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A module that is everything required to understands Druid Segments

There is a newer version: 0.12.3

/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.query;

import com.fasterxml.jackson.core.type.TypeReference;
import com.google.common.base.Function;

/**
*/
public interface CacheStrategy>
{
  /**
   * Computes the cache key for the given query
   *
   * @param query the query to compute a cache key for
   * @return the cache key
   */
  byte[] computeCacheKey(QueryType query);

  /**
   * Returns the class type of what is used in the cache
   *
   * @return Returns the class type of what is used in the cache
   */
  TypeReference getCacheObjectClazz();

  /**
   * Returns a function that converts from the QueryType's result type to something cacheable.
   *
   * The resulting function must be thread-safe.
   *
   * @return a thread-safe function that converts the QueryType's result type into something cacheable
   */
  Function prepareForCache();

  /**
   * A function that does the inverse of the operation that the function prepareForCache returns
   *
   * @return A function that does the inverse of the operation that the function prepareForCache returns
   */
  Function pullFromCache();
}