storm-client/src/jvm/org/apache/storm/spout/SpoutOutputCollector.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.spout;

import java.util.List;
import org.apache.storm.task.OutputCollector;
import org.apache.storm.utils.Utils;

/**
 * This output collector exposes the API for emitting tuples from an {@link org.apache.storm.topology.IRichSpout}. The main difference
 * between this output collector and {@link OutputCollector} for {@link org.apache.storm.topology.IRichBolt} is that spouts can tag messages
 * with ids so that they can be acked or failed later on. This is the Spout portion of Storm's API to guarantee that each message is fully
 * processed at least once.
 */
public class SpoutOutputCollector implements ISpoutOutputCollector {
    ISpoutOutputCollector delegate;

    public SpoutOutputCollector(ISpoutOutputCollector delegate) {
        this.delegate = delegate;
    }

    /**
     * Emits a new tuple to the specified output stream with the given message ID. When Storm detects that this tuple has been fully
     * processed, or has failed to be fully processed, the spout will receive an ack or fail callback respectively with the messageId as
     * long as the messageId was not null. If the messageId was null, Storm will not track the tuple and no callback will be received. Note
     * that Storm's event logging functionality will only work if the messageId is serializable via Kryo or the Serializable interface. The
     * emitted values must be immutable.
     *
     * @return the list of task ids that this tuple was sent to
     */
    @Override
    public List<Integer> emit(String streamId, List<Object> tuple, Object messageId) {
        return delegate.emit(streamId, tuple, messageId);
    }

    /**
     * Emits a new tuple to the default output stream with the given message ID. When Storm detects that this tuple has been fully
     * processed, or has failed to be fully processed, the spout will receive an ack or fail callback respectively with the messageId as
     * long as the messageId was not null. If the messageId was null, Storm will not track the tuple and no callback will be received. Note
     * that Storm's event logging functionality will only work if the messageId is serializable via Kryo or the Serializable interface. The
     * emitted values must be immutable.
     *
     * @return the list of task ids that this tuple was sent to
     */
    public List<Integer> emit(List<Object> tuple, Object messageId) {
        return delegate.emit(Utils.DEFAULT_STREAM_ID, tuple, messageId);
    }

    /**
     * Emits a tuple to the default output stream with a null message id. Storm will not track this message so ack and fail will never be
     * called for this tuple. The emitted values must be immutable.
     */
    public List<Integer> emit(List<Object> tuple) {
        return emit(tuple, null);
    }

    /**
     * Emits a tuple to the specified output stream with a null message id. Storm will not track this message so ack and fail will never be
     * called for this tuple. The emitted values must be immutable.
     */
    public List<Integer> emit(String streamId, List<Object> tuple) {
        return emit(streamId, tuple, null);
    }

    /**
     * Emits a tuple to the specified task on the specified output stream. This output stream must have been declared as a direct stream,
     * and the specified task must use a direct grouping on this stream to receive the message. Note that Storm's event logging
     * functionality will only work if the messageId is serializable via Kryo or the Serializable interface. The emitted values must be
     * immutable.
     */
    @Override
    public void emitDirect(int taskId, String streamId, List<Object> tuple, Object messageId) {
        delegate.emitDirect(taskId, streamId, tuple, messageId);
    }

    /**
     * Emits a tuple to the specified task on the default output stream. This output stream must have been declared as a direct stream, and
     * the specified task must use a direct grouping on this stream to receive the message. Note that Storm's event logging functionality
     * will only work if the messageId is serializable via Kryo or the Serializable interface. The emitted values must be immutable.
     */
    public void emitDirect(int taskId, List<Object> tuple, Object messageId) {
        emitDirect(taskId, Utils.DEFAULT_STREAM_ID, tuple, messageId);
    }

    /**
     * Emits a tuple to the specified task on the specified output stream. This output stream must have been declared as a direct stream,
     * and the specified task must use a direct grouping on this stream to receive the message. The emitted values must be immutable.
     *
     * <p>Because no message id is specified, Storm will not track this message so ack and fail will never be called for this tuple.
     */
    public void emitDirect(int taskId, String streamId, List<Object> tuple) {
        emitDirect(taskId, streamId, tuple, null);
    }

    /**
     * Emits a tuple to the specified task on the default output stream. This output stream must have been declared as a direct stream, and
     * the specified task must use a direct grouping on this stream to receive the message. The emitted values must be immutable.
     *
     * <p>Because no message id is specified, Storm will not track this message so ack and fail will never be called for this tuple.
     */
    public void emitDirect(int taskId, List<Object> tuple) {
        emitDirect(taskId, tuple, null);
    }

    @Override
    public void flush() {
        delegate.flush();
    }

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

    @Override
    public long getPendingCount() {
        return delegate.getPendingCount();
    }
}