From 7b6ad7a960dd330e8c8401a598bd2f2ec6901100 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Fri, 23 Nov 2018 11:04:16 +0100 Subject: [PATCH] make park/unpark example more realistic --- src/libstd/thread/mod.rs | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/src/libstd/thread/mod.rs b/src/libstd/thread/mod.rs index 99f8fa390d2..4a5ba9b800e 100644 --- a/src/libstd/thread/mod.rs +++ b/src/libstd/thread/mod.rs @@ -827,22 +827,33 @@ pub fn sleep(dur: Duration) { /// /// ``` /// use std::thread; +/// use std::sync::{Arc, atomic::{Ordering, AtomicBool}}; /// use std::time::Duration; /// -/// let parked_thread = thread::Builder::new() -/// .spawn(|| { +/// let flag = Arc::new(AtomicBool::new(false)); +/// let flag2 = Arc::clone(&flag); +/// +/// let parked_thread = thread::spawn(move || { +/// // We want to wait until the flag is set. We *could* just spin, but using +/// // park/unpark is more efficient. +/// while !flag2.load(Ordering::Acquire) { /// println!("Parking thread"); /// thread::park(); /// // We *could* get here spuriously, i.e., way before the 10ms below are over! +/// // But that is no problem, we are in a loop until the flag is set anyway. /// println!("Thread unparked"); -/// }) -/// .unwrap(); +/// } +/// println!("Flag received"); +/// }); /// /// // Let some time pass for the thread to be spawned. /// thread::sleep(Duration::from_millis(10)); /// +/// // Set the flag, and let the thread wake up. /// // There is no race condition here, if `unpark` /// // happens first, `park` will return immediately. +/// // Hence there is no risk of a deadlock. +/// flag.store(true, Ordering::Release); /// println!("Unpark the thread"); /// parked_thread.thread().unpark(); ///