phases: keep internal state as rev-num instead of node-id Node-id are expensive to work with, dealing with revision is much simple and faster. The fact we still used node-id here shows how few effort have been put into making the phase logic fast. We tend to no longer use node-id internally for about ten years. This has a large impact of repository with many draft roots. For example this Mozilla-try copy have ½ Million draft roots and `perf::unbundle` see a significant improvement. ### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog # benchmark.name = hg.perf.perf-unbundle # bin-env-vars.hg.flavor = no-rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.issue6528 = disabled # benchmark.variants.revs = last-1 before:: 1.746791 seconds after:: 1.278379 seconds (-26.82%) # benchmark.variants.revs = last-10 before:: 3.145774 seconds after:: 2.103735 seconds (-33.13%) # benchmark.variants.revs = last-100 before:: 3.487635 seconds after:: 2.446749 seconds (-29.85%) # benchmark.variants.revs = last-1000 before:: 5.007568 seconds after:: 3.989923 seconds (-20.32%)

phases: do filtering at read time This remove the need for the `filterunknown` method at all.

phases: always write with a repo In the future change that move the internal representation of phase-roots from node-id to rev-num, we will use a repository to translate revision numbers back to node at write time. Since that future change is quite complicated already, we do this small API change beforehand.

phases: mark `phasecache.phaseroots` private We are about to change its content from nodeid to revnum. So anyone directly using the content might be in unexpected troubles. We start by making it private to explicitly break any such user (and discourage them to do so).

phases: check secret presence the right way during discovery There is an official function for this, lets use it. This will prevent the code to break in the future while we refactor the phase code.

phases: explicitly filter stripped revision at strip time Explicit is better than implicit. The current logic is bit subtle and fragile. It also get in the way of using something else than node-id as internal storage. We replace it with a more explicit filtering while striping.

debug: add a debug::unbundle command that simulate the unbundle from a push The code have different behavior when the unbundle comes from a push, so we introduce a command that can simulate such unbundle. For our copy of mozilla-try-2023-03-22, this make the unbundle jump from 2.5 seconds (with `hg unbundle`) to 15 seconds (with `hg debug::unbundle`). That 15 seconds timings is consistent with the issue seen in production.