| // 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") { |
| { |
| delay = 100; |
| numBuffers = 10; |
| incommingBufLength = 10; |
| } |
| }; |
| |
| Element source2 = new FakeSource("source2") { |
| { |
| delay = 100; |
| numBuffers = 10; |
| 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(); |
| } |
| } |