Configurable state cache size and enforce exact state cache size (#2314)

* Allow configuring state cache size via cli

* Track used cache size

* Expose memory counter to informant

* Enforce max cache size constraint exactly

* Default to 64 MiB

Co-Authored-By: cmichi <mich@elmueller.net>

* Remove self as parameter

substrate/core/cli/src/informant.rs

@@ -76,6 +76,12 @@ pub fn start<C>(service: &Service<C>, exit: ::exit_future::Exit, handle: TaskExe
 				TransferRateFormat(bandwidth_upload),
 			);
 
+			let backend = (*client).backend();
+			let used_state_cache_size = match backend.used_state_cache_size(){
+				Some(size) => size,
+				None => 0,
+			};
+
 			// get cpu usage and memory usage of this process
 			let (cpu_usage, memory) = if sys.refresh_process(self_pid) {
 				let proc = sys.get_process(self_pid).expect("Above refresh_process succeeds, this should be Some(), qed");
@@ -99,6 +105,7 @@ pub fn start<C>(service: &Service<C>, exit: ::exit_future::Exit, handle: TaskExe
 				"finalized_hash" => ?info.chain.finalized_hash,
 				"bandwidth_download" => bandwidth_download,
 				"bandwidth_upload" => bandwidth_upload,
+				"used_state_cache_size" => used_state_cache_size,
 			);
 		} else {
 			warn!("Error getting best block information");

substrate/core/cli/src/lib.rs

@@ -404,6 +404,7 @@ where
 	config.database_path =
 		db_path(&base_path, config.chain_spec.id()).to_string_lossy().into();
 	config.database_cache_size = cli.database_cache_size;
+	config.state_cache_size = cli.state_cache_size;
 	config.pruning = match cli.pruning {
 		Some(ref s) if s == "archive" => PruningMode::ArchiveAll,
 		None => PruningMode::default(),

substrate/core/cli/src/params.rs

@@ -313,6 +313,10 @@ pub struct RunCmd {
 	#[structopt(long = "db-cache", value_name = "MiB")]
 	pub database_cache_size: Option<u32>,
 
+	/// Specify the state cache size
+	#[structopt(long = "state-cache-size", value_name = "Bytes", default_value = "67108864")]
+	pub state_cache_size: usize,
+
 	/// Listen to all RPC interfaces (default is local)
 	#[structopt(long = "rpc-external")]
 	pub rpc_external: bool,