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.ipc;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.ReadableByteChannel;
  import org.apache.arrow.memory.ArrowBuf;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /** Adapter around {@link ReadableByteChannel} that reads into {@linkplain ArrowBuf}s. */
  public class ReadChannel implements AutoCloseable {
  
    private static final Logger LOGGER = LoggerFactory.getLogger(ReadChannel.class);
  
    private ReadableByteChannel in;
    private long bytesRead = 0;
  
    public ReadChannel(ReadableByteChannel in) {
      this.in = in;
    }
  
    public long bytesRead() {
      return bytesRead;
    }
  
    /**
     * Reads bytes into buffer until it is full (buffer.remaining() == 0). Returns the number of bytes
     * read which can be less than full if there are no more.
     *
     * @param buffer The buffer to read to
     * @return the number of byte read
     * @throws IOException if nit enough bytes left to read
     */
    public int readFully(ByteBuffer buffer) throws IOException {
      if (LOGGER.isDebugEnabled()) {
        LOGGER.debug("Reading buffer with size: {}", buffer.remaining());
      }
      int totalRead = 0;
      while (buffer.remaining() != 0) {
        int read = in.read(buffer);
        if (read == -1) {
          this.bytesRead += totalRead;
          return totalRead;
        }
        totalRead += read;
        if (read == 0) {
          break;
        }
      }
      this.bytesRead += totalRead;
      return totalRead;
    }
  
    /**
     * Reads up to len into buffer. Returns bytes read.
     *
     * @param buffer the buffer to read to
     * @param length the amount of bytes to read
     * @return the number of bytes read
     * @throws IOException if nit enough bytes left to read
     */
    public long readFully(ArrowBuf buffer, long length) throws IOException {
      boolean fullRead = true;
      long bytesLeft = length;
      while (fullRead && bytesLeft > 0) {
        int bytesToRead = (int) Math.min(bytesLeft, Integer.MAX_VALUE);
        int n = readFully(buffer.nioBuffer(buffer.writerIndex(), bytesToRead));
        buffer.writerIndex(buffer.writerIndex() + n);
        fullRead = n == bytesToRead;
        bytesLeft -= n;
      }
      return length - bytesLeft;
    }
  
    @Override
    public void close() throws IOException {
      if (this.in != null) {
        in.close();
        in = null;
      }
    }
  }
  