public void run() {
try {
while (true) {
Runnable cur;
synchronized (q) {
while ((cur = q.poll()) == null) q.wait();
}
cur.run();
cur = null;
}
} catch (InterruptedException e) {
}
}
public void defer(Runnable r) {
synchronized (q) {
q.add(r);
q.notify();
}
}