Refactor threadpool task types (#300)

Replaces homegrown Arc with std Arc

Is this safer? Unknown. At least we don't have to maintain an arc
implementation anymore. This will also make it easier to filter out tsan
false positives.

Also split task/mod.rs into multiple files.

tokio-threadpool/src/worker/entry.rs

@@ -4,6 +4,7 @@ use worker::state::{State, PUSHED_MASK};
 
 use std::cell::UnsafeCell;
 use std::fmt;
+use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::atomic::Ordering::{Acquire, AcqRel, Relaxed};
 
@@ -21,10 +22,10 @@ pub(crate) struct WorkerEntry {
     next_sleeper: UnsafeCell<usize>,
 
     // Worker half of deque
-    deque: deque::Deque<Task>,
+    deque: deque::Deque<Arc<Task>>,
 
     // Stealer half of deque
-    steal: deque::Stealer<Task>,
+    steal: deque::Stealer<Arc<Task>>,
 
     // Thread parker
     pub park: UnsafeCell<BoxPark>,
@@ -77,7 +78,7 @@ impl WorkerEntry {
     /// Submit a task to this worker while currently on the same thread that is
     /// running the worker.
     #[inline]
-    pub fn submit_internal(&self, task: Task) {
+    pub fn submit_internal(&self, task: Arc<Task>) {
         self.push_internal(task);
     }
 
@@ -89,7 +90,7 @@ impl WorkerEntry {
     /// # Ordering
     ///
     /// The `state` must have been obtained with an `Acquire` ordering.
-    pub fn submit_external(&self, task: Task, mut state: State) -> bool {
+    pub fn submit_external(&self, task: Arc<Task>, mut state: State) -> bool {
         use worker::Lifecycle::*;
 
         // Push the task onto the external queue
@@ -186,7 +187,7 @@ impl WorkerEntry {
     ///
     /// This **must** only be called by the thread that owns the worker entry.
     /// This function is not `Sync`.
-    pub fn pop_task(&self) -> deque::Steal<Task> {
+    pub fn pop_task(&self) -> deque::Steal<Arc<Task>> {
         self.deque.steal()
     }
 
@@ -194,7 +195,7 @@ impl WorkerEntry {
     ///
     /// This is called by *other* workers to steal a task for processing. This
     /// function is `Sync`.
-    pub fn steal_task(&self) -> deque::Steal<Task> {
+    pub fn steal_task(&self) -> deque::Steal<Arc<Task>> {
         self.steal.steal()
     }
 
@@ -207,12 +208,12 @@ impl WorkerEntry {
     }
 
     #[inline]
-    fn push_external(&self, task: Task) {
+    fn push_external(&self, task: Arc<Task>) {
         self.inbound.push(task);
     }
 
     #[inline]
-    pub fn push_internal(&self, task: Task) {
+    pub fn push_internal(&self, task: Arc<Task>) {
         self.deque.push(task);
     }
 

tokio-threadpool/src/worker/mod.rs

@@ -309,7 +309,7 @@ impl Worker {
         found_work
     }
 
-    fn run_task(&self, task: Task, notify: &Arc<Notifier>, sender: &mut Sender) {
+    fn run_task(&self, task: Arc<Task>, notify: &Arc<Notifier>, sender: &mut Sender) {
         use task::Run::*;
 
         match task.run(notify, sender) {