Asynchronous RPC support (#2017)

* Async RPC

* Limiting number of transactions in queue

* Fixing tests

* Bumping serde and jsonrpc-core

* serde updated to 0.8

* fixed failing tests

* Bumping ipc server

* Fixing API for endpoints

* Experimenting with tests without --release mode

signer/src/ws_server/session.rs

@@ -22,7 +22,7 @@ use std::path::{PathBuf, Path};
 use std::sync::Arc;
 use std::str::FromStr;
 use jsonrpc_core::IoHandler;
-use util::H256;
+use util::{H256, Mutex};
 
 #[cfg(feature = "ui")]
 mod signer {
@@ -95,7 +95,7 @@ fn add_headers(mut response: ws::Response, mime: &str) -> ws::Response {
 }
 
 pub struct Session {
-	out: ws::Sender,
+	out: Arc<Mutex<ws::Sender>>,
 	skip_origin_validation: bool,
 	self_origin: String,
 	authcodes_path: PathBuf,
@@ -145,12 +145,16 @@ impl ws::Handler for Session {
 
 	fn on_message(&mut self, msg: ws::Message) -> ws::Result<()> {
 		let req = try!(msg.as_text());
-		match self.handler.handle_request(req) {
-			Some(res) => {
-				self.out.send(res)
-			},
-			None => Ok(()),
+		if let Some(async) = self.handler.handle_request(req) {
+			let out = self.out.clone();
+			async.on_result(move |result| {
+				let res = out.lock().send(result);
+				if let Err(e) = res {
+					warn!(target: "signer", "Error while sending response: {:?}", e);
+				}
+			});
 		}
+		Ok(())
 	}
 }
 
@@ -177,7 +181,7 @@ impl ws::Factory for Factory {
 
 	fn connection_made(&mut self, sender: ws::Sender) -> Self::Handler {
 		Session {
-			out: sender,
+			out: Arc::new(Mutex::new(sender)),
 			handler: self.handler.clone(),
 			skip_origin_validation: self.skip_origin_validation,
 			self_origin: self.self_origin.clone(),