OutputCollector.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.storm.task;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;

import org.apache.storm.tuple.Tuple;
import org.apache.storm.utils.Utils;

/**
 * This output collector exposes the API for emitting tuples from an IRichBolt.
 * This is the core API for emitting tuples. For a simpler API, and a more restricted
 * form of stream processing, see IBasicBolt and BasicOutputCollector.
 */
public class OutputCollector implements IOutputCollector {
  private IOutputCollector delegate;


  public OutputCollector(IOutputCollector delegate) {
    this.delegate = delegate;
  }

  /**
   * Emits a new tuple to a specific stream with a single anchor. The emitted values must be
   * immutable.
   *
   * @param streamId the stream to emit to
   * @param anchor the tuple to anchor to
   * @param tuple the new output tuple from this bolt
   * @return the list of task ids that this new tuple was sent to
   */
  public List<Integer> emit(String streamId, Tuple anchor, List<Object> tuple) {
    return emit(streamId, Arrays.asList(anchor), tuple);
  }

  /**
   * Emits a new unanchored tuple to the specified stream. Because it's unanchored,
   * if a failure happens downstream, this new tuple won't affect whether any
   * spout tuples are considered failed or not. The emitted values must be
   * immutable.
   *
   * @param streamId the stream to emit to
   * @param tuple the new output tuple from this bolt
   * @return the list of task ids that this new tuple was sent to
   */
  public List<Integer> emit(String streamId, List<Object> tuple) {
    return emit(streamId, (Collection<Tuple>) null, tuple);
  }

  /**
   * Emits a new tuple to the default stream anchored on a group of input tuples. The emitted
   * values must be immutable.
   *
   * @param anchors the tuples to anchor to
   * @param tuple the new output tuple from this bolt
   * @return the list of task ids that this new tuple was sent to
   */
  public List<Integer> emit(Collection<Tuple> anchors, List<Object> tuple) {
    return emit(Utils.DEFAULT_STREAM_ID, anchors, tuple);
  }


  /**
   * Emits a new tuple to the default stream anchored on a single tuple. The emitted values must be
   * immutable.
   *
   * @param anchor the tuple to anchor to
   * @param tuple the new output tuple from this bolt
   * @return the list of task ids that this new tuple was sent to
   */
  public List<Integer> emit(Tuple anchor, List<Object> tuple) {
    return emit(Utils.DEFAULT_STREAM_ID, anchor, tuple);
  }

  /**
   * Emits a new unanchored tuple to the default stream. Beacuse it's unanchored,
   * if a failure happens downstream, this new tuple won't affect whether any
   * spout tuples are considered failed or not. The emitted values must be
   * immutable.
   *
   * @param tuple the new output tuple from this bolt
   * @return the list of task ids that this new tuple was sent to
   */
  public List<Integer> emit(List<Object> tuple) {
    return emit(Utils.DEFAULT_STREAM_ID, tuple);
  }

  /**
   * Emits a tuple directly to the specified task id on the specified stream.
   * If the target bolt does not subscribe to this bolt using a direct grouping,
   * the tuple will not be sent. If the specified output stream is not declared
   * as direct, or the target bolt subscribes with a non-direct grouping,
   * an error will occur at runtime. The emitted values must be
   * immutable.
   *
   * @param taskId the taskId to send the new tuple to
   * @param streamId the stream to send the tuple on. It must be declared as a direct stream in the topology definition.
   * @param anchor the tuple to anchor to
   * @param tuple the new output tuple from this bolt
   */
  public void emitDirect(int taskId, String streamId, Tuple anchor, List<Object> tuple) {
    emitDirect(taskId, streamId, Arrays.asList(anchor), tuple);
  }

  /**
   * Emits a tuple directly to the specified task id on the specified stream.
   * If the target bolt does not subscribe to this bolt using a direct grouping,
   * the tuple will not be sent. If the specified output stream is not declared
   * as direct, or the target bolt subscribes with a non-direct grouping,
   * an error will occur at runtime. Note that this method does not use anchors,
   * so downstream failures won't affect the failure status of any spout tuples.
   * The emitted values must be immutable.
   *
   * @param taskId the taskId to send the new tuple to
   * @param streamId the stream to send the tuple on. It must be declared as a direct stream in the topology definition.
   * @param tuple the new output tuple from this bolt
   */
  public void emitDirect(int taskId, String streamId, List<Object> tuple) {
    emitDirect(taskId, streamId, (Collection<Tuple>) null, tuple);
  }

  /**
   * Emits a tuple directly to the specified task id on the default stream.
   * If the target bolt does not subscribe to this bolt using a direct grouping,
   * the tuple will not be sent. If the specified output stream is not declared
   * as direct, or the target bolt subscribes with a non-direct grouping,
   * an error will occur at runtime. The emitted values must be
   * immutable.
   * <p>
   * <p>The default stream must be declared as direct in the topology definition.
   * See OutputDeclarer#declare for how this is done when defining topologies
   * in Java.</p>
   *
   * @param taskId the taskId to send the new tuple to
   * @param anchors the tuples to anchor to
   * @param tuple the new output tuple from this bolt
   */
  public void emitDirect(int taskId, Collection<Tuple> anchors, List<Object> tuple) {
    emitDirect(taskId, Utils.DEFAULT_STREAM_ID, anchors, tuple);
  }

  /**
   * Emits a tuple directly to the specified task id on the default stream.
   * If the target bolt does not subscribe to this bolt using a direct grouping,
   * the tuple will not be sent. If the specified output stream is not declared
   * as direct, or the target bolt subscribes with a non-direct grouping,
   * an error will occur at runtime. The emitted values must be
   * immutable.
   * <p>
   * <p>The default stream must be declared as direct in the topology definition.
   * See OutputDeclarer#declare for how this is done when defining topologies
   * in Java.</p>
   *
   * @param taskId the taskId to send the new tuple to
   * @param anchor the tuple to anchor to
   * @param tuple the new output tuple from this bolt
   */
  public void emitDirect(int taskId, Tuple anchor, List<Object> tuple) {
    emitDirect(taskId, Utils.DEFAULT_STREAM_ID, anchor, tuple);
  }


  /**
   * Emits a tuple directly to the specified task id on the default stream.
   * If the target bolt does not subscribe to this bolt using a direct grouping,
   * the tuple will not be sent. If the specified output stream is not declared
   * as direct, or the target bolt subscribes with a non-direct grouping,
   * an error will occur at runtime. The emitted values must be
   * immutable.
   * <p>
   * <p>The default stream must be declared as direct in the topology definition.
   * See OutputDeclarer#declare for how this is done when defining topologies
   * in Java.</p>
   * <p>
   * <p>Note that this method does not use anchors, so downstream failures won't
   * affect the failure status of any spout tuples.</p>
   *
   * @param taskId the taskId to send the new tuple to
   * @param tuple the new output tuple from this bolt
   */
  public void emitDirect(int taskId, List<Object> tuple) {
    emitDirect(taskId, Utils.DEFAULT_STREAM_ID, tuple);
  }

  @Override
  public List<Integer> emit(String streamId, Collection<Tuple> anchors, List<Object> tuple) {
    return delegate.emit(streamId, anchors, tuple);
  }

  @Override
  public void emitDirect(
      int taskId, String streamId, Collection<Tuple> anchors, List<Object> tuple) {
    delegate.emitDirect(taskId, streamId, anchors, tuple);
  }

  @Override
  public void ack(Tuple input) {
    delegate.ack(input);
  }

  @Override
  public void fail(Tuple input) {
    delegate.fail(input);
  }

  @Override
  public void reportError(Throwable error) {
    delegate.reportError(error);
  }
}