Add Application::Executor associated type

futures/src/executor/async_std.rs

@@ -0,0 +1,15 @@
+use crate::Executor;
+
+use futures::Future;
+
+pub struct AsyncStd;
+
+impl Executor for AsyncStd {
+    fn new() -> Result<Self, futures::io::Error> {
+        Ok(Self)
+    }
+
+    fn spawn(&self, future: impl Future<Output = ()> + Send + 'static) {
+        let _ = async_std::task::spawn(future);
+    }
+}

futures/src/executor/null.rs

@@ -0,0 +1,13 @@
+use crate::Executor;
+
+use futures::Future;
+
+pub struct Null;
+
+impl Executor for Null {
+    fn new() -> Result<Self, futures::io::Error> {
+        Ok(Self)
+    }
+
+    fn spawn(&self, _future: impl Future<Output = ()> + Send + 'static) {}
+}

futures/src/executor/thread_pool.rs

@@ -0,0 +1,15 @@
+use crate::Executor;
+
+use futures::Future;
+
+pub type ThreadPool = futures::executor::ThreadPool;
+
+impl Executor for futures::executor::ThreadPool {
+    fn new() -> Result<Self, futures::io::Error> {
+        futures::executor::ThreadPool::new()
+    }
+
+    fn spawn(&self, future: impl Future<Output = ()> + Send + 'static) {
+        self.spawn_ok(future);
+    }
+}

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)
+    }
+}