[Scylla] - Investigate performance improvements

[jr1221]

Description

Now that the rust implementation is finished, there could be many performance improvements added to it. These boil down to three categories. CPU time, memory allocation, and polling/async frequencies.

Acceptance Criteria

• Async: Investigate polling/async frequencies and ensure select! is not providing an overhead, probably using tokio_console
• Memory alloc: Investigate any data cloning in hot routes, like the query or especially the batch insert, and eliminate them.
• CPU time: Investigate the use of rayon to parallelize db batching or other large functions.
• CPU Time: Search for any computational overheads and see if SIMD compliant functions exist.

Proposed Solution

Possibly rearrange selects into dedicated tasks, implement rayon par_iter, implement simd common, etc.

Mocks

No response

[jr1221]

Fix this clone!

Argos/scylla-server-rust/src/processors/db_handler.rs

Line 221 in 5b6a10c

self.data_queue.clear();