ceph/src/arrow/java/vector/src/main/java/org/apache/arrow/vector/ipc/ReadChannel.java

   1 /*
   2  * Licensed to the Apache Software Foundation (ASF) under one or more
   3  * contributor license agreements.  See the NOTICE file distributed with
   4  * this work for additional information regarding copyright ownership.
   5  * The ASF licenses this file to You under the Apache License, Version 2.0
   6  * (the "License"); you may not use this file except in compliance with
   7  * the License.  You may obtain a copy of the License at
   8  *
   9  *    http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  */
  17
  18 package org.apache.arrow.vector.ipc;
  19
  20 import java.io.IOException;
  21 import java.nio.ByteBuffer;
  22 import java.nio.channels.ReadableByteChannel;
  23
  24 import org.apache.arrow.memory.ArrowBuf;
  25 import org.slf4j.Logger;
  26 import org.slf4j.LoggerFactory;
  27
  28 /**
  29  * Adapter around {@link ReadableByteChannel} that reads into {@linkplain ArrowBuf}s.
  30  */
  31 public class ReadChannel implements AutoCloseable {
  32
  33   private static final Logger LOGGER = LoggerFactory.getLogger(ReadChannel.class);
  34
  35   private ReadableByteChannel in;
  36   private long bytesRead = 0;
  37
  38   public ReadChannel(ReadableByteChannel in) {
  39     this.in = in;
  40   }
  41
  42   public long bytesRead() {
  43     return bytesRead;
  44   }
  45
  46   /**
  47    * Reads bytes into buffer until it is full (buffer.remaining() == 0). Returns the
  48    * number of bytes read which can be less than full if there are no more.
  49    *
  50    * @param buffer The buffer to read to
  51    * @return the number of byte read
  52    * @throws IOException if nit enough bytes left to read
  53    */
  54   public int readFully(ByteBuffer buffer) throws IOException {
  55     if (LOGGER.isDebugEnabled()) {
  56       LOGGER.debug("Reading buffer with size: {}", buffer.remaining());
  57     }
  58     int totalRead = 0;
  59     while (buffer.remaining() != 0) {
  60       int read = in.read(buffer);
  61       if (read == -1) {
  62         this.bytesRead += totalRead;
  63         return totalRead;
  64       }
  65       totalRead += read;
  66       if (read == 0) {
  67         break;
  68       }
  69     }
  70     this.bytesRead += totalRead;
  71     return totalRead;
  72   }
  73
  74   /**
  75    * Reads up to len into buffer. Returns bytes read.
  76    *
  77    * @param buffer the buffer to read to
  78    * @param length the amount of bytes to read
  79    * @return the number of bytes read
  80    * @throws IOException if nit enough bytes left to read
  81    */
  82   public long readFully(ArrowBuf buffer, long length) throws IOException {
  83     boolean fullRead = true;
  84     long bytesLeft = length;
  85     while (fullRead && bytesLeft > 0) {
  86       int bytesToRead = (int) Math.min(bytesLeft, Integer.MAX_VALUE);
  87       int n = readFully(buffer.nioBuffer(buffer.writerIndex(), bytesToRead));
  88       buffer.writerIndex(buffer.writerIndex() + n);
  89       fullRead = n == bytesToRead;
  90       bytesLeft -= n;
  91     }
  92     return length - bytesLeft;
  93   }
  94
  95   @Override
  96   public void close() throws IOException {
  97     if (this.in != null) {
  98       in.close();
  99       in = null;
 100     }
 101   }
 102 }