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: manager.rs
    path of file: ./repos/CYFS/src/component/cyfs-bdt/src/ndn/chunk
    
    the code of the file until where you have to start completion: use std::{
    collections::{BTreeMap, LinkedList}, 
    sync::{Mutex},
};
use async_std::{
    io::Cursor
};
use async_trait::async_trait;
use cyfs_base::*;
use cyfs_util::*;
use crate::{
    types::*, 
    stack::{WeakStack, Stack},
};
use super::super::{
    download::*
};
use super::{
    storage::*,  
    cache::*,
    download::*
};

#[derive(Clone)]
pub struct Config {
    pub raw_caches: RawCacheCon
    
    pub(in super::super) fn on_schedule(&self, _now: Timestamp) {
        let downloaders = {
            let mut downloaders = self.downloaders.lock().unwrap();
            downloaders.get_all()
        };
        for downloader in downloaders {
            downloader.on_drain(0);
        }

        {
            let mut remove = LinkedList::new();
            let mut caches = self.caches.lock().unwrap();
            for (chunk, cache) in caches.iter() {
                if cache.to_strong().is_none() {
                    remove.push_back(chunk.clone());
                }
            }

            for chunk in remove {
                caches.remove(&chunk);
            }
        }
    } 