fix(madsim-tokio): add try_current (#224)

* add try_current

* bump madsim-tokio version to 0.2.29

madsim-tokio/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "madsim-tokio"
-version = "0.2.28"
+version = "0.2.29"
 edition = "2021"
 authors = ["Runji Wang <[email protected]>"]
 description = "The `tokio` simulator on madsim."

madsim-tokio/src/sim/runtime.rs

@@ -1,6 +1,7 @@
 use madsim::task::{AbortHandle, JoinHandle};
 use spin::Mutex;
 use std::{future::Future, io};
+use tokio::runtime::TryCurrentError;
 
 /// Builds Tokio Runtime with custom configuration values.
 pub struct Builder {}
@@ -118,10 +119,15 @@ pub struct Handle;
 
 impl Handle {
  /// Returns a handle to the current runtime.
- pub fn current() -> Handle {
+ pub fn current() -> Self {
  Handle
  }
 
+ /// Returns a handle to the current runtime.
+ pub fn try_current() -> Result<Self, TryCurrentError> {
+ Ok(Handle)
+ }
+
  /// Enters the runtime context.
  ///
  /// FIXME: This is currently a no-op.