// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package streamer;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import streamer.debug.FakeSink;
import streamer.debug.FakeSource;
/**
* Message queue for safe transfer of packets between threads.
*/
public class Queue extends BaseElement {
protected LinkedBlockingQueue<ByteBuffer> queue = new LinkedBlockingQueue<ByteBuffer>();
public Queue(String id) {
super(id);
}
@Override
public void poll(boolean block) {
try {
ByteBuffer buf = null;
if (block) {
buf = queue.take();
} else {
buf = queue.poll(100, TimeUnit.MILLISECONDS);
}
if (buf != null)
pushDataToAllOuts(buf);
} catch (Exception e) {
sendEventToAllPads(Event.STREAM_CLOSE, Direction.OUT);
closeQueue();
}
}
@Override
public void handleData(ByteBuffer buf, Link link) {
if (verbose)
System.out.println("[" + this + "] INFO: Data received: " + buf + ".");
// Put incoming data into queue
try {
queue.put(buf);
} catch (Exception e) {
sendEventToAllPads(Event.STREAM_CLOSE, Direction.IN);
closeQueue();
}
}
@Override
public void handleEvent(Event event, Direction direction) {
switch (event) {
case LINK_SWITCH_TO_PULL_MODE:
// Do not propagate this event, because this element is boundary between
// threads
break;
default:
super.handleEvent(event, direction);
}
}
@Override
protected void onClose() {
super.onClose();
closeQueue();
}
private void closeQueue() {
queue.clear();
queue.add(null);
// Drop queue to indicate that upstream is closed.
// May produce NPE in poll().
queue = null;
}
@Override
public String toString() {
return "Queue(" + id + ")";
}
/**
* Example.
*/
public static void main(String args[]) {
// System.setProperty("streamer.Link.debug", "true");
System.setProperty("streamer.Element.debug", "true");
Element source1 = new FakeSource("source1") {
{
this.delay = 100;
this.numBuffers = 10;
this.incommingBufLength = 10;
}
};
Element source2 = new FakeSource("source2") {
{
this.delay = 100;
this.numBuffers = 10;
this.incommingBufLength = 10;
}
};
Pipeline pipeline = new PipelineImpl("test");
pipeline.add(source1);
pipeline.add(source2);
pipeline.add(new Queue("queue"));
pipeline.add(new FakeSink("sink"));
// Main flow
pipeline.link("source1", "in1< queue");
pipeline.link("source2", "in2< queue");
pipeline.link("queue", "sink");
new Thread(pipeline.getLink("source1", STDOUT)).start();
new Thread(pipeline.getLink("source2", STDOUT)).start();
pipeline.getLink("sink", STDIN).run();
}
}