Add Mutex::try_lock and (Unbounded)Receiver::try_recv (#1939)

1 files changed, 16 insertions, 1 deletions

diff --git a/tokio/src/sync/mpsc/unbounded.rs b/tokio/src/sync/mpsc/unbounded.rs
index 07a173c2..4a6ba8ee 100644
--- a/tokio/src/sync/mpsc/unbounded.rs
+++ b/tokio/src/sync/mpsc/unbounded.rs
@@ -1,6 +1,6 @@
 use crate::loom::sync::atomic::AtomicUsize;
 use crate::sync::mpsc::chan;
-use crate::sync::mpsc::error::SendError;
+use crate::sync::mpsc::error::{SendError, TryRecvError};
 
 use std::fmt;
 use std::task::{Context, Poll};
@@ -123,6 +123,21 @@ impl<T> UnboundedReceiver<T> {
         poll_fn(|cx| self.poll_recv(cx)).await
     }
 
+    /// Attempts to return a pending value on this receiver without blocking.
+    ///
+    /// This method will never block the caller in order to wait for data to
+    /// become available. Instead, this will always return immediately with
+    /// a possible option of pending data on the channel.
+    ///
+    /// This is useful for a flavor of "optimistic check" before deciding to
+    /// block on a receiver.
+    ///
+    /// Compared with recv, this function has two failure cases instead of
+    /// one (one for disconnection, one for an empty buffer).
+    pub fn try_recv(&mut self) -> Result<T, TryRecvError> {
+        self.chan.try_recv()
+    }
+
     /// Closes the receiving half of a channel, without dropping it.
     ///
     /// This prevents any further messages from being sent on the channel while