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| package puzzle; | |
| import java.util.ArrayList; | |
| import java.util.concurrent.locks.ReentrantLock; | |
| public abstract class Buffer<T> { | |
| private ArrayList<T> _items = null; | |
| private ArrayList<T> _prepare = null; | |
| ReentrantLock _gate = new ReentrantLock(); | |
| public void Add(T item) { | |
| _gate.lock(); | |
| try { | |
| if (_items == null) { | |
| _items = new ArrayList<T>(); | |
| } | |
| _items.add(item); | |
| } finally { | |
| _gate.unlock(); | |
| } | |
| } | |
| public abstract void FlushItem(T item); | |
| public void Flush() { | |
| ArrayList<T> items; | |
| _gate.lock(); | |
| try { | |
| items = _prepare; | |
| _prepare = null; | |
| } finally { | |
| _gate.unlock(); | |
| } | |
| if (items != null) { | |
| for (T item: items) { | |
| FlushItem(item); | |
| } | |
| } | |
| } | |
| public void Prepre() { | |
| _gate.lock(); | |
| try { | |
| if (_prepare != null) { | |
| throw new RuntimeException("last prepre is not flushed"); | |
| } | |
| _prepare = _items; | |
| _items = null; | |
| } finally { | |
| _gate.unlock(); | |
| } | |
| } | |
| public static class Item { | |
| private int count = 2; | |
| private int seq; | |
| public Item(int n) { | |
| seq = n; | |
| } | |
| public void First() { | |
| if (count != 2) { | |
| throw new RuntimeException(String.format("expected 2 got %d", count)); | |
| } | |
| count--; | |
| } | |
| public void Second() { | |
| if (count != 1) { | |
| throw new RuntimeException(String.format("expected 1 got %d", count)); | |
| } | |
| count--; | |
| System.out.format("item:%d done\n", seq); | |
| } | |
| } | |
| public static void main(String[] args) throws InterruptedException { | |
| final Buffer<Item> first = new Buffer<Item>() { | |
| @Override | |
| public void FlushItem(Item item) { | |
| item.First(); | |
| } | |
| }; | |
| final Buffer<Item> second = new Buffer<Item>() { | |
| @Override | |
| public void FlushItem(Item item) { | |
| item.Second(); | |
| } | |
| }; | |
| Thread t1 = new Thread(new Runnable() { | |
| @Override | |
| public void run() { | |
| int n = 0; | |
| while (true) { | |
| Item item = new Item(n); | |
| n++; | |
| first.Add(item); | |
| second.Add(item); | |
| try { | |
| Thread.sleep(1); | |
| } catch (InterruptedException e) { | |
| } | |
| } | |
| } | |
| }); | |
| t1.start(); | |
| Thread t2 = new Thread(new Runnable() { | |
| @Override | |
| public void run() { | |
| while (true) { | |
| second.Prepre(); | |
| first.Prepre(); | |
| first.Flush(); | |
| second.Flush(); | |
| try { | |
| Thread.sleep(10); | |
| } catch (InterruptedException e) { | |
| } | |
| } | |
| } | |
| }); | |
| t2.start(); | |
| t2.join(); | |
| } | |
| } |
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