Add termination callback for worker threads

Author: kateinoigakukun

Diff for: Runtime/src/index.ts

@@ -80,6 +80,12 @@ export type SwiftRuntimeThreadChannel =
               tid: number,
               listener: (unownedJob: number) => void
           ) => void;
+
+          /**
+           * This function is expected to be set in the main thread and called
+           * when the worker thread is terminated.
+           */
+          terminateWorkerThread?: (tid: number) => void;
       };
 
 export type SwiftRuntimeOptions = {
@@ -627,6 +633,12 @@ export class SwiftRuntime {
                     );
                 }
             },
+            swjs_terminate_worker_thread: (tid) => {
+                const threadChannel = this.options.threadChannel;
+                if (threadChannel && "terminateWorkerThread" in threadChannel) {
+                    threadChannel.terminateWorkerThread?.(tid);
+                } // Otherwise, just ignore the termination request
+            },
             swjs_get_worker_thread_id: () => {
                 // Main thread's tid is always -1
                 return this.tid || -1;

Diff for: Runtime/src/types.ts

@@ -110,6 +110,7 @@ export interface ImportedFunctions {
     swjs_listen_wake_event_from_main_thread: () => void;
     swjs_wake_up_worker_thread: (tid: number) => void;
     swjs_listen_main_job_from_worker_thread: (tid: number) => void;
+    swjs_terminate_worker_thread: (tid: number) => void;
     swjs_get_worker_thread_id: () => number;
 }
 

Diff for: Sources/JavaScriptEventLoop/WebWorkerTaskExecutor.swift

@@ -245,6 +245,12 @@ public final class WebWorkerTaskExecutor: TaskExecutor {
         func terminate() {
             trace("Worker.terminate")
             state.store(.terminated, ordering: .sequentiallyConsistent)
+            let tid = self.tid.load(ordering: .sequentiallyConsistent)
+            guard tid != 0 else {
+                // The worker is not started yet.
+                return
+            }
+            swjs_terminate_worker_thread(tid)
         }
     }
 

Diff for: Sources/JavaScriptKit/Runtime/index.js

@@ -303,6 +303,8 @@ IMPORT_JS_FUNCTION(swjs_wake_up_worker_thread, void, (int tid))
 
 IMPORT_JS_FUNCTION(swjs_listen_main_job_from_worker_thread, void, (int tid))
 
+IMPORT_JS_FUNCTION(swjs_terminate_worker_thread, void, (int tid))
+
 IMPORT_JS_FUNCTION(swjs_get_worker_thread_id, int, (void))
 
 /// MARK: - thread local storage