Use paritytech/nohash-hasher and add comments.

Cargo.toml

@@ -7,6 +7,7 @@ license = "MIT"
 [dependencies]
 bytes = "0.4"
 futures = "0.1"
+nohash-hasher = { git = "https://github.com/paritytech/nohash-hasher" }
 log = "0.4"
 parking_lot = "0.6"
 quick-error = "0.1"

src/lib.rs

@@ -20,6 +20,7 @@
 extern crate bytes;
 #[macro_use]
 extern crate futures;
+extern crate nohash_hasher;
 #[macro_use]
 extern crate log;
 extern crate parking_lot;

src/notify/mod.rs → src/notify.rs

@@ -17,11 +17,10 @@
 // WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 // CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-mod hash;
 
 use futures::{executor, task};
 use parking_lot::Mutex;
-use self::hash::HashMap;
+use nohash_hasher::IntMap;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
 
@@ -32,26 +31,35 @@ task_local!{
 }
 
 
+/// A notifier maintains a collection of tasks which should be
+/// notified at some point. Useful in conjuction with `futures::executor::Spawn`.
 pub struct Notifier {
-    tasks: Mutex<HashMap<usize, task::Task>>
+    tasks: Mutex<IntMap<usize, task::Task>>
 }
 
 impl Notifier {
     pub fn new() -> Self {
-        Notifier { tasks: Mutex::new(HashMap::default()) }
+        Notifier { tasks: Mutex::new(IntMap::default()) }
     }
 
+    /// Insert the current task to the set of tasks to be notified.
+    ///
+    /// # Panics
+    ///
+    /// If called outside of a tokio task.
     pub fn insert_current(&self) {
         self.tasks.lock().insert(TASK_ID.with(|&t| t), task::current());
     }
 
+    /// Notify all registered tasks.
     pub fn notify_all(&self) {
         let mut tasks = self.tasks.lock();
         for (_, t) in tasks.drain() {
             t.notify();
         }
     }
 
+    /// Return the number of currently registered tasks.
     pub fn len(&self) -> usize {
         self.tasks.lock().len()
     }