In Substrate, consensus is break into 2 parts:

• Block Authoring: decide who can produce blocks.

  • PoA (Aura in substrate): Only an authorized set of nodes produce blocks in round-robin.
  • PoW: Any node can produce a block at any time, if and only if the node has solved a computationally-intensive problem.

• Block Finalization: decide which fork is the main chain.

  • Longest chain: the chain with highest block.
  • The Greedy Heaviest Observed SubTree (GHOST): the heaviest chain that has the most blocks built on it.

  

Let’s first discover how the consensus module cope with others

https://github.com/paritytech/substrate/blob/28a30847513ec41ce66c7b07bf750d93e786d41d/bin/node/cli/benches/block_production.rs#L171C41-L171C41

This is the code to benchmark block production. By looking into the code, we can learn how block authoring (consensus module) fits into the whole block production system.

let mut block_builder = client.new_block(Default::default()).unwrap();
block_builder.push(extrinsic_set_time(1)).unwrap();
import_block(client, block_builder.build().unwrap());

Claude Answer

What is the running process of the PoW consensus module? How it is cope with other parts of substrate?

1. The PoW consensus is registered as an "engine" in the Substrate node. This injects it into the import queue and block authoring logic.
2. When the node imports a new block, it goes through the import queue.
3. The PowVerifier does preliminary seal verification on the block before import. This avoids duplicate verification.
4. The PowBlockImport does full verification on seal, parent difficulty, etc. and imports the block. It updates the auxiliary difficulty storage.
5. For block authoring, the mining worker periodically fetches the best chain head via the SelectChain fork-choice logic.
6. It calls into the PowAlgorithm to calculate the next difficulty target.
7. The Proposer creates the inherents and builds the block proposal with this difficulty.
8. The miner tries to find a valid seal for this new block and submits it back via the MiningHandle.
9. This flows back into the import queue to be verified and imported.

Block Finalization