Github user trkurc commented on a diff in the pull request:
https://github.com/apache/nifi/pull/179#discussion_r50490153
--- Diff:
nifi-commons/nifi-processor-utilities/src/main/java/org/apache/nifi/processor/util/listen/dispatcher/DatagramChannelDispatcher.java
---
@@ -0,0 +1,164 @@
+/*
+ * 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 org.apache.nifi.processor.util.listen.dispatcher;
+
+import org.apache.commons.io.IOUtils;
+import org.apache.nifi.logging.ProcessorLog;
+import org.apache.nifi.processor.util.listen.event.Event;
+import org.apache.nifi.processor.util.listen.event.EventFactory;
+import org.apache.nifi.processor.util.listen.event.EventFactoryUtil;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.net.StandardSocketOptions;
+import java.nio.ByteBuffer;
+import java.nio.channels.DatagramChannel;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.Selector;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.BlockingQueue;
+
+/**
+ * Reads from the Datagram channel into an available buffer. If data is
read then the buffer is queued for
+ * processing, otherwise the buffer is returned to the buffer pool.
+ */
+public class DatagramChannelDispatcher<E extends Event<DatagramChannel>>
implements ChannelDispatcher {
+
+ private final EventFactory<E> eventFactory;
+ private final BlockingQueue<ByteBuffer> bufferPool;
+ private final BlockingQueue<E> events;
+ private final ProcessorLog logger;
+
+ private Selector selector;
+ private DatagramChannel datagramChannel;
+ private volatile boolean stopped = false;
+
+ public DatagramChannelDispatcher(final EventFactory<E> eventFactory,
+ final BlockingQueue<ByteBuffer>
bufferPool,
+ final BlockingQueue<E> events,
+ final ProcessorLog logger) {
+ this.eventFactory = eventFactory;
+ this.bufferPool = bufferPool;
+ this.events = events;
+ this.logger = logger;
+
+ if (bufferPool == null || bufferPool.size() == 0) {
+ throw new IllegalArgumentException("A pool of available
ByteBuffers is required");
+ }
+ }
+
+ @Override
+ public void open(final int port, int maxBufferSize) throws IOException
{
+ datagramChannel = DatagramChannel.open();
+ datagramChannel.configureBlocking(false);
+ if (maxBufferSize > 0) {
+ datagramChannel.setOption(StandardSocketOptions.SO_RCVBUF,
maxBufferSize);
+ final int actualReceiveBufSize =
datagramChannel.getOption(StandardSocketOptions.SO_RCVBUF);
+ if (actualReceiveBufSize < maxBufferSize) {
+ logger.warn("Attempted to set Socket Buffer Size to " +
maxBufferSize + " bytes but could only set to "
+ + actualReceiveBufSize + "bytes. You may want to
consider changing the Operating System's "
+ + "maximum receive buffer");
+ }
+ }
+ datagramChannel.socket().bind(new InetSocketAddress(port));
+ selector = Selector.open();
+ datagramChannel.register(selector, SelectionKey.OP_READ);
+ }
+
+ @Override
+ public void run() {
+ final ByteBuffer buffer = bufferPool.poll();
+ while (!stopped) {
+ try {
+ int selected = selector.select();
+ if (selected > 0){
+ Iterator<SelectionKey> selectorKeys =
selector.selectedKeys().iterator();
+ while (selectorKeys.hasNext()) {
+ SelectionKey key = selectorKeys.next();
+ selectorKeys.remove();
+ if (!key.isValid()) {
+ continue;
+ }
+ DatagramChannel channel = (DatagramChannel)
key.channel();
+ SocketAddress socketAddress;
+ buffer.clear();
+ while (!stopped && (socketAddress =
channel.receive(buffer)) != null) {
+ String sender = "";
+ if (socketAddress instanceof
InetSocketAddress) {
+ sender = ((InetSocketAddress)
socketAddress).getAddress().toString();
+ }
+
+ // create a byte array from the buffer
+ buffer.flip();
+ byte bytes[] = new byte[buffer.limit()];
+ buffer.get(bytes, 0, buffer.limit());
+
+ final Map<String,String> metadata =
EventFactoryUtil.createMapWithSender(sender);
+ final E event = eventFactory.create(bytes,
metadata, null);
+
+ // queue the raw message with the sender,
block until space is available
+ events.put(event);
+ buffer.clear();
+ }
+ }
+ }
+ } catch (InterruptedException e) {
+ stopped = true;
+ } catch (IOException e) {
+ logger.error("Error reading from DatagramChannel", e);
+ }
+ }
+
+ if (buffer != null) {
+ try {
+ bufferPool.put(buffer);
+ } catch (InterruptedException e) {
+ // nothing to do here
--- End diff --
when reviewing one of @olegz's patches, I thought this was a another place
where adding a Thread.currentThread().interrupt() made sense
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