repo-or-peer: deprecate calling `islocal` on non-path object There object have a `.local()` method and should use it.

tests: add the missing space to test-hghave.t (issue6762) log() in run-tests.py add a space to the end of all messages that it prints, and I missed this fact in my previous patch.

share: stop using 'islocal' with repo instance Having this level of polymorphism of the `islocal` function is weird, and we already have a way to know if the repo is local from the object itself. We are about to deprecate passing a non-bytes object to `islocal`, so clean this up beforehand. We might want to clean up this function too in the future, however this is another adventure.

peer-or-repo: make sure object in "scheme" have a `instance` object The previous form of having heterogeneous object in the dictionnary makes things more complicated than they needed to be. I am not super happy about the current (especially around 'islocal', that most item do not have), but this is already much better.

peer-or-repo: move the object setup in its own function The `_peerorrepo` function is problematic, because it can build different types of object (repository and peer). This make it hard to adjust the arguments to the type of object we needs. So this patch start a series of change to create peer and repo without going through a common function. We move the part of the function doing object setup it its own function to make it simpler to reuse in others contexts.

delta-find: use a single snapshot cache when applying a group to an object This will avoid walking the revlog over and over again in some situations. The difference is hard to show in our current benchmark suite, as the gain is lower than their overall instability.

delta-find: make sure we only use newer full snapshot as candidate The current code does not needs to protect against this, as there are no older snapshot in the current cache. However as we are getting ready to reuse this cache from one revision to another, we need the code to protect itself about what's coming.

delta-find: use sets instead of list in the snapshot cache This seems more appropriate.

delta-find: use a smarter object for snapshot caching This open the way for a longer lived cache.

find-delta: pass the cache-delta usage policy alongside the cache-delta The idea is to give higher level code more control to what will happens with the cache delta passed. This should help with controling how we treat delta's from different sources. The final goal of this change is to allow for server modes where the client can blindly accept any server delta without regards to any local constraints. This will be implemented in later changesets.

find-delta: move most of the debug-find-delta code in the debug module Lets us that module more. It will help us to keep revlog implementation details close to each other.

find-delta: minor preparatory change We are about to add more item in the cachedelta object, so lets access the item by index instead of doing a full extensions.

find-delta: rename _isgooddeltainfo Lets move to a more readable name now that we are allowed to. This cannot hurt.

test-revlog-raw: drop the overwrite of dead code The revlog class no longer have a _isgooddeltainfo method for a long time. So overwriting it does not get us anything. The test have been wrapping the right code since then anyway.

emitrevision: consider ancestors revision to emit as available base This should make more delta base valid. This notably affects: * case where we skipped some parent with empty delta to directly delta against an ancestors * case where an intermediate snapshots is stored. This change means we could sent largish intermediate snapshots over the wire. However this is actually a sub goal here. Sending snapshots over the wire means the client have a high odd of simply storing the pre-computed delta instead of doing a lengthy process that will… end up doing the same intermediate snapshot. In addition the overall size of snapshot (or any level) is "only" some or the overall delta size. (0.17% for my mercurial clone, 20% for my clone of Mozilla try). So Sending them other the wire is unlikely to change large impact on the bandwidth used. If we decide that minimising the bandwidth is an explicit goal, we should introduce new logic to filter-out snapshot as delta. The current code has no notion explicite of snapshot so far, they just tended to fall into the wobbly filtering options. In some cases, this patch can yield large improvement to the bundling time: ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = perf-bundle # benchmark.variants.revs = last-100000 before: 68.787066 seconds after: 47.552677 seconds (-30.87%) That translate to large improvement to the pull time : ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = pull # benchmark.variants.issue6528 = disabled # benchmark.variants.revs = last-100000 before: 142.186625 seconds after: 75.897745 seconds (-46.62%) No significant negative impact have been observed.

sqlitestore: add an `ancestors` method We will need it during bundling. The implementation mirror the one in revlog.

emitrevision: if we need to compute a delta on the fly, try p1 or p2 first Falling back to `prev` does not yield any real value on modern storage and result in pathological changes to be created on the other side. Doing a delta against a parent will likely be smaller (helping the network) and will be safer to apply on the client (helping future pulls by Triggering intermediate snapshop where they will be needed by later deltas).

emitrevision: simplify the fallback to computed delta Not using the stored delta, or having a full snapshot on disk behave the same ways, so lets use the same code path for that, this is simpler, and it update will be simpler.

emitrevision: also check the parents in the availability closure One of the point of having a closure is to gather the logic in it. So we gather the logic. The `parents[:]` part is a bit ugly but will be replaced by better code soon anyway.

emitrevision: add a small closure to check if a base is usable We will make more use of this and make it more complex too.

reuse-delta-base: improves some documentation The current code got me a bit confused initially. So a bit more documentation around it cannot hurt.

tests: expect the message from 1baf0fffd82f in test-hghave.t (issue6762) Couldn't reproduce locally, but apparently this message may occasionally pop up when running this test.

branching: merge stable into default

changelog-v2: add a configuration to disable rank computation We encountered a graph where rank computation was pathologically slow. We add an option to disable this computation while this is getting fixed. Disabling the rank computation should allow for testing other changelog-v2 features undisturbed (like changeset-based copy tracing). I am purposely not adding a test for the new non-default code path, as this is a temporary work around of an experimental feature.

debugrevlog: display total stored information This is an interesting statistis, so let's display it.

debug-revlog: details about non-ancestors delta-bases Deltas against a base that is not an ancestor of the revision that owns this delta are notable. For example, they introduce complexity during the bundling process as the base might not exist on the unbundling side. We detect them in `hg debugrevlog` and print information about them.

debug-revlog: move the code in revlogutils module We have a module dedicated to debug code, let us use it.

debug-revlog: move the --dump code in `revlogutils` module We have a module dedicated to debug code, let us use it.

delta-find: set the default candidate chunk size to 10 I ran performance and storage tests on repositories of various sizes and shapes for the following values of the config : 5, 10, 20, 50, 100, no-chunking The performance tests do not show any statistical impact on computation times for large pushes and pulls. For searching for an individual delta, this can provide a significant performance improvement with a minor degradation of space-quality on the result. (see data at the end of the commit). For overall store size, the change : - does not have any impact on many small repositories, - has an observable, but very negligible impact on most larger repositories. - One private repository we use for testing sees a small increase in size (1%) in the narrower version. We will try to get more numbers on a larger version of that repository to make sure nothing pathological happens. We pick "10" as the limit as "5" seems a bit more risky. There are room to improve the current code, by using more aggressive filtering and better (i.e any) sorting of the candidates. However this is already a large improvement for pathological cases, with little impact in the common situations. The initial motivation for this change is to fix performance of delta computation for a file where the previous code ended up testing 20 000 possible candidate-bases in one go, which is… slow. This affected about ½ of the file revisions leading to atrocious performance, especially during some push/pull operations. Details about individual delta finding timing: ---------------------------------------------- The vast majority of benchmark cases are unchanged but the three below. The first two do not see any impact on the final delta. The last one sees a change in delta-size that is negligible compared to the full text size. ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = perf-delta-find # benchmark.variants.rev = manifest-snapshot-many-tries-a (revision 756096) ∞: 5.844783 5: 4.473523 (-23.46%) 10: 4.970053 (-14.97%) 20: 5.770386 (-1.27%) 50 5.821358 100: 5.834887 MANIFESTLOG: rev = 756096: (no-limit) delta-base = 301840 search-rounds = 6 try-count = 60 delta-type = snapshot snap-depth = 7 delta-size = 179 MANIFESTLOG: rev=756096: (limit = 10) delta-base=301840 search-rounds=9 try-count=51 delta-type=snapshot snap-depth=7 delta-size=179 ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = perf-delta-find # benchmark.variants.rev = manifest-snapshot-many-tries-d (revision 754060) ∞: 5.017663 5: 3.655931 (-27.14%) 10: 4.095436 (-18.38%) 20: 4.828949 (-3.76%) 50 4.987574 100: 4.994889 MANIFESTLOG: rev=754060: (no limit) delta-base=301840 search-rounds=5 try-count=53 delta-type=snapshot snap-depth=7 delta-size = 179 MANIFESTLOG: rev=754060: (limite = 10) delta-base=301840 search-rounds=8 try-count=45 delta-type=snapshot snap-depth=7 delta-size = 179 ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = perf-delta-find # bin-env-vars.hg.flavor = rust # benchmark.variants.rev = manifest-snapshot-many-tries-e (revision 693368) ∞: 4.869282 5: 2.039732 (-58.11%) 10: 2.413537 (-50.43%) 20: 4.449639 (-8.62%) 50 4.865863 100: 4.882649 MANIFESTLOG: rev=693368: delta-base=693336 search-rounds=6 try-count=53 delta-type=snapshot snap-depth=6 full-test-size=131065 delta-size=199 MANIFESTLOG: rev=693368: delta-base=278023 search-rounds=5 try-count=21 delta-type=snapshot snap-depth=4 full-test-size=131065 delta-size=278 Raw data for store size (in bytes) for various chunk size value below: ---------------------------------------------------------------------- 440 134 384 5 pypy/.hg/store/ 440 134 384 10 pypy/.hg/store/ 440 134 384 20 pypy/.hg/store/ 440 134 384 50 pypy/.hg/store/ 440 134 384 100 pypy/.hg/store/ 440 134 384 ... pypy/.hg/store/ 666 987 471 5 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 10 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 20 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 50 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 100 netbsd-xsrc-2022-11-15/.hg/store/ 666 987 471 ... netbsd-xsrc-2022-11-15/.hg/store/ 852 844 884 5 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 10 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 20 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 50 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 100 netbsd-pkgsrc-2022-11-15/.hg/store/ 852 844 884 ... netbsd-pkgsrc-2022-11-15/.hg/store/ 1 504 227 981 5 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 871 10 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 20 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 50 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 100 netbeans-2018-08-01-sparse-zstd/.hg/store/ 1 504 227 813 ... netbeans-2018-08-01-sparse-zstd/.hg/store/ 3 875 801 068 5 netbsd-src-2022-11-15/.hg/store/ 3 875 696 767 10 netbsd-src-2022-11-15/.hg/store/ 3 875 696 757 20 netbsd-src-2022-11-15/.hg/store/ 3 875 696 653 50 netbsd-src-2022-11-15/.hg/store/ 3 875 696 653 100 netbsd-src-2022-11-15/.hg/store/ 3 875 696 653 ... netbsd-src-2022-11-15/.hg/store/ 4 531 441 314 5 mozilla-central/.hg/store/ 4 531 435 157 10 mozilla-central/.hg/store/ 4 531 432 045 20 mozilla-central/.hg/store/ 4 531 429 119 50 mozilla-central/.hg/store/ 4 531 429 119 100 mozilla-central/.hg/store/ 4 531 429 119 ... mozilla-central/.hg/store/ 4 875 861 390 5 mozilla-unified/.hg/store/ 4 875 855 155 10 mozilla-unified/.hg/store/ 4 875 852 027 20 mozilla-unified/.hg/store/ 4 875 848 851 50 mozilla-unified/.hg/store/ 4 875 848 851 100 mozilla-unified/.hg/store/ 4 875 848 851 ... mozilla-unified/.hg/store/ 11 498 764 601 5 mozilla-try/.hg/store/ 11 497 968 858 10 mozilla-try/.hg/store/ 11 497 958 730 20 mozilla-try/.hg/store/ 11 497 927 156 50 mozilla-try/.hg/store/ 11 497 925 963 100 mozilla-try/.hg/store/ 11 497 923 428 ... mozilla-try/.hg/store/ 10 047 914 031 5 private-repo 9 969 132 101 10 private-repo 9 944 745 015 20 private-repo 9 939 756 703 50 private-repo 9 939 833 016 100 private-repo 9 939 822 035 ... private-repo

delta-find: add a way to control the number of bases tested at the same time See inline comment for details. The feature is currently disabled, but should be enabled by default to mitigate some existing pathological cases. Also see the next changeset for details.