com.palantir.giraffe.file.base

Class AbstractSeekableByteChannel

java.lang.Object

com.palantir.giraffe.file.base.AbstractSeekableByteChannel

All Implemented Interfaces:

Closeable, AutoCloseable, ByteChannel, Channel, ReadableByteChannel, SeekableByteChannel, WritableByteChannel

public abstract class AbstractSeekableByteChannel
extends Object
implements SeekableByteChannel

An abstract base classe for SeekableByteChannel implementations.

This class makes close() idempotent and provides utilities for managing the channel's position. All I/O operations are left to subclasses.

Field Summary

Fields

Modifier and Type	Field and Description
protected long	position This channel's position.

Constructor Summary

Constructors

Constructor and Description
AbstractSeekableByteChannel()

Method Summary

Methods

Modifier and Type	Method and Description
protected int	advancePosition(int numBytes) Advances this channel's position by the given number of bytes, if it is positive.
protected void	checkIsOpen() Checks that this channel is open.
void	close()
protected abstract void	doClose() Performs implementation-specific close actions.
boolean	isOpen()
long	position()
SeekableByteChannel	position(long newPosition)
protected boolean	truncatePosition(long size) Sets this channel's position to size if it is less than the current position.

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.SeekableByteChannel

read, size, truncate, write

Field Detail

position

protected long position

This channel's position. While implementations may access this directly, they are encouraged to use advancePosition(int) and truncatePosition(long) when possible. This is exposed primarily for efficiency when reading the position or setting it to an exact value.

Constructor Detail

AbstractSeekableByteChannel

public AbstractSeekableByteChannel()

Method Detail

isOpen

public final boolean isOpen()

Specified by:

isOpen in interface Channel

close

public final void close()
                 throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Channel

Throws:

IOException

doClose

protected abstract void doClose()
                         throws IOException

Performs implementation-specific close actions. This method is called at most once.

Throws:

IOException - if an I/O error occurs while closing this channel.

position

public long position()
              throws IOException

Specified by:

position in interface SeekableByteChannel

Throws:

IOException

position

public SeekableByteChannel position(long newPosition)
                             throws IOException

Specified by:

position in interface SeekableByteChannel

Throws:

IOException

advancePosition

protected final int advancePosition(int numBytes)

Advances this channel's position by the given number of bytes, if it is positive. If the number of bytes is zero or negative, the position is not changed.

Parameters:

numBytes - the number of bytes transferred

Returns:

the input number of bytes

truncatePosition

protected final boolean truncatePosition(long size)

Sets this channel's position to size if it is less than the current position.

Parameters:

size - the new size of the underlying resource

Returns:

true if this channel's position changed, false otherwise

checkIsOpen

protected final void checkIsOpen()
                          throws ClosedChannelException

Checks that this channel is open. Implementations should call this at the start of every I/O method.

Throws:

ClosedChannelException - if this channel is closed