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: lib.rs
    path of file: ./repos/tikv/components/test_util/src
    
    the code of the file until where you have to start completion: // Copyright 2018 TiKV Project Authors. Licensed under Apache-2.0.

#![feature(test)]

extern crate test;
#[macro_use]
extern crate slog_global;

pub mod encryption;
mod kv_generator;
mod logging;
mod macros;
mod runner;
mod security;

use std::{
    env,
    fmt::Debug,
    sync::atomic::{AtomicU16, Ordering},
    thread,
    time::Duration,
};

use rand::Rng;
use tikv_util::sys::thread::StdThreadBuildWrapper;

pub use crate::{
    encryption::*,
    kv_generator::*,
    logging::*,
    runner::{clear_failpoints, run_failpoint_tests, run_test_with_hook, run_tests, TestHook},
    security::*,
};

pub fn setup_for_ci() {
    // We use backtrace in tests to record suspicious problems. And loading
    // backtrace the first time can take several seconds. Spawning a thre
    
pub fn setup_for_ci() {
    // We use backtrace in tests to record suspicious problems. And loading
    // backtrace the first time can take several seconds. Spawning a thread and
    // load it ahead of time to avoid causing timeout.
    thread::Builder::new()
        .name(tikv_util::thd_name!("backtrace-loader"))
        .spawn_wrapper(::backtrace::Backtrace::new)
        .unwrap();

    if env::var("CI").is_ok() {
        // HACK! Use `epollex` as the polling engine for gRPC when running CI tests on
        // Linux and it hasn't been set before.
        // See more: https://github.com/grpc/grpc/blob/v1.17.2/src/core/lib/iomgr/ev_posix.cc#L124
        // See more: https://grpc.io/grpc/core/md_doc_core_grpc-polling-engines.html
        #[cfg(target_os = "linux")]
        {
            if env::var("GRPC_POLL_STRATEGY").is_err() {
                env::set_var("GRPC_POLL_STRATEGY", "epollex");
            }
        }

        if env::var("LOG_FILE").is_ok() {
            logging::init_log_for_test();
        }
    }

    if env::var("PANIC_ABORT").is_ok() {
        // Panics as aborts, it's helpful for debugging,
        // but also stops tests immediately.
        tikv_util::set_panic_hook(true, "./");
    }

    tikv_util::check_environment_variables();

    if let Err(e) = tikv_util::config::check_max_open_fds(4096) {
        panic!(
            "To run test, please make sure the maximum number of open file descriptors not \
             less than 4096: {:?}",
            e
        );
    }
}