[ISSUE #246] finish data processing when function return null

[elenacliu]

246

During test, I modified the mapping function in WordCount.java a little to generate null value. This is the output results.

[elenacliu]

Here are my examples:

example1:

/*
 * 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.rocketmq.streams.examples;

import org.apache.rocketmq.common.MixAll;
import org.apache.rocketmq.streams.core.RocketMQStream;
import org.apache.rocketmq.streams.core.function.ValueMapperAction;
import org.apache.rocketmq.streams.core.rstream.StreamBuilder;
import org.apache.rocketmq.streams.core.topology.TopologyBuilder;
import org.apache.rocketmq.streams.core.util.Pair;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.List;
import java.util.Properties;

public class WordCount {
    public static void main(String[] args) {
        StreamBuilder builder = new StreamBuilder("wordCount");

        builder.source("sourceTopic", total -> {
                    String value = new String(total, StandardCharsets.UTF_8);
                    return new Pair<>(null, value);
                })
                .flatMap((ValueMapperAction<String, List<String>>) value -> {
                    String[] splits = value.toLowerCase().split("\\W+");
                    splits[0] = null;
                    return Arrays.asList(splits);
                })
                .keyBy(value -> value)
                .count()
                .toRStream()
                .print();

        TopologyBuilder topologyBuilder = builder.build();

        Properties properties = new Properties();
        properties.put(MixAll.NAMESRV_ADDR_PROPERTY, "127.0.0.1:9876");

        RocketMQStream rocketMQStream = new RocketMQStream(topologyBuilder, properties);

        Runtime.getRuntime().addShutdownHook(new Thread("wordcount-shutdown-hook") {
            @Override
            public void run() {
                rocketMQStream.stop();
            }
        });

        rocketMQStream.start();
    }
}

example2:

/*
 * 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.rocketmq.streams.examples;

import org.apache.rocketmq.common.MixAll;
import org.apache.rocketmq.streams.core.RocketMQStream;
import org.apache.rocketmq.streams.core.function.ValueMapperAction;
import org.apache.rocketmq.streams.core.rstream.StreamBuilder;
import org.apache.rocketmq.streams.core.topology.TopologyBuilder;
import org.apache.rocketmq.streams.core.util.Pair;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.List;
import java.util.Properties;

public class WordCount {
    public static void main(String[] args) {
        StreamBuilder builder = new StreamBuilder("wordCount");

        builder.source("sourceTopic", total -> {
                    String value = new String(total, StandardCharsets.UTF_8);
                    return new Pair<>(null, value);
                })
                .flatMap((ValueMapperAction<String, List<String>>) value -> {
                    // String[] splits = value.toLowerCase().split("\\W+");
                    // splits[0] = null;
                    // return Arrays.asList(splits);
                    return null;
                })
                .keyBy(value -> value)
                .count()
                .toRStream()
                .print();

        TopologyBuilder topologyBuilder = builder.build();

        Properties properties = new Properties();
        properties.put(MixAll.NAMESRV_ADDR_PROPERTY, "127.0.0.1:9876");

        RocketMQStream rocketMQStream = new RocketMQStream(topologyBuilder, properties);

        Runtime.getRuntime().addShutdownHook(new Thread("wordcount-shutdown-hook") {
            @Override
            public void run() {
                rocketMQStream.stop();
            }
        });

        rocketMQStream.start();
    }
}

[elenacliu]

Besides I'm wondering will there be a complete test framework in the future to test the functions?

[ni-ze]

Besides I'm wondering will there be a complete test framework in the future to test the functions?

Yes, Open source projects should have complete unit tests. Are you interested in participating in unit testing contributions?

[elenacliu]

Besides I'm wondering will there be a complete test framework in the future to test the functions?

Yes, Open source projects should have complete unit tests. Are you interested in participating in unit testing contributions?

Yes I'm interested in that, but I have little idea about how to setup a complete test framework in java now. Maybe you can provide a framework in the near future and other committers can add unit tests to it.