Add timeouts to more driver spin loops

common/src/lib.rs

@@ -16,6 +16,8 @@ pub mod io;
 mod logger;
 /// The Scatter Gather List (SGL) API for drivers.
 pub mod sgl;
+/// Low latency timeout for driver loops
+pub mod timeout;
 
 pub use logger::{output_level, file_level, setup_logging};
 

common/src/timeout.rs

@@ -0,0 +1,45 @@
+use std::{thread, time::{Duration, Instant}};
+
+pub struct Timeout {
+    instant: Instant,
+    duration: Duration,
+}
+
+impl Timeout {
+    #[inline]
+    pub fn new(duration: Duration) -> Self {
+        Self {
+            instant: Instant::now(),
+            duration,
+        }
+    }
+
+    #[inline]
+    pub fn from_micros(micros: u64) -> Self {
+        Self::new(Duration::from_micros(micros))
+    }
+
+    #[inline]
+    pub fn from_millis(millis: u64) -> Self {
+        Self::new(Duration::from_millis(millis))
+    }
+
+    #[inline]
+    pub fn from_secs(secs: u64) -> Self {
+        Self::new(Duration::from_secs(secs))
+    }
+
+    #[inline]
+    pub fn run(&self) -> Result<(), ()> {
+        if self.instant.elapsed() < self.duration {
+            // Sleeps in Redox are only evaluated on PIT ticks (a few ms), which is not
+            // short enough for a reasonably responsive timeout. However, the clock is
+            // highly accurate. So, we yield instead of sleep to reduce latency.
+            //TODO: allow timeout that spins instead of yields?
+            std::thread::yield_now();
+            Ok(())
+        } else {
+            Err(())
+        }
+    }
+}