Custom RPC implementation for node. (#3109)

* Allow RPCs to be customized.

* Implement node-rpc extensions.

* Working on a test.

* Add node-testing crate.

* Fix genesis test config

* Fix nonce lookups.

* Clean up.

* Fix expected block type.

* Make the RPC extension function optional.

* Fix service doc test.

* Bump jsonrpc.

* Bump client version.

* Update Cargo.lock

* Update jsonrpc.

* Fix build.

* Remove unused imports.

* Fix signed extra.

* Post merge clean up.

* Fix tests.

* Patch hashmap-core.

* Fix build.

* Fix build.

* Remove hashmap_core patches.

substrate/core/rpc/src/lib.rs

@@ -15,19 +15,23 @@
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Substrate RPC interfaces.
+//!
+//! A collection of RPC methods and subscriptions supported by all substrate clients.
 
 #![warn(missing_docs)]
 
 mod errors;
 mod helpers;
+mod metadata;
 mod subscriptions;
 
+use jsonrpc_core as rpc;
+
+pub use metadata::Metadata;
+pub use rpc::IoHandlerExtension as RpcExtension;
 pub use subscriptions::Subscriptions;
 
 pub mod author;
 pub mod chain;
-pub mod metadata;
 pub mod state;
 pub mod system;
-
-use jsonrpc_core as rpc;

substrate/core/rpc/src/metadata.rs

@@ -52,3 +52,9 @@ impl Metadata {
 		(rx, Self::new(tx))
 	}
 }
+
+impl From<mpsc::Sender<String>> for Metadata {
+	fn from(sender: mpsc::Sender<String>) -> Self {
+		Self::new(sender)
+	}
+}

substrate/core/rpc/src/system/mod.rs

@@ -29,8 +29,8 @@ use network;
 use sr_primitives::traits::{self, Header as HeaderT};
 
 use self::error::Result;
-pub use self::helpers::{Properties, SystemInfo, Health, PeerInfo};
 
+pub use self::helpers::{Properties, SystemInfo, Health, PeerInfo};
 pub use self::gen_client::Client as SystemClient;
 
 /// Substrate system RPC API