message: nydus-cached: remove EXIT_EVTFD mutex
diff: @@ -12,20 +12,18 @@ extern crate nydus_storage as storage;
  use std::io::Result;
  use std::os::unix::prelude::AsRawFd;
  -use std::sync::{atomic::AtomicBool, Mutex};
  +use std::sync::atomic::AtomicBool;
  use clap::{App, Arg};
  use mio::unix::SourceFd;
  use mio::{Events, Interest, Poll, Token};
  use nydus_app::{dump_program_info, setup_logging, BuildTimeInfo};
  use nydus_storage::remote::{RemoteBlobMgr, Server};
  -use vmm_sys_util::eventfd::EventFd;
  const CLIENT_TOKEN: Token = Token(1);
  lazy_static! {
  static ref EVENT_MANAGER_RUN: AtomicBool = AtomicBool::new(true);
  - static ref EXIT_EVTFD: Mutex::<Option<EventFd>> = Mutex::<Option<EventFd>>::default();
  }
  fn main() -> Result<()> {
  