Package loci.common

Class NIOByteBufferProvider

java.lang.Object
loci.common.NIOByteBufferProvider
public class NIOByteBufferProvider
extends java.lang.Object
Provides a facade to byte buffer allocation that enables FileChannel.map() usage on platforms where it's unlikely to give us problems and heap allocation where it is. References:
  • http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5092131
  • http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6417205
Author:
Chris Allan (callan at blackcat dot ca)

  • Field Summary

    Fields 
    Modifier and Type Field Description
    static int MINIMUM_JAVA_VERSION
    The minimum Java version we know is safe for memory mapped I/O.

  • Constructor Summary

    Constructors 
    Constructor Description
    NIOByteBufferProvider​(java.nio.channels.FileChannel channel, java.nio.channels.FileChannel.MapMode mapMode)
    Default constructor.

  • Method Summary

    Modifier and Type Method Description
    java.nio.ByteBuffer allocate​(long bufferStartPosition, int newSize)
    Allocates or maps the desired file data into memory.
    protected java.nio.ByteBuffer allocateDirect​(long bufferStartPosition, int newSize)
    Allocates memory and copies the desired file data into it.
    protected java.nio.ByteBuffer allocateMappedByteBuffer​(long bufferStartPosition, int newSize)
    Memory maps the desired file data into memory.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

  • Constructor Details

    • NIOByteBufferProvider

      public NIOByteBufferProvider​(java.nio.channels.FileChannel channel, java.nio.channels.FileChannel.MapMode mapMode)
      Default constructor.
      Parameters:
      channel - File channel to allocate or map byte buffers from.
      mapMode - The map mode. Required but only used if memory mapped I/O is to occur.

  • Method Details

    • allocate

      public java.nio.ByteBuffer allocate​(long bufferStartPosition, int newSize) throws java.io.IOException
      Allocates or maps the desired file data into memory.
      Parameters:
      bufferStartPosition - The absolute position of the start of the buffer.
      newSize - The buffer size.
      Returns:
      A newly allocated or mapped NIO byte buffer.
      Throws:
      java.io.IOException - If there is an issue mapping, aligning or allocating the buffer.

    • allocateDirect

      protected java.nio.ByteBuffer allocateDirect​(long bufferStartPosition, int newSize) throws java.io.IOException
      Allocates memory and copies the desired file data into it.
      Parameters:
      bufferStartPosition - The absolute position of the start of the buffer.
      newSize - The buffer size.
      Returns:
      A newly allocated NIO byte buffer.
      Throws:
      java.io.IOException - If there is an issue aligning or allocating the buffer.

    • allocateMappedByteBuffer

      protected java.nio.ByteBuffer allocateMappedByteBuffer​(long bufferStartPosition, int newSize) throws java.io.IOException
      Memory maps the desired file data into memory.
      Parameters:
      bufferStartPosition - The absolute position of the start of the buffer.
      newSize - The buffer size.
      Returns:
      A newly mapped NIO byte buffer.
      Throws:
      java.io.IOException - If there is an issue mapping, aligning or allocating the buffer.