Runtime worker threads (#7089)

* std variant

* principal work

* format and naming

* format and naming continued

* working nested fork

* add comment

* naming and tabs

* line width

* fix wording

* address review

* refactor dynamic dispatch

* update wasmtime

* some care

* move ext

* more refactor

* doc effort

* simplify

* doc effort

* tests and docs

* address review

* naming

* explain some args

* add example

* unwinding for native and tests

* rename stray

* fix refs

* fix tests

* fix warnings

* stray naming

* fixes and comments

* Update primitives/io/src/tasks.rs

Co-authored-by: cheme <emericchevalier.pro@gmail.com>

* make examples "compile"

* dyn_dispatch -> spawn_call

* fix impl

* address review

* Update primitives/io/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update primitives/io/src/tasks.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update primitives/io/src/async_externalities.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update primitives/io/src/tasks.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update frame/example-parallel/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* fix compilation

* Update client/executor/common/src/wasm_runtime.rs

Co-authored-by: Sergei Shulepov <sergei@parity.io>

* address review

* Update client/executor/wasmtime/src/instance_wrapper.rs

Co-authored-by: Sergei Shulepov <sergei@parity.io>

* Update client/executor/src/native_executor.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update primitives/io/src/tasks.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/executor/src/native_executor.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update primitives/io/src/tasks.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/executor/wasmtime/src/instance_wrapper.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* address some issues

* address more issues

* wasm_only interface

* define sp_tasks

* avoid anyhow

* fix example

Co-authored-by: cheme <emericchevalier.pro@gmail.com>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Sergei Shulepov <sergei@parity.io>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/executor/common/src/error.rs

@@ -81,6 +81,25 @@ pub enum Error {
 	/// Execution of a host function failed.
 	#[display(fmt="Host function {} execution failed with: {}", _0, _1)]
 	FunctionExecution(String, String),
+	/// No table is present.
+	///
+	/// Call was requested that requires table but none was present in the instance.
+	#[display(fmt="No table exported by wasm blob")]
+	NoTable,
+	/// No table entry is present.
+	///
+	/// Call was requested that requires specific entry in the table to be present.
+	#[display(fmt="No table entry with index {} in wasm blob exported table", _0)]
+	#[from(ignore)]
+	NoTableEntryWithIndex(u32),
+	/// Table entry is not a function.
+	#[display(fmt="Table element with index {} is not a function in wasm blob exported table", _0)]
+	#[from(ignore)]
+	TableElementIsNotAFunction(u32),
+	/// Function in table is null and thus cannot be called.
+	#[display(fmt="Table entry with index {} in wasm blob is null", _0)]
+	#[from(ignore)]
+	FunctionRefIsNull(u32),
 }
 
 impl std::error::Error for Error {

substrate/client/executor/common/src/wasm_runtime.rs

@@ -19,6 +19,46 @@
 use crate::error::Error;
 use sp_wasm_interface::Value;
 
+/// A method to be used to find the entrypoint when calling into the runtime
+///
+/// Contains variants on how to resolve wasm function that will be invoked.
+pub enum InvokeMethod<'a> {
+	/// Call function exported with this name.
+	///
+	/// Located function should have (u32, u32) -> u64 signature.
+	Export(&'a str),
+	/// Call a function found in the exported table found under the given index.
+	///
+	/// Located function should have (u32, u32) -> u64 signature.
+	Table(u32),
+	/// Call function by reference from table through a wrapper.
+	///
+	/// Invoked function (`dispatcher_ref`) function
+	/// should have (u32, u32, u32) -> u64 signature.
+	///
+	/// `func` will be passed to the invoked function as a first argument.
+	TableWithWrapper {
+		/// Wrapper for the call.
+		///
+		/// Function pointer, index into runtime exported table.
+		dispatcher_ref: u32,
+		/// Extra argument for dispatch.
+		///
+		/// Common usage would be to use it as an actual wasm function pointer
+		/// that should be invoked, but can be used as any extra argument on the
+		/// callee side.
+		///
+		/// This is typically generated and invoked by the runtime itself.
+		func: u32,
+	},
+}
+
+impl<'a> From<&'a str> for InvokeMethod<'a> {
+	fn from(val: &'a str) -> InvokeMethod<'a> {
+		InvokeMethod::Export(val)
+	}
+}
+
 /// A trait that defines an abstract WASM runtime module.
 ///
 /// This can be implemented by an execution engine.
@@ -31,11 +71,24 @@ pub trait WasmModule: Sync + Send {
 ///
 /// This can be implemented by an execution engine.
 pub trait WasmInstance: Send {
-	/// Call a method on this WASM instance and reset it afterwards.
+	/// Call a method on this WASM instance.
+	///
+	/// Before execution, instance is reset.
+	///
 	/// Returns the encoded result on success.
-	fn call(&self, method: &str, data: &[u8]) -> Result<Vec<u8>, Error>;
+	fn call(&self, method: InvokeMethod, data: &[u8]) -> Result<Vec<u8>, Error>;
+
+	/// Call an exported method on this WASM instance.
+	///
+	/// Before execution, instance is reset.
+	///
+	/// Returns the encoded result on success.
+	fn call_export(&self, method: &str, data: &[u8]) -> Result<Vec<u8>, Error> {
+		self.call(method.into(), data)
+	}
 
 	/// Get the value from a global with the given `name`.
+	///
 	/// This method is only suitable for getting immutable globals.
 	fn get_global_const(&self, name: &str) -> Result<Option<Value>, Error>;
 }