client/cli: Add delayed pruning mode and make it default

Signed-off-by: Alexandru Vasile <[email protected]>

client/cli/src/config.rs

@@ -42,6 +42,18 @@ pub(crate) const NODE_NAME_MAX_LENGTH: usize = 64;
 /// Default sub directory to store network config.
 pub(crate) const DEFAULT_NETWORK_CONFIG_PATH: &str = "network";
 
+/// Delay the pruning of blocks by a given number of finalizations.
+///
+/// This value should be set to a sensible amount to accommodate the RPC
+/// Spec V2 requirements of block pinning.
+///
+/// The user derives no benefits from controlling this, as the RPC API
+/// should be uniform across the nodes.
+///
+/// This ensures that users have roughly 32 * 6 seconds (block finalization)
+/// ~ 3 minutes to fetch the details of blocks.
+pub(crate) const DELAYED_PRUNING: u32 = 32;
+
 /// The recommended open file descriptor limit to be configured for the process.
 const RECOMMENDED_OPEN_FILE_DESCRIPTOR_LIMIT: u64 = 10_000;
 
@@ -255,7 +267,7 @@ pub trait CliConfiguration<DCV: DefaultConfigurationValues = ()>: Sized {
 	fn blocks_pruning(&self) -> Result<BlocksPruning> {
 		self.pruning_params()
 			.map(|x| x.blocks_pruning())
-			.unwrap_or_else(|| Ok(BlocksPruning::KeepFinalized))
+			.unwrap_or_else(|| Ok(BlocksPruning::Delayed(DELAYED_PRUNING)))
 	}
 
 	/// Get the chain ID (string).

client/cli/src/params/pruning_params.rs

@@ -30,12 +30,16 @@ pub struct PruningParams {
 	/// or for all of the canonical blocks (i.e 'archive-canonical').
 	#[clap(alias = "pruning", long, value_name = "PRUNING_MODE")]
 	pub state_pruning: Option<String>,
-	/// Specify the blocks pruning mode, a number of blocks to keep or 'archive'.
+	/// Specify the blocks pruning mode.
 	///
-	/// Default is to keep all finalized blocks.
-	/// otherwise, all blocks can be kept (i.e 'archive'),
-	/// or for all canonical blocks (i.e 'archive-canonical'),
-	/// or for the last N blocks (i.e a number).
+	/// The options are as follows:
+	///   'delayed'            Pruning of blocks is delayed for a sensible amount of time to
+	///                        satisfy the RPC Spec V2.
+	///   'archive'            Keep all blocks.
+	///   'archive-canonical'  Keep all finalized (canonical) blocks.
+	///   [number]             Keep the last N finalized (canonical) blocks.
+	///
+	/// Default is the 'delayed' option.
 	///
 	/// NOTE: only finalized blocks are subject for removal!
 	#[clap(alias = "keep-blocks", long, value_name = "COUNT")]
@@ -66,6 +70,7 @@ impl PruningParams {
 			Some(bp) => match bp.as_str() {
 				"archive" => Ok(BlocksPruning::KeepAll),
 				"archive-canonical" => Ok(BlocksPruning::KeepFinalized),
+				"delayed" => Ok(BlocksPruning::Delayed(crate::DELAYED_PRUNING)),
 				bc => bc
 					.parse()
 					.map_err(|_| {