Data race found by `miri test`

[ParkMyCar]

Commit: d74d1e3c7cd922577767c8c2f9a8bdf7b7018e69 Rust Version: cargo 1.70.0-nightly (0e474cfd7 2023-03-31) OS: macOS 13.4 CPU: Apple M2 Max

Running cargo +nightly miri test in the root of the crate, fails on the first test:

test cht::map::bucket::tests::get_insert_remove

with the error:

error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at alloc218679. (2) just happened here

I also disabled the race detector with MIRIFLAGS="-Zmiri-disable-data-race-detector", but when running with this flag the test never completes.

Note: I started looking into Moka because recently we tried using it in https://github.com/MaterializeInc/materialize/pull/19614, but had to revert it because we were observing memory corruption.

---

Full Stack Trace:

error: Undefined Behavior: Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at alloc218679. (2) just happened here
   --> /Users/parker.timmerman/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.15/src/atomic.rs:204:9
    |
204 |         &*(ptr as *const T)
    |         ^^^^^^^^^^^^^^^^^^^ Data race detected between (1) Write on thread `<unnamed>` and (2) Read on thread `<unnamed>` at alloc218679. (2) just happened here
    |
help: and (1) occurred earlier here
   --> src/cht/map/bucket_array_ref.rs:308:58
    |
308 |                 maybe_new_bucket_array.unwrap_or_else(|| Owned::new(BucketArray::default()));
    |                                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE (of the first span):
    = note: inside `<cht::map::bucket::BucketArray<i32, i32> as crossbeam_epoch::Pointable>::deref::<'_>` at /Users/parker.timmerman/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.15/src/atomic.rs:204:9: 204:28
    = note: inside `crossbeam_epoch::Shared::<'_, cht::map::bucket::BucketArray<i32, i32>>::as_ref` at /Users/parker.timmerman/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-epoch-0.9.15/src/atomic.rs:1518:18: 1518:31
note: inside `cht::map::bucket_array_ref::BucketArrayRef::<'_, i32, i32, std::collections::hash_map::RandomState>::get`
   --> src/cht/map/bucket_array_ref.rs:303:54
    |
303 |             if let Some(bucket_array_ref) = unsafe { bucket_array_ptr.as_ref() } {
    |                                                      ^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside `cht::map::bucket_array_ref::BucketArrayRef::<'_, i32, i32, std::collections::hash_map::RandomState>::insert_with_or_modify_entry_and::<i32, [closure@src/cht/segment.rs:310:17: 310:19], [closure@src/cht/segment.rs:311:17: 311:24], [closure@src/cht/segment.rs:829:77: 829:83]>`
   --> src/cht/map/bucket_array_ref.rs:207:27
    |
207 |         let current_ref = self.get(guard);
    |                           ^^^^^^^^^^^^^^^
note: inside `cht::segment::HashMap::<i32, i32>::insert_entry_and::<i32, [closure@src/cht/segment.rs:829:77: 829:83]>`
   --> src/cht/segment.rs:304:22
    |
304 |           let result = self
    |  ______________________^
305 | |             .bucket_array_ref(hash)
306 | |             // .insert_entry_and(key, hash, value, with_previous_entry);
307 | |             .insert_with_or_modify_entry_and(
...   |
312 | |                 with_previous_entry,
313 | |             );
    | |_____________^
note: inside closure
   --> src/cht/segment.rs:829:36
    |
829 |                         assert_eq!(map.insert_entry_and(j, map.hash(&j), j, |_, v| *v), None);
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^