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package javax.mail;
import java.io.*;
import java.util.Vector;
import javax.mail.event.MailEvent;
/**
* Package private class used by Store & Folder to dispatch events.
* This class implements an event queue, and a dispatcher thread that
* dequeues and dispatches events from the queue.
*
* Pieces stolen from sun.misc.Queue.
*
* @author Bill Shannon
*/
class EventQueue implements Runnable {
static class QueueElement {
QueueElement next = null;
QueueElement prev = null;
MailEvent event = null;
Vector vector = null;
QueueElement(MailEvent event, Vector vector) {
this.event = event;
this.vector = vector;
}
}
private QueueElement head = null;
private QueueElement tail = null;
private Thread qThread;
public EventQueue() {
qThread = new Thread(this, "JavaMail-EventQueue");
qThread.setDaemon(true); // not a user thread
qThread.start();
}
/**
* Enqueue an event.
*/
public synchronized void enqueue(MailEvent event, Vector vector) {
QueueElement newElt = new QueueElement(event, vector);
if (head == null) {
head = newElt;
tail = newElt;
} else {
newElt.next = head;
head.prev = newElt;
head = newElt;
}
notifyAll();
}
/**
* Dequeue the oldest object on the queue.
* Used only by the run() method.
*
* @return the oldest object on the queue.
* @exception java.lang.InterruptedException if another thread has
* interrupted this thread.
*/
private synchronized QueueElement dequeue()
throws InterruptedException {
while (tail == null)
wait();
QueueElement elt = tail;
tail = elt.prev;
if (tail == null) {
head = null;
} else {
tail.next = null;
}
elt.prev = elt.next = null;
return elt;
}
/**
* Pull events off the queue and dispatch them.
*/
public void run() {
QueueElement qe;
try {
loop:
while ((qe = dequeue()) != null) {
MailEvent e = qe.event;
Vector v = qe.vector;
for (int i = 0; i < v.size(); i++)
try {
e.dispatch(v.elementAt(i));
} catch (Throwable t) {
if (t instanceof InterruptedException)
break loop;
// ignore anything else thrown by the listener
}
qe = null; e = null; v = null;
}
} catch (InterruptedException e) {
// just die
}
}
/**
* Stop the dispatcher so we can be destroyed.
*/
void stop() {
if (qThread != null) {
qThread.interrupt(); // kill our thread
qThread = null;
}
}
}
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