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.kafka.connect.storage;
  
  import java.util.Collection;
  import java.util.Map;
  
  /**
   * <p>
   * OffsetStorageReader provides access to the offset storage used by sources. This can be used by
   * connectors to determine offsets to start consuming data from. This is most commonly used during
   * initialization of a task, but can also be used during runtime, e.g. when reconfiguring a task.
   * </p>
   * <p>
   * Offsets are always defined as Maps of Strings to primitive types, i.e. all types supported by
   * {@link org.apache.kafka.connect.data.Schema} other than Array, Map, and Struct.
   * </p>
   */
  public interface OffsetStorageReader {
      /**
       * Get the offset for the specified partition. If the data isn't already available locally, this
       * gets it from the backing store, which may require some network round trips.
       *
       * @param partition object uniquely identifying the partition of data
       * @return object uniquely identifying the offset in the partition of data
       */
      <T> Map<String, Object> offset(Map<String, T> partition);
  
      /**
       * <p>
       * Get a set of offsets for the specified partition identifiers. This may be more efficient
       * than calling {@link #offset(Map)} repeatedly.
       * </p>
       * <p>
       * Note that when errors occur, this method omits the associated data and tries to return as
       * many of the requested values as possible. This allows a task that's managing many partitions to
       * still proceed with any available data. Therefore, implementations should take care to check
       * that the data is actually available in the returned response. The only case when an
       * exception will be thrown is if the entire request failed, e.g. because the underlying
       * storage was unavailable.
       * </p>
       *
       * @param partitions set of identifiers for partitions of data
       * @return a map of partition identifiers to decoded offsets
       */
      <T> Map<Map<String, T>, Map<String, Object>> offsets(Collection<Map<String, T>> partitions);
  }
  