Implementing a zero-copy block cache reader with current `rebase` semantics (opens in new tab)

Hi everyone, I’m currently developing an append-only, structured stream database/storage. It is able to support multiple streams, where each of the streams has one append-only writer and functionally unlimited concurrent seekable readers. Internally I have a BufferManager that keeps a freely accessible pool of 1MiB slots. The writer appends directly to one of these slots, and when it is full, it is compressed, flushed to disk, and the writer rotates to a new one. Any data a writer has written...