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.arrow.vector.compression;
  
  import java.util.EnumMap;
  import java.util.Map;
  import java.util.ServiceLoader;
  import org.apache.arrow.memory.ArrowBuf;
  import org.apache.arrow.memory.BufferAllocator;
  
  /** The codec for compression/decompression. */
  public interface CompressionCodec {
  
    /**
     * Compress a buffer.
     *
     * @param allocator the allocator for allocating memory for compressed buffer.
     * @param uncompressedBuffer the buffer to compress. Implementation of this method should take
     *     care of releasing this buffer.
     * @return the compressed buffer
     */
    ArrowBuf compress(BufferAllocator allocator, ArrowBuf uncompressedBuffer);
  
    /**
     * Decompress a buffer.
     *
     * @param allocator the allocator for allocating memory for decompressed buffer.
     * @param compressedBuffer the buffer to be decompressed. Implementation of this method should
     *     take care of releasing this buffer.
     * @return the decompressed buffer.
     */
    ArrowBuf decompress(BufferAllocator allocator, ArrowBuf compressedBuffer);
  
    /**
     * Gets the type of the codec.
     *
     * @return the type of the codec.
     */
    CompressionUtil.CodecType getCodecType();
  
    /** Factory to create compression codec. */
    interface Factory {
      /**
       * This combines all the available factories registered as service providers in the module path.
       * For each {@link CompressionUtil.CodecType compression codec type}, it will use whatever
       * factory supports it, i.e. doesn't throw on `createCodec(type)`. If multiple factories
       * registered as service providers support the same codec type, the first one encountered while
       * iterating over the {@link ServiceLoader} will be selected. A codec type that is not supported
       * by any registered service provider will fall back to {@link
       * NoCompressionCodec.Factory#INSTANCE} for backwards compatibility.
       */
      Factory INSTANCE = bestEffort();
  
      /** Creates the codec based on the codec type. */
      CompressionCodec createCodec(CompressionUtil.CodecType codecType);
  
      /** Creates the codec based on the codec type and compression level. */
      CompressionCodec createCodec(CompressionUtil.CodecType codecType, int compressionLevel);
  
      private static Factory bestEffort() {
        final ServiceLoader<Factory> serviceLoader = ServiceLoader.load(Factory.class);
        final Map<CompressionUtil.CodecType, Factory> factories =
            new EnumMap<>(CompressionUtil.CodecType.class);
        for (Factory factory : serviceLoader) {
          for (CompressionUtil.CodecType codecType : CompressionUtil.CodecType.values()) {
            try {
              factory.createCodec(codecType); // will throw if not supported
              factories.putIfAbsent(codecType, factory);
            } catch (Throwable ignored) {
            }
          }
        }
  
        final Factory fallback = NoCompressionCodec.Factory.INSTANCE;
        return new Factory() {
          @Override
          public CompressionCodec createCodec(CompressionUtil.CodecType codecType) {
            return factories.getOrDefault(codecType, fallback).createCodec(codecType);
          }
  
          @Override
          public CompressionCodec createCodec(
              CompressionUtil.CodecType codecType, int compressionLevel) {
            return factories
                .getOrDefault(codecType, fallback)
                .createCodec(codecType, compressionLevel);
          }
        };
      }
    }
  }
  