content: /*
   * 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.asterix.common.external;
  
  import org.apache.hyracks.api.comm.IFrameWriter;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.storage.am.common.api.ITupleFilter;
  
  /**
   * A super interface implemented by a data source adapter. An adapter can be a
   * pull based or push based. This interface provides all common APIs that need
   * to be implemented by each adapter irrespective of the the kind of
   * adapter(pull or push).
   */
  @FunctionalInterface
  public interface IDataSourceAdapter {
  
      public enum AdapterType {
          INTERNAL,
          EXTERNAL
      }
  
      /**
       * Triggers the adapter to begin ingesting data from the external source.
       *
       * @param partition
       *            The adapter could be running with a degree of parallelism.
       *            partition corresponds to the i'th parallel instance.
       * @param writer
       *            The instance of frame writer that is used by the adapter to
       *            write frame to. Adapter packs the fetched bytes (from external source),
       *            packs them into frames and forwards the frames to an upstream receiving
       *            operator using the instance of IFrameWriter.
       * @param tupleFilter
       *            If not {@code null} then only tuple matching this filter should be emitted
       * @param outputLimit
       *            Limits the number of tuples that should be emitted
       *            (after applying the filter if it's specified).
       *            {@code -1} if there is not limit.
       * @throws Exception
       */
      void start(int partition, IFrameWriter writer, ITupleFilter tupleFilter, long outputLimit)
              throws HyracksDataException, InterruptedException;
  
      /**
       * Triggers the adapter to begin ingesting data from the external source.
       *
       * @param partition
       *            The adapter could be running with a degree of parallelism.
       *            partition corresponds to the i'th parallel instance.
       * @param writer
       *            The instance of frame writer that is used by the adapter to
       *            write frame to. Adapter packs the fetched bytes (from external source),
       *            packs them into frames and forwards the frames to an upstream receiving
       *            operator using the instance of IFrameWriter.
       * @throws Exception
       */
      default void start(int partition, IFrameWriter writer) throws HyracksDataException, InterruptedException {
          start(partition, writer, null, -1);
      }
  
      /**
       * @return The number of processed tuples by this adapter
       */
      default long getProcessedTuples() {
          throw new UnsupportedOperationException();
      }
  }
  