Avail block funnel

An analogous to the evm block funnel, but for Avail.

Note that there are two Avail funnels:

• Avail block funnel for when Avail is the main chain for your app
• Avail parallel funnel for when a different chain is the main chain for your app, and you sync Avail in parallel for extra data

Configuration

Avail:
  type: avail-main
  lightClient: 'http://localhost:7007'
  rpc: ws://127.0.0.1:9944
  funnelBlockGroupSize: 100
  presyncStepSize: 1000
  genesisHash: "0xdd60847daa1119ecc9bdd006b140087737ac03d260ce110ecd7cb33cf721be35"

Conceptually

This funnel will do the following:

1. Get the latest block number with verified data availability from the Avail light client through the v2/status endpoint. Reference.
2. Fetch a group of funnelBlockGroupSize headers (or less if we're already at the tip).
3. Fetch all the submitted data from the Avail light client through the v2/blocks/{block_number}/data endpoint (reference). This means full blocks are never processed, because the light client can filter by app id.
4. Use TextDecoder to read the binary input as text, and continue with the Paima concise format processing.

Note that this means we download blocks from Avail even if they are not related to our rollup, as we use the Avail blockchain as the clock for our application.

Here is a visual representation of the flow: