com.faunos.util.io
Class MemoryFileChannel

java.lang.Object
  java.nio.channels.spi.AbstractInterruptibleChannel
      java.nio.channels.FileChannel
          com.faunos.util.io.MemoryFileChannel

All Implemented Interfaces:

Closeable, ByteChannel, Channel, GatheringByteChannel, InterruptibleChannel, ReadableByteChannel, ScatteringByteChannel, WritableByteChannel

public class MemoryFileChannel
extends FileChannel

An in-memory FileChannel. The implementation is backed by a ByteBuffer. As the FileChannel's size is increased beyond the capacity of the backing buffer, a larger backing buffer is allocated.

Unsupported Operations

A number of the FileChannel methods are not implemented here. They are listed below.

• FileChannel.lock()
• FileChannel.tryLock()
• lock(long, long, boolean)
• tryLock(long, long, boolean)
• map(java.nio.channels.FileChannel.MapMode, long, long)

Invoking any of these methods raises an UnsupportedOperationException

Author:

Babak Farhang

Nested Class Summary

Nested classes/interfaces inherited from class java.nio.channels.FileChannel

FileChannel.MapMode

Constructor Summary

MemoryFileChannel(ByteBuffer buffer)
Creates a new instance initially backed by the given buffer.

MemoryFileChannel(int initCapacity)
Creates a new empty instance with the specified initial capacity.

MemoryFileChannel(int initCapacity, boolean direct)
Creates a new empty instance with the specified initial capacity and buffer allocation policy.

Method Summary

void	force(boolean metaData)
protected void	implCloseChannel()
FileLock	lock(long position, long size, boolean shared)
MappedByteBuffer	map(FileChannel.MapMode mode, long position, long size)
long	position()
FileChannel	position(long newPosition)
int	read(ByteBuffer dst)
long	read(ByteBuffer[] dsts, int offset, int length)
int	read(ByteBuffer dst, long position)
long	size()
long	transferFrom(ReadableByteChannel src, long position, long count)
long	transferTo(long position, long count, WritableByteChannel target)
FileChannel	truncate(long size)
FileLock	tryLock(long position, long size, boolean shared)
int	write(ByteBuffer src)
long	write(ByteBuffer[] srcs, int offset, int length)
int	write(ByteBuffer src, long position)

Methods inherited from class java.nio.channels.FileChannel

lock, read, tryLock, write

Methods inherited from class java.nio.channels.spi.AbstractInterruptibleChannel

begin, close, end, isOpen

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.nio.channels.Channel

close, isOpen

Methods inherited from interface java.nio.channels.Channel

close, isOpen

Methods inherited from interface java.nio.channels.Channel

close, isOpen

Methods inherited from interface java.nio.channels.Channel

close, isOpen

Constructor Detail

MemoryFileChannel

public MemoryFileChannel(ByteBuffer buffer)

Creates a new instance initially backed by the given buffer. This constructor was specifically introduced in order to provide a read-view of the existing contents of a buffer.

MemoryFileChannel

public MemoryFileChannel(int initCapacity)

Creates a new empty instance with the specified initial capacity. The backing buffer will be direct.

MemoryFileChannel

public MemoryFileChannel(int initCapacity,
                         boolean direct)

Creates a new empty instance with the specified initial capacity and buffer allocation policy.

Parameters:

direct - if true, then the backing buffer will be allocated directly.

See Also:

ByteBuffer.allocate(int), ByteBuffer.allocateDirect(int)

Method Detail

read

public int read(ByteBuffer dst)
         throws IOException

Specified by:

read in interface ReadableByteChannel

Specified by:

read in class FileChannel

Throws:

IOException

read

public long read(ByteBuffer[] dsts,
                 int offset,
                 int length)
          throws IOException

Specified by:

read in interface ScatteringByteChannel

Specified by:

read in class FileChannel

Throws:

IOException

write

public int write(ByteBuffer src)
          throws IOException

Specified by:

write in interface WritableByteChannel

Specified by:

write in class FileChannel

Throws:

IOException

write

public long write(ByteBuffer[] srcs,
                  int offset,
                  int length)
           throws IOException

Specified by:

write in interface GatheringByteChannel

Specified by:

write in class FileChannel

Throws:

IOException

position

public long position()
              throws IOException

Specified by:

position in class FileChannel

Throws:

IOException

position

public FileChannel position(long newPosition)
                     throws IOException

Specified by:

position in class FileChannel

Throws:

IOException

size

public long size()
          throws IOException

Specified by:

size in class FileChannel

Throws:

IOException

truncate

public FileChannel truncate(long size)
                     throws IOException

Specified by:

truncate in class FileChannel

Throws:

IOException

force

public void force(boolean metaData)
           throws IOException

Specified by:

force in class FileChannel

Throws:

IOException

transferTo

public long transferTo(long position,
                       long count,
                       WritableByteChannel target)
                throws IOException

Specified by:

transferTo in class FileChannel

Throws:

IOException

transferFrom

public long transferFrom(ReadableByteChannel src,
                         long position,
                         long count)
                  throws IOException

Specified by:

transferFrom in class FileChannel

Throws:

IOException

read

public int read(ByteBuffer dst,
                long position)
         throws IOException

Specified by:

read in class FileChannel

Throws:

IOException

write

public int write(ByteBuffer src,
                 long position)
          throws IOException

Specified by:

write in class FileChannel

Throws:

IOException

map

public MappedByteBuffer map(FileChannel.MapMode mode,
                            long position,
                            long size)
                     throws UnsupportedOperationException

Specified by:

map in class FileChannel

Throws:

UnsupportedOperationException

lock

public FileLock lock(long position,
                     long size,
                     boolean shared)
              throws UnsupportedOperationException

Specified by:

lock in class FileChannel

Throws:

UnsupportedOperationException

tryLock

public FileLock tryLock(long position,
                        long size,
                        boolean shared)
                 throws UnsupportedOperationException

Specified by:

tryLock in class FileChannel

Throws:

UnsupportedOperationException

implCloseChannel

protected void implCloseChannel()
                         throws IOException

Specified by:

implCloseChannel in class AbstractInterruptibleChannel

Throws:

IOException