以下基本对象池是否正常工作？我有一个更加复杂的基于同样的想法(即维护一个信号量和一个BlockingQueue).我的问题是 – 我需要同时使用信号量和BlockingQueue吗？我是对的,我不需要做任何同步吗？
import java.util.Collection;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Semaphore;
public final class Pool<T> {
private final BlockingQueue<T> objects;
private final Semaphore permits;
public Pool(Collection<? extends T> objects) {
// we have as many permits as objects in our pool:
this.permits = new Semaphore(objects.size());
this.objects = new ArrayBlockingQueue<T>(objects.size(),false,objects);
}
public T borrow() {
this.permits.acquireUninterruptibly();
// we have a permit,so there must be one in there:
return this.objects.poll();
}
public void giveBack(T object) {
this.objects.add(object);
this.permits.release();
}
}
解决方法
如已经指出的那样,一个有限的BlockingQueue就足够了.例如,以下代码将执行您想要的：
import java.util.Collection;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
public final class Pool<T> {
private final BlockingQueue<T> objects;
public Pool(Collection<? extends T> objects) {
this.objects = new ArrayBlockingQueue<T>(objects.size(),objects);
}
public T borrow() throws InterruptedException {
return this.objects.take();
}
public void giveBack(T object) throws InterruptedException {
this.objects.put(object);
}
}
另外,您可能需要考虑使用BlockingQueue.poll()来支持借用()的定时版本.
如果您没有有限的阻塞队列数据结构,那么您可以在任何数据结构之上强加一个信号量,以创建线程安全和绑定的行为.
