revlog-compression: release note entry for update the config to be a list I updated the changeset, but forgot to phabsend apparently. Differential Revision: https://phab.mercurial-scm.org/D8165

rust-nodemap: a method for full invalidation This will be used for exceptional operations, such as a `__delitem__` on the `MixedIndex` with Rust nodemap. In principle, `NodeTree` should also be able to forget an entry in an efficient way, by accepting to insert `Element::None` instead of only `Element::Rev(r)`, but that seems really overkill at this point. We need to support exceptional operations such as `__delitem__`, only for completeness of the revlog index as seen from Python. The Python callers don't seem to even really need it, deciding to drop the nodemap unconditionally at at higher level when calling `hg strip`. Also, `hg strip` is very costly for reasons that are unrelated to nodemap aspects. Differential Revision: https://phab.mercurial-scm.org/D8098

rust-nodemap: accounting for dead blocks By the very append-only nature of the `NodeTree`, inserting new blocks has the effect of making some of the older ones useless as they become unreachable. Therefore some automatic housekeeping will need to be provided. This is standard procedure in the word of databases, under names such as "repack" or "vacuum". The new `masked_readonly_blocks()` will provide callers with useful information to decide if the nodetree is ripe for repacking, but all the `NodeTree` can provide is how many blocks have been masked in the currently mutable part. Analysing the readonly part would be way too long to do it for each transaction and defeat the whole purpose of nodemap persistence. Serializing callers (from the Python layer) will get this figure before each extraction and maintain an aggregate counter of unreachable blocks separately. Note: at this point, the most efficient repacking is just to restart afresh with a full rescan. Differential Revision: https://phab.mercurial-scm.org/D8097