Module concache::manual

A concurrent hash map implementation with a hand-written epoch-based memory management scheme.

This implementation provides a lock-free hash map using buckets that hold lock-free linked lists. Memory is safely destructed and reclaimed using a simplified variant of Quiescent-State-Based Reclamation. Table resizing is not yet supported, but the map will also never fill due to the linked implementation; instead, performance will decrease as the map is filled with more keys.

The interface to this map is somewhat different from HashMap to support concurrent operation. When you create a new Map,you are given a MapHandle, which allows access to the map's data. To read or mutate the map for elsewhere, you call [MapHandle::clone], which gives you a new MapHandle that provides concurrent access to the same map.

Similarly to crossbeam::epoch, this Map does not guarantee that destructors are called. In practice though, as long as threads do not leak MapHandles, destructors will all eventually be called.

Note that unlike HashMap, this Map requires its values to be Copy. This greatly simplifies the map's interface; accesses to the map's data have to be carefully guarded, and there is no simple way to expose references into the map through a method call. Later, we may provide temporary access through closures, similar to evmap's ReadHandle::get_and, but for the time being, values have to be Copy.

Structs

Map	A shared, concurrent hash map.
MapHandle	A handle to a shared Map.