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Copy pathDoubleQueue.java
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296 lines (266 loc) · 6.02 KB
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import java.util.AbstractQueue;
import java.util.Collection;
import java.util.Iterator;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.log4j.Logger;
/**
* 创建人：sp.fu <br>
* 功能描述：双缓冲工作队列，线程安全 <br>
* 版本： <br>
* ====================================== <br>
* 修改记录 <br>
* ====================================== <br>
* 序号 姓名 日期 版本 简单描述 <br>
*
*/
public class DoubleQueue<E> extends AbstractQueue<E> implements
BlockingQueue<E>, java.io.Serializable {
private static final long serialVersionUID = 1011398447523020L;
public static final int DEFALUT_QUEUE_CAPACITY = 50000;
private Logger logger = Logger.getLogger(DoubleQueue.class.getName());
/** The read lock */
private ReentrantLock readLock;
//写锁
private ReentrantLock writeLock;
//是否满,信号量
private Condition notFull;
private Condition awake;
//读写数组
private transient E[] writeArray;
private transient E[] readArray;
//读写计数
private volatile int writeCount;
private volatile int readCount;
//写数组下标指针
private int writeArrayTP;
private int writeArrayHP;
//读数组下标指针
private int readArrayTP;
private int readArrayHP;
private int capacity;
public DoubleQueue(int capacity) {
//默认
this.capacity = DEFALUT_QUEUE_CAPACITY;
if (capacity > 0) {
this.capacity = capacity;
}
readArray = (E[])new Object[capacity];
writeArray = (E[])new Object[capacity];
readLock = new ReentrantLock();
writeLock = new ReentrantLock();
notFull = writeLock.newCondition();
awake = writeLock.newCondition();
}
private void insert(E e) {
writeArray[writeArrayTP] = e;
++writeArrayTP;
++writeCount;
}
private E extract() {
E e = readArray[readArrayHP];
readArray[readArrayHP] = null;
++readArrayHP;
--readCount;
return e;
}
/**
* 交换读写队列指针
* @param timeout
* @param isInfinite
* @throws InterruptedException
*/
private long queueSwap(long timeout, boolean isInfinite)
throws InterruptedException {
writeLock.lock();
try {
if (writeCount <= 0) {
logger.debug("Write Count:" + writeCount
+ ", Write Queue is empty, do not switch!");
try {
logger.debug("Queue is empty, need wait....");
if (isInfinite && timeout <= 0) {
awake.await();
return -1;
} else {
return awake.awaitNanos(timeout);
}
} catch (InterruptedException ie) {
awake.signal();
throw ie;
}
} else {
E[] tmpArray = readArray;
readArray = writeArray;
writeArray = tmpArray;
readCount = writeCount;
readArrayHP = 0;
readArrayTP = writeArrayTP;
writeCount = 0;
writeArrayHP = readArrayHP;
writeArrayTP = 0;
notFull.signal();
logger.debug("Queue switch successfully!");
return -1;
}
} finally {
writeLock.unlock();
}
}
@Override
public boolean offer(E e, long timeout, TimeUnit unit)
throws InterruptedException {
if (e == null) {
throw new NullPointerException();
}
long nanoTime = unit.toNanos(timeout);
writeLock.lockInterruptibly();
try {
for (;;) {
if (writeCount < writeArray.length) {
insert(e);
if (writeCount == 1) {
awake.signal();
}
return true;
}
// Time out
if (nanoTime <= 0) {
logger.debug("offer wait time out!");
return false;
}
// keep waiting
try {
logger.debug("Queue is full, need wait....");
nanoTime = notFull.awaitNanos(nanoTime);
} catch (InterruptedException ie) {
notFull.signal();
throw ie;
}
}
} finally {
writeLock.unlock();
}
}
//取
@Override
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
long nanoTime = unit.toNanos(timeout);
readLock.lockInterruptibly();
try {
for (;;) {
if (readCount > 0) {
return extract();
}
if (nanoTime <= 0) {
logger.debug("poll time out!");
return null;
}
nanoTime = queueSwap(nanoTime, false);
}
} finally {
readLock.unlock();
}
}
//等待500毫秒
@Override
public E poll() {
E ret = null;
try {
ret = poll(500L, TimeUnit.MILLISECONDS);
} catch (Exception e) {
ret = null;
}
return ret;
}
//查看
@Override
public E peek() {
E e = null;
readLock.lock();
try {
if (readCount > 0) {
e = readArray[readArrayHP];
}
} finally {
readLock.unlock();
}
return e;
}
//默认500毫秒
@Override
public boolean offer(E e) {
boolean ret = false;
try {
ret = offer(e, 500L, TimeUnit.MILLISECONDS);
} catch (Exception e2) {
ret = false;
}
return ret;
}
@Override
public void put(E e) throws InterruptedException {
offer(e, 500L, TimeUnit.MILLISECONDS); // never need to block
}
@Override
public E take() throws InterruptedException {
return poll(500L, TimeUnit.MILLISECONDS);
}
@Override
public int remainingCapacity() {
return this.capacity;
}
@Override
public int drainTo(Collection<? super E> c) {
return 0;
}
@Override
public int drainTo(Collection<? super E> c, int maxElements) {
return 0;
}
@Override
public Iterator<E> iterator() {
return null;
}
//当前读队列中还有多少个
@Override
public int size() {
int size = 0;
readLock.lock();
try {
if (readCount > 0) {
size = readCount;
}
} finally {
readLock.unlock();
}
return size;
}
//清理
public void clear() {
writeLock.lock();
try {
readCount = 0;
readArrayHP = 0;
writeCount = 0;
writeArrayTP = 0;
logger.debug("Queue clear successfully!");
} finally {
writeLock.unlock();
}
}
public static void main(String[] args) {
try {
DoubleQueue<String> q = new DoubleQueue<String>(1000);
q.put("shiping");
q.put("fu");
q.poll();
System.out.println(q.size());
} catch (InterruptedException e) {
// Auto-generated catch block
e.printStackTrace();
}
}
}