Module org.postgresql.pljava.internal

Package org.postgresql.pljava.internal

Class ByteBufferInputStream

java.lang.Object

java.io.InputStream

org.postgresql.pljava.internal.ByteBufferInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

DatumImpl.IStream

public abstract class ByteBufferInputStream
extends InputStream

Wrap a readable ByteBuffer as an InputStream.

An implementing class must provide a buffer() method that returns the ByteBuffer, and the method is responsible for knowing when the memory region windowed by the ByteBuffer is no longer to be accessed, and throwing an exception in that case.

The implementing class may supply an object that the InputStream operations will be synchronized on.

The underlying buffer's position and mark are used to maintain the corresponding values for the input stream.

Field Summary

Fields

Modifier and Type	Field	Description
protected final Object	m_lock	The object on which the InputStream operations will synchronize.
protected boolean	m_open	Whether this stream is open; initially true.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ByteBufferInputStream()	Construct an instance whose critical sections will synchronize on the instance itself.
protected	ByteBufferInputStream(Object lock)	Construct an instance, given an object on which to synchronize.

Method Summary

Modifier and Type	Method	Description
int	available()
protected abstract ByteBuffer	buffer()	Return the ByteBuffer being wrapped, or throw an exception if the memory windowed by the buffer should no longer be accessed.
void	close()
void	mark(int readlimit)
boolean	markSupported()	Return true; this class does support mark and reset.
protected void	pin()	Pin resources if necessary during a reading operation.
int	read()
int	read(byte[] b, int off, int len)
void	reset()
long	skip(long n)
protected void	unpin()	Unpin resources if necessary after a reading operation.

Methods inherited from class java.io.InputStream

nullInputStream, read, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo

Methods inherited from class java.lang.Object

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

Field Details

m_lock

protected final Object m_lock

The object on which the InputStream operations will synchronize.

m_open

protected boolean m_open

Whether this stream is open; initially true.

Constructor Details

ByteBufferInputStream

protected ByteBufferInputStream()

Construct an instance whose critical sections will synchronize on the instance itself.

ByteBufferInputStream

protected ByteBufferInputStream(Object lock)

Construct an instance, given an object on which to synchronize.

Parameters:

lock - The Object to synchronize on.

Method Details

pin

protected void pin()
            throws IOException

Pin resources if necessary during a reading operation.

This default implementation does nothing. A subclass should override it if (in addition to synchronizing on m_lock), some pinning of a resource is needed during access operations.

Throws:

IOException

unpin

protected void unpin()

Unpin resources if necessary after a reading operation.

This default implementation does nothing.

buffer

protected abstract ByteBuffer buffer()
                              throws IOException

Return the ByteBuffer being wrapped, or throw an exception if the memory windowed by the buffer should no longer be accessed.

The monitor on m_lock is held when this method is called.

This method also should throw an exception if m_open is false. It is called everywhere that should happen, so it is the perfect place for the test, and allows the implementing class to use a customized message in the exception.

All uses of the buffer in this class are preceded by pin() and followed by unpin() (whose default implementations in this class do nothing). If a subclass overrides pin with a version that throws the appropriate exception in either case or both, it is then redundant and unnecessary for buffer to check the same conditions.

Throws:

IOException

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

public int read(byte[] b,
 int off,
 int len)
         throws IOException

Overrides:

read in class InputStream

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

available

public int available()
              throws IOException

Overrides:

available in class InputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException

mark

public void mark(int readlimit)

Overrides:

mark in class InputStream

reset

public void reset()
           throws IOException

Overrides:

reset in class InputStream

Throws:

IOException

markSupported

public boolean markSupported()

Return true; this class does support mark and reset.

Overrides:

markSupported in class InputStream