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.cassandra.io.util;
  
  import java.io.DataOutput;
  import java.io.IOError;
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.charset.StandardCharsets;
  import java.util.zip.CRC32;
  
  import javax.annotation.Nonnull;
  
  import org.apache.cassandra.io.FSWriteError;
  
  public class ChecksumWriter
  {
      private final CRC32 incrementalChecksum = new CRC32();
      private final DataOutput incrementalOut;
      private final CRC32 fullChecksum = new CRC32();
  
      public ChecksumWriter(DataOutput incrementalOut)
      {
          this.incrementalOut = incrementalOut;
      }
  
      public void writeChunkSize(int length)
      {
          try
          {
              incrementalOut.writeInt(length);
          }
          catch (IOException e)
          {
              throw new IOError(e);
          }
      }
  
      // checksumIncrementalResult indicates if the checksum we compute for this buffer should itself be
      // included in the full checksum, translating to if the partial checksum is serialized along with the
      // data it checksums (in which case the file checksum as calculated by external tools would mismatch if
      // we did not include it), or independently.
  
      // CompressedSequentialWriters serialize the partial checksums inline with the compressed data chunks they
      // corroborate, whereas ChecksummedSequentialWriters serialize them to a different file.
      public void appendDirect(ByteBuffer bb, boolean checksumIncrementalResult)
      {
          try
          {
              ByteBuffer toAppend = bb.duplicate();
              toAppend.mark();
              incrementalChecksum.update(toAppend);
              toAppend.reset();
  
              int incrementalChecksumValue = (int) incrementalChecksum.getValue();
              incrementalOut.writeInt(incrementalChecksumValue);
  
              fullChecksum.update(toAppend);
              if (checksumIncrementalResult)
              {
                  ByteBuffer byteBuffer = ByteBuffer.allocate(4);
                  byteBuffer.putInt(incrementalChecksumValue);
                  assert byteBuffer.arrayOffset() == 0;
                  fullChecksum.update(byteBuffer.array(), 0, byteBuffer.array().length);
              }
              incrementalChecksum.reset();
  
          }
          catch (IOException e)
          {
              throw new IOError(e);
          }
      }
  
      public void writeFullChecksum(@Nonnull File digestFile)
      {
          try (FileOutputStreamPlus fos = new FileOutputStreamPlus(digestFile))
          {
              fos.write(String.valueOf(fullChecksum.getValue()).getBytes(StandardCharsets.UTF_8));
              fos.flush();
              fos.getChannel().force(true);
          }
          catch (IOException e)
          {
              throw new FSWriteError(e, digestFile);
          }
      }
  }
  
  