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match: sort patterns before compiling them into a regex While investigating cripping performance for `hg cat` in some context, I discovered that, for large inputs, building a regex from out of order patterns result may result in a *much* slower regex and a much slower associated matcher's performance. So we are now sorting the patterns to help the regex engine. There is more to the story as we rely on regexp more than we should. See the next changeset for details. Benchmarks ========== In the following benchmark we are comparing the `hg cat` and `hg files` run time when matching against the full list of files in the repository. They are run: - without the rust extensions - with the standard python enfine (so without re2) sort vs non-sorted - Before this changeset (3f5137543773) --------------------------------------------------------- ###### hg files ############################################################### ### mercurial-2018-08-01-zstd-sparse-revlog sorted: 0.230092 seconds shuffled: 0.234235 seconds (+1.80%) ### pypy-2018-08-01-zstd-sparse-revlog sorted: 0.613567 seconds shuffled: 0.801880 seconds (+30.69%) ### mozilla-central-2018-08-01-zstd-sparse-revlog sorted: 62.474221 seconds shuffled: 1364.180218 seconds (+2083.59%) ### netbeans-2018-08-01-zstd-sparse-revlog sorted: 21.541828 seconds shuffled: 172.759857 seconds (+701.97%) ###### hg cat ################################################################# ### mercurial-2018-08-01-zstd-sparse-revlog sorted: 0.764407 seconds shuffled: 0.768924 seconds ### pypy-2018-08-01-zstd-sparse-revlog sorted: 2.065220 seconds shuffled: 2.276388 seconds (+10.22%) ### netbeans-2018-08-01-zstd-sparse-revlog sorted: 40.967983 seconds shuffled: 216.388709 seconds (+428.19%) ### mozilla-central-2018-08-01-zstd-sparse-revlog sorted: 105.228510 seconds shuffled: 1448.722784 seconds (+1276.74%) sort vs non-sorted - With this changeset ---------------------------------------- ###### hg files ############################################################### ### mercurial-2018-08-01-zstd-sparse-revlog all-list-pattern-sorted: 0.230069 all-list-pattern-shuffled: 0.231165 ### pypy-2018-08-01-zstd-sparse-revlog all-list-pattern-sorted: 0.616799 all-list-pattern-shuffled: 0.616393 ### netbeans-2018-08-01-zstd-sparse-revlog all-list-pattern-sorted: 21.586773 all-list-pattern-shuffled: 21.908197 ### mozilla-central-2018-08-01-zstd-sparse-revlog all-list-pattern-sorted: 61.279490 all-list-pattern-shuffled: 62.473549 ###### hg cat ################################################################# ### mercurial-2018-08-01-zstd-sparse-revlog sorted: 0.763883 seconds shuffled: 0.765848 seconds ### pypy-2018-08-01-zstd-sparse-revlog sorted: 2.070498 seconds shuffled: 2.069197 seconds ### netbeans-2018-08-01-zstd-sparse-revlog sorted: 41.392423 seconds shuffled: 41.648689 seconds ### mozilla-central-2018-08-01-zstd-sparse-revlog sorted: 103.315670 seconds shuffled: 104.369358 seconds
author Pierre-Yves David <pierre-yves.david@octobus.net>
date Sat, 01 Apr 2023 05:57:09 +0200
parents 32b527417ba3
children
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== New Features ==
 
 * `hg purge` is now a core command using `--confirm` by default.
 
 * The `rev-branch-cache` is now updated incrementally whenever changesets
   are added.

 * The new options `experimental.bundlecompthreads` and
   `experimental.bundlecompthreads.<engine>` can be used to instruct
   the compression engines for bundle operations to use multiple threads
   for compression. The default is single threaded operation. Currently
   only supported for zstd.

== Default Format Change ==

These changes affects newly created repositories (or new clone) done with
Mercurial 5.8.

  * The `ZSTD` compression will now be used by default for new repositories
    when available. This compression format was introduced in Mercurial 5.0,
    released in May 2019. See `hg help config.format.revlog-compression` for
    details.

  * Mercurial installation built with the Rust parts will now use the
    "persistent nodemap" feature by default. This feature was introduced in
    Mercurial 5.4 (May 2020). However Mercurial instalation built without the
    fast Rust implementation will refuse to interract with them by default.
    This restriction can be lifted through configuration.

    See `hg help config.format.use-persistent-nodemap` for details

== New Experimental Features ==

 * There's a new `diff.merge` config option to show the changes
    relative to an automerge for merge changesets. This makes it
    easier to detect and review manual changes performed in merge
    changesets. It is supported by `hg diff --change`, `hg log -p`
    `hg incoming -p`, and `hg outgoing -p` so far.


== Bug Fixes ==

 * gracefully recover from inconsistent persistent-nodemap data from disk.


== Backwards Compatibility Changes ==

 * In normal repositories, the first parent of a changeset is not null,
   unless both parents are null (like the first changeset). Some legacy
   repositories violate this condition. The revlog code will now
   silentely swap the parents if this condition is tested. This can
   change the output of `hg log` when explicitly asking for first or
   second parent. The changesets "nodeid" are not affected.


== Internal API Changes ==

 * `changelog.branchinfo` is deprecated and will be removed after 5.8.
   It is superseded by `changelogrevision.branchinfo`.

 * Callbacks for revlog.addgroup and the changelog._nodeduplicatecallback hook
   now get a revision number as argument instead of a node.

 * revlog.addrevision returns the revision number instead of the node.

 * `nodes.nullid` and related constants are being phased out as part of
   the deprecation of SHA1. Repository instances and related classes
   provide access via `nodeconstants` and in some cases `nullid` attributes.