build: add mock storage (#40)

crates/committer/src/storage.rs

@@ -1,2 +1,3 @@
 pub(crate) mod errors;
+pub(crate) mod map_storage;
 pub(crate) mod storage_trait;

crates/committer/src/storage/map_storage.rs

@@ -0,0 +1,29 @@
+use std::collections::HashMap;
+
+use crate::storage::storage_trait::{Storage, StorageKey, StorageValue};
+
+pub(crate) struct MapStorage {
+    storage: HashMap<StorageKey, StorageValue>,
+}
+
+impl Storage for MapStorage {
+    fn get(&self, key: &StorageKey) -> Option<&StorageValue> {
+        self.storage.get(key)
+    }
+
+    fn set(&mut self, key: StorageKey, value: StorageValue) -> Option<StorageValue> {
+        self.storage.insert(key, value)
+    }
+
+    fn mget(&self, keys: &[StorageKey]) -> Vec<Option<&StorageValue>> {
+        keys.iter().map(|key| self.get(key)).collect::<Vec<_>>()
+    }
+
+    fn mset(&mut self, key_to_value: HashMap<StorageKey, StorageValue>) {
+        self.storage.extend(key_to_value);
+    }
+
+    fn delete(&mut self, key: &StorageKey) -> Option<StorageValue> {
+        self.storage.remove(key)
+    }
+}

crates/committer/src/storage/storage_trait.rs

@@ -1,22 +1,27 @@
-use crate::storage::errors::StorageError;
 use std::collections::HashMap;
 
 #[allow(dead_code)]
+#[derive(Eq, Hash, PartialEq)]
 pub(crate) struct StorageKey(Vec<u8>);
 
 #[allow(dead_code)]
 pub(crate) struct StorageValue(Vec<u8>);
 
 pub(crate) trait Storage {
     /// Returns value from storage, if it exists.
-    fn get(&self, key: &StorageKey) -> Option<StorageValue>;
-    /// Sets value in storage.
-    fn set(&mut self, key: &StorageKey, value: &StorageValue);
-    /// Returns values from storage in same order of given keys. If key does not exist,
-    /// value is None.
-    fn mget(&self, keys: &[StorageKey]) -> [Option<StorageValue>];
+    fn get(&self, key: &StorageKey) -> Option<&StorageValue>;
+
+    /// Sets value in storage. If key already exists, its value is overwritten and the old value is
+    /// returned.
+    fn set(&mut self, key: StorageKey, value: StorageValue) -> Option<StorageValue>;
+
+    /// Returns values from storage in same order of given keys. Value is None for keys that do not
+    /// exist.
+    fn mget(&self, keys: &[StorageKey]) -> Vec<Option<&StorageValue>>;
+
     /// Sets values in storage.
-    fn mset(&mut self, key_to_value: &HashMap<StorageKey, StorageValue>);
-    /// Deletes value from storage. Returns error if key does not exist.
-    fn delete(&mut self, key: &StorageKey) -> Result<(), StorageError>;
+    fn mset(&mut self, key_to_value: HashMap<StorageKey, StorageValue>);
+
+    /// Deletes value from storage and returns its value if it exists. Returns None if not.
+    fn delete(&mut self, key: &StorageKey) -> Option<StorageValue>;
 }