Make interpreter async (#130)

Co-authored-by: folex <0xdxdy@gmail.com>
Co-authored-by: Pavel Murygin <pavel.murygin@gmail.com>

crates/data-store/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "avm-data-store"
+version = "0.1.0"
+authors = ["Fluence Labs"]
+edition = "2018"
+license = "Apache-2.0"
+
+[lib]
+name = "avm_data_store"
+path = "src/lib.rs"

crates/data-store/src/lib.rs

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2021 Fluence Labs Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/// This trait should be used to persist prev_data between successive calls of an interpreter o.
+pub trait DataStore<E> {
+    fn initialize(&mut self) -> Result<(), E>;
+
+    fn store_data(&mut self, data: &[u8], key: &str) -> Result<(), E>;
+
+    fn read_data(&mut self, key: &str) -> Result<Vec<u8>, E>;
+
+    fn cleanup_data(&mut self, key: &str) -> Result<(), E>;
+}