dyn overseer channel capacity (#5454)

* allow runtime adjustment of signal channel size

Closes #5436

polkadot/cli/src/cli.rs

@@ -138,6 +138,12 @@ pub struct RunCmd {
 	/// telemetry, if telemetry is enabled.
 	#[clap(long)]
 	pub no_hardware_benchmarks: bool,
+
+	/// Overseer message capacity override.
+	///
+	/// **Dangerous!** Do not touch unless explicitly adviced to.
+	#[clap(long)]
+	pub overseer_channel_capacity_override: Option<usize>,
 }
 
 #[allow(missing_docs)]

polkadot/cli/src/command.rs

@@ -332,6 +332,7 @@ where
 				None,
 				false,
 				overseer_gen,
+				cli.run.overseer_channel_capacity_override,
 				hwbench,
 			)
 			.map(|full| full.task_manager)

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_builder.rs

@@ -150,6 +150,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 								#baggage_name: self. #baggage_name,
 							)*
 							spawner: self.spawner,
+
+							channel_capacity: self.channel_capacity,
+							signal_capacity: self.signal_capacity,
 						}
 					}
 					/// Specify the the initialization function for a subsystem
@@ -171,6 +174,10 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 								#baggage_name: self. #baggage_name,
 							)*
 							spawner: self.spawner,
+
+
+							channel_capacity: self.channel_capacity,
+							signal_capacity: self.signal_capacity,
 						}
 					}
 				}
@@ -207,6 +214,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 								#baggage_name: self. #baggage_name,
 							)*
 							spawner: self.spawner,
+
+							channel_capacity: self.channel_capacity,
+							signal_capacity: self.signal_capacity,
 						}
 					}
 				}
@@ -254,6 +264,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 							#to_keep_baggage_name: self. #to_keep_baggage_name,
 						)*
 						spawner: self.spawner,
+
+						channel_capacity: self.channel_capacity,
+						signal_capacity: self.signal_capacity,
 					}
 				}
 			}
@@ -272,6 +285,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 							#to_keep_baggage_name: self. #to_keep_baggage_name,
 						)*
 						spawner: self.spawner,
+
+						channel_capacity: self.channel_capacity,
+						signal_capacity: self.signal_capacity,
 					}
 				}
 			}
@@ -359,13 +375,12 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 			pub fn handle(&self) -> #handle {
 				self.handle.clone()
 			}
-		}
 
-		impl ::std::default::Default for #connector {
-			fn default() -> Self {
+			/// Create a new connector with non-default event channel capacity.
+			pub fn with_event_capacity(event_channel_capacity: usize) -> Self {
 				let (events_tx, events_rx) = #support_crate ::metered::channel::<
 					#event
-					>(SIGNAL_CHANNEL_CAPACITY);
+					>(event_channel_capacity);
 
 				Self {
 					handle: events_tx,
@@ -373,6 +388,12 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 				}
 			}
 		}
+
+		impl ::std::default::Default for #connector {
+			fn default() -> Self {
+				Self::with_event_capacity(SIGNAL_CHANNEL_CAPACITY)
+			}
+		}
 	});
 
 	ts.extend(quote!{
@@ -385,6 +406,11 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 				#baggage_name: #baggage_passthrough_state_generics,
 			)*
 			spawner: InitStateSpawner,
+			// user provided runtime overrides,
+			// if `None`, the `overlord(message_capacity=123,..)` is used
+			// or the default value.
+			channel_capacity: Option<usize>,
+			signal_capacity: Option<usize>,
 		}
 	});
 
@@ -406,6 +432,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 						#field_name: Missing::<#field_type>::default(),
 					)*
 					spawner: Missing::<S>::default(),
+
+					channel_capacity: None,
+					signal_capacity: None,
 				}
 			}
 		}
@@ -419,18 +448,48 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 			#spawner_where_clause
 		{
 			/// The `spawner` to use for spawning tasks.
-			pub fn spawner(self, spawner: S) -> #builder<Init<S>, #( #subsystem_passthrough_state_generics, )* #( #baggage_passthrough_state_generics, )*>
+			pub fn spawner(self, spawner: S) -> #builder<
+				Init<S>,
+				#( #subsystem_passthrough_state_generics, )*
+				#( #baggage_passthrough_state_generics, )*
+			>
 			{
 				#builder {
 					#(
 						#field_name: self. #field_name,
 					)*
 					spawner: Init::<S>::Value(spawner),
+
+					channel_capacity: self.channel_capacity,
+					signal_capacity: self.signal_capacity,
 				}
 			}
 		}
 	});
 
+	// message and signal channel capacity
+	ts.extend(quote! {
+		impl<S, #( #subsystem_passthrough_state_generics, )* #( #baggage_passthrough_state_generics, )*>
+			#builder<Init<S>, #( #subsystem_passthrough_state_generics, )* #( #baggage_passthrough_state_generics, )*>
+		where
+			#spawner_where_clause,
+		{
+			/// Set the interconnecting signal channel capacity.
+			pub fn signal_channel_capacity(mut self, capacity: usize) -> Self
+			{
+				self.signal_capacity = Some(capacity);
+				self
+			}
+
+			/// Set the interconnecting message channel capacities.
+			pub fn message_channel_capacity(mut self, capacity: usize) -> Self
+			{
+				self.channel_capacity = Some(capacity);
+				self
+			}
+		}
+	});
+
 	ts.extend(quote! {
 		/// Type used to represent a builder where all fields are initialized and the overseer could be constructed.
 		pub type #initialized_builder<#initialized_builder_generics> = #builder<Init<S>, #( Init<#field_type>, )*>;
@@ -446,7 +505,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 			/// Complete the construction and create the overseer type.
 			pub fn build(self)
 				-> ::std::result::Result<(#overseer_name<S, #( #baggage_generic_ty, )*>, #handle), #error_ty> {
-				let connector = #connector ::default();
+				let connector = #connector ::with_event_capacity(
+					self.signal_capacity.unwrap_or(SIGNAL_CHANNEL_CAPACITY)
+				);
 				self.build_with_connector(connector)
 			}
 
@@ -470,7 +531,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 					=
 						#support_crate ::metered::channel::<
 							MessagePacket< #consumes >
-						>(CHANNEL_CAPACITY);
+						>(
+							self.channel_capacity.unwrap_or(CHANNEL_CAPACITY)
+						);
 				)*
 
 				#(
@@ -510,7 +573,9 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 					let message_rx: SubsystemIncomingMessages< #consumes > = #support_crate ::select(
 						#channel_name_rx, #channel_name_unbounded_rx
 					);
-					let (signal_tx, signal_rx) = #support_crate ::metered::channel(SIGNAL_CHANNEL_CAPACITY);
+					let (signal_tx, signal_rx) = #support_crate ::metered::channel(
+						self.signal_capacity.unwrap_or(SIGNAL_CHANNEL_CAPACITY)
+					);
 
 					// Generate subsystem name based on overseer field name.
 					let subsystem_string = String::from(stringify!(#subsystem_name));

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.

polkadot/node/test/service/src/lib.rs

@@ -98,6 +98,7 @@ pub fn new_full(
 		false,
 		polkadot_service::RealOverseerGen,
 		None,
+		None,
 	)
 }
 

polkadot/parachain/test-parachains/adder/collator/src/main.rs

@@ -65,12 +65,13 @@ fn main() -> Result<()> {
 							config,
 							polkadot_service::IsCollator::Yes(collator.collator_key()),
 							None,
-							true,
+							false,
 							None,
 							None,
 							false,
 							polkadot_service::RealOverseerGen,
 							None,
+							None,
 						)
 						.map_err(|e| e.to_string())?;
 						let mut overseer_handle = full_node

polkadot/parachain/test-parachains/undying/collator/src/main.rs

@@ -65,12 +65,13 @@ fn main() -> Result<()> {
 							config,
 							polkadot_service::IsCollator::Yes(collator.collator_key()),
 							None,
-							true,
+							false,
 							None,
 							None,
 							false,
 							polkadot_service::RealOverseerGen,
 							None,
+							None,
 						)
 						.map_err(|e| e.to_string())?;
 						let mut overseer_handle = full_node