Merge pull request #741 from jprendes/async-shim-v3

Remove sync wrappers for containerd client

crates/containerd-shim-wasm/src/sandbox/async_utils.rs

@@ -0,0 +1,26 @@
+#![cfg_attr(windows, allow(dead_code))] // this is currently used only for linux
+
+use std::future::Future;
+
+thread_local! {
+    // A thread local runtime that can be used to run futures to completion.
+    // It is a current_thread runtime so that it doesn't spawn new threads.
+    // It is thread local as different threads might want to run futures concurrently.
+    static RUNTIME: tokio::runtime::Runtime = {
+        tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+    };
+}
+
+pub trait AmbientRuntime: Future {
+    fn block_on(self) -> Self::Output
+    where
+        Self: Sized,
+    {
+        RUNTIME.with(|runtime| runtime.block_on(self))
+    }
+}
+
+impl<F: Future> AmbientRuntime for F {}