Fix deadlock from disposal under certain circumstances

Fixes #302

src/isolate/scheduler.cc

@@ -171,24 +171,24 @@ Scheduler::AsyncWait::~AsyncWait() {
 }
 
 void Scheduler::AsyncWait::Ready() {
-	auto lock = scheduler.Lock();
-	ready = true;
-	if (done) {
+	auto lock = state.write();
+	lock->ready = true;
+	if (lock->done) {
 		scheduler.cv.notify_one();
 	}
 }
 
 void Scheduler::AsyncWait::Wait() {
 	std::unique_lock<std::mutex> lock{scheduler.mutex};
-	while (!ready || !done) {
+	while (!state.read()->did_initialize()) {
 		scheduler.cv.wait(lock);
 	}
 }
 
 void Scheduler::AsyncWait::Wake() {
-	auto lock = scheduler.Lock();
-	done = true;
-	if (ready) {
+	auto lock = state.write();
+	lock->done = true;
+	if (lock->ready) {
 		scheduler.cv.notify_one();
 	}
 }

src/isolate/scheduler.h

@@ -68,9 +68,17 @@ class Scheduler {
 				void Wake();
 
 			private:
+				struct state_t {
+					bool ready = false;
+					bool done = false;
+
+					bool did_initialize() const {
+						return ready || done;
+					}
+				};
+
 				class LockedScheduler& scheduler;
-				bool done = false;
-				bool ready = false;
+				lockable_t<state_t> state;
 		};
 
 		// Task queues

tests/self-async-dispose.js

@@ -0,0 +1,9 @@
+const ivm = require('isolated-vm');
+
+const isolate = new ivm.Isolate();
+const context = isolate.createContextSync();
+context.global.setSync("getProm", () => {}, { reference: true });
+context.eval("getProm.applySync()").catch(() => console.log('pass'));
+context.release();
+process.nextTick(() => {});
+isolate.dispose();