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: barrier_condvar.rs
    path of file: ./repos/rCore-Tutorial-v3/user/src/bin
    
    the code of the file until where you have to start completion: #![no_std]
#![no_main]

#[macro_use]
extern crate user_lib;
extern crate alloc;

use alloc::vec::Vec;
use core::cell::UnsafeCell;
use lazy_static::*;
use user_lib::{
    condvar_create, condvar_signal, condvar_wa
    
    pub fn block(&self) {
        mutex_lock(self.mutex_id);
        let count = self.count.get();
        // SAFETY: Here, the accesses of the count is in the
        // critical section protected by the mutex.
        unsafe {
            *count = *count + 1;
        }
        if unsafe { *count } == THREAD_NUM {
            condvar_signal(self.condvar_id);
        } else {
            condvar_wait(self.condvar_id, self.mutex_id);
            condvar_signal(self.condvar_id);
        }
        mutex_unlock(self.mutex_id);
    }