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.common.compress;
  
  import org.apache.kafka.common.KafkaException;
  import org.apache.kafka.common.record.CompressionType;
  import org.apache.kafka.common.utils.BufferSupplier;
  import org.apache.kafka.common.utils.ByteBufferInputStream;
  import org.apache.kafka.common.utils.ByteBufferOutputStream;
  import org.apache.kafka.common.utils.ChunkedBytesStream;
  
  import com.github.luben.zstd.BufferPool;
  import com.github.luben.zstd.RecyclingBufferPool;
  import com.github.luben.zstd.ZstdInputStreamNoFinalizer;
  import com.github.luben.zstd.ZstdOutputStreamNoFinalizer;
  
  import java.io.BufferedOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.util.Objects;
  
  import static org.apache.kafka.common.record.CompressionType.ZSTD;
  
  public class ZstdCompression implements Compression {
  
      private final int level;
  
      private ZstdCompression(int level) {
          this.level = level;
      }
  
      @Override
      public CompressionType type() {
          return ZSTD;
      }
  
      @Override
      public OutputStream wrapForOutput(ByteBufferOutputStream bufferStream, byte messageVersion) {
          try {
              // Set input buffer (uncompressed) to 16 KB (none by default) to ensure reasonable performance
              // in cases where the caller passes a small number of bytes to write (potentially a single byte).
              return new BufferedOutputStream(new ZstdOutputStreamNoFinalizer(bufferStream, RecyclingBufferPool.INSTANCE, level), 16 * 1024);
          } catch (Throwable e) {
              throw new KafkaException(e);
          }
      }
  
      @Override
      public InputStream wrapForInput(ByteBuffer buffer, byte messageVersion, BufferSupplier decompressionBufferSupplier) {
          try {
              return new ChunkedBytesStream(wrapForZstdInput(buffer, decompressionBufferSupplier),
                      decompressionBufferSupplier,
                      decompressionOutputSize(),
                      false);
          } catch (Throwable e) {
              throw new KafkaException(e);
          }
      }
  
      // visible for testing
      public static ZstdInputStreamNoFinalizer wrapForZstdInput(ByteBuffer buffer, BufferSupplier decompressionBufferSupplier) throws IOException {
          // We use our own BufferSupplier instead of com.github.luben.zstd.RecyclingBufferPool since our
          // implementation doesn't require locking or soft references. The buffer allocated by this buffer pool is
          // used by zstd-jni for 1\ reading compressed data from input stream into a buffer before passing it over JNI
          // 2\ implementation of skip inside zstd-jni where buffer is obtained and released with every call
          final BufferPool bufferPool = new BufferPool() {
              @Override
              public ByteBuffer get(int capacity) {
                  return decompressionBufferSupplier.get(capacity);
              }
  
              @Override
              public void release(ByteBuffer buffer) {
                  decompressionBufferSupplier.release(buffer);
              }
          };
          // Ideally, data from ZstdInputStreamNoFinalizer should be read in a bulk because every call to
          // `ZstdInputStreamNoFinalizer#read()` is a JNI call. The caller is expected to
          // balance the tradeoff between reading large amount of data vs. making multiple JNI calls.
          return new ZstdInputStreamNoFinalizer(new ByteBufferInputStream(buffer), bufferPool);
      }
  
      /**
       * Size of intermediate buffer which contains uncompressed data.
       * This size should be <= ZSTD_BLOCKSIZE_MAX
       * see: https://github.com/facebook/zstd/blob/189653a9c10c9f4224a5413a6d6a69dd01d7c3bd/lib/zstd.h#L854
       */
      @Override
      public int decompressionOutputSize() {
          // 16KB has been chosen based on legacy implementation introduced in https://github.com/apache/kafka/pull/6785
          return 16 * 1024;
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
          if (o == null || getClass() != o.getClass()) return false;
          ZstdCompression that = (ZstdCompression) o;
          return level == that.level;
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(level);
      }
  
      public static class Builder implements Compression.Builder<ZstdCompression> {
          private int level = ZSTD.defaultLevel();
  
          public Builder level(int level) {
              if (level < ZSTD.minLevel() || ZSTD.maxLevel() < level) {
                  throw new IllegalArgumentException("zstd doesn't support given compression level: " + level);
              }
  
              this.level = level;
              return this;
          }
  
          @Override
          public ZstdCompression build() {
              return new ZstdCompression(level);
          }
      }
  }
  