fhevm-listener: batch/parallel INSERT of events to table computations

[rudy-6-4]

Goal:

• reduce the network load on the listener/database.
• reduce the latency of events to db (by removing wait time)
• increase the efficiency/capacity of the listener by better CPU use

Currently we insert events by events sequentially and wait between insertions.

Steps:

1. Enable parallelism between IO & events preparation: while a insert in DB is in progress, we can deserialize and prepare the nexts events

• as long as the ongoing insert is not finished we prepare the events (this can be handle by the insert function)

2. Enable batch: next time we contact the DB for insertion , we can batch the ready prepared events for a batch INSERT

3. Enable multiple insert: same but we accept a bounded number (e.g. 2 or 3) of multiple INSERT are ongoing. e.g. if a number of minimum events are ready and an insertion slot is ready than we insert