(This set of tutorials mainly focuses on two aspects: Sentinel's core workflow and the sliding time window current limiting algorithm. First explain the principle in detail, and then take everyone to understand the source code of Sentienl on the premise of a thorough understanding of the principle. Through the analysis of Sentinel's core source code, you will have a deep understanding of Sentinel's underlying working principle and workflow, and a clear understanding of how current limiting, fusing, and downgrading are implemented.)