From 0b5761c190031a71faf06bbe758386ed58a910d5 Mon Sep 17 00:00:00 2001
From: Abutalib Aghayev <agayev@psu.edu>
Date: Thu, 27 Oct 2022 15:55:51 -0400
Subject: [PATCH] rt: add a method to determine if the runtime is
 multi-threaded.

---
 tokio/src/runtime/handle.rs | 28 +++++++++++++++++++++++++++-
 tokio/src/runtime/mod.rs    |  9 +++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/tokio/src/runtime/handle.rs b/tokio/src/runtime/handle.rs
index 91974252610..005f50e0494 100644
--- a/tokio/src/runtime/handle.rs
+++ b/tokio/src/runtime/handle.rs
@@ -1,4 +1,4 @@
-use crate::runtime::scheduler;
+use crate::runtime::{scheduler, Flavor};
 
 /// Handle to the runtime.
 ///
@@ -101,6 +101,32 @@ impl Handle {
         }
     }
 
+    /// Returns the flavor of the current `Runtime`.
+    ///
+    /// ```
+    /// use tokio::runtime::{Handle, Flavor};
+    ///
+    /// #[tokio::main(flavor = "current_thread")]
+    /// async fn main() {
+    ///   assert_eq!(Flavor::CurrentThread, Handle::current().get_flavor());
+    /// }
+    /// ```
+    ///
+    /// ```
+    /// use tokio::runtime::{Handle, Flavor};
+    ///
+    /// #[tokio::main(flavor = "multi_thread", worker_threads = 4)]
+    /// async fn main() {
+    ///   assert_eq!(Flavor::MultiThread, Handle::current().get_flavor());
+    /// }
+    /// ```
+    pub fn get_flavor(&self) -> Flavor {
+        match self.inner {
+            scheduler::Handle::CurrentThread(_) => Flavor::CurrentThread,
+            scheduler::Handle::MultiThread(_) => Flavor::MultiThread,
+        }
+    }
+
     /// Returns a Handle view over the currently running Runtime
     ///
     /// Returns an error if no Runtime has been started
diff --git a/tokio/src/runtime/mod.rs b/tokio/src/runtime/mod.rs
index b69d696cdef..012cf059ad3 100644
--- a/tokio/src/runtime/mod.rs
+++ b/tokio/src/runtime/mod.rs
@@ -312,6 +312,15 @@ cfg_rt! {
         blocking_pool: BlockingPool,
     }
 
+    /// The flavor of the `Runtime`.
+    #[derive(Debug, PartialEq)]
+    pub enum Flavor {
+        /// The flavor that executes all tasks on the current thread.
+        CurrentThread,
+        /// The flavor that executes tasks across multiple threads.
+        MultiThread,
+    }
+
     /// The runtime scheduler is either a multi-thread or a current-thread executor.
     #[derive(Debug)]
     enum Scheduler {