feat(ext/ffi): Thread safe callbacks (#14942)

1 files changed, 101 insertions, 0 deletions

diff --git a/test_ffi/tests/thread_safe_test.js b/test_ffi/tests/thread_safe_test.js
new file mode 100644
index 000000000..e54114055
--- /dev/null
+++ b/test_ffi/tests/thread_safe_test.js
@@ -0,0 +1,101 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+// deno-lint-ignore-file
+
+const targetDir = Deno.execPath().replace(/[^\/\\]+$/, "");
+const [libPrefix, libSuffix] = {
+  darwin: ["lib", "dylib"],
+  linux: ["lib", "so"],
+  windows: ["", "dll"],
+}[Deno.build.os];
+const libPath = `${targetDir}/${libPrefix}test_ffi.${libSuffix}`;
+
+const resourcesPre = Deno.resources();
+
+const dylib = Deno.dlopen(libPath, {
+  store_function: {
+    parameters: ["function"],
+    result: "void",
+  },
+  call_stored_function: {
+    parameters: [],
+    result: "void",
+  },
+  call_stored_function_thread_safe: {
+    parameters: [],
+    result: "void",
+  },
+});
+
+let resolveWorker;
+let workerResponsePromise;
+
+const worker = new Worker(
+  new URL("./thread_safe_test_worker.js", import.meta.url).href,
+  { type: "module" },
+);
+
+worker.addEventListener("message", () => {
+  if (resolveWorker) {
+    resolveWorker();
+  }
+});
+
+const sendWorkerMessage = async (data) => {
+  workerResponsePromise = new Promise((res) => {
+    resolveWorker = res;
+  });
+  worker.postMessage(data);
+  await workerResponsePromise;
+};
+
+// Test step 1: Register main thread callback, trigger on worker thread
+
+const mainThreadCallback = new Deno.UnsafeCallback(
+  { parameters: [], result: "void" },
+  () => {
+    console.log("Callback on main thread");
+  },
+);
+
+mainThreadCallback.ref();
+
+dylib.symbols.store_function(mainThreadCallback.pointer);
+
+await sendWorkerMessage("call");
+
+// Test step 2: Register on worker thread, trigger on main thread
+
+await sendWorkerMessage("register");
+
+dylib.symbols.call_stored_function();
+
+// Unref both main and worker thread callbacks and terminate the wrorker: Note, the stored function pointer in lib is now dangling.
+
+mainThreadCallback.unref();
+await sendWorkerMessage("unref");
+worker.terminate();
+
+// Test step 3: Register a callback that will be the only thing left keeping the isolate from exiting.
+// Rely on it to keep Deno running until the callback comes in and unrefs the callback, after which Deno should exit.
+
+const cleanupCallback = new Deno.UnsafeCallback(
+  { parameters: [], result: "void" },
+  () => {
+    console.log("Callback being called");
+    Promise.resolve().then(() => cleanup());
+  },
+);
+
+cleanupCallback.ref();
+
+function cleanup() {
+  cleanupCallback.unref();
+  console.log("Isolate should now exit");
+}
+
+dylib.symbols.store_function(cleanupCallback.pointer);
+
+console.log(
+  "Calling callback, isolate should stay asleep until callback is called",
+);
+dylib.symbols.call_stored_function_thread_safe();