In ArrayBlockingQueue, why copy final member field into local final variable?
- by mjlee
In ArrayBlockingQueue, any method that requires lock will get set 'final' local variable before calling 'lock()'.
public boolean offer(E e) {
if (e == null) throw new NullPointerException();
final ReentrantLock lock = this.lock;
lock.lock();
try {
if (count == items.length)
return false;
else {
insert(e);
return true;
}
} finally {
lock.unlock();
}
}
Is there any reason to set a local variable 'lock' from 'this.lock' when field 'this.lock' is final also.
Additionally, it also set local variable of E[] before acting on.
private E extract() {
final E[] items = this.items;
E x = items[takeIndex];
items[takeIndex] = null;
takeIndex = inc(takeIndex);
--count;
notFull.signal();
return x;
}
Is there any reason for copying to local final variable?
