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-rw-r--r--library/std/src/sync/mpmc/array.rs18
-rw-r--r--library/std/src/sync/mpmc/utils.rs12
2 files changed, 7 insertions, 23 deletions
diff --git a/library/std/src/sync/mpmc/array.rs b/library/std/src/sync/mpmc/array.rs
index c1e3e48b0..c6bb09b04 100644
--- a/library/std/src/sync/mpmc/array.rs
+++ b/library/std/src/sync/mpmc/array.rs
@@ -319,19 +319,10 @@ impl<T> Channel<T> {
) -> Result<(), SendTimeoutError<T>> {
let token = &mut Token::default();
loop {
- // Try sending a message several times.
- let backoff = Backoff::new();
- loop {
- if self.start_send(token) {
- let res = unsafe { self.write(token, msg) };
- return res.map_err(SendTimeoutError::Disconnected);
- }
-
- if backoff.is_completed() {
- break;
- } else {
- backoff.spin_light();
- }
+ // Try sending a message.
+ if self.start_send(token) {
+ let res = unsafe { self.write(token, msg) };
+ return res.map_err(SendTimeoutError::Disconnected);
}
if let Some(d) = deadline {
@@ -379,6 +370,7 @@ impl<T> Channel<T> {
pub(crate) fn recv(&self, deadline: Option<Instant>) -> Result<T, RecvTimeoutError> {
let token = &mut Token::default();
loop {
+ // Try receiving a message.
if self.start_recv(token) {
let res = unsafe { self.read(token) };
return res.map_err(|_| RecvTimeoutError::Disconnected);
diff --git a/library/std/src/sync/mpmc/utils.rs b/library/std/src/sync/mpmc/utils.rs
index cfe42750d..d053d69e2 100644
--- a/library/std/src/sync/mpmc/utils.rs
+++ b/library/std/src/sync/mpmc/utils.rs
@@ -105,10 +105,8 @@ impl Backoff {
/// Backs off using lightweight spinning.
///
- /// This method should be used for:
- /// - Retrying an operation because another thread made progress. i.e. on CAS failure.
- /// - Waiting for an operation to complete by spinning optimistically for a few iterations
- /// before falling back to parking the thread (see `Backoff::is_completed`).
+ /// This method should be used for retrying an operation because another thread made
+ /// progress. i.e. on CAS failure.
#[inline]
pub fn spin_light(&self) {
let step = self.step.get().min(SPIN_LIMIT);
@@ -134,10 +132,4 @@ impl Backoff {
self.step.set(self.step.get() + 1);
}
-
- /// Returns `true` if quadratic backoff has completed and parking the thread is advised.
- #[inline]
- pub fn is_completed(&self) -> bool {
- self.step.get() > SPIN_LIMIT
- }
}