Add Application::Executor associated type

futures/src/executor/tokio.rs

@@ -0,0 +1,19 @@
+use crate::Executor;
+
+use futures::Future;
+
+pub type Tokio = tokio::runtime::Runtime;
+
+impl Executor for Tokio {
+    fn new() -> Result<Self, futures::io::Error> {
+        tokio::runtime::Runtime::new()
+    }
+
+    fn spawn(&self, future: impl Future<Output = ()> + Send + 'static) {
+        let _ = tokio::runtime::Runtime::spawn(self, future);
+    }
+
+    fn enter<R>(&self, f: impl FnOnce() -> R) -> R {
+        tokio::runtime::Runtime::enter(self, f)
+    }
+}