threadpool: update crossbeam dependencies (#874)

tokio-threadpool/src/task/mod.rs

@@ -1,10 +1,8 @@
 mod blocking;
 mod blocking_state;
-mod queue;
 mod state;
 
 pub(crate) use self::blocking::{Blocking, CanBlock};
-pub(crate) use self::queue::Queue;
 use self::blocking_state::BlockingState;
 use self::state::State;
 

tokio-threadpool/src/task/queue.rs

@@ -1,34 +0,0 @@
-use task::Task;
-
-use std::sync::Arc;
-
-use crossbeam_channel::{unbounded, Receiver, Sender};
-
-#[derive(Debug)]
-pub(crate) struct Queue {
-    // TODO(stjepang): Use a custom, faster MPMC queue implementation that supports `steal_many()`.
-    chan: (Sender<Arc<Task>>, Receiver<Arc<Task>>),
-}
-
-// ===== impl Queue =====
-
-impl Queue {
-    /// Create a new, empty, `Queue`.
-    pub fn new() -> Queue {
-        Queue {
-            chan: unbounded(),
-        }
-    }
-
-    /// Push a task onto the queue.
-    #[inline]
-    pub fn push(&self, task: Arc<Task>) {
-        self.chan.0.send(task).unwrap();
-    }
-
-    /// Pop a task from the queue.
-    #[inline]
-    pub fn pop(&self) -> Option<Arc<Task>> {
-        self.chan.1.try_recv().ok()
-    }
-}