Replace runtime cache with synchronous clone

core/executor/src/lib.rs

@@ -35,11 +35,13 @@ mod wasm_executor;
 mod native_executor;
 mod sandbox;
 mod allocator;
+mod wasm_runtimes_cache;
 
 pub mod error;
 pub use wasmi;
 pub use wasm_executor::WasmExecutor;
 pub use native_executor::{with_native_environment, NativeExecutor, NativeExecutionDispatch};
+pub use wasm_runtimes_cache::RuntimesCache;
 pub use state_machine::Externalities;
 pub use runtime_version::{RuntimeVersion, NativeVersion};
 pub use parity_codec::Codec;

core/executor/src/native_executor.rs

@@ -14,86 +14,23 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
-use std::{borrow::BorrowMut, result, cell::{RefMut, RefCell}};
+use std::{result, cell::RefCell, panic::UnwindSafe};
 use crate::error::{Error, Result};
 use state_machine::{CodeExecutor, Externalities};
 use crate::wasm_executor::WasmExecutor;
-use wasmi::{Module as WasmModule, ModuleRef as WasmModuleInstanceRef};
 use runtime_version::{NativeVersion, RuntimeVersion};
-use std::{collections::HashMap, panic::UnwindSafe};
 use parity_codec::{Decode, Encode};
 use crate::RuntimeInfo;
 use primitives::{Blake2Hasher, NativeOrEncoded};
-use primitives::storage::well_known_keys;
 use log::trace;
 
-/// Default num of pages for the heap
-const DEFAULT_HEAP_PAGES: u64 = 1024;
+use crate::RuntimesCache;
 
 // For the internal Runtime Cache:
 // Is it compatible enough to run this natively or do we need to fall back on the WasmModule
 
-enum RuntimePreproc {
-	InvalidCode,
-	ValidCode(WasmModuleInstanceRef, Option<RuntimeVersion>),
-}
-
-type CacheType = HashMap<[u8; 32], RuntimePreproc>;
-
 thread_local! {
-	static RUNTIMES_CACHE: RefCell<CacheType> = RefCell::new(HashMap::new());
-}
-
-/// fetch a runtime version from the cache or if there is no cached version yet, create
-/// the runtime version entry for `code`, determines whether `Compatibility::IsCompatible`
-/// can be used by comparing returned RuntimeVersion to `ref_version`
-fn fetch_cached_runtime_version<'a, E: Externalities<Blake2Hasher>>(
-	wasm_executor: &WasmExecutor,
-	cache: &'a mut RefMut<CacheType>,
-	ext: &mut E,
-	default_heap_pages: Option<u64>,
-) -> Result<(&'a WasmModuleInstanceRef, &'a Option<RuntimeVersion>)> {
-	let code_hash = match ext.original_storage_hash(well_known_keys::CODE) {
-		Some(code_hash) => code_hash,
-		None => return Err(Error::InvalidCode(vec![])),
-	};
-
-	let maybe_runtime_preproc = cache.borrow_mut().entry(code_hash.into())
-		.or_insert_with(|| {
-			let code = match ext.original_storage(well_known_keys::CODE) {
-				Some(code) => code,
-				None => return RuntimePreproc::InvalidCode,
-			};
-			let heap_pages = ext.storage(well_known_keys::HEAP_PAGES)
-				.and_then(|pages| u64::decode(&mut &pages[..]))
-				.or(default_heap_pages)
-				.unwrap_or(DEFAULT_HEAP_PAGES);
-			match WasmModule::from_buffer(code)
-				.map_err(|_| Error::InvalidCode(vec![]))
-				.and_then(|module| wasm_executor.prepare_module(ext, heap_pages as usize, &module))
-			{
-				Ok(module) => {
-					let version = wasm_executor.call_in_wasm_module(ext, &module, "Core_version", &[])
-						.ok()
-						.and_then(|v| RuntimeVersion::decode(&mut v.as_slice()));
-					RuntimePreproc::ValidCode(module, version)
-				}
-				Err(e) => {
-					trace!(target: "executor", "Invalid code presented to executor ({:?})", e);
-					RuntimePreproc::InvalidCode
-				}
-			}
-		});
-
-	match maybe_runtime_preproc {
-		RuntimePreproc::InvalidCode => {
-			let code = ext.original_storage(well_known_keys::CODE).unwrap_or(vec![]);
-			Err(Error::InvalidCode(code))
-		},
-		RuntimePreproc::ValidCode(m, v) => {
-			Ok((m, v))
-		}
-	}
+	static RUNTIMES_CACHE: RefCell<RuntimesCache> = RefCell::new(RuntimesCache::new());
 }
 
 fn safe_call<F, U>(f: F) -> Result<U>
@@ -176,10 +113,11 @@ impl<D: NativeExecutionDispatch> RuntimeInfo for NativeExecutor<D> {
 		&self,
 		ext: &mut E,
 	) -> Option<RuntimeVersion> {
-		RUNTIMES_CACHE.with(|c|
-			fetch_cached_runtime_version(&self.fallback, &mut c.borrow_mut(), ext, self.default_heap_pages)
+		RUNTIMES_CACHE.with(|cache| {
+			let cache = &mut cache.borrow_mut();
+			cache.fetch_runtime(&self.fallback, ext, self.default_heap_pages, None)
 				.ok()?.1.clone()
-		)
+		})
 	}
 }
 
@@ -198,13 +136,15 @@ impl<D: NativeExecutionDispatch> CodeExecutor<Blake2Hasher> for NativeExecutor<D
 		data: &[u8],
 		use_native: bool,
 		native_call: Option<NC>,
-	) -> (Result<NativeOrEncoded<R>>, bool) {
-		RUNTIMES_CACHE.with(|c| {
-			let mut c = c.borrow_mut();
-			let (module, onchain_version) = match fetch_cached_runtime_version(
-				&self.fallback, &mut c, ext, self.default_heap_pages) {
-					Ok((module, onchain_version)) => (module, onchain_version),
-					Err(e) => return (Err(e), false),
+	) -> (Result<NativeOrEncoded<R>>, bool){
+		RUNTIMES_CACHE.with(|cache| {
+			let cache = &mut cache.borrow_mut();
+			let (module, onchain_version) = match cache.fetch_runtime(
+				&self.fallback, ext, self.default_heap_pages,
+				Some(&self.native_version.runtime_version)
+			) {
+				Ok((module, onchain_version)) => (module, onchain_version),
+				Err(e) => return (Err(e), false),
 			};
 			match (
 				use_native,
@@ -224,15 +164,15 @@ impl<D: NativeExecutionDispatch> CodeExecutor<Blake2Hasher> for NativeExecutor<D
 					);
 					(
 						self.fallback
-							.call_in_wasm_module(ext, module, method, data)
+							.call_in_wasm_module(ext, &module, method, data)
 							.map(NativeOrEncoded::Encoded),
 						false
 					)
 				}
 				(false, _, _) => {
 					(
 						self.fallback
-							.call_in_wasm_module(ext, module, method, data)
+							.call_in_wasm_module(ext, &module, method, data)
 							.map(NativeOrEncoded::Encoded),
 						false
 					)

core/executor/src/wasm_runtimes_cache.rs

@@ -0,0 +1,185 @@
+// Copyright 2017-2019 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/>.
+
+//! Implements a cache for pre-created Wasm runtime module instances.
+
+use crate::error::{Error, Result};
+use crate::wasm_executor::WasmExecutor;
+use log::trace;
+use parity_codec::Decode;
+use primitives::Blake2Hasher;
+use primitives::storage::well_known_keys;
+use runtime_version::RuntimeVersion;
+use state_machine::Externalities;
+use wasmi::{Module as WasmModule, ModuleRef as WasmModuleInstanceRef};
+
+#[derive(Clone)]
+enum RuntimePreproc {
+	InvalidCode,
+	ValidCode(WasmModuleInstanceRef, Option<RuntimeVersion>),
+}
+
+#[derive(Debug)]
+enum Action {
+	Clone,
+	Invalid,
+	Reset,
+}
+
+/// Default num of pages for the heap
+const DEFAULT_HEAP_PAGES: u64 = 1024;
+
+/// Cache a runtime instances. When an instance is requested,
+/// the template instance is cloned synchronously.
+pub struct RuntimesCache {
+	template_instance: Option<RuntimePreproc>,
+}
+
+impl RuntimesCache {
+	/// Creates a new instance of a runtimes cache.
+	pub fn new() -> RuntimesCache {
+		RuntimesCache {
+			template_instance: None,
+		}
+	}
+
+	/// Fetch a runtime instance from a template instance. If there is no template
+	/// instance yet, initialization happens automatically.
+	///
+	/// # Parameters
+	///
+	/// `wasm_executor`- Rust wasm executor. Executes the provided code in a
+	/// sandboxed Wasm runtime.
+	///
+	/// `ext` - Externalities to use for the runtime. This is used for setting
+	/// up an initial "template instance", which will be cloned when this method
+	/// is called. The parameter is only needed to call into he Wasm module to
+	/// find out the `Core_version`.
+	///
+	/// `default_heap_pages` - Default number of 64KB pages to allocate for
+	/// Wasm execution. Defaults to `DEFAULT_HEAP_PAGES` if `None` is provided.
+	///
+	/// `maybe_requested_version` - If `Some(RuntimeVersion)` is provided the
+	/// template instance will be checked for compatibility. In case of
+	/// incompatibility the template instance will be reset.
+	///
+	/// # Return value
+	///
+	/// If no error occurred a `RuntimePreproc::ValidCode` is returned, containing
+	/// a wasmi `ModuleRef` with an optional `RuntimeVersion` (if the call
+	/// `Core_version` returned a version).
+	///
+	/// In case an error occurred `RuntimePreproc::InvalidCode` is returned with an
+	/// appropriate description.
+	pub fn fetch_runtime<E: Externalities<Blake2Hasher>>(
+		&mut self,
+		wasm_executor: &WasmExecutor,
+		ext: &mut E,
+		default_heap_pages: Option<u64>,
+		maybe_requested_version: Option<&RuntimeVersion>,
+	) -> Result<(WasmModuleInstanceRef, Option<RuntimeVersion>)> {
+		if let None = self.template_instance {
+			trace!(target: "runtimes_cache",
+				   "no template instance found, creating now.");
+			let template =
+				self.create_wasm_instance(wasm_executor, ext, default_heap_pages);
+			self.template_instance = Some(template);
+		}
+
+		let action = match maybe_requested_version {
+			None => Action::Clone,
+			Some(ref version) => {
+				match self.template_instance {
+					None => Action::Clone,
+					Some(RuntimePreproc::InvalidCode) => Action::Invalid,
+					Some(RuntimePreproc::ValidCode(_, None)) => Action::Reset,
+					Some(RuntimePreproc::ValidCode(_, Some(ref template_version))) => {
+						if template_version.can_call_with(&version) {
+							Action::Clone
+						} else {
+							trace!(target: "runtimes_cache",
+								   "resetting cache because new version received");
+							Action::Reset
+						}
+					},
+				}
+			},
+		};
+
+		let runtime_preproc = match action {
+			Action::Clone => {
+				self.template_instance
+					.clone()
+					.expect("if non-existent, template was created at beginning of function; qed")
+			},
+			Action::Reset => {
+				let new_template = self.create_wasm_instance(wasm_executor, ext, default_heap_pages);
+				self.template_instance = Some(new_template);
+				self.template_instance
+					.clone()
+					.expect("template was created right before; qed")
+			},
+			Action::Invalid => {
+				RuntimePreproc::InvalidCode
+			}
+		};
+
+		match runtime_preproc {
+			RuntimePreproc::InvalidCode => {
+				let code = ext.original_storage(well_known_keys::CODE).unwrap_or(vec![]);
+				Err(Error::InvalidCode(code))
+			},
+			RuntimePreproc::ValidCode(r, v) => {
+				Ok((r, v))
+			}
+		}
+	}
+
+	fn create_wasm_instance<E: Externalities<Blake2Hasher>>(
+		&self,
+		wasm_executor: &WasmExecutor,
+		ext: &mut E,
+		default_heap_pages: Option<u64>,
+	) -> RuntimePreproc {
+		let code = match ext.original_storage(well_known_keys::CODE) {
+			Some(code) => code,
+			None => return RuntimePreproc::InvalidCode,
+		};
+
+		let heap_pages = ext.storage(well_known_keys::HEAP_PAGES)
+			.and_then(|pages| u64::decode(&mut &pages[..]))
+			.or(default_heap_pages)
+			.unwrap_or(DEFAULT_HEAP_PAGES);
+
+		match WasmModule::from_buffer(code)
+			.map_err(|_| Error::InvalidCode(vec![]))
+			.and_then(|module| wasm_executor.prepare_module(ext, heap_pages as usize, &module))
+			{
+				Ok(module) => {
+					let version = wasm_executor.call_in_wasm_module(ext, &module, "Core_version", &[])
+						.ok()
+						.and_then(|v| {
+							RuntimeVersion::decode(&mut v.as_slice())
+						});
+					RuntimePreproc::ValidCode(module, version)
+				}
+				Err(e) => {
+					trace!(target: "runtimes_cache", "Invalid code presented to executor ({:?})", e);
+					RuntimePreproc::InvalidCode
+				}
+			}
+	}
+}