content: /*
   * Copyright (C) 2018 The Android Open Source Project
   *
   * Licensed 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 com.google.android.exoplayer2.upstream.cache;
  
  import com.google.android.exoplayer2.upstream.DataSpec;
  
  /** Factory for cache keys. */
  public interface CacheKeyFactory {
  
    /** Default {@link CacheKeyFactory}. */
    CacheKeyFactory DEFAULT =
        (dataSpec) -> dataSpec.key != null ? dataSpec.key : dataSpec.uri.toString();
  
    /**
     * Returns the cache key of the resource containing the data defined by a {@link DataSpec}.
     *
     * <p>Note that since the returned cache key corresponds to the whole resource, implementations
     * must not return different cache keys for {@link DataSpec DataSpecs} that define different
     * ranges of the same resource. As a result, implementations should not use fields such as {@link
     * DataSpec#position} and {@link DataSpec#length}.
     *
     * @param dataSpec The {@link DataSpec}.
     * @return The cache key of the resource.
     */
    String buildCacheKey(DataSpec dataSpec);
  }
  