Add LifecycleHandler::pre_new_process

src/lib.rs

@@ -412,6 +412,8 @@ async fn spawn_child(
     user_envs: &[(OsString, OsString)],
     lifecycle_handler: &mut dyn LifecycleHandler,
 ) -> io::Result<process::Child> {
+    lifecycle_handler.pre_new_process().await;
+
     let mut args = env::args();
     let process_name = args.next().unwrap();
 

src/lifecycle.rs

@@ -19,6 +19,9 @@ pub trait LifecycleHandler: Send {
         Ok(())
     }
 
+    /// Called before the child process has been spawned.
+    async fn pre_new_process(&mut self) {}
+
     /// Called after `send_to_new_process` if the child process fails to start successfully.
     /// This gives you an opportunity to undo any state changes made in `send_to_new_process`.
     async fn new_process_failed(&mut self) {}