From 69346c7dcb5e4065511f833adedb21ce97e617fd Mon Sep 17 00:00:00 2001
From: Mark Logan <mark@mystenlabs.com>
Date: Fri, 16 Sep 2022 12:13:29 -0700
Subject: [PATCH] spawn_blocking() api

---
 msim-tokio/src/sim/runtime.rs | 14 +++++++++++++-
 msim/src/sim/runtime/mod.rs   |  9 +++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/msim-tokio/src/sim/runtime.rs b/msim-tokio/src/sim/runtime.rs
index 85a435f..5e6a253 100644
--- a/msim-tokio/src/sim/runtime.rs
+++ b/msim-tokio/src/sim/runtime.rs
@@ -6,7 +6,7 @@ use std::time::Duration;
 use msim::runtime as ms_runtime;
 use msim::task::JoinHandle;
 
-use tracing::debug;
+use tracing::{debug, warn};
 
 #[derive(Clone)]
 pub struct Handle {
@@ -48,6 +48,18 @@ impl Handle {
     {
         ms_runtime::NodeHandle::current().spawn(future)
     }
+
+    pub fn spawn_blocking<F, R>(&self, f: F) -> JoinHandle<R>
+    where
+        F: FnOnce() -> R + Send + 'static,
+        R: Send + 'static,
+    {
+        warn!(
+            "spawn_blocking() call in simulator may cause deadlocks if spawned task \
+            attempts to do I/O"
+        );
+        ms_runtime::NodeHandle::current().spawn_blocking(f)
+    }
 }
 
 pub struct EnterGuard<'a>(ms_runtime::EnterGuard, std::marker::PhantomData<&'a Handle>);
diff --git a/msim/src/sim/runtime/mod.rs b/msim/src/sim/runtime/mod.rs
index eec05c8..19a7a10 100644
--- a/msim/src/sim/runtime/mod.rs
+++ b/msim/src/sim/runtime/mod.rs
@@ -364,6 +364,15 @@ impl NodeHandle {
         self.task.spawn(future)
     }
 
+    /// Spawn a blocking task.
+    pub fn spawn_blocking<F, R>(&self, f: F) -> JoinHandle<R>
+    where
+        F: FnOnce() -> R + Send + 'static,
+        R: Send + 'static,
+    {
+        self.task.spawn(async move { f() })
+    }
+
     /// Join the node.
     /// TODO: unimplemented
     pub fn join(self) -> Result<(), ()> {