message processing warts

[aatifsyed]

• Document why it's ok to ignore the cron error:

  forest/src/interpreter/vm.rs

  Lines 344 to 346 in 7e8d981

  	if let Err(e) = self.run_cron(epoch, callback.as_mut()) {
  	tracing::error!("End of epoch cron failed to run: {}", e);
  	}

• Consider inlining message processing:

  forest/src/interpreter/vm.rs

  Line 293 in 7e8d981

  let mut process_msg = |msg: &ChainMessage| -> Result<(), anyhow::Error> {

• Refactor callback for message replay:

  forest/src/state_manager/mod.rs

  Lines 493 to 518 in 7e8d981

  	const ERROR_MSG: &str = "replay_halt";
  	// This isn't ideal to have, since the execution is synchronous, but this needs
  	// to be the case because the state transition has to be in blocking
  	// thread to avoid starving executor
  	let (m_tx, m_rx) = std::sync::mpsc::channel();
  	let (r_tx, r_rx) = std::sync::mpsc::channel();
  	let callback = move |cid: &Cid, unsigned: &ChainMessage, apply_ret: &ApplyRet| {
  	if *cid == mcid {
  	m_tx.send(unsigned.message().clone())?;
  	r_tx.send(apply_ret.clone())?;
  	anyhow::bail!(ERROR_MSG);
  	}
  	Ok(())
  	};
  	let result = self
  	.compute_tipset_state(Arc::clone(ts), Some(callback))
  	.await;
  	if let Err(error_message) = result {
  	if error_message.to_string() != ERROR_MSG {
  	return Err(Error::Other(format!(
  	"unexpected error during execution : {error_message:}"
  	)));
  	}
  	}

  • Callback should return ControlFlow, not Result if it's going to break.