feat(port_std): implement assert_current_thread again

Author: yvt

src/constance_port_std/src/lib.rs

@@ -124,7 +124,11 @@ impl TaskState {
 
     fn assert_current_thread(&self) {
         // `self` must represent the current thread
-        // TODO
+        let expected_thread_id = match &*self.tsm.lock() {
+            Tsm::Running(thread_id) => *thread_id,
+            _ => unreachable!(),
+        };
+        assert_eq!(ums::current_thread(), Some(expected_thread_id));
     }
 
     unsafe fn exit_and_dispatch(&self, state: &'static State) -> ! {

src/constance_port_std/src/ums.rs

@@ -335,3 +335,8 @@ fn finalize_thread(
     // Invoke the scheduler
     state_guard.unpark_next_thread();
 }
+
+/// Get the current worker thread.
+pub fn current_thread() -> Option<ThreadId> {
+    TLB.with(|cell| cell.get().map(|tlb| tlb.thread_id))
+}