Remove tokio dependencies (#2935)

* Remove dependencies on tokio

* Make service not depend on tokio

* Fix service tests

* Manually poll the import queue if failed to start

* Spawn all tasks at the end

* Remove executor from TelemetryOnConnect

* Remove TaskExecutor from offchain workers

* Remove TaskExecutor from AuthoritySetup

* Remove TaskExecutor from service

* Remove tokio dependency from RPC

* Remove finality-grandpa from WASM checks

* Fix offchain tests

* Line widths

* Fix RPC tests

* Fix service tests

* Fix bad futures polling

* Address some concerns

* Better error handling

* Is it the connectivity test that's not passing? I don't know, let's try

* Revert "Is it the connectivity test that's not passing? I don't know, let's try"

This reverts commit 28bbe51f0e2e4885fe1f901e11078604604cb212.

* Fix test

substrate/core/service/src/components.rs

@@ -18,7 +18,6 @@
 
 use std::{sync::Arc, net::SocketAddr, ops::Deref, ops::DerefMut};
 use serde::{Serialize, de::DeserializeOwned};
-use tokio::runtime::TaskExecutor;
 use crate::chain_spec::ChainSpec;
 use client_db;
 use client::{self, Client, runtime_api};
@@ -34,7 +33,7 @@ use crate::config::Configuration;
 use primitives::{Blake2Hasher, H256};
 use rpc::{self, apis::system::SystemInfo};
 use parking_lot::Mutex;
-use futures::sync::mpsc;
+use futures::{prelude::*, future::Executor, sync::mpsc};
 
 // Type aliases.
 // These exist mainly to avoid typing `<F as Factory>::Foo` all over the code.
@@ -262,7 +261,7 @@ pub trait OffchainWorker<C: Components> {
 		number: &FactoryBlockNumber<C::Factory>,
 		offchain: &offchain::OffchainWorkers<ComponentClient<C>, ComponentBlock<C>>,
 		pool: &Arc<TransactionPool<C::TransactionPoolApi>>,
-	) -> error::Result<()>;
+	) -> error::Result<Box<dyn Future<Item = (), Error = ()> + Send>>;
 }
 
 impl<C: Components> OffchainWorker<Self> for C where
@@ -273,8 +272,8 @@ impl<C: Components> OffchainWorker<Self> for C where
 		number: &FactoryBlockNumber<C::Factory>,
 		offchain: &offchain::OffchainWorkers<ComponentClient<C>, ComponentBlock<C>>,
 		pool: &Arc<TransactionPool<C::TransactionPoolApi>>,
-	) -> error::Result<()> {
-		Ok(offchain.on_block_imported(number, pool))
+	) -> error::Result<Box<dyn Future<Item = (), Error = ()> + Send>> {
+		Ok(Box::new(offchain.on_block_imported(number, pool)))
 	}
 }
 
@@ -298,6 +297,9 @@ impl<C: Components, T> ServiceTrait<C> for T where
 	+ OffchainWorker<C>
 {}
 
+/// Alias for a an implementation of `futures::future::Executor`.
+pub type TaskExecutor = Arc<dyn Executor<Box<dyn Future<Item = (), Error = ()> + Send>> + Send + Sync>;
+
 /// A collection of types and methods to build a service on top of the substrate service.
 pub trait ServiceFactory: 'static + Sized {
 	/// Block type.
@@ -351,10 +353,10 @@ pub trait ServiceFactory: 'static + Sized {
 	) -> Result<Self::SelectChain, error::Error>;
 
 	/// Build full service.
-	fn new_full(config: FactoryFullConfiguration<Self>, executor: TaskExecutor)
+	fn new_full(config: FactoryFullConfiguration<Self>)
 		-> Result<Self::FullService, error::Error>;
 	/// Build light service.
-	fn new_light(config: FactoryFullConfiguration<Self>, executor: TaskExecutor)
+	fn new_light(config: FactoryFullConfiguration<Self>)
 		-> Result<Self::LightService, error::Error>;
 
 	/// ImportQueue for a full client
@@ -455,12 +457,11 @@ pub struct FullComponents<Factory: ServiceFactory> {
 impl<Factory: ServiceFactory> FullComponents<Factory> {
 	/// Create new `FullComponents`
 	pub fn new(
-		config: FactoryFullConfiguration<Factory>,
-		task_executor: TaskExecutor
+		config: FactoryFullConfiguration<Factory>
 	) -> Result<Self, error::Error> {
 		Ok(
 			Self {
-				service: Service::new(config, task_executor)?,
+				service: Service::new(config)?,
 			}
 		)
 	}
@@ -480,6 +481,15 @@ impl<Factory: ServiceFactory> DerefMut for FullComponents<Factory> {
 	}
 }
 
+impl<Factory: ServiceFactory> Future for FullComponents<Factory> {
+	type Item = ();
+	type Error = ();
+
+	fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+		self.service.poll()
+	}
+}
+
 impl<Factory: ServiceFactory> Components for FullComponents<Factory> {
 	type Factory = Factory;
 	type Executor = FullExecutor<Factory>;
@@ -555,11 +565,10 @@ impl<Factory: ServiceFactory> LightComponents<Factory> {
 	/// Create new `LightComponents`
 	pub fn new(
 		config: FactoryFullConfiguration<Factory>,
-		task_executor: TaskExecutor
 	) -> Result<Self, error::Error> {
 		Ok(
 			Self {
-				service: Service::new(config, task_executor)?,
+				service: Service::new(config)?,
 			}
 		)
 	}
@@ -573,6 +582,15 @@ impl<Factory: ServiceFactory> Deref for LightComponents<Factory> {
 	}
 }
 
+impl<Factory: ServiceFactory> Future for LightComponents<Factory> {
+	type Item = ();
+	type Error = ();
+
+	fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+		self.service.poll()
+	}
+}
+
 impl<Factory: ServiceFactory> Components for LightComponents<Factory> {
 	type Factory = Factory;
 	type Executor = LightExecutor<Factory>;