Motivation:
The uncached access to PoolChunk can be made faster, and avoid allocating boxed Longs, if we have a primitive hash map and priority queue implementation for it.
Modification:
Add bespoke primitive implementations of a hash map and a priority queue for PoolChunk.
Remove all the long-boxing caused by the previous implementation.
The hashmap is a linear probing map with a fairly short probe that keeps the search within a couple of cache lines.
The priority queue is the same binary heap algorithm that's described in Algorithms by Sedgewick and Wayne.
The implementation avoids the Long boxing by relying on a long[] array.
This makes the internal-remove method faster, which is an important operation in PoolChunk.
Result:
Roughly 13% performance uplift in buffer allocations that miss cache.
86730f53ca