/* * Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */package sun.misc;import java.util.Enumeration;import java.util.NoSuchElementException;/** * Queue: implements a simple queue mechanism. Allows for enumeration of the * elements. * * @author Herb Jellinek */public class Queue { int length = 0; QueueElement head = null; QueueElement tail = null; public Queue() { } /** * Enqueue an object. */ public synchronized void enqueue(Object obj) { QueueElement newElt = new QueueElement(obj); if (head == null) { head = newElt; tail = newElt; length = 1; } else { newElt.next = head; head.prev = newElt; head = newElt; length++; } notify(); } /** * Dequeue the oldest object on the queue. Will wait indefinitely. * * @return the oldest object on the queue. * @exception java.lang.InterruptedException if any thread has * interrupted this thread. */ public Object dequeue() throws InterruptedException { return dequeue(0L); } /** * Dequeue the oldest object on the queue. * @param timeOut the number of milliseconds to wait for something * to arrive. * * @return the oldest object on the queue. * @exception java.lang.InterruptedException if any thread has * interrupted this thread. */ public synchronized Object dequeue(long timeOut) throws InterruptedException { while (tail == null) { wait(timeOut); } QueueElement elt = tail; tail = elt.prev; if (tail == null) { head = null; } else { tail.next = null; } length--; return elt.obj; } /** * Is the queue empty? * @return true if the queue is empty. */ public synchronized boolean isEmpty() { return (tail == null); } /** * Returns an enumeration of the elements in Last-In, First-Out * order. Use the Enumeration methods on the returned object to * fetch the elements sequentially. */ public final synchronized Enumeration elements() { return new LIFOQueueEnumerator(this); } /** * Returns an enumeration of the elements in First-In, First-Out * order. Use the Enumeration methods on the returned object to * fetch the elements sequentially. */ public final synchronized Enumeration reverseElements() { return new FIFOQueueEnumerator(this); } public synchronized void dump(String msg) { System.err.println(">> "+msg); System.err.println("["+length+" elt(s); head = "+ (head == null ? "null" : (head.obj)+"")+ " tail = "+(tail == null ? "null" : (tail.obj)+"")); QueueElement cursor = head; QueueElement last = null; while (cursor != null) { System.err.println(" "+cursor); last = cursor; cursor = cursor.next; } if (last != tail) { System.err.println(" tail != last: "+tail+", "+last); } System.err.println("]"); }}final class FIFOQueueEnumerator implements Enumeration { Queue queue; QueueElement cursor; FIFOQueueEnumerator(Queue q) { queue = q; cursor = q.tail; } public boolean hasMoreElements() { return (cursor != null); } public Object nextElement() { synchronized (queue) { if (cursor != null) { QueueElement result = cursor; cursor = cursor.prev; return result.obj; } } throw new NoSuchElementException("FIFOQueueEnumerator"); }}final class LIFOQueueEnumerator implements Enumeration { Queue queue; QueueElement cursor; LIFOQueueEnumerator(Queue q) { queue = q; cursor = q.head; } public boolean hasMoreElements() { return (cursor != null); } public Object nextElement() { synchronized (queue) { if (cursor != null) { QueueElement result = cursor; cursor = cursor.next; return result.obj; } } throw new NoSuchElementException("LIFOQueueEnumerator"); }}class QueueElement { QueueElement next = null; QueueElement prev = null; Object obj = null; QueueElement(Object obj) { this.obj = obj; } public String toString() { return "QueueElement[obj="+obj+(prev == null ? " null" : " prev")+ (next == null ? " null" : " next")+"]"; }}
/*
* Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.misc;
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* Queue: implements a simple queue mechanism. Allows for enumeration of the
* elements.
*
* @author Herb Jellinek
*/
public class Queue {
int length = 0;
QueueElement head = null;
QueueElement tail = null;
public Queue() {
}
/**
* Enqueue an object.
*/
public synchronized void enqueue(Object obj) {
QueueElement newElt = new QueueElement(obj);
if (head == null) {
head = newElt;
tail = newElt;
length = 1;
} else {
newElt.next = head;
head.prev = newElt;
head = newElt;
length++;
}
notify();
}
/**
* Dequeue the oldest object on the queue. Will wait indefinitely.
*
* @return the oldest object on the queue.
* @exception java.lang.InterruptedException if any thread has
* interrupted this thread.
*/
public Object dequeue() throws InterruptedException {
return dequeue(0L);
}
/**
* Dequeue the oldest object on the queue.
* @param timeOut the number of milliseconds to wait for something
* to arrive.
*
* @return the oldest object on the queue.
* @exception java.lang.InterruptedException if any thread has
* interrupted this thread.
*/
public synchronized Object dequeue(long timeOut)
throws InterruptedException {
while (tail == null) {
wait(timeOut);
}
QueueElement elt = tail;
tail = elt.prev;
if (tail == null) {
head = null;
} else {
tail.next = null;
}
length--;
return elt.obj;
}
/**
* Is the queue empty?
* @return true if the queue is empty.
*/
public synchronized boolean isEmpty() {
return (tail == null);
}
/**
* Returns an enumeration of the elements in Last-In, First-Out
* order. Use the Enumeration methods on the returned object to
* fetch the elements sequentially.
*/
public final synchronized Enumeration elements() {
return new LIFOQueueEnumerator(this);
}
/**
* Returns an enumeration of the elements in First-In, First-Out
* order. Use the Enumeration methods on the returned object to
* fetch the elements sequentially.
*/
public final synchronized Enumeration reverseElements() {
return new FIFOQueueEnumerator(this);
}
public synchronized void dump(String msg) {
System.err.println(">> "+msg);
System.err.println("["+length+" elt(s); head = "+
(head == null ? "null" : (head.obj)+"")+
" tail = "+(tail == null ? "null" : (tail.obj)+""));
QueueElement cursor = head;
QueueElement last = null;
while (cursor != null) {
System.err.println(" "+cursor);
last = cursor;
cursor = cursor.next;
}
if (last != tail) {
System.err.println(" tail != last: "+tail+", "+last);
}
System.err.println("]");
}
}
final class FIFOQueueEnumerator implements Enumeration {
Queue queue;
QueueElement cursor;
FIFOQueueEnumerator(Queue q) {
queue = q;
cursor = q.tail;
}
public boolean hasMoreElements() {
return (cursor != null);
}
public Object nextElement() {
synchronized (queue) {
if (cursor != null) {
QueueElement result = cursor;
cursor = cursor.prev;
return result.obj;
}
}
throw new NoSuchElementException("FIFOQueueEnumerator");
}
}
final class LIFOQueueEnumerator implements Enumeration {
Queue queue;
QueueElement cursor;
LIFOQueueEnumerator(Queue q) {
queue = q;
cursor = q.head;
}
public boolean hasMoreElements() {
return (cursor != null);
}
public Object nextElement() {
synchronized (queue) {
if (cursor != null) {
QueueElement result = cursor;
cursor = cursor.next;
return result.obj;
}
}
throw new NoSuchElementException("LIFOQueueEnumerator");
}
}
class QueueElement {
QueueElement next = null;
QueueElement prev = null;
Object obj = null;
QueueElement(Object obj) {
this.obj = obj;
}
public String toString() {
return "QueueElement[obj="+obj+(prev == null ? " null" : " prev")+
(next == null ? " null" : " next")+"]";
}
}