compact_prios exceeds max_levels

[skyzh]

This panic is not guaranteed to be triggered. Will look into details later.

thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: Any', /home/skyzh/.cargo/git/checkouts/yatp-e704b73c3ee279b6/6bbea16/src/pool.rs:46:26
stack backtrace:
   0: rust_begin_unwind
             at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/std/src/panicking.rs:495:5
   1: core::panicking::panic_fmt
             at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/core/src/panicking.rs:92:14
   2: core::option::expect_none_failed
             at /rustc/f5230fbf76bafd86ee4376a0e26e551df8d17fec/library/core/src/option.rs:1268:5
   3: core::result::Result<T,E>::unwrap
             at /home/skyzh/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/result.rs:973:23
   4: yatp::pool::ThreadPool<T>::shutdown
             at /home/skyzh/.cargo/git/checkouts/yatp-e704b73c3ee279b6/6bbea16/src/pool.rs:46:17
   5: <agatedb::db::Agate as core::ops::drop::Drop>::drop
             at ./src/db.rs:98:9
   6: core::ptr::drop_in_place
             at /home/skyzh/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:175:1
   7: agatedb::db::tests::with_agate_test::{{closure}}
             at ./src/db.rs:617:9
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[skyzh]

The reason seems to be that the thread panics before pool shutdown. Not an issue related to yatp.

thread 'agatedb-5' panicked at 'assertion failed: level + 1 < self.opts.max_levels', src/levels.rs:534:9

[skyzh]

It seems that badger would panic if last level is full https://github.com/dgraph-io/badger/blob/master/levels.go#L1318

[skyzh]

Last level will never be in compact_prios https://github.com/dgraph-io/badger/blob/master/levels.go#L556

[skyzh]

Fixed in c2dd96d