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: worker_pool.rs
    path of file: ./repos/rust-brotli/src/enc
    
    the code of the file until where you have to start completion: #![cfg(feature = "std")]
use core::mem;
use std;

use alloc::{Allocator, SliceWrapper};
use enc::backward_references::UnionHasher;
use enc::fixed_queue::{FixedQueue, MAX_THREADS};
use enc::threading::{
    BatchSpawnable
    
    fn drop(&mut self) {
        {
            let (lock, cvar) = &*self.queue.0;
            let mut local_queue = lock.lock().unwrap();
            local_queue.immediate_shutdown = true;
            cvar.notify_all();
        }
        for thread_handle in self.join.iter_mut() {
            if let Some(th) = thread_handle.take() {
                th.join().unwrap();
            }
        }
    }