[storage] Add resize_value() to Storage #156 (#157)

* Update file_storage.rs

* Update storage.rs

* Update pr.yaml

.github/workflows/pr.yaml

@@ -44,7 +44,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: taiki-e/install-action@cargo-llvm-cov
       - run: rustup component add llvm-tools-preview
-      - run: cargo llvm-cov --fail-uncovered-regions 81 --fail-uncovered-functions 0 --fail-uncovered-lines 0
+      - run: cargo llvm-cov --fail-uncovered-regions 83 --fail-uncovered-functions 0 --fail-uncovered-lines 0
 
   test:
     runs-on: ubuntu-latest

src/storage.rs

@@ -57,6 +57,22 @@ pub(crate) trait Storage<T: StorageImpl = Self>: StorageImpl<T> {
         self.commit()
     }
 
+    fn resize_value(&mut self, index: i64, new_size: u64) -> Result<(), DbError> {
+        if new_size == 0 {
+            return Err(DbError::Storage("value size cannot be 0".to_string()));
+        }
+
+        let mut record = self.record(index)?;
+
+        if record.size != new_size {
+            self.transaction();
+            self.move_record_to_end(index, new_size, new_size, &mut record)?;
+            self.commit()?;
+        }
+
+        Ok(())
+    }
+
     fn shrink_to_fit(&mut self) -> Result<(), DbError> {
         self.transaction();
         let indexes = self.indexes_by_position();

src/storage/file_storage.rs

@@ -252,6 +252,78 @@ mod tests {
         );
     }
 
+    #[test]
+    fn resize_value_greater() {
+        let test_file = TestFile::from("./file_storage-resize_value_greater.agdb");
+        let mut storage = FileStorage::try_from(test_file.file_name().clone()).unwrap();
+
+        let index = storage.insert(&10_i64).unwrap();
+        let expected_size = std::mem::size_of::<i64>() as u64;
+
+        assert_eq!(storage.value_size(index), Ok(expected_size));
+
+        storage.resize_value(index, expected_size * 2).unwrap();
+
+        assert_eq!(storage.value_size(index), Ok(expected_size * 2));
+    }
+
+    #[test]
+    fn resize_value_missing_index() {
+        let test_file = TestFile::from("./file_storage-resize_value_missing_index.agdb");
+        let mut storage = FileStorage::try_from(test_file.file_name().clone()).unwrap();
+
+        assert_eq!(
+            storage.resize_value(1, 1),
+            Err(DbError::Storage("index '1' not found".to_string()))
+        );
+    }
+
+    #[test]
+    fn resize_value_same() {
+        let test_file = TestFile::from("./file_storage-resize_value_same.agdb");
+        let mut storage = FileStorage::try_from(test_file.file_name().clone()).unwrap();
+
+        let index = storage.insert(&10_i64).unwrap();
+        let expected_size = std::mem::size_of::<i64>() as u64;
+
+        assert_eq!(storage.value_size(index), Ok(expected_size));
+
+        storage.resize_value(index, expected_size).unwrap();
+
+        assert_eq!(storage.value_size(index), Ok(expected_size));
+    }
+
+    #[test]
+    fn resize_value_smaller() {
+        let test_file = TestFile::from("./file_storage-resize_value_smaller.agdb");
+        let mut storage = FileStorage::try_from(test_file.file_name().clone()).unwrap();
+
+        let index = storage.insert(&10_i64).unwrap();
+        let expected_size = std::mem::size_of::<i64>() as u64;
+
+        assert_eq!(storage.value_size(index), Ok(expected_size));
+
+        storage.resize_value(index, expected_size / 2).unwrap();
+
+        assert_eq!(storage.value_size(index), Ok(expected_size / 2));
+    }
+
+    #[test]
+    fn resize_value_zero() {
+        let test_file = TestFile::from("./file_storage-resize_value_zero.agdb");
+        let mut storage = FileStorage::try_from(test_file.file_name().clone()).unwrap();
+
+        let index = storage.insert(&10_i64).unwrap();
+        let expected_size = std::mem::size_of::<i64>() as u64;
+
+        assert_eq!(storage.value_size(index), Ok(expected_size));
+
+        assert_eq!(
+            storage.resize_value(index, 0),
+            Err(DbError::Storage("value size cannot be 0".to_string()))
+        );
+    }
+
     #[test]
     fn restore_from_open_file() {
         let test_file = TestFile::from("./file_storage-restore_from_open_file.agdb");