diff options
Diffstat (limited to 'src/libstd/sync/spsc_queue.rs')
| -rw-r--r-- | src/libstd/sync/spsc_queue.rs | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/src/libstd/sync/spsc_queue.rs b/src/libstd/sync/spsc_queue.rs index d1fde759cc1..a2c61a2b135 100644 --- a/src/libstd/sync/spsc_queue.rs +++ b/src/libstd/sync/spsc_queue.rs @@ -194,14 +194,16 @@ impl<T: Send> Queue<T> { } } - /// Tests whether this queue is empty or not. Remember that there can only - /// be one tester/popper, and also keep in mind that the answer returned - /// from this is likely to change if it is `false`. - pub fn is_empty(&self) -> bool { + /// Attempts to peek at the head of the queue, returning `None` if the queue + /// has no data currently + pub fn peek<'a>(&'a mut self) -> Option<&'a mut T> { + // This is essentially the same as above with all the popping bits + // stripped out. unsafe { let tail = self.tail; let next = (*tail).next.load(Acquire); - return next.is_null(); + if next.is_null() { return None } + return (*next).value.as_mut(); } } } @@ -223,8 +225,9 @@ impl<T: Send> Drop for Queue<T> { #[cfg(test)] mod test { use prelude::*; - use super::Queue; use native; + use super::Queue; + use sync::arc::UnsafeArc; #[test] fn smoke() { @@ -272,7 +275,6 @@ mod test { let (a, b) = UnsafeArc::new2(Queue::new(bound)); let (port, chan) = Chan::new(); native::task::spawn(proc() { - let mut c = c; for _ in range(0, 100000) { loop { match unsafe { (*b.get()).pop() } { |