dyn overseer channel capacity (#5454)

* allow runtime adjustment of signal channel size

Closes #5436

polkadot/node/service/src/lib.rs

@@ -719,6 +719,7 @@ pub fn new_full<RuntimeApi, ExecutorDispatch, OverseerGenerator>(
 	program_path: Option<std::path::PathBuf>,
 	overseer_enable_anyways: bool,
 	overseer_gen: OverseerGenerator,
+	overseer_message_channel_capacity_override: Option<usize>,
 	hwbench: Option<sc_sysinfo::HwBench>,
 ) -> Result<NewFull<Arc<FullClient<RuntimeApi, ExecutorDispatch>>>, Error>
 where
@@ -1038,6 +1039,7 @@ where
 					chain_selection_config,
 					dispute_coordinator_config,
 					pvf_checker_enabled,
+					overseer_message_channel_capacity_override,
 				},
 			)
 			.map_err(|e| {
@@ -1326,6 +1328,7 @@ pub fn build_full(
 	telemetry_worker_handle: Option<TelemetryWorkerHandle>,
 	overseer_enable_anyways: bool,
 	overseer_gen: impl OverseerGen,
+	overseer_message_channel_override: Option<usize>,
 	hwbench: Option<sc_sysinfo::HwBench>,
 ) -> Result<NewFull<Client>, Error> {
 	#[cfg(feature = "rococo-native")]
@@ -1343,6 +1346,7 @@ pub fn build_full(
 			None,
 			overseer_enable_anyways,
 			overseer_gen,
+			overseer_message_channel_override,
 			hwbench,
 		)
 		.map(|full| full.with_client(Client::Rococo))
@@ -1360,6 +1364,7 @@ pub fn build_full(
 			None,
 			overseer_enable_anyways,
 			overseer_gen,
+			overseer_message_channel_override,
 			hwbench,
 		)
 		.map(|full| full.with_client(Client::Kusama))
@@ -1377,6 +1382,7 @@ pub fn build_full(
 			None,
 			overseer_enable_anyways,
 			overseer_gen,
+			overseer_message_channel_override,
 			hwbench,
 		)
 		.map(|full| full.with_client(Client::Westend))
@@ -1394,6 +1400,10 @@ pub fn build_full(
 			None,
 			overseer_enable_anyways,
 			overseer_gen,
+			overseer_message_channel_override.map(|capacity| {
+				gum::warn!("Channel capacity should _never_ be tampered with on polkadot!");
+				capacity
+			}),
 			hwbench,
 		)
 		.map(|full| full.with_client(Client::Polkadot))

polkadot/node/service/src/overseer.rs

@@ -111,6 +111,8 @@ where
 	pub dispute_coordinator_config: DisputeCoordinatorConfig,
 	/// Enable PVF pre-checking
 	pub pvf_checker_enabled: bool,
+	/// Overseer channel capacity override.
+	pub overseer_message_channel_capacity_override: Option<usize>,
 }
 
 /// Obtain a prepared `OverseerBuilder`, that is initialized
@@ -138,6 +140,7 @@ pub fn prepared_overseer_builder<'a, Spawner, RuntimeClient>(
 		chain_selection_config,
 		dispute_coordinator_config,
 		pvf_checker_enabled,
+		overseer_message_channel_capacity_override,
 	}: OverseerGenArgs<'a, Spawner, RuntimeClient>,
 ) -> Result<
 	InitializedOverseerBuilder<
@@ -292,7 +295,12 @@ where
 		.known_leaves(LruCache::new(KNOWN_LEAVES_CACHE_SIZE))
 		.metrics(metrics)
 		.spawner(spawner);
-	Ok(builder)
+
+	if let Some(capacity) = overseer_message_channel_capacity_override {
+		Ok(builder.message_channel_capacity(capacity))
+	} else {
+		Ok(builder)
+	}
 }
 
 /// Trait for the `fn` generating the overseer.