You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: server.rs
    path of file: ./repos/rust-by-practice/zh-CN/assets/mini-redis/src
    
    the code of the file until where you have to start completion: //! Minimal Redis server implementation
//!
//! Provides an async `run` function that listens for inbound connections,
//! spawning a task per con
    
    fn drop(&mut self) {
        // Add a permit back to the semaphore.
        //
        // Doing so unblocks the listener if the max number of
        // connections has been reached.
        //
        // This is done in a `Drop` implementation in order to guarantee that
        // the permit is added even if the task handling the connection panics.
        // If `add_permit` was called at the end of the `run` function and some
        // bug causes a panic. The permit would never be returned to the
        // semaphore.
        self.limit_connections.add_permits(1);
    }