samza-test/src/main/java/org/apache/samza/test/integration/SimpleStatefulTask.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 org.apache.samza.test.integration;

import org.apache.samza.context.Context;
import org.apache.samza.storage.kv.Entry;
import org.apache.samza.storage.kv.KeyValueIterator;
import org.apache.samza.storage.kv.KeyValueStore;
import org.apache.samza.system.IncomingMessageEnvelope;
import org.apache.samza.task.InitableTask;
import org.apache.samza.task.MessageCollector;
import org.apache.samza.task.StreamTask;
import org.apache.samza.task.TaskCoordinator;
import org.apache.samza.task.TaskCoordinator.RequestScope;

/**
 * This is a simple task that writes each message to a state store and prints them all out on reload.
 *
 * It is useful for command line testing with the kafka console producer and consumer and text messages.
 */
public class SimpleStatefulTask implements StreamTask, InitableTask {

  private KeyValueStore<String, String> store;

  @SuppressWarnings("unchecked")
  public void init(Context context) {
    this.store = (KeyValueStore<String, String>) context.getTaskContext().getStore("mystore");
    System.out.println("Contents of store: ");
    KeyValueIterator<String, String> iter = store.all();
    while (iter.hasNext()) {
      Entry<String, String> entry = iter.next();
      System.out.println(entry.getKey() + " => " + entry.getValue());
    }
    iter.close();
  }

  public void process(IncomingMessageEnvelope envelope, MessageCollector collector, TaskCoordinator coordinator) {
    System.out.println("Adding " + envelope.getMessage() + " => " + envelope.getMessage() + " to the store.");
    store.put((String) envelope.getMessage(), (String) envelope.getMessage());
    coordinator.commit(RequestScope.ALL_TASKS_IN_CONTAINER);
  }

}