SparkStreamingOutput.java

/**
 * 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 demo.jaxrs.server.socket;

import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.Map;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;

import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.StreamingOutput;

public class SparkStreamingOutput implements StreamingOutput {
    private Map<String, BlockingQueue<String>> sparkResponses;
    private String jobId;
    private BlockingQueue<String> queue;
    public SparkStreamingOutput(Map<String, BlockingQueue<String>> sparkResponses, String jobId,
                                BlockingQueue<String> queue) {
        this.sparkResponses = sparkResponses;
        this.jobId = jobId;
        this.queue = queue;
    }

    @Override
    public void write(final OutputStream output) throws IOException, WebApplicationException {
        PrintStream out = new PrintStream(output, true);
        try {
            while (true) {
                String responseEntry = queue.poll(1, TimeUnit.MILLISECONDS);
                if (responseEntry != null) {
                    if ("<batchEnd>".equals(responseEntry)) {
                        sparkResponses.remove(jobId);
                        break;
                    } else {
                        out.println(responseEntry);
                    }
                }
            }
        } catch (InterruptedException ex) {
            // ignore
        }

    }
}