Integrated trie benchmark: part 2 (#5702)

substrate/bin/node/bench/src/simple_trie.rs

@@ -0,0 +1,68 @@
+// 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/>.
+
+use std::{collections::HashMap, sync::Arc};
+
+use kvdb::KeyValueDB;
+use node_primitives::Hash;
+use sp_trie::DBValue;
+use hash_db::{HashDB, AsHashDB, Prefix, Hasher as _};
+
+pub type Hasher = sp_core::Blake2Hasher;
+
+/// Immutable generated trie database with root.
+pub struct SimpleTrie<'a> {
+	pub db: Arc<dyn KeyValueDB>,
+	pub overlay: &'a mut HashMap<Vec<u8>, Option<Vec<u8>>>,
+}
+
+impl<'a> AsHashDB<Hasher, DBValue> for SimpleTrie<'a> {
+	fn as_hash_db(&self) -> &dyn hash_db::HashDB<Hasher, DBValue> { &*self }
+
+	fn as_hash_db_mut<'b>(&'b mut self) -> &'b mut (dyn HashDB<Hasher, DBValue> + 'b) {
+		&mut *self
+	}
+}
+
+impl<'a> HashDB<Hasher, DBValue> for SimpleTrie<'a> {
+	fn get(&self, key: &Hash, prefix: Prefix) -> Option<DBValue> {
+		let key = sp_trie::prefixed_key::<Hasher>(key, prefix);
+		if let Some(value) = self.overlay.get(&key) {
+			return value.clone();
+		}
+		self.db.get(0, &key).expect("Database backend error")
+	}
+
+	fn contains(&self, hash: &Hash, prefix: Prefix) -> bool {
+		self.get(hash, prefix).is_some()
+	}
+
+	fn insert(&mut self, prefix: Prefix, value: &[u8]) -> Hash {
+		let key = Hasher::hash(value);
+		self.emplace(key, prefix, value.to_vec());
+		key
+	}
+
+	fn emplace(&mut self, key: Hash, prefix: Prefix, value: DBValue) {
+		let key = sp_trie::prefixed_key::<Hasher>(&key, prefix);
+		self.overlay.insert(key, Some(value));
+	}
+
+	fn remove(&mut self, key: &Hash, prefix: Prefix) {
+		let key = sp_trie::prefixed_key::<Hasher>(key, prefix);
+		self.overlay.insert(key, None);
+	}
+}