chainsaw-update: use a graph with branching in graph This will be relevant for the next improvement of `chainsaw-update`.

chainsaw-update: log actual locks breaking Previously, the command would simply state that it was about to break locks, not if there was actually some to break. This version is race-free. It would be also possible to display the content of the lock before hand (not race-free but informative in almost all cases).

vfs: have tryunlink tell what it did It is useful in certain circumstances to know whether vfs.tryunlink() actually removed something or not, be it for logging purposes.

chainsaw: new extension for dangerous operations The first provided command is `chainsaw-update`, whose one and single job is to make sure that it will pull, update and purge the target repository, no matter what may be in the way (locks, notably), see docstring for rationale.

rust: disable the RustIndex without persistent nodemap See rational inline.

rust: stop claiming the C index is compatible with the rust code This is no longer the case since the introduction of the pure Rust Index, and was probably not the case since the MixedIndex itself. So we fix the dedicated attribute value.

rust-index: remove one collect when converting back Turns out this is slightly faster. Sending the results back to Python is still the most costly (like 75% of the time) of the whole method, but it's about as fast as it can be now. hg perf::phases on mozilla-try-2023-03-22 before: 0.267114 after: 0.247101

rust-index: improve phase computation speed While less memory efficient, using an array is *much* faster than using a HashMap, especially with the default hasher. It even makes the code simpler, so I'm not really sure what I was thinking in the first place, maybe it's more obvious now. This fix a significant performance regression when using the rust version of the code. (however, the C code still outperform rust on this operation) hg perf::phases on mozilla-try-2023-03-22 - 6.6.3: 0.451239 seconds - before: 0.982495 seconds - after: 0.265347 seconds - C code: 0.183241 second

phases: directly update the phase sets in advanceboundary This is similar to what we do in retractboundary. There is no need to invalidate the cache if we have everything at hand to update it.

phases: large rework of advance boundary In a similar spirit as the rework of retractboundary, the new algorithm is doing an amount of work in the order of magnitude of the amount of changeset that changes phases. (except to find new roots in impacted higher phases if any may exists). This result in a very significant speedup for repository with many old draft like mozilla try. runtime of perf:unbundle for a bundle constaining a single changeset (C code): before 6.7 phase work: 14.497 seconds before this change: 6.311 seconds (-55%) with this change: 2.240 seconds (-85%) Combined with the other patches that fixes the phases computation in the Rust index, the rust code with a persistent nodemap get back to quite interresting performances with 2.026 seconds for the same operation, about 10% faster than the C code.