Make blocks per request configurable

client/cli/src/params/network_params.rs

@@ -146,6 +146,13 @@ pub struct NetworkParams {
 		verbatim_doc_comment
 	)]
 	pub sync: SyncMode,
+
+	/// Maximum number of blocks per request.
+	///
+	/// Try reducing this number from the default value if you have a slow network connection
+	/// and observe block requests timing out.
+	#[arg(long, value_name = "COUNT", default_value_t = 64)]
+	pub max_blocks_per_request: u32,
 }
 
 impl NetworkParams {
@@ -235,6 +242,7 @@ impl NetworkParams {
 				allow_private_ip,
 			},
 			max_parallel_downloads: self.max_parallel_downloads,
+			max_blocks_per_request: self.max_blocks_per_request,
 			enable_dht_random_walk: !self.reserved_only,
 			allow_non_globals_in_dht,
 			kademlia_disjoint_query_paths: self.kademlia_disjoint_query_paths,

client/network/src/config.rs

@@ -566,6 +566,7 @@ pub struct NetworkConfiguration {
 
 	/// List of request-response protocols that the node supports.
 	pub request_response_protocols: Vec<RequestResponseConfig>,
+
 	/// Configuration for the default set of nodes used for block syncing and transactions.
 	pub default_peers_set: SetConfig,
 
@@ -590,6 +591,9 @@ pub struct NetworkConfiguration {
 	/// Maximum number of peers to ask the same blocks in parallel.
 	pub max_parallel_downloads: u32,
 
+	/// Maximum number of blocks per request.
+	pub max_blocks_per_request: u32,
+
 	/// Initial syncing mode.
 	pub sync_mode: SyncMode,
 
@@ -653,6 +657,7 @@ impl NetworkConfiguration {
 			node_name: node_name.into(),
 			transport: TransportConfig::Normal { enable_mdns: false, allow_private_ip: true },
 			max_parallel_downloads: 5,
+			max_blocks_per_request: 64,
 			sync_mode: SyncMode::Full,
 			enable_dht_random_walk: true,
 			allow_non_globals_in_dht: false,

client/network/sync/src/block_request_handler.rs

@@ -17,7 +17,10 @@
 //! Helper for handling (i.e. answering) block requests from a remote peer via the
 //! `crate::request_responses::RequestResponsesBehaviour`.
 
-use crate::schema::v1::{block_request::FromBlock, BlockResponse, Direction};
+use crate::{
+	schema::v1::{block_request::FromBlock, BlockResponse, Direction},
+	MAX_BLOCKS_IN_RESPONSE,
+};
 
 use codec::{Decode, Encode};
 use futures::{
@@ -50,7 +53,6 @@ use std::{
 };
 
 const LOG_TARGET: &str = "sync";
-const MAX_BLOCKS_IN_RESPONSE: usize = 128;
 const MAX_BODY_BYTES: usize = 8 * 1024 * 1024;
 const MAX_NUMBER_OF_SAME_REQUESTS_PER_PEER: usize = 2;
 

client/network/sync/src/blocks.rs

@@ -109,7 +109,7 @@ impl<B: BlockT> BlockCollection<B> {
 	pub fn needed_blocks(
 		&mut self,
 		who: PeerId,
-		count: usize,
+		count: u32,
 		peer_best: NumberFor<B>,
 		common: NumberFor<B>,
 		max_parallel: u32,

client/network/sync/src/engine.rs

@@ -264,6 +264,14 @@ where
 			SyncOperationMode::Warp => SyncMode::Warp,
 		};
 		let max_parallel_downloads = network_config.max_parallel_downloads;
+		let max_blocks_per_request = if network_config.max_blocks_per_request >
+			crate::MAX_BLOCKS_IN_RESPONSE as u32
+		{
+			log::info!(target: "sync", "clamping maximum blocks per request to {}", crate::MAX_BLOCKS_IN_RESPONSE);
+			crate::MAX_BLOCKS_IN_RESPONSE as u32
+		} else {
+			network_config.max_blocks_per_request
+		};
 		let cache_capacity = NonZeroUsize::new(
 			(network_config.default_peers_set.in_peers as usize +
 				network_config.default_peers_set.out_peers as usize)
@@ -318,6 +326,7 @@ where
 			roles,
 			block_announce_validator,
 			max_parallel_downloads,
+			max_blocks_per_request,
 			warp_sync_params,
 			metrics_registry,
 			network_service.clone(),