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: standalone.rs
    path of file: ./repos/readyset/readyset-client/src/consensus
    
    the code of the file until where you have to start completion: //! [`StandaloneAuthority`] is intended to be used within a single (standalone) process, and state
//! can't be shared between different processes, but within a single process it acts as any other
//! authority. As such each process has a singleton "Store" that keeps handles for all deployments
//! used by the process.
//!
//! Since RockDB can't be opened by multiple processes with the settings we use, it also guarantees
//! state won't be accidentally shared.
//!
//! The [`StandaloneAuthority`] will persist the controller state and any other key to a RocksDB
//! database on disk, while keeping leadership and workers data ephemeral.

use std::collections::hash_map::Entry;
use std::collections::{HashMap, HashSet};
use std::path::PathBuf;
use std::sync::{Arc, OnceLock};
use std::time::Duration;

use anyhow::Error;
use async_trait::async_trait;
#[cfg(feature = "failure_injection")]
use failpoint_macros::set_failpoint;
use parking_lot::{Mutex, RwLock};
#[cfg(feature = "failure_injection")]
use readyset_errors::ReadySetError;
use readyset_errors::{internal, internal_err, set_failpoint_return_err, ReadySetResult};
use rocksdb::{WriteBatchWithTransaction, DB};
use serd
    
    async fn it_works() {
        let dir = tempdir().unwrap();

        let authority =
            Arc::new(StandaloneAuthority::new(dir.path().to_str().unwrap(), "it_works").unwrap());
        assert!(authority.try_read::<u32>("/a").await.unwrap().is_none());
        assert_eq!(
            authority
                .read_modify_write("/a", |_: Option<u32>| -> Result<u32, u32> { Ok(12) })
                .await
                .unwrap(),
            Ok(12)
        );
        assert_eq!(authority.try_read("/a").await.unwrap(), Some(12));

        let payload = LeaderPayload {
            controller_uri: url::Url::parse("http://127.0.0.1:8500").unwrap(),
            nonce: 1,
        };
        let expected_leader_payload = payload.clone();
        assert_eq!(
            authority.become_leader(payload.clone()).await.unwrap(),
            Some(payload)
        );
        assert_eq!(
            &authority.get_leader().await.unwrap(),
            &expected_leader_payload
        );
        {
            let authority = authority.clone();
            let payload = LeaderPayload {
                controller_uri: url::Url::parse("http://127.0.0.1:2182").unwrap(),
                nonce: 2,
            };
            authority.become_leader(payload).await.unwrap();
        }

        assert_eq!(
            &authority.get_leader().await.unwrap(),
            &expected_leader_payload
        );
    }