The mutation compactor has a validator which it uses to validate the stream of mutation fragments that passes through it. This validator is supposed to validate the stream as it enters the compactor, as opposed to its compacted form (output). This was true for most fragment kinds except range tombstones, as purged range tombstones were not visible to
the validator for the most part.
This mistake was introduced by https://github.com/scylladb/scylladb/commite2c9cdb576, which itself was a flawed attempt at fixing an error seen because purged tombstones were not terminated by the compactor.
This patch corrects this mistake by fixing the above problem properly: on page-cut, if the validator has an active tombstone, a closing tombstone is generated for it, to avoid the false-positive error. With this, range tombstones can be validated again as they come in.
The existing unit test checking the validation in the compactor is greatly expanded to check all (I hope) different validation scenarios.
Closes#13817
* github.com:scylladb/scylladb:
test/mutation_test: test_compactor_validator_sanity_test
mutation/mutation_compactor: fix indentation
mutation/mutation_compactor: validate the input stream
mutation: mutation_fragment_stream_validating_filter: add accessor to underlying validator
readers: reader-from-fragment: don't modify stream when created without range
5860820934