feat: delayed finalization

Based on inkdevhub/swanky-node#61

Author: Frank Bell

README.md

@@ -15,6 +15,14 @@ for a production deployment, but a great fit for development and testing:_
   [#42](https://github.com/paritytech/substrate-contracts-node/pull/42).
   Hereby blocks are authored immediately at every transaction, so there
   is none of the typical six seconds block time associated with `grandpa` or `aura`.
+  * By default, either manual or instant seal does not result in block finalization unless the `engine_finalizeBlock` 
+    RPC is executed. However, it is possible to configure the finalization of sealed blocks to occur after a certain 
+    amount of time by setting the `--finalize-delay-sec` option to a specific value, which specifies the number of seconds 
+    to delay before finalizing the blocks. Using a value of `0` would lead to instant finalization, with the blocks being 
+    finalized immediately upon being sealed.
+    ```shell
+    ./target/release/substrate-contracts-node --finalize-delay-sec 5
+    ```
 * _If no CLI arguments are passed the node is started in development mode
   by default._
 * A custom logging filter is applied by default that hides block production noise

node/src/cli.rs

@@ -83,6 +83,10 @@ pub struct Cli {
 	/// Relay chain arguments
 	#[arg(raw = true)]
 	pub relay_chain_args: Vec<String>,
+
+	/// The number of seconds to delay before finalizing blocks. A value of `0` would lead to instant finalization.
+	#[clap(long)]
+	pub finalize_delay_sec: Option<u64>,
 }
 
 #[derive(Debug)]

node/src/command.rs

@@ -225,7 +225,7 @@ pub fn run() -> Result<()> {
 
 			runner.run_node_until_exit(|config| async move {
 				if config.chain_spec.name() == "Development" { // TODO
-					return service::dev::new_full(config).map_err(sc_cli::Error::Service);
+					return service::dev::new_full(config, cli.finalize_delay_sec).map_err(sc_cli::Error::Service);
 				}
 
 				let hwbench = (!cli.no_hardware_benchmarks)

node/src/service/dev.rs

@@ -101,7 +101,7 @@ pub fn new_partial(
 	})
 }
 
-pub fn new_full(config: Configuration) -> Result<TaskManager, ServiceError> {
+pub fn new_full(config: Configuration, finalize_delay_sec: Option<u64>) -> Result<TaskManager, ServiceError> {
 	let sc_service::PartialComponents {
 		client,
 		backend,
@@ -195,7 +195,7 @@ pub fn new_full(config: Configuration) -> Result<TaskManager, ServiceError> {
 	let params = sc_consensus_manual_seal::InstantSealParams {
 		block_import: client.clone(),
 		env: proposer,
-		client,
+		client: client.clone(),
 		pool: transaction_pool,
 		select_chain,
 		consensus_data_provider: None,
@@ -206,6 +206,20 @@ pub fn new_full(config: Configuration) -> Result<TaskManager, ServiceError> {
 
 	let authorship_future = sc_consensus_manual_seal::run_instant_seal(params);
 
+	if let Some(sec) = finalize_delay_sec {
+		let delayed_finalize_params = sc_consensus_manual_seal::DelayedFinalizeParams {
+			client,
+			spawn_handle: task_manager.spawn_handle(),
+			delay_sec: sec,
+		};
+
+		task_manager.spawn_essential_handle().spawn_blocking(
+			"delayed_finalize",
+			None,
+			sc_consensus_manual_seal::run_delayed_finalize(delayed_finalize_params),
+		);
+	}
+
 	task_manager
 		.spawn_essential_handle()
 		.spawn_blocking("instant-seal", None, authorship_future);