asterix-external-data/src/main/java/edu/uci/ics/asterix/external/data/operator/FeedIntakeOperatorNodePushable.java

/*
 * Copyright 2009-2012 by The Regents of the University of California
 * Licensed 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 from
 * 
 *     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 edu.uci.ics.asterix.external.data.operator;

import java.nio.ByteBuffer;
import java.util.concurrent.LinkedBlockingQueue;

import edu.uci.ics.asterix.external.dataset.adapter.IDatasourceAdapter;
import edu.uci.ics.asterix.external.feed.lifecycle.AlterFeedMessage;
import edu.uci.ics.asterix.external.feed.lifecycle.FeedId;
import edu.uci.ics.asterix.external.feed.lifecycle.FeedManager;
import edu.uci.ics.asterix.external.feed.lifecycle.IFeedManager;
import edu.uci.ics.asterix.external.feed.lifecycle.IFeedMessage;
import edu.uci.ics.asterix.feed.managed.adapter.IManagedFeedAdapter;
import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
import edu.uci.ics.hyracks.dataflow.std.base.AbstractUnaryInputUnaryOutputOperatorNodePushable;

/**
 * The runtime for @see{FeedIntakeOperationDescriptor}
 */
public class FeedIntakeOperatorNodePushable extends AbstractUnaryInputUnaryOutputOperatorNodePushable {

    private final IDatasourceAdapter adapter;
    private final int partition;
    private final IFeedManager feedManager;
    private final FeedId feedId;
    private final LinkedBlockingQueue<IFeedMessage> inbox;
    private FeedInboxMonitor feedInboxMonitor;

    public FeedIntakeOperatorNodePushable(FeedId feedId, IDatasourceAdapter adapter, int partition) {
        this.adapter = adapter;
        this.partition = partition;
        this.feedManager = (IFeedManager) FeedManager.INSTANCE;
        this.feedId = feedId;
        inbox = new LinkedBlockingQueue<IFeedMessage>();
    }

    @Override
    public void open() throws HyracksDataException {
        if (adapter instanceof IManagedFeedAdapter) {
            feedInboxMonitor = new FeedInboxMonitor((IManagedFeedAdapter) adapter, inbox, partition);
            feedInboxMonitor.start();
            feedManager.registerFeedMsgQueue(feedId, inbox);
        }
        writer.open();
        try {
            adapter.start(partition, writer);
        } catch (Exception e) {
            e.printStackTrace();
            throw new HyracksDataException(e);
            /* 
             we do not throw an exception, but allow the operator to close
             gracefully throwing an exception here would result in a job abort and a
             transaction roll back that undoes all the work done so far.
             */

        } finally {
            writer.close();
            if (adapter instanceof IManagedFeedAdapter) {
                feedManager.unregisterFeedMsgQueue(feedId, inbox);
            }
        }
    }

    @Override
    public void fail() throws HyracksDataException {
        writer.close();
    }

    @Override
    public void close() throws HyracksDataException {
        writer.close();
    }

    @Override
    public void nextFrame(ByteBuffer buffer) throws HyracksDataException {
        // do nothing
    }
}

class FeedInboxMonitor extends Thread {

    private LinkedBlockingQueue<IFeedMessage> inbox;
    private final IManagedFeedAdapter adapter;

    public FeedInboxMonitor(IManagedFeedAdapter adapter, LinkedBlockingQueue<IFeedMessage> inbox, int partition) {
        this.inbox = inbox;
        this.adapter = adapter;
    }

    @Override
    public void run() {
        while (true) {
            try {
                IFeedMessage feedMessage = inbox.take();
                switch (feedMessage.getMessageType()) {
                    case STOP:
                        adapter.stop();
                        break;
                    case ALTER:
                        adapter.alter(((AlterFeedMessage) feedMessage).getAlteredConfParams());
                        break;
                }
            } catch (InterruptedException ie) {
                break;
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    }

}