org.apache.druid.indexing.common.tasklogs.SwitchingTaskLogStreamer Maven / Gradle / Ivy

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/*
 * 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.druid.indexing.common.tasklogs;

import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.common.io.ByteSource;
import com.google.inject.Inject;
import org.apache.druid.tasklogs.TaskLogStreamer;

import java.io.IOException;
import java.util.List;

/**
 * Provides task logs based on a series of underlying task log providers.
 */
public class SwitchingTaskLogStreamer implements TaskLogStreamer
{
  private final List providers;

  @Inject
  public SwitchingTaskLogStreamer(List providers)
  {
    this.providers = ImmutableList.copyOf(providers);
  }

  @Override
  public Optional streamTaskLog(String taskid, long offset) throws IOException
  {
    for (TaskLogStreamer provider : providers) {
      final Optional stream = provider.streamTaskLog(taskid, offset);
      if (stream.isPresent()) {
        return stream;
      }
    }

    return Optional.absent();
  }

  @Override
  public Optional streamTaskReports(String taskid) throws IOException
  {
    for (TaskLogStreamer provider : providers) {
      final Optional stream = provider.streamTaskReports(taskid);
      if (stream.isPresent()) {
        return stream;
      }
    }

    return Optional.absent();
  }
}