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/dev/error.rs

@@ -18,10 +18,10 @@
 
 //! Error helpers for Dev RPC module.
 
-use jsonrpsee::{
-	core::Error as JsonRpseeError,
-	types::error::{CallError, ErrorObject},
-};
+use jsonrpsee::types::error::{ErrorObject, ErrorObjectOwned};
+
+/// Dev RPC Result type.
+pub type Result<T> = std::result::Result<T, Error>;
 
 /// Dev RPC errors.
 #[derive(Debug, thiserror::Error)]
@@ -46,21 +46,16 @@ pub enum Error {
 /// Base error code for all dev errors.
 const BASE_ERROR: i32 = crate::error::base::DEV;
 
-impl From<Error> for JsonRpseeError {
+impl From<Error> for ErrorObjectOwned {
 	fn from(e: Error) -> Self {
 		let msg = e.to_string();
 
 		match e {
-			Error::BlockQueryError(_) =>
-				CallError::Custom(ErrorObject::owned(BASE_ERROR + 1, msg, None::<()>)),
-			Error::BlockExecutionFailed =>
-				CallError::Custom(ErrorObject::owned(BASE_ERROR + 3, msg, None::<()>)),
-			Error::WitnessCompactionFailed =>
-				CallError::Custom(ErrorObject::owned(BASE_ERROR + 4, msg, None::<()>)),
-			Error::ProofExtractionFailed =>
-				CallError::Custom(ErrorObject::owned(BASE_ERROR + 5, msg, None::<()>)),
+			Error::BlockQueryError(_) => ErrorObject::owned(BASE_ERROR + 1, msg, None::<()>),
+			Error::BlockExecutionFailed => ErrorObject::owned(BASE_ERROR + 3, msg, None::<()>),
+			Error::WitnessCompactionFailed => ErrorObject::owned(BASE_ERROR + 4, msg, None::<()>),
+			Error::ProofExtractionFailed => ErrorObject::owned(BASE_ERROR + 5, msg, None::<()>),
 			Error::UnsafeRpcCalled(e) => e.into(),
 		}
-		.into()
 	}
 }

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

@@ -23,7 +23,8 @@
 pub mod error;
 
 use codec::{Decode, Encode};
-use jsonrpsee::{core::RpcResult, proc_macros::rpc};
+use error::Error;
+use jsonrpsee::proc_macros::rpc;
 use scale_info::TypeInfo;
 use serde::{Deserialize, Serialize};
 
@@ -59,5 +60,5 @@ pub trait DevApi<Hash> {
 	/// at the queried node. If either the specified block or the parent is pruned,
 	/// this function will return `None`.
 	#[method(name = "dev_getBlockStats")]
-	fn block_stats(&self, block_hash: Hash) -> RpcResult<Option<BlockStats>>;
+	fn block_stats(&self, block_hash: Hash) -> Result<Option<BlockStats>, Error>;
 }