Statically register host WASM functions (#10394)

* Statically register host WASM functions

* Fix `substrate-test-client` compilation

* Move `ExtendedHostFunctions` to `sp-wasm-interface`

* Fix `sp-runtime-interface` tests' compilation

* Fix `sc-executor-wasmtime` tests' compilation

* Use `runtime_interface` macro in `test-runner`

* Fix `sc-executor` tests' compilation

* Reformatting/`rustfmt`

* Add an extra comment regarding the `H` generic arg in `create_runtime`

* Even more `rustfmt`

* Depend on `wasmtime` without default features in `sp-wasm-interface`

* Bump version of `sp-wasm-interface` to 4.0.1

* Bump `sp-wasm-interface` in `Cargo.lock` too

* Bump all of the `sp-wasm-interface` requirements to 4.0.1

Maybe this will appease cargo-unleash?

* Revert "Bump all of the `sp-wasm-interface` requirements to 4.0.1"

This reverts commit 0f7ccf8e0f371542861121b145ab87af6541ac30.

* Make `cargo-unleash` happy (maybe)

* Use `cargo-unleash` to bump the crates' versions

* Align to review comments

substrate/client/executor/Cargo.toml

@@ -24,8 +24,8 @@ sp-panic-handler = { version = "4.0.0-dev", path = "../../primitives/panic-handl
 wasmi = "0.9.1"
 lazy_static = "1.4.0"
 sp-api = { version = "4.0.0-dev", path = "../../primitives/api" }
-sp-wasm-interface = { version = "4.0.0", path = "../../primitives/wasm-interface" }
-sp-runtime-interface = { version = "4.0.0", path = "../../primitives/runtime-interface" }
+sp-wasm-interface = { version = "4.1.0-dev", path = "../../primitives/wasm-interface" }
+sp-runtime-interface = { version = "4.1.0-dev", path = "../../primitives/runtime-interface" }
 sp-externalities = { version = "0.10.0", path = "../../primitives/externalities" }
 sc-executor-common = { version = "0.10.0-dev", path = "common" }
 sc-executor-wasmi = { version = "0.10.0-dev", path = "wasmi" }

substrate/client/executor/common/Cargo.toml

@@ -20,7 +20,7 @@ codec = { package = "parity-scale-codec", version = "2.0.0" }
 wasmi = "0.9.1"
 sp-core = { version = "4.1.0-dev", path = "../../../primitives/core" }
 sc-allocator = { version = "4.1.0-dev", path = "../../allocator" }
-sp-wasm-interface = { version = "4.0.0", path = "../../../primitives/wasm-interface" }
+sp-wasm-interface = { version = "4.1.0-dev", path = "../../../primitives/wasm-interface" }
 sp-maybe-compressed-blob = { version = "4.1.0-dev", path = "../../../primitives/maybe-compressed-blob" }
 sp-serializer = { version = "4.0.0-dev", path = "../../../primitives/serializer" }
 thiserror = "1.0.30"

substrate/client/executor/runtime-test/src/lib.rs

@@ -332,6 +332,14 @@ sp_core::wasm_export_functions! {
    fn test_panic_in_spawned() {
 	   sp_tasks::spawn(tasks::panicker, vec![]).join();
    }
+
+	fn test_return_i8() -> i8 {
+		-66
+	}
+
+	fn test_take_i8(value: i8) {
+		assert_eq!(value, -66);
+	}
 }
 
 #[cfg(not(feature = "std"))]

substrate/client/executor/src/integration_tests/mod.rs

@@ -34,7 +34,6 @@ use sp_core::{
 use sp_runtime::traits::BlakeTwo256;
 use sp_state_machine::TestExternalities as CoreTestExternalities;
 use sp_trie::{trie_types::Layout, TrieConfiguration};
-use sp_wasm_interface::HostFunctions as _;
 use std::sync::Arc;
 use tracing_subscriber::layer::SubscriberExt;
 
@@ -124,14 +123,8 @@ fn call_in_wasm<E: Externalities>(
 	execution_method: WasmExecutionMethod,
 	ext: &mut E,
 ) -> Result<Vec<u8>, String> {
-	let executor = crate::WasmExecutor::new(
-		execution_method,
-		Some(1024),
-		HostFunctions::host_functions(),
-		8,
-		None,
-		2,
-	);
+	let executor =
+		crate::WasmExecutor::<HostFunctions>::new(execution_method, Some(1024), 8, None, 2);
 	executor.uncached_call(
 		RuntimeBlob::uncompress_if_needed(&wasm_binary_unwrap()[..]).unwrap(),
 		ext,
@@ -475,10 +468,9 @@ test_wasm_execution!(should_trap_when_heap_exhausted);
 fn should_trap_when_heap_exhausted(wasm_method: WasmExecutionMethod) {
 	let mut ext = TestExternalities::default();
 
-	let executor = crate::WasmExecutor::new(
+	let executor = crate::WasmExecutor::<HostFunctions>::new(
 		wasm_method,
 		Some(17), // `17` is the initial number of pages compiled into the binary.
-		HostFunctions::host_functions(),
 		8,
 		None,
 		2,
@@ -501,11 +493,10 @@ fn mk_test_runtime(wasm_method: WasmExecutionMethod, pages: u64) -> Arc<dyn Wasm
 	let blob = RuntimeBlob::uncompress_if_needed(&wasm_binary_unwrap()[..])
 		.expect("failed to create a runtime blob out of test runtime");
 
-	crate::wasm_runtime::create_wasm_runtime_with_code(
+	crate::wasm_runtime::create_wasm_runtime_with_code::<HostFunctions>(
 		wasm_method,
 		pages,
 		blob,
-		HostFunctions::host_functions(),
 		true,
 		None,
 	)
@@ -589,10 +580,9 @@ fn heap_is_reset_between_calls(wasm_method: WasmExecutionMethod) {
 
 test_wasm_execution!(parallel_execution);
 fn parallel_execution(wasm_method: WasmExecutionMethod) {
-	let executor = std::sync::Arc::new(crate::WasmExecutor::new(
+	let executor = std::sync::Arc::new(crate::WasmExecutor::<HostFunctions>::new(
 		wasm_method,
 		Some(1024),
-		HostFunctions::host_functions(),
 		8,
 		None,
 		2,
@@ -763,11 +753,10 @@ fn memory_is_cleared_between_invocations(wasm_method: WasmExecutionMethod) {
 	 )
 	)"#).unwrap();
 
-	let runtime = crate::wasm_runtime::create_wasm_runtime_with_code(
+	let runtime = crate::wasm_runtime::create_wasm_runtime_with_code::<HostFunctions>(
 		wasm_method,
 		1024,
 		RuntimeBlob::uncompress_if_needed(&binary[..]).unwrap(),
-		HostFunctions::host_functions(),
 		true,
 		None,
 	)
@@ -780,3 +769,22 @@ fn memory_is_cleared_between_invocations(wasm_method: WasmExecutionMethod) {
 	let res = instance.call_export("returns_no_bss_mutable_static", &[0]).unwrap();
 	assert_eq!(1, u64::decode(&mut &res[..]).unwrap());
 }
+
+test_wasm_execution!(return_i8);
+fn return_i8(wasm_method: WasmExecutionMethod) {
+	let mut ext = TestExternalities::default();
+	let mut ext = ext.ext();
+
+	assert_eq!(
+		call_in_wasm("test_return_i8", &[], wasm_method, &mut ext).unwrap(),
+		(-66_i8).encode()
+	);
+}
+
+test_wasm_execution!(take_i8);
+fn take_i8(wasm_method: WasmExecutionMethod) {
+	let mut ext = TestExternalities::default();
+	let mut ext = ext.ext();
+
+	call_in_wasm("test_take_i8", &(-66_i8).encode(), wasm_method, &mut ext).unwrap();
+}

substrate/client/executor/src/lib.rs

@@ -67,17 +67,15 @@ mod tests {
 	use sc_executor_common::runtime_blob::RuntimeBlob;
 	use sc_runtime_test::wasm_binary_unwrap;
 	use sp_io::TestExternalities;
-	use sp_wasm_interface::HostFunctions;
 
 	#[test]
 	fn call_in_interpreted_wasm_works() {
 		let mut ext = TestExternalities::default();
 		let mut ext = ext.ext();
 
-		let executor = WasmExecutor::new(
+		let executor = WasmExecutor::<sp_io::SubstrateHostFunctions>::new(
 			WasmExecutionMethod::Interpreted,
 			Some(8),
-			sp_io::SubstrateHostFunctions::host_functions(),
 			8,
 			None,
 			2,

substrate/client/executor/src/native_executor.rs

@@ -24,6 +24,7 @@ use crate::{
 
 use std::{
 	collections::HashMap,
+	marker::PhantomData,
 	panic::{AssertUnwindSafe, UnwindSafe},
 	path::PathBuf,
 	result,
@@ -46,7 +47,7 @@ use sp_core::{
 use sp_externalities::ExternalitiesExt as _;
 use sp_tasks::new_async_externalities;
 use sp_version::{GetNativeVersion, NativeVersion, RuntimeVersion};
-use sp_wasm_interface::{Function, HostFunctions};
+use sp_wasm_interface::{ExtendedHostFunctions, HostFunctions};
 
 /// Default num of pages for the heap
 const DEFAULT_HEAP_PAGES: u64 = 2048;
@@ -91,22 +92,36 @@ pub trait NativeExecutionDispatch: Send + Sync {
 
 /// An abstraction over Wasm code executor. Supports selecting execution backend and
 /// manages runtime cache.
-#[derive(Clone)]
-pub struct WasmExecutor {
+pub struct WasmExecutor<H> {
 	/// Method used to execute fallback Wasm code.
 	method: WasmExecutionMethod,
 	/// The number of 64KB pages to allocate for Wasm execution.
 	default_heap_pages: u64,
-	/// The host functions registered with this instance.
-	host_functions: Arc<Vec<&'static dyn Function>>,
 	/// WASM runtime cache.
 	cache: Arc<RuntimeCache>,
 	/// The path to a directory which the executor can leverage for a file cache, e.g. put there
 	/// compiled artifacts.
 	cache_path: Option<PathBuf>,
+
+	phantom: PhantomData<H>,
 }
 
-impl WasmExecutor {
+impl<H> Clone for WasmExecutor<H> {
+	fn clone(&self) -> Self {
+		Self {
+			method: self.method,
+			default_heap_pages: self.default_heap_pages,
+			cache: self.cache.clone(),
+			cache_path: self.cache_path.clone(),
+			phantom: self.phantom,
+		}
+	}
+}
+
+impl<H> WasmExecutor<H>
+where
+	H: HostFunctions,
+{
 	/// Create new instance.
 	///
 	/// # Parameters
@@ -127,7 +142,6 @@ impl WasmExecutor {
 	pub fn new(
 		method: WasmExecutionMethod,
 		default_heap_pages: Option<u64>,
-		host_functions: Vec<&'static dyn Function>,
 		max_runtime_instances: usize,
 		cache_path: Option<PathBuf>,
 		runtime_cache_size: u8,
@@ -135,13 +149,13 @@ impl WasmExecutor {
 		WasmExecutor {
 			method,
 			default_heap_pages: default_heap_pages.unwrap_or(DEFAULT_HEAP_PAGES),
-			host_functions: Arc::new(host_functions),
 			cache: Arc::new(RuntimeCache::new(
 				max_runtime_instances,
 				cache_path.clone(),
 				runtime_cache_size,
 			)),
 			cache_path,
+			phantom: PhantomData,
 		}
 	}
 
@@ -173,12 +187,11 @@ impl WasmExecutor {
 			AssertUnwindSafe<&mut dyn Externalities>,
 		) -> Result<Result<R>>,
 	{
-		match self.cache.with_instance(
+		match self.cache.with_instance::<H, _, _>(
 			runtime_code,
 			ext,
 			self.method,
 			self.default_heap_pages,
-			&*self.host_functions,
 			allow_missing_host_functions,
 			|module, instance, version, ext| {
 				let module = AssertUnwindSafe(module);
@@ -208,11 +221,10 @@ impl WasmExecutor {
 		export_name: &str,
 		call_data: &[u8],
 	) -> std::result::Result<Vec<u8>, String> {
-		let module = crate::wasm_runtime::create_wasm_runtime_with_code(
+		let module = crate::wasm_runtime::create_wasm_runtime_with_code::<H>(
 			self.method,
 			self.default_heap_pages,
 			runtime_blob,
-			self.host_functions.to_vec(),
 			allow_missing_host_functions,
 			self.cache_path.as_deref(),
 		)
@@ -235,7 +247,10 @@ impl WasmExecutor {
 	}
 }
 
-impl sp_core::traits::ReadRuntimeVersion for WasmExecutor {
+impl<H> sp_core::traits::ReadRuntimeVersion for WasmExecutor<H>
+where
+	H: HostFunctions,
+{
 	fn read_runtime_version(
 		&self,
 		wasm_code: &[u8],
@@ -269,7 +284,10 @@ impl sp_core::traits::ReadRuntimeVersion for WasmExecutor {
 	}
 }
 
-impl CodeExecutor for WasmExecutor {
+impl<H> CodeExecutor for WasmExecutor<H>
+where
+	H: HostFunctions,
+{
 	type Error = Error;
 
 	fn call<
@@ -299,7 +317,10 @@ impl CodeExecutor for WasmExecutor {
 	}
 }
 
-impl RuntimeVersionOf for WasmExecutor {
+impl<H> RuntimeVersionOf for WasmExecutor<H>
+where
+	H: HostFunctions,
+{
 	fn runtime_version(
 		&self,
 		ext: &mut dyn Externalities,
@@ -313,13 +334,17 @@ impl RuntimeVersionOf for WasmExecutor {
 
 /// A generic `CodeExecutor` implementation that uses a delegate to determine wasm code equivalence
 /// and dispatch to native code when possible, falling back on `WasmExecutor` when not.
-pub struct NativeElseWasmExecutor<D> {
+pub struct NativeElseWasmExecutor<D>
+where
+	D: NativeExecutionDispatch,
+{
 	/// Dummy field to avoid the compiler complaining about us not using `D`.
 	_dummy: std::marker::PhantomData<D>,
 	/// Native runtime version info.
 	native_version: NativeVersion,
 	/// Fallback wasm executor.
-	wasm: WasmExecutor,
+	wasm:
+		WasmExecutor<ExtendedHostFunctions<sp_io::SubstrateHostFunctions, D::ExtendHostFunctions>>,
 }
 
 impl<D: NativeExecutionDispatch> NativeElseWasmExecutor<D> {
@@ -337,24 +362,9 @@ impl<D: NativeExecutionDispatch> NativeElseWasmExecutor<D> {
 		max_runtime_instances: usize,
 		runtime_cache_size: u8,
 	) -> Self {
-		let extended = D::ExtendHostFunctions::host_functions();
-		let mut host_functions = sp_io::SubstrateHostFunctions::host_functions()
-			.into_iter()
-			// filter out any host function overrides provided.
-			.filter(|host_fn| {
-				extended
-					.iter()
-					.find(|ext_host_fn| host_fn.name() == ext_host_fn.name())
-					.is_none()
-			})
-			.collect::<Vec<_>>();
-
-		// Add the custom host functions provided by the user.
-		host_functions.extend(extended);
 		let wasm_executor = WasmExecutor::new(
 			fallback_method,
 			default_heap_pages,
-			host_functions,
 			max_runtime_instances,
 			None,
 			runtime_cache_size,
@@ -645,8 +655,21 @@ mod tests {
 			8,
 			2,
 		);
+
+		fn extract_host_functions<H>(
+			_: &WasmExecutor<H>,
+		) -> Vec<&'static dyn sp_wasm_interface::Function>
+		where
+			H: HostFunctions,
+		{
+			H::host_functions()
+		}
+
 		my_interface::HostFunctions::host_functions().iter().for_each(|function| {
-			assert_eq!(executor.wasm.host_functions.iter().filter(|f| f == &function).count(), 2);
+			assert_eq!(
+				extract_host_functions(&executor.wasm).iter().filter(|f| f == &function).count(),
+				2
+			);
 		});
 
 		my_interface::say_hello_world("hey");

substrate/client/executor/src/wasm_runtime.rs

@@ -37,7 +37,7 @@ use std::{
 	sync::Arc,
 };
 
-use sp_wasm_interface::Function;
+use sp_wasm_interface::HostFunctions;
 
 /// Specification of different methods of executing the runtime Wasm code.
 #[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
@@ -199,14 +199,14 @@ impl RuntimeCache {
 	///
 	/// `wasm_method` - Type of WASM backend to use.
 	///
-	/// `host_functions` - The host functions that should be registered for the Wasm runtime.
-	///
 	/// `allow_missing_func_imports` - Ignore missing function imports.
 	///
 	/// `max_runtime_instances` - The size of the instances cache.
 	///
 	/// `f` - Function to execute.
 	///
+	/// `H` - A compile-time list of host functions to expose to the runtime.
+	///
 	/// # Returns result of `f` wrapped in an additional result.
 	/// In case of failure one of two errors can be returned:
 	///
@@ -214,17 +214,17 @@ impl RuntimeCache {
 	///
 	/// `Error::InvalidMemoryReference` is returned if no memory export with the
 	/// identifier `memory` can be found in the runtime.
-	pub fn with_instance<'c, R, F>(
+	pub fn with_instance<'c, H, R, F>(
 		&self,
 		runtime_code: &'c RuntimeCode<'c>,
 		ext: &mut dyn Externalities,
 		wasm_method: WasmExecutionMethod,
 		default_heap_pages: u64,
-		host_functions: &[&'static dyn Function],
 		allow_missing_func_imports: bool,
 		f: F,
 	) -> Result<Result<R, Error>, Error>
 	where
+		H: HostFunctions,
 		F: FnOnce(
 			&Arc<dyn WasmModule>,
 			&mut dyn WasmInstance,
@@ -247,12 +247,11 @@ impl RuntimeCache {
 
 			let time = std::time::Instant::now();
 
-			let result = create_versioned_wasm_runtime(
+			let result = create_versioned_wasm_runtime::<H>(
 				&code,
 				ext,
 				wasm_method,
 				heap_pages,
-				host_functions.into(),
 				allow_missing_func_imports,
 				self.max_runtime_instances,
 				self.cache_path.as_deref(),
@@ -288,14 +287,16 @@ impl RuntimeCache {
 }
 
 /// Create a wasm runtime with the given `code`.
-pub fn create_wasm_runtime_with_code(
+pub fn create_wasm_runtime_with_code<H>(
 	wasm_method: WasmExecutionMethod,
 	heap_pages: u64,
 	blob: RuntimeBlob,
-	host_functions: Vec<&'static dyn Function>,
 	allow_missing_func_imports: bool,
 	cache_path: Option<&Path>,
-) -> Result<Arc<dyn WasmModule>, WasmError> {
+) -> Result<Arc<dyn WasmModule>, WasmError>
+where
+	H: HostFunctions,
+{
 	match wasm_method {
 		WasmExecutionMethod::Interpreted => {
 			// Wasmi doesn't have any need in a cache directory.
@@ -307,13 +308,13 @@ pub fn create_wasm_runtime_with_code(
 			sc_executor_wasmi::create_runtime(
 				blob,
 				heap_pages,
-				host_functions,
+				H::host_functions(),
 				allow_missing_func_imports,
 			)
 			.map(|runtime| -> Arc<dyn WasmModule> { Arc::new(runtime) })
 		},
 		#[cfg(feature = "wasmtime")]
-		WasmExecutionMethod::Compiled => sc_executor_wasmtime::create_runtime(
+		WasmExecutionMethod::Compiled => sc_executor_wasmtime::create_runtime::<H>(
 			blob,
 			sc_executor_wasmtime::Config {
 				heap_pages,
@@ -327,7 +328,6 @@ pub fn create_wasm_runtime_with_code(
 					parallel_compilation: true,
 				},
 			},
-			host_functions,
 		)
 		.map(|runtime| -> Arc<dyn WasmModule> { Arc::new(runtime) }),
 	}
@@ -392,16 +392,18 @@ pub fn read_embedded_version(blob: &RuntimeBlob) -> Result<Option<RuntimeVersion
 	}
 }
 
-fn create_versioned_wasm_runtime(
+fn create_versioned_wasm_runtime<H>(
 	code: &[u8],
 	ext: &mut dyn Externalities,
 	wasm_method: WasmExecutionMethod,
 	heap_pages: u64,
-	host_functions: Vec<&'static dyn Function>,
 	allow_missing_func_imports: bool,
 	max_instances: usize,
 	cache_path: Option<&Path>,
-) -> Result<VersionedRuntime, WasmError> {
+) -> Result<VersionedRuntime, WasmError>
+where
+	H: HostFunctions,
+{
 	// The incoming code may be actually compressed. We decompress it here and then work with
 	// the uncompressed code from now on.
 	let blob = sc_executor_common::runtime_blob::RuntimeBlob::uncompress_if_needed(&code)?;
@@ -411,11 +413,10 @@ fn create_versioned_wasm_runtime(
 	// runtime.
 	let mut version: Option<_> = read_embedded_version(&blob)?;
 
-	let runtime = create_wasm_runtime_with_code(
+	let runtime = create_wasm_runtime_with_code::<H>(
 		wasm_method,
 		heap_pages,
 		blob,
-		host_functions,
 		allow_missing_func_imports,
 		cache_path,
 	)?;

substrate/client/executor/wasmi/Cargo.toml

@@ -19,7 +19,7 @@ wasmi = "0.9.1"
 codec = { package = "parity-scale-codec", version = "2.0.0" }
 sc-executor-common = { version = "0.10.0-dev", path = "../common" }
 sc-allocator = { version = "4.1.0-dev", path = "../../allocator" }
-sp-wasm-interface = { version = "4.0.0", path = "../../../primitives/wasm-interface" }
-sp-runtime-interface = { version = "4.0.0", path = "../../../primitives/runtime-interface" }
+sp-wasm-interface = { version = "4.1.0-dev", path = "../../../primitives/wasm-interface" }
+sp-runtime-interface = { version = "4.1.0-dev", path = "../../../primitives/runtime-interface" }
 sp-core = { version = "4.1.0-dev", path = "../../../primitives/core" }
 scoped-tls = "1.0"

substrate/client/executor/wasmtime/Cargo.toml

@@ -19,8 +19,8 @@ log = "0.4.8"
 parity-wasm = "0.42.0"
 codec = { package = "parity-scale-codec", version = "2.0.0" }
 sc-executor-common = { version = "0.10.0-dev", path = "../common" }
-sp-wasm-interface = { version = "4.0.0", path = "../../../primitives/wasm-interface" }
-sp-runtime-interface = { version = "4.0.0", path = "../../../primitives/runtime-interface" }
+sp-wasm-interface = { version = "4.1.0-dev", path = "../../../primitives/wasm-interface", features = ["wasmtime"] }
+sp-runtime-interface = { version = "4.1.0-dev", path = "../../../primitives/runtime-interface" }
 sp-core = { version = "4.1.0-dev", path = "../../../primitives/core" }
 sc-allocator = { version = "4.1.0-dev", path = "../../allocator" }
 wasmtime = { version = "0.31.0", default-features = false, features = [

substrate/client/executor/wasmtime/src/host.rs

@@ -62,11 +62,11 @@ impl HostState {
 /// A `HostContext` implements `FunctionContext` for making host calls from a Wasmtime
 /// runtime. The `HostContext` exists only for the lifetime of the call and borrows state from
 /// a longer-living `HostState`.
-pub(crate) struct HostContext<'a, 'b> {
-	pub(crate) caller: &'a mut Caller<'b, StoreData>,
+pub(crate) struct HostContext<'a> {
+	pub(crate) caller: Caller<'a, StoreData>,
 }
 
-impl<'a, 'b> HostContext<'a, 'b> {
+impl<'a> HostContext<'a> {
 	fn host_state(&self) -> &HostState {
 		self.caller
 			.data()
@@ -98,7 +98,7 @@ impl<'a, 'b> HostContext<'a, 'b> {
 	}
 }
 
-impl<'a, 'b> sp_wasm_interface::FunctionContext for HostContext<'a, 'b> {
+impl<'a> sp_wasm_interface::FunctionContext for HostContext<'a> {
 	fn read_memory_into(
 		&self,
 		address: Pointer<u8>,
@@ -136,7 +136,7 @@ impl<'a, 'b> sp_wasm_interface::FunctionContext for HostContext<'a, 'b> {
 	}
 }
 
-impl<'a, 'b> Sandbox for HostContext<'a, 'b> {
+impl<'a> Sandbox for HostContext<'a> {
 	fn memory_get(
 		&mut self,
 		memory_id: MemoryId,
@@ -320,12 +320,12 @@ impl<'a, 'b> Sandbox for HostContext<'a, 'b> {
 	}
 }
 
-struct SandboxContext<'a, 'b, 'c> {
-	host_context: &'a mut HostContext<'b, 'c>,
+struct SandboxContext<'a, 'b> {
+	host_context: &'a mut HostContext<'b>,
 	dispatch_thunk: Func,
 }
 
-impl<'a, 'b, 'c> sandbox::SandboxContext for SandboxContext<'a, 'b, 'c> {
+impl<'a, 'b> sandbox::SandboxContext for SandboxContext<'a, 'b> {
 	fn invoke(
 		&mut self,
 		invoke_args_ptr: Pointer<u8>,

substrate/client/executor/wasmtime/src/imports.rs

@@ -19,14 +19,11 @@
 use crate::{
 	host::HostContext,
 	runtime::{Store, StoreData},
-	util,
 };
 use sc_executor_common::error::WasmError;
-use sp_wasm_interface::{Function, ValueType};
-use std::{any::Any, convert::TryInto};
-use wasmtime::{
-	Caller, Extern, ExternType, Func, FuncType, ImportType, Memory, MemoryType, Module, Trap, Val,
-};
+use sp_wasm_interface::{FunctionContext, HostFunctions};
+use std::{collections::HashMap, convert::TryInto};
+use wasmtime::{Extern, ExternType, Func, FuncType, ImportType, Memory, MemoryType, Module, Trap};
 
 pub struct Imports {
 	/// Contains the index into `externs` where the memory import is stored if any. `None` if there
@@ -37,16 +34,19 @@ pub struct Imports {
 
 /// Goes over all imports of a module and prepares a vector of `Extern`s that can be used for
 /// instantiation of the module. Returns an error if there are imports that cannot be satisfied.
-pub(crate) fn resolve_imports(
+pub(crate) fn resolve_imports<H>(
 	store: &mut Store,
 	module: &Module,
-	host_functions: &[&'static dyn Function],
 	heap_pages: u64,
 	allow_missing_func_imports: bool,
-) -> Result<Imports, WasmError> {
+) -> Result<Imports, WasmError>
+where
+	H: HostFunctions,
+{
 	let mut externs = vec![];
 	let mut memory_import_index = None;
-	for import_ty in module.imports() {
+	let mut pending_func_imports = HashMap::new();
+	for (index, import_ty) in module.imports().enumerate() {
 		let name = import_name(&import_ty)?;
 
 		if import_ty.module() != "env" {
@@ -57,19 +57,89 @@ pub(crate) fn resolve_imports(
 			)))
 		}
 
-		let resolved = match name {
-			"memory" => {
-				memory_import_index = Some(externs.len());
-				resolve_memory_import(store, &import_ty, heap_pages)?
+		if name == "memory" {
+			memory_import_index = Some(index);
+			externs.push((index, resolve_memory_import(store, &import_ty, heap_pages)?));
+			continue
+		}
+
+		match import_ty.ty() {
+			ExternType::Func(func_ty) => {
+				pending_func_imports.insert(name.to_owned(), (index, import_ty, func_ty));
 			},
 			_ =>
-				resolve_func_import(store, &import_ty, host_functions, allow_missing_func_imports)?,
+				return Err(WasmError::Other(format!(
+					"host doesn't provide any non function imports besides 'memory': {}:{}",
+					import_ty.module(),
+					name,
+				))),
 		};
-		externs.push(resolved);
 	}
+
+	let mut registry = Registry { store, externs, pending_func_imports };
+
+	H::register_static(&mut registry)?;
+	let mut externs = registry.externs;
+
+	if !registry.pending_func_imports.is_empty() {
+		if allow_missing_func_imports {
+			for (_, (index, import_ty, func_ty)) in registry.pending_func_imports {
+				externs.push((
+					index,
+					MissingHostFuncHandler::new(&import_ty)?.into_extern(store, &func_ty),
+				));
+			}
+		} else {
+			let mut names = Vec::new();
+			for (name, (_, import_ty, _)) in registry.pending_func_imports {
+				names.push(format!("'{}:{}'", import_ty.module(), name));
+			}
+			let names = names.join(", ");
+			return Err(WasmError::Other(format!(
+				"runtime requires function imports which are not present on the host: {}",
+				names
+			)))
+		}
+	}
+
+	externs.sort_unstable_by_key(|&(index, _)| index);
+	let externs = externs.into_iter().map(|(_, ext)| ext).collect();
+
 	Ok(Imports { memory_import_index, externs })
 }
 
+struct Registry<'a, 'b> {
+	store: &'a mut Store,
+	externs: Vec<(usize, Extern)>,
+	pending_func_imports: HashMap<String, (usize, ImportType<'b>, FuncType)>,
+}
+
+impl<'a, 'b> sp_wasm_interface::HostFunctionRegistry for Registry<'a, 'b> {
+	type State = StoreData;
+	type Error = WasmError;
+	type FunctionContext = HostContext<'a>;
+
+	fn with_function_context<R>(
+		caller: wasmtime::Caller<Self::State>,
+		callback: impl FnOnce(&mut dyn FunctionContext) -> R,
+	) -> R {
+		callback(&mut HostContext { caller })
+	}
+
+	fn register_static<Params, Results>(
+		&mut self,
+		fn_name: &str,
+		func: impl wasmtime::IntoFunc<Self::State, Params, Results>,
+	) -> Result<(), Self::Error> {
+		if let Some((index, _, _)) = self.pending_func_imports.remove(fn_name) {
+			let func = Func::wrap(&mut *self.store, func);
+			self.externs.push((index, Extern::Func(func)));
+		}
+
+		Ok(())
+	}
+}
+
 /// When the module linking proposal is supported the import's name can be `None`.
 /// Because we are not using this proposal we could safely unwrap the name.
 /// However, we opt for an error in order to avoid panics at all costs.
@@ -139,115 +209,6 @@ fn resolve_memory_import(
 	Ok(Extern::Memory(memory))
 }
 
-fn resolve_func_import(
-	store: &mut Store,
-	import_ty: &ImportType,
-	host_functions: &[&'static dyn Function],
-	allow_missing_func_imports: bool,
-) -> Result<Extern, WasmError> {
-	let name = import_name(&import_ty)?;
-
-	let func_ty = match import_ty.ty() {
-		ExternType::Func(func_ty) => func_ty,
-		_ =>
-			return Err(WasmError::Other(format!(
-				"host doesn't provide any non function imports besides 'memory': {}:{}",
-				import_ty.module(),
-				name,
-			))),
-	};
-
-	let host_func = match host_functions.iter().find(|host_func| host_func.name() == name) {
-		Some(host_func) => host_func,
-		None if allow_missing_func_imports =>
-			return Ok(MissingHostFuncHandler::new(import_ty)?.into_extern(store, &func_ty)),
-		None =>
-			return Err(WasmError::Other(format!(
-				"host doesn't provide such function: {}:{}",
-				import_ty.module(),
-				name,
-			))),
-	};
-	if &func_ty != &wasmtime_func_sig(*host_func) {
-		return Err(WasmError::Other(format!(
-			"signature mismatch for: {}:{}",
-			import_ty.module(),
-			name,
-		)))
-	}
-
-	Ok(HostFuncHandler::new(*host_func).into_extern(store))
-}
-
-/// This structure implements `Callable` and acts as a bridge between wasmtime and
-/// substrate host functions.
-struct HostFuncHandler {
-	host_func: &'static dyn Function,
-}
-
-fn call_static<'a>(
-	static_func: &'static dyn Function,
-	wasmtime_params: &[Val],
-	wasmtime_results: &mut [Val],
-	mut caller: Caller<'a, StoreData>,
-) -> Result<(), wasmtime::Trap> {
-	let unwind_result = {
-		let mut host_ctx = HostContext { caller: &mut caller };
-
-		// `from_wasmtime_val` panics if it encounters a value that doesn't fit into the values
-		// available in substrate.
-		//
-		// This, however, cannot happen since the signature of this function is created from
-		// a `dyn Function` signature of which cannot have a non substrate value by definition.
-		let mut params = wasmtime_params.iter().cloned().map(util::from_wasmtime_val);
-
-		std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
-			static_func.execute(&mut host_ctx, &mut params)
-		}))
-	};
-
-	let execution_result = match unwind_result {
-		Ok(execution_result) => execution_result,
-		Err(err) => return Err(Trap::new(stringify_panic_payload(err))),
-	};
-
-	match execution_result {
-		Ok(Some(ret_val)) => {
-			debug_assert!(
-				wasmtime_results.len() == 1,
-				"wasmtime function signature, therefore the number of results, should always \
-				correspond to the number of results returned by the host function",
-			);
-			wasmtime_results[0] = util::into_wasmtime_val(ret_val);
-			Ok(())
-		},
-		Ok(None) => {
-			debug_assert!(
-				wasmtime_results.len() == 0,
-				"wasmtime function signature, therefore the number of results, should always \
-				correspond to the number of results returned by the host function",
-			);
-			Ok(())
-		},
-		Err(msg) => Err(Trap::new(msg)),
-	}
-}
-
-impl HostFuncHandler {
-	fn new(host_func: &'static dyn Function) -> Self {
-		Self { host_func }
-	}
-
-	fn into_extern(self, store: &mut Store) -> Extern {
-		let host_func = self.host_func;
-		let func_ty = wasmtime_func_sig(self.host_func);
-		let func = Func::new(store, func_ty, move |caller, params, result| {
-			call_static(host_func, params, result, caller)
-		});
-		Extern::Func(func)
-	}
-}
-
 /// A `Callable` handler for missing functions.
 struct MissingHostFuncHandler {
 	module: String,
@@ -270,33 +231,3 @@ impl MissingHostFuncHandler {
 		Extern::Func(func)
 	}
 }
-
-fn wasmtime_func_sig(func: &dyn Function) -> wasmtime::FuncType {
-	let signature = func.signature();
-	let params = signature.args.iter().cloned().map(into_wasmtime_val_type);
-
-	let results = signature.return_value.iter().cloned().map(into_wasmtime_val_type);
-
-	wasmtime::FuncType::new(params, results)
-}
-
-fn into_wasmtime_val_type(val_ty: ValueType) -> wasmtime::ValType {
-	match val_ty {
-		ValueType::I32 => wasmtime::ValType::I32,
-		ValueType::I64 => wasmtime::ValType::I64,
-		ValueType::F32 => wasmtime::ValType::F32,
-		ValueType::F64 => wasmtime::ValType::F64,
-	}
-}
-
-/// Attempt to convert a opaque panic payload to a string.
-fn stringify_panic_payload(payload: Box<dyn Any + Send + 'static>) -> String {
-	match payload.downcast::<&'static str>() {
-		Ok(msg) => msg.to_string(),
-		Err(payload) => match payload.downcast::<String>() {
-			Ok(msg) => *msg,
-			// At least we tried...
-			Err(_) => "Box<Any>".to_string(),
-		},
-	}
-}

substrate/client/executor/wasmtime/src/instance_wrapper.rs

@@ -24,7 +24,7 @@ use sc_executor_common::{
 	error::{Error, Result},
 	wasm_runtime::InvokeMethod,
 };
-use sp_wasm_interface::{Function, Pointer, Value, WordSize};
+use sp_wasm_interface::{HostFunctions, Pointer, Value, WordSize};
 use wasmtime::{
 	AsContext, AsContextMut, Extern, Func, Global, Instance, Memory, Module, Table, Val,
 };
@@ -138,13 +138,15 @@ fn extern_func(extern_: &Extern) -> Option<&Func> {
 
 impl InstanceWrapper {
 	/// Create a new instance wrapper from the given wasm module.
-	pub fn new(
+	pub fn new<H>(
 		module: &Module,
-		host_functions: &[&'static dyn Function],
 		heap_pages: u64,
 		allow_missing_func_imports: bool,
 		max_memory_size: Option<usize>,
-	) -> Result<Self> {
+	) -> Result<Self>
+	where
+		H: HostFunctions,
+	{
 		let limits = if let Some(max_memory_size) = max_memory_size {
 			wasmtime::StoreLimitsBuilder::new().memory_size(max_memory_size).build()
 		} else {
@@ -161,10 +163,9 @@ impl InstanceWrapper {
 
 		// Scan all imports, find the matching host functions, and create stubs that adapt arguments
 		// and results.
-		let imports = crate::imports::resolve_imports(
+		let imports = crate::imports::resolve_imports::<H>(
 			&mut store,
 			module,
-			host_functions,
 			heap_pages,
 			allow_missing_func_imports,
 		)?;

substrate/client/executor/wasmtime/src/runtime.rs

@@ -23,6 +23,7 @@ use crate::{
 	instance_wrapper::{EntryPoint, InstanceWrapper},
 	util,
 };
+use core::marker::PhantomData;
 
 use sc_allocator::FreeingBumpHeapAllocator;
 use sc_executor_common::{
@@ -33,7 +34,7 @@ use sc_executor_common::{
 	wasm_runtime::{InvokeMethod, WasmInstance, WasmModule},
 };
 use sp_runtime_interface::unpack_ptr_and_len;
-use sp_wasm_interface::{Function, Pointer, Value, WordSize};
+use sp_wasm_interface::{HostFunctions, Pointer, Value, WordSize};
 use std::{
 	path::{Path, PathBuf},
 	sync::{
@@ -79,29 +80,31 @@ impl StoreData {
 
 pub(crate) type Store = wasmtime::Store<StoreData>;
 
-enum Strategy {
+enum Strategy<H> {
 	FastInstanceReuse {
 		instance_wrapper: InstanceWrapper,
 		globals_snapshot: GlobalsSnapshot<wasmtime::Global>,
 		data_segments_snapshot: Arc<DataSegmentsSnapshot>,
 		heap_base: u32,
 	},
-	RecreateInstance(InstanceCreator),
+	RecreateInstance(InstanceCreator<H>),
 }
 
-struct InstanceCreator {
+struct InstanceCreator<H> {
 	module: Arc<wasmtime::Module>,
-	host_functions: Vec<&'static dyn Function>,
 	heap_pages: u64,
 	allow_missing_func_imports: bool,
 	max_memory_size: Option<usize>,
+	phantom: PhantomData<H>,
 }
 
-impl InstanceCreator {
+impl<H> InstanceCreator<H>
+where
+	H: HostFunctions,
+{
 	fn instantiate(&mut self) -> Result<InstanceWrapper> {
-		InstanceWrapper::new(
+		InstanceWrapper::new::<H>(
 			&*self.module,
-			&self.host_functions,
 			self.heap_pages,
 			self.allow_missing_func_imports,
 			self.max_memory_size,
@@ -141,19 +144,21 @@ struct InstanceSnapshotData {
 
 /// A `WasmModule` implementation using wasmtime to compile the runtime module to machine code
 /// and execute the compiled code.
-pub struct WasmtimeRuntime {
+pub struct WasmtimeRuntime<H> {
 	module: Arc<wasmtime::Module>,
 	snapshot_data: Option<InstanceSnapshotData>,
 	config: Config,
-	host_functions: Vec<&'static dyn Function>,
+	phantom: PhantomData<H>,
 }
 
-impl WasmModule for WasmtimeRuntime {
+impl<H> WasmModule for WasmtimeRuntime<H>
+where
+	H: HostFunctions,
+{
 	fn new_instance(&self) -> Result<Box<dyn WasmInstance>> {
 		let strategy = if let Some(ref snapshot_data) = self.snapshot_data {
-			let mut instance_wrapper = InstanceWrapper::new(
+			let mut instance_wrapper = InstanceWrapper::new::<H>(
 				&self.module,
-				&self.host_functions,
 				self.config.heap_pages,
 				self.config.allow_missing_func_imports,
 				self.config.max_memory_size,
@@ -169,19 +174,19 @@ impl WasmModule for WasmtimeRuntime {
 				&mut InstanceGlobals { instance: &mut instance_wrapper },
 			);
 
-			Strategy::FastInstanceReuse {
+			Strategy::<H>::FastInstanceReuse {
 				instance_wrapper,
 				globals_snapshot,
 				data_segments_snapshot: snapshot_data.data_segments_snapshot.clone(),
 				heap_base,
 			}
 		} else {
-			Strategy::RecreateInstance(InstanceCreator {
+			Strategy::<H>::RecreateInstance(InstanceCreator {
 				module: self.module.clone(),
-				host_functions: self.host_functions.clone(),
 				heap_pages: self.config.heap_pages,
 				allow_missing_func_imports: self.config.allow_missing_func_imports,
 				max_memory_size: self.config.max_memory_size,
+				phantom: PhantomData,
 			})
 		};
 
@@ -191,11 +196,14 @@ impl WasmModule for WasmtimeRuntime {
 
 /// A `WasmInstance` implementation that reuses compiled module and spawns instances
 /// to execute the compiled code.
-pub struct WasmtimeInstance {
-	strategy: Strategy,
+pub struct WasmtimeInstance<H> {
+	strategy: Strategy<H>,
 }
 
-impl WasmInstance for WasmtimeInstance {
+impl<H> WasmInstance for WasmtimeInstance<H>
+where
+	H: HostFunctions,
+{
 	fn call(&mut self, method: InvokeMethod, data: &[u8]) -> Result<Vec<u8>> {
 		match &mut self.strategy {
 			Strategy::FastInstanceReuse {
@@ -483,13 +491,18 @@ enum CodeSupplyMode<'a> {
 
 /// Create a new `WasmtimeRuntime` given the code. This function performs translation from Wasm to
 /// machine code, which can be computationally heavy.
-pub fn create_runtime(
+///
+/// The `H` generic parameter is used to statically pass a set of host functions which are exposed
+/// to the runtime.
+pub fn create_runtime<H>(
 	blob: RuntimeBlob,
 	config: Config,
-	host_functions: Vec<&'static dyn Function>,
-) -> std::result::Result<WasmtimeRuntime, WasmError> {
+) -> std::result::Result<WasmtimeRuntime<H>, WasmError>
+where
+	H: HostFunctions,
+{
 	// SAFETY: this is safe because it doesn't use `CodeSupplyMode::Artifact`.
-	unsafe { do_create_runtime(CodeSupplyMode::Verbatim { blob }, config, host_functions) }
+	unsafe { do_create_runtime::<H>(CodeSupplyMode::Verbatim { blob }, config) }
 }
 
 /// The same as [`create_runtime`] but takes a precompiled artifact, which makes this function
@@ -503,23 +516,27 @@ pub fn create_runtime(
 ///
 /// It is ok though if the `compiled_artifact` was created by code of another version or with
 /// different configuration flags. In such case the caller will receive an `Err` deterministically.
-pub unsafe fn create_runtime_from_artifact(
+pub unsafe fn create_runtime_from_artifact<H>(
 	compiled_artifact: &[u8],
 	config: Config,
-	host_functions: Vec<&'static dyn Function>,
-) -> std::result::Result<WasmtimeRuntime, WasmError> {
-	do_create_runtime(CodeSupplyMode::Artifact { compiled_artifact }, config, host_functions)
+) -> std::result::Result<WasmtimeRuntime<H>, WasmError>
+where
+	H: HostFunctions,
+{
+	do_create_runtime::<H>(CodeSupplyMode::Artifact { compiled_artifact }, config)
 }
 
 /// # Safety
 ///
 /// This is only unsafe if called with [`CodeSupplyMode::Artifact`]. See
 /// [`create_runtime_from_artifact`] to get more details.
-unsafe fn do_create_runtime(
+unsafe fn do_create_runtime<H>(
 	code_supply_mode: CodeSupplyMode<'_>,
 	config: Config,
-	host_functions: Vec<&'static dyn Function>,
-) -> std::result::Result<WasmtimeRuntime, WasmError> {
+) -> std::result::Result<WasmtimeRuntime<H>, WasmError>
+where
+	H: HostFunctions,
+{
 	// Create the engine, store and finally the module from the given code.
 	let mut wasmtime_config = common_config(&config.semantics)?;
 	if let Some(ref cache_path) = config.cache_path {
@@ -566,7 +583,7 @@ unsafe fn do_create_runtime(
 		},
 	};
 
-	Ok(WasmtimeRuntime { module: Arc::new(module), snapshot_data, config, host_functions })
+	Ok(WasmtimeRuntime { module: Arc::new(module), snapshot_data, config, phantom: PhantomData })
 }
 
 fn instrument(

substrate/client/executor/wasmtime/src/tests.rs

@@ -78,7 +78,7 @@ impl RuntimeBuilder {
 				.expect("failed to create a runtime blob out of test runtime")
 		};
 
-		let rt = crate::create_runtime(
+		let rt = crate::create_runtime::<HostFunctions>(
 			blob,
 			crate::Config {
 				heap_pages: self.heap_pages,
@@ -98,10 +98,6 @@ impl RuntimeBuilder {
 					parallel_compilation: true,
 				},
 			},
-			{
-				use sp_wasm_interface::HostFunctions as _;
-				HostFunctions::host_functions()
-			},
 		)
 		.expect("cannot create runtime");
 
@@ -316,9 +312,7 @@ fn test_max_memory_pages() {
 #[cfg_attr(build_type = "debug", ignore)]
 #[test]
 fn test_instances_without_reuse_are_not_leaked() {
-	use sp_wasm_interface::HostFunctions;
-
-	let runtime = crate::create_runtime(
+	let runtime = crate::create_runtime::<HostFunctions>(
 		RuntimeBlob::uncompress_if_needed(&wasm_binary_unwrap()[..]).unwrap(),
 		crate::Config {
 			heap_pages: 2048,
@@ -332,7 +326,6 @@ fn test_instances_without_reuse_are_not_leaked() {
 				parallel_compilation: true,
 			},
 		},
-		sp_io::SubstrateHostFunctions::host_functions(),
 	)
 	.unwrap();