SchemaBatch and ChangeSet changes immutable sov_state::Storage …

…migration (#5)

* Temporary constructor for the ChangeSet while migration

* Public "get" for schema batch

src/cache/change_set.rs

@@ -25,9 +25,14 @@ impl ChangeSet {
         }
     }
 
+    /// Create new `ChangeSet
+    pub fn new_with_operations(id: SnapshotId, operations: SchemaBatch) -> Self {
+        Self { id, operations }
+    }
+
     /// Get value from its own cache
     pub fn get<S: Schema>(&self, key: &impl KeyCodec<S>) -> anyhow::Result<Option<&Operation>> {
-        self.operations.get(key)
+        self.operations.get_operation(key)
     }
 
     /// Get the ID of this [`ChangeSet`].

src/schema_batch.rs

@@ -50,7 +50,8 @@ impl SchemaBatch {
         column_writes.insert(key, operation);
     }
 
-    pub(crate) fn get<S: Schema>(
+    /// Getting the operation from current schema batch if present
+    pub(crate) fn get_operation<S: Schema>(
         &self,
         key: &impl KeyCodec<S>,
     ) -> anyhow::Result<Option<&Operation>> {
@@ -63,6 +64,17 @@ impl SchemaBatch {
         }
     }
 
+    /// Getting value by key if it was written in this batch.
+    /// Deleted operation will return None as well as missing key
+    pub fn get_value<S: Schema>(&self, key: &impl KeyCodec<S>) -> anyhow::Result<Option<S::Value>> {
+        let operation = self.get_operation(key)?;
+        if let Some(operation) = operation {
+            let value = operation.decode_value::<S>()?;
+            return Ok(value);
+        }
+        Ok(None)
+    }
+
     /// Iterator over all values in lexicographic order.
     pub fn iter<S: Schema>(&self) -> btree_map::Iter<SchemaKey, Operation> {
         self.last_writes
@@ -319,7 +331,7 @@ mod tests {
 
             let get_value = |field: &TestField| -> Option<TestField> {
                 batch1
-                    .get::<TestSchema1>(field)
+                    .get_operation::<TestSchema1>(field)
                     .unwrap()
                     .unwrap()
                     .decode_value::<TestSchema1>()