Netty分布式从recycler对象回收站获取对象过程剖析

public static void main(String[] args){
    User user1 = RECYCLER.get();
    user1.recycle();
    User user2 = RECYCLER.get();
    user2.recycle();
    System.out.println(user1==user2);
}

public final T get() {
    if (maxCapacityPerThread == 0) {
        return newObject((Handle<T>) NOOP_HANDLE);
    }
    Stack<T> stack = threadLocal.get();
    DefaultHandle<T> handle = stack.pop();
    if (handle == null) {
        handle = stack.newHandle();
        handle.value = newObject(handle);
    }
    return (T) handle.value;
}

private static final Handle NOOP_HANDLE = new Handle() {
    @Override
    public void recycle(Object object) {
        
    }
};

DefaultHandle<T> newHandle() {
    return new DefaultHandle<T>(this);
}

DefaultHandle(Stack<?> stack) {
    this.stack = stack;
}

DefaultHandle<T> handle = stack.pop();

DefaultHandle<T> pop() {
    int size = this.size;
    if (size == 0) {
        if (!scavenge()) {
            return null;
        }
        size = this.size;
    }
    size --;
    DefaultHandle ret = elements[size];
    elements[size] = null;
    if (ret.lastRecycledId != ret.recycleId) {
        throw new IllegalStateException("recycled multiple times");
    }
    ret.recycleId = 0;
    ret.lastRecycledId = 0;
    this.size = size;
    return ret;
}

public final T get() {
    if (maxCapacityPerThread == 0) {
        return newObject((Handle<T>) NOOP_HANDLE);
    }
    Stack<T> stack = threadLocal.get();
    DefaultHandle<T> handle = stack.pop();
    if (handle == null) {
        handle = stack.newHandle();
        handle.value = newObject(handle);
    }
    return (T) handle.value;
}