api/src/main/java/com/datatorrent/api/DefaultInputPort.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 com.datatorrent.api;

import org.apache.hadoop.classification.InterfaceStability;

import com.datatorrent.api.Context.PortContext;
import com.datatorrent.api.Operator.InputPort;

/**
 * Default abstract implementation for input ports.
 * An operator would typically define a derived inner class with the process method.
 * This class is designed for use with a transient field, i.e. not to be serialized with the operator state.
 *
 * @param <T>
 * @since 0.3.2
 */
public abstract class DefaultInputPort<T> implements InputPort<T>, Sink<T>
{
  private int count;
  private boolean connected = false;

  /**
   * <p>Constructor for DefaultInputPort.</p>
   */
  public DefaultInputPort()
  {
  }

  /** {@inheritDoc} */
  @Override
  public Sink<T> getSink()
  {
    return this;
  }

  /** {@inheritDoc} */
  @Override
  public void setConnected(boolean connected)
  {
    this.connected = connected;
  }

  /**
   * Returns true if this port is connected and false otherwise.
   * @return true if this port is connected and false otherwise.
   */
  public boolean isConnected()
  {
    return connected;
  }

  /** {@inheritDoc} */
  @Override
  public StreamCodec<T> getStreamCodec()
  {
    return null;
  }

  /** {@inheritDoc} */
  @Override
  public void put(T tuple)
  {
    count++;
    process(tuple);
  }

  /** {@inheritDoc} */
  @Override
  public int getCount(boolean reset)
  {
    try {
      return count;
    } finally {
      if (reset) {
        count = 0;
      }
    }
  }

  /** {@inheritDoc} */
  @Override
  public void setup(PortContext context)
  {
  }

  /** {@inheritDoc} */
  @Override
  public void teardown()
  {
  }

  /**
   * <p>process.</p>
   */
  public abstract void process(T tuple);

  @InterfaceStability.Evolving
  protected int incrementCount()
  {
    return ++count;
  }
}