rpc: backpressured RPC server (bump jsonrpsee 0.20) (#1313)

This is a rather big change in jsonrpsee, the major things in this bump
are:
- Server backpressure (the subscription impls are modified to deal with
that)
- Allow custom error types / return types (remove jsonrpsee::core::Error
and jsonrpee::core::CallError)
- Bug fixes (graceful shutdown in particular not used by substrate
anyway)
   - Less dependencies for the clients in particular
   - Return type requires Clone in method call responses
   - Moved to tokio channels
   - Async subscription API (not used in this PR)

Major changes in this PR:
- The subscriptions are now bounded and if subscription can't keep up
with the server it is dropped
- CLI: add parameter to configure the jsonrpc server bounded message
buffer (default is 64)
- Add our own subscription helper to deal with the unbounded streams in
substrate

The most important things in this PR to review is the added helpers
functions in `substrate/client/rpc/src/utils.rs` and the rest is pretty
much chore.

Regarding the "bounded buffer limit" it may cause the server to handle
the JSON-RPC calls
slower than before.

The message size limit is bounded by "--rpc-response-size" thus "by
default 10MB * 64 = 640MB"
but the subscription message size is not covered by this limit and could
be capped as well.

Hopefully the last release prior to 1.0, sorry in advance for a big PR

Previous attempt: https://github.com/paritytech/substrate/pull/13992

Resolves https://github.com/paritytech/polkadot-sdk/issues/748, resolves
https://github.com/paritytech/polkadot-sdk/issues/627

substrate/client/rpc-api/src/system/error.rs

@@ -19,9 +19,9 @@
 //! System RPC module errors.
 
 use crate::system::helpers::Health;
-use jsonrpsee::{
-	core::Error as JsonRpseeError,
-	types::error::{CallError, ErrorObject},
+use jsonrpsee::types::{
+	error::{ErrorCode, ErrorObject},
+	ErrorObjectOwned,
 };
 
 /// System RPC Result type.
@@ -36,6 +36,12 @@ pub enum Error {
 	/// Peer argument is malformatted.
 	#[error("{0}")]
 	MalformattedPeerArg(String),
+	/// Call to an unsafe RPC was denied.
+	#[error(transparent)]
+	UnsafeRpcCalled(#[from] crate::policy::UnsafeRpcError),
+	/// Internal error.
+	#[error("{0}")]
+	Internal(String),
 }
 
 // Base code for all system errors.
@@ -45,17 +51,16 @@ const NOT_HEALTHY_ERROR: i32 = BASE_ERROR + 1;
 // Peer argument is malformatted.
 const MALFORMATTED_PEER_ARG_ERROR: i32 = BASE_ERROR + 2;
 
-impl From<Error> for JsonRpseeError {
-	fn from(e: Error) -> Self {
+impl From<Error> for ErrorObjectOwned {
+	fn from(e: Error) -> ErrorObjectOwned {
 		match e {
 			Error::NotHealthy(ref h) =>
-				CallError::Custom(ErrorObject::owned(NOT_HEALTHY_ERROR, e.to_string(), Some(h))),
-			Error::MalformattedPeerArg(e) => CallError::Custom(ErrorObject::owned(
-				MALFORMATTED_PEER_ARG_ERROR + 2,
-				e,
-				None::<()>,
-			)),
+				ErrorObject::owned(NOT_HEALTHY_ERROR, e.to_string(), Some(h)),
+			Error::MalformattedPeerArg(e) =>
+				ErrorObject::owned(MALFORMATTED_PEER_ARG_ERROR, e, None::<()>),
+			Error::UnsafeRpcCalled(e) => e.into(),
+			Error::Internal(e) =>
+				ErrorObjectOwned::owned(ErrorCode::InternalError.code(), e, None::<()>),
 		}
-		.into()
 	}
 }

substrate/client/rpc-api/src/system/helpers.rs

@@ -38,7 +38,7 @@ pub struct SystemInfo {
 }
 
 /// Health struct returned by the RPC
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct Health {
 	/// Number of connected peers
@@ -58,7 +58,7 @@ impl fmt::Display for Health {
 }
 
 /// Network Peer information
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct PeerInfo<Hash, Number> {
 	/// Peer ID
@@ -72,7 +72,7 @@ pub struct PeerInfo<Hash, Number> {
 }
 
 /// The role the node is running as
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub enum NodeRole {
 	/// The node is a full node
 	Full,
@@ -81,7 +81,7 @@ pub enum NodeRole {
 }
 
 /// The state of the syncing of the node.
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct SyncState<Number> {
 	/// Height of the block at which syncing started.

substrate/client/rpc-api/src/system/mod.rs

@@ -18,38 +18,36 @@
 
 //! Substrate system API.
 
-use jsonrpsee::{
-	core::{JsonValue, RpcResult},
-	proc_macros::rpc,
-};
-
-pub use self::helpers::{Health, NodeRole, PeerInfo, SyncState, SystemInfo};
-
 pub mod error;
 pub mod helpers;
 
+use jsonrpsee::{core::JsonValue, proc_macros::rpc};
+
+pub use self::helpers::{Health, NodeRole, PeerInfo, SyncState, SystemInfo};
+pub use error::Error;
+
 /// Substrate system RPC API
 #[rpc(client, server)]
 pub trait SystemApi<Hash, Number> {
 	/// Get the node's implementation name. Plain old string.
 	#[method(name = "system_name")]
-	fn system_name(&self) -> RpcResult<String>;
+	fn system_name(&self) -> Result<String, Error>;
 
 	/// Get the node implementation's version. Should be a semver string.
 	#[method(name = "system_version")]
-	fn system_version(&self) -> RpcResult<String>;
+	fn system_version(&self) -> Result<String, Error>;
 
 	/// Get the chain's name. Given as a string identifier.
 	#[method(name = "system_chain")]
-	fn system_chain(&self) -> RpcResult<String>;
+	fn system_chain(&self) -> Result<String, Error>;
 
 	/// Get the chain's type.
 	#[method(name = "system_chainType")]
-	fn system_type(&self) -> RpcResult<sc_chain_spec::ChainType>;
+	fn system_type(&self) -> Result<sc_chain_spec::ChainType, Error>;
 
 	/// Get a custom set of properties as a JSON object, defined in the chain spec.
 	#[method(name = "system_properties")]
-	fn system_properties(&self) -> RpcResult<sc_chain_spec::Properties>;
+	fn system_properties(&self) -> Result<sc_chain_spec::Properties, Error>;
 
 	/// Return health status of the node.
 	///
@@ -57,22 +55,22 @@ pub trait SystemApi<Hash, Number> {
 	/// - connected to some peers (unless running in dev mode)
 	/// - not performing a major sync
 	#[method(name = "system_health")]
-	async fn system_health(&self) -> RpcResult<Health>;
+	async fn system_health(&self) -> Result<Health, Error>;
 
 	/// Returns the base58-encoded PeerId of the node.
 	#[method(name = "system_localPeerId")]
-	async fn system_local_peer_id(&self) -> RpcResult<String>;
+	async fn system_local_peer_id(&self) -> Result<String, Error>;
 
 	/// Returns the multi-addresses that the local node is listening on
 	///
 	/// The addresses include a trailing `/p2p/` with the local PeerId, and are thus suitable to
 	/// be passed to `addReservedPeer` or as a bootnode address for example.
 	#[method(name = "system_localListenAddresses")]
-	async fn system_local_listen_addresses(&self) -> RpcResult<Vec<String>>;
+	async fn system_local_listen_addresses(&self) -> Result<Vec<String>, Error>;
 
 	/// Returns currently connected peers
 	#[method(name = "system_peers")]
-	async fn system_peers(&self) -> RpcResult<Vec<PeerInfo<Hash, Number>>>;
+	async fn system_peers(&self) -> Result<Vec<PeerInfo<Hash, Number>>, Error>;
 
 	/// Returns current state of the network.
 	///
@@ -81,7 +79,7 @@ pub trait SystemApi<Hash, Number> {
 	// TODO: the future of this call is uncertain: https://github.com/paritytech/substrate/issues/1890
 	// https://github.com/paritytech/substrate/issues/5541
 	#[method(name = "system_unstable_networkState")]
-	async fn system_network_state(&self) -> RpcResult<JsonValue>;
+	async fn system_network_state(&self) -> Result<JsonValue, Error>;
 
 	/// Adds a reserved peer. Returns the empty string or an error. The string
 	/// parameter should encode a `p2p` multiaddr.
@@ -89,25 +87,25 @@ pub trait SystemApi<Hash, Number> {
 	/// `/ip4/198.51.100.19/tcp/30333/p2p/QmSk5HQbn6LhUwDiNMseVUjuRYhEtYj4aUZ6WfWoGURpdV`
 	/// is an example of a valid, passing multiaddr with PeerId attached.
 	#[method(name = "system_addReservedPeer")]
-	async fn system_add_reserved_peer(&self, peer: String) -> RpcResult<()>;
+	async fn system_add_reserved_peer(&self, peer: String) -> Result<(), Error>;
 
 	/// Remove a reserved peer. Returns the empty string or an error. The string
 	/// should encode only the PeerId e.g. `QmSk5HQbn6LhUwDiNMseVUjuRYhEtYj4aUZ6WfWoGURpdV`.
 	#[method(name = "system_removeReservedPeer")]
-	async fn system_remove_reserved_peer(&self, peer_id: String) -> RpcResult<()>;
+	async fn system_remove_reserved_peer(&self, peer_id: String) -> Result<(), Error>;
 
 	/// Returns the list of reserved peers
 	#[method(name = "system_reservedPeers")]
-	async fn system_reserved_peers(&self) -> RpcResult<Vec<String>>;
+	async fn system_reserved_peers(&self) -> Result<Vec<String>, Error>;
 
 	/// Returns the roles the node is running as.
 	#[method(name = "system_nodeRoles")]
-	async fn system_node_roles(&self) -> RpcResult<Vec<NodeRole>>;
+	async fn system_node_roles(&self) -> Result<Vec<NodeRole>, Error>;
 
 	/// Returns the state of the syncing of the node: starting block, current best block, highest
 	/// known block.
 	#[method(name = "system_syncState")]
-	async fn system_sync_state(&self) -> RpcResult<SyncState<Number>>;
+	async fn system_sync_state(&self) -> Result<SyncState<Number>, Error>;
 
 	/// Adds the supplied directives to the current log filter
 	///
@@ -115,9 +113,9 @@ pub trait SystemApi<Hash, Number> {
 	///
 	/// `sync=debug,state=trace`
 	#[method(name = "system_addLogFilter")]
-	fn system_add_log_filter(&self, directives: String) -> RpcResult<()>;
+	fn system_add_log_filter(&self, directives: String) -> Result<(), Error>;
 
 	/// Resets the log filter to Substrate defaults
 	#[method(name = "system_resetLogFilter")]
-	fn system_reset_log_filter(&self) -> RpcResult<()>;
+	fn system_reset_log_filter(&self) -> Result<(), Error>;
 }