1 * (glob)

Pull with try-base
------------------

We requested to use the (bad) delta

  $ cp -aR local-pre-pull local-try-base
  $ hg -R local-try-base pull --quiet --config 'paths.default:pulled-delta-reuse-policy=try-base'
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)

Case where we force a "bad" delta to be applied
===============================================

We build a very different file content to force a full snapshot

  $ cp -aR peer-bad-delta peer-bad-delta-with-full
  $ cp -aR local-pre-pull local-pre-pull-full
  $ echo '[paths]' >> local-pre-pull-full/.hg/hgrc
  $ echo 'default=../peer-bad-delta-with-full' >> local-pre-pull-full/.hg/hgrc

  $ hg -R peer-bad-delta-with-full update 'desc("merge")' --quiet
  $ ($TESTDIR/seq.py 2000 2100; $TESTDIR/seq.py 500 510; $TESTDIR/seq.py 3000 3050) \
  > | $TESTDIR/sha256line.py > peer-bad-delta-with-full/my-file.txt
  $ hg -R peer-bad-delta-with-full commit -m 'trigger-full'
  DBG-DELTAS: FILELOG:my-file.txt: rev=4: delta-base=4 * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)

Check that "try-base" behavior challenge the delta
--------------------------------------------------

The bundling process creates a delta against the previous revision, however this
is an invalid chain for the client, so it is not considered and we do a full
snapshot again.

  $ cp -aR local-pre-pull-full local-try-base-full
  $ hg -R local-try-base-full pull --quiet \
  > --config 'paths.default:pulled-delta-reuse-policy=try-base'
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=4: delta-base=4 * (glob)

Check that "forced" behavior do not challenge the delta, even if it is full.
---------------------------------------------------------------------------

A full bundle should be accepted as full bundle without recomputation

  $ cp -aR local-pre-pull-full local-forced-full
  $ hg -R local-forced-full pull --quiet \
  > --config 'paths.default:pulled-delta-reuse-policy=forced'
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=4: delta-base=4 is-cached=1 - search-rounds=0 try-count=0 - delta-type=full   snap-depth=0 - * (glob)

Check that "forced" behavior do not challenge the delta, even if it is bad.
---------------------------------------------------------------------------

The client does not challenge anything and applies the bizarre delta directly.

Note: If the bundling process becomes smarter, this test might no longer work
(as the server won't be sending "bad" deltas anymore) and might need something
more subtle to test this behavior.

  $ hg bundle -R peer-bad-delta-with-full --all --config devel.bundle.delta=p1 all-p1.hg
  5 changesets found
  $ cp -aR local-pre-pull-full local-forced-full-p1
  $ hg -R local-forced-full-p1 pull --quiet \
  > --config 'paths.*:pulled-delta-reuse-policy=forced' all-p1.hg
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=2 is-cached=1 *search-rounds=0 try-count=0* (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=4: delta-base=3 is-cached=1 *search-rounds=0 try-count=0* (glob)

Check that running "forced" on a non-general delta repository does not corrupt it
---------------------------------------------------------------------------------

Even if requested to be used, some of the delta in the revlog cannot be stored on a non-general delta repository. We check that the bundle application was correct.

  $ hg init \
  >    --config format.usegeneraldelta=no \
  >    --config format.sparse-revlog=no \
  >    local-forced-full-p1-no-gd
  $ hg debugformat -R local-forced-full-p1-no-gd | grep generaldelta
  generaldelta:        no
  $ hg -R local-forced-full-p1-no-gd pull --quiet local-pre-pull-full \
  >    --config debug.revlog.debug-delta=no
  $ hg -R local-forced-full-p1-no-gd pull --quiet \
  > --config 'paths.*:pulled-delta-reuse-policy=forced' all-p1.hg
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: CHANGELOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: MANIFESTLOG: * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=3: delta-base=0 * - search-rounds=1 try-count=1 * (glob)
  DBG-DELTAS: FILELOG:my-file.txt: rev=4: delta-base=4 * - search-rounds=1 try-count=1 * (glob)
  $ hg -R local-forced-full-p1-no-gd verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checking dirstate
  checked 5 changesets with 5 changes to 1 files