When multiple miners dig into the same block, the system will select the block with the most accumulated computing power. When this happens, it may be necessary to roll back already processed blocks and process new blocks. When a block is currently being processed, an operation history is created based on the block hash.
When a block needs to be rolled back, this history is traversed, the current data is overwritten with the old data, and the history is deleted. Thereby, the rollback of the block is simply implemented.