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.IOException;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.nio.channels.WritableByteChannel;
  
  import io.netty.util.concurrent.FastThreadLocal;
  import org.apache.cassandra.utils.ByteBufferUtil;
  
  import static org.apache.cassandra.config.CassandraRelevantProperties.DATA_OUTPUT_STREAM_PLUS_TEMP_BUFFER_SIZE;
  
  /**
   * Abstract base class for DataOutputStreams that accept writes from ByteBuffer or Memory and also provide
   * access to the underlying WritableByteChannel associated with their output stream.
   *
   * If no channel is provided by derived classes then a wrapper channel is provided.
   */
  public abstract class DataOutputStreamPlus extends OutputStream implements DataOutputPlus
  {
      //Dummy wrapper channel for derived implementations that don't have a channel
      protected final WritableByteChannel channel;
  
      protected DataOutputStreamPlus()
      {
          this.channel = newDefaultChannel();
      }
  
      protected DataOutputStreamPlus(WritableByteChannel channel)
      {
          this.channel = channel;
      }
  
      private static final int MAX_BUFFER_SIZE = DATA_OUTPUT_STREAM_PLUS_TEMP_BUFFER_SIZE.getInt();
  
      /*
       * Factored out into separate method to create more flexibility around inlining
       */
      protected static byte[] retrieveTemporaryBuffer(int minSize)
      {
          byte[] bytes = tempBuffer.get();
          if (bytes.length < Math.min(minSize, MAX_BUFFER_SIZE))
          {
              // increase in powers of 2, to avoid wasted repeat allocations
              bytes = new byte[Math.min(MAX_BUFFER_SIZE, 2 * Integer.highestOneBit(minSize))];
              tempBuffer.set(bytes);
          }
          return bytes;
      }
  
      private static final FastThreadLocal<byte[]> tempBuffer = new FastThreadLocal<byte[]>()
      {
          @Override
          public byte[] initialValue()
          {
              return new byte[16];
          }
      };
  
      // Derived classes can override and *construct* a real channel, if it is not possible to provide one to the constructor
      protected WritableByteChannel newDefaultChannel()
      {
          return new WritableByteChannel()
          {
  
              @Override
              public boolean isOpen()
              {
                  return true;
              }
  
              @Override
              public void close()
              {
              }
  
              @Override
              public int write(ByteBuffer src) throws IOException
              {
                  int toWrite = src.remaining();
  
                  if (src.hasArray())
                  {
                      DataOutputStreamPlus.this.write(src.array(), src.arrayOffset() + src.position(), src.remaining());
                      src.position(src.limit());
                      return toWrite;
                  }
  
                  if (toWrite < 16)
                  {
                      int offset = src.position();
                      for (int i = 0 ; i < toWrite ; i++)
                          DataOutputStreamPlus.this.write(src.get(i + offset));
                      src.position(src.limit());
                      return toWrite;
                  }
  
                  byte[] buf = retrieveTemporaryBuffer(toWrite);
  
                  int totalWritten = 0;
                  while (totalWritten < toWrite)
                  {
                      int toWriteThisTime = Math.min(buf.length, toWrite - totalWritten);
  
                      ByteBufferUtil.copyBytes(src, src.position() + totalWritten, buf, 0, toWriteThisTime);
  
                      DataOutputStreamPlus.this.write(buf, 0, toWriteThisTime);
  
                      totalWritten += toWriteThisTime;
                  }
  
                  src.position(src.limit());
                  return totalWritten;
              }
  
          };
      }
  
  }
  