create parallel tasks extension (#5249)

substrate/primitives/api/test/tests/runtime_calls.rs

@@ -200,6 +200,7 @@ fn record_proof_works() {
 		&backend,
 		&mut overlay,
 		&executor,
+		sp_core::tasks::executor(),
 		"Core_execute_block",
 		&block.encode(),
 		&runtime_code,

substrate/primitives/core/Cargo.toml

@@ -34,6 +34,7 @@ sp-debug-derive = { version = "2.0.0-alpha.2", path = "../debug-derive" }
 sp-externalities = { version = "0.8.0-alpha.2", optional = true, path = "../externalities" }
 sp-storage = { version = "2.0.0-alpha.2", default-features = false, path = "../storage" }
 parity-util-mem = { version = "0.5.2", default-features = false, features = ["primitive-types"] }
+futures = { version = "0.3.1", optional = true }
 
 # full crypto
 ed25519-dalek = { version = "1.0.0-pre.3", default-features = false, features = ["u64_backend", "alloc"], optional = true }
@@ -102,7 +103,9 @@ std = [
 	"sp-externalities",
 	"sp-storage/std",
 	"sp-runtime-interface/std",
-	"zeroize/alloc"
+	"zeroize/alloc",
+	"futures",
+	"futures/thread-pool",
 ]
 
 # This feature enables all crypto primitives for `no_std` builds like microcontrollers

substrate/primitives/core/src/lib.rs

@@ -70,6 +70,8 @@ mod changes_trie;
 #[cfg(feature = "std")]
 pub mod traits;
 pub mod testing;
+#[cfg(feature = "std")]
+pub mod tasks;
 
 pub use self::hash::{H160, H256, H512, convert_hash};
 pub use self::uint::U256;

substrate/primitives/core/src/tasks.rs

@@ -0,0 +1,56 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Module for low-level asynchronous processing.
+
+use crate::traits::CloneableSpawn;
+use futures::{executor, task};
+
+/// Simple task executor.
+///
+/// Uses single thread for scheduling tasks. Can be cloned and used in
+/// runtime host (implements `CloneableSpawn`).
+#[derive(Debug, Clone)]
+pub struct Executor {
+	pool: executor::ThreadPool,
+}
+
+impl Executor {
+	fn new() -> Self {
+		Self {
+			pool: executor::ThreadPool::builder().pool_size(1).create()
+				.expect("Failed to create task executor")
+		}
+	}
+}
+
+impl task::Spawn for Executor {
+	fn spawn_obj(&self, future: task::FutureObj<'static, ()>)
+	-> Result<(), task::SpawnError> {
+		self.pool.spawn_obj(future)
+	}
+}
+
+impl CloneableSpawn for Executor {
+	fn clone(&self) -> Box<dyn CloneableSpawn> {
+		Box::new(Clone::clone(self))
+	}
+}
+
+/// Create tasks executor.
+pub fn executor() -> Box<dyn CloneableSpawn> {
+	Box::new(Executor::new())
+}

substrate/primitives/core/src/traits.rs

@@ -212,3 +212,21 @@ impl CallInWasmExt {
 		Self(Box::new(inner))
 	}
 }
+
+/// Something that can spawn tasks and also can be cloned.
+pub trait CloneableSpawn: futures::task::Spawn + Send + Sync {
+	/// Clone as heap-allocated handle.
+	fn clone(&self) -> Box<dyn CloneableSpawn>;
+}
+
+sp_externalities::decl_extension! {
+	/// Task executor extension.
+	pub struct TaskExecutorExt(Box<dyn CloneableSpawn>);
+}
+
+impl TaskExecutorExt {
+	/// New instance of task executor extension.
+	pub fn new(spawn_handle: Box<dyn CloneableSpawn>) -> Self {
+		Self(spawn_handle)
+	}
+}

substrate/primitives/externalities/Cargo.toml

@@ -12,4 +12,4 @@ documentation = "https://docs.rs/sp-externalities"
 [dependencies]
 sp-storage = { version = "2.0.0-alpha.2", path = "../storage" }
 sp-std = { version = "2.0.0-alpha.2", path = "../std" }
-environmental = { version = "1.1.1" }
+environmental = { version = "1.1.1" }

substrate/primitives/state-machine/src/ext.rs

@@ -573,7 +573,6 @@ mod tests {
 	const CHILD_UUID_1: &[u8] = b"unique_id_1";
 	const CHILD_INFO_1: ChildInfo<'static> = ChildInfo::new_default(CHILD_UUID_1);
 
-
 	fn prepare_overlay_with_changes() -> OverlayedChanges {
 		OverlayedChanges {
 			prospective: vec![

substrate/primitives/state-machine/src/lib.rs

@@ -74,6 +74,7 @@ pub use trie_backend::TrieBackend;
 pub use error::{Error, ExecutionError};
 pub use in_memory_backend::InMemory as InMemoryBackend;
 pub use stats::{UsageInfo, UsageUnit};
+pub use sp_core::traits::CloneableSpawn;
 
 type CallResult<R, E> = Result<NativeOrEncoded<R>, E>;
 
@@ -210,8 +211,10 @@ impl<'a, B, H, N, Exec> StateMachine<'a, B, H, N, Exec> where
 		call_data: &'a [u8],
 		mut extensions: Extensions,
 		runtime_code: &'a RuntimeCode,
+		spawn_handle: Box<dyn CloneableSpawn>,
 	) -> Self {
 		extensions.register(CallInWasmExt::new(exec.clone()));
+		extensions.register(sp_core::traits::TaskExecutorExt::new(spawn_handle));
 
 		Self {
 			backend,
@@ -437,6 +440,7 @@ pub fn prove_execution<B, H, N, Exec>(
 	mut backend: B,
 	overlay: &mut OverlayedChanges,
 	exec: &Exec,
+	spawn_handle: Box<dyn CloneableSpawn>,
 	method: &str,
 	call_data: &[u8],
 	runtime_code: &RuntimeCode,
@@ -454,6 +458,7 @@ where
 		trie_backend,
 		overlay,
 		exec,
+		spawn_handle,
 		method,
 		call_data,
 		runtime_code,
@@ -473,6 +478,7 @@ pub fn prove_execution_on_trie_backend<S, H, N, Exec>(
 	trie_backend: &TrieBackend<S, H>,
 	overlay: &mut OverlayedChanges,
 	exec: &Exec,
+	spawn_handle: Box<dyn CloneableSpawn>,
 	method: &str,
 	call_data: &[u8],
 	runtime_code: &RuntimeCode,
@@ -494,6 +500,7 @@ where
 		call_data,
 		Extensions::default(),
 		runtime_code,
+		spawn_handle,
 	);
 
 	let result = sm.execute_using_consensus_failure_handler::<_, NeverNativeValue, fn() -> _>(
@@ -510,6 +517,7 @@ pub fn execution_proof_check<H, N, Exec>(
 	proof: StorageProof,
 	overlay: &mut OverlayedChanges,
 	exec: &Exec,
+	spawn_handle: Box<dyn CloneableSpawn>,
 	method: &str,
 	call_data: &[u8],
 	runtime_code: &RuntimeCode,
@@ -525,6 +533,7 @@ where
 		&trie_backend,
 		overlay,
 		exec,
+		spawn_handle,
 		method,
 		call_data,
 		runtime_code,
@@ -536,6 +545,7 @@ pub fn execution_proof_check_on_trie_backend<H, N, Exec>(
 	trie_backend: &TrieBackend<MemoryDB<H>, H>,
 	overlay: &mut OverlayedChanges,
 	exec: &Exec,
+	spawn_handle: Box<dyn CloneableSpawn>,
 	method: &str,
 	call_data: &[u8],
 	runtime_code: &RuntimeCode,
@@ -555,6 +565,7 @@ where
 		call_data,
 		Extensions::default(),
 		runtime_code,
+		spawn_handle,
 	);
 
 	sm.execute_using_consensus_failure_handler::<_, NeverNativeValue, fn() -> _>(
@@ -820,6 +831,7 @@ mod tests {
 			&[],
 			Default::default(),
 			&wasm_code,
+			sp_core::tasks::executor(),
 		);
 
 		assert_eq!(
@@ -849,6 +861,7 @@ mod tests {
 			&[],
 			Default::default(),
 			&wasm_code,
+			sp_core::tasks::executor(),
 		);
 
 		assert_eq!(state_machine.execute(ExecutionStrategy::NativeElseWasm).unwrap(), vec![66]);
@@ -875,6 +888,7 @@ mod tests {
 			&[],
 			Default::default(),
 			&wasm_code,
+			sp_core::tasks::executor(),
 		);
 
 		assert!(
@@ -905,6 +919,7 @@ mod tests {
 			remote_backend,
 			&mut Default::default(),
 			&executor,
+			sp_core::tasks::executor(),
 			"test",
 			&[],
 			&RuntimeCode::empty(),
@@ -916,6 +931,7 @@ mod tests {
 			remote_proof,
 			&mut Default::default(),
 			&executor,
+			sp_core::tasks::executor(),
 			"test",
 			&[],
 			&RuntimeCode::empty(),