freenet.support.io

Class NullBucket

java.lang.Object

freenet.support.io.NullBucket

All Implemented Interfaces:

Bucket, RandomAccessBucket, java.io.Serializable

public class NullBucket
extends java.lang.Object
implements Bucket, java.io.Serializable, RandomAccessBucket

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
long	length
static java.io.InputStream	nullIn
static java.io.OutputStream	nullOut

Constructor Summary

Constructors

Constructor and Description
NullBucket()
NullBucket(long length)

Method Summary

Modifier and Type	Method and Description
RandomAccessBucket	createShadow() Create a shallow read-only copy of this bucket, using different objects but using the same external storage.
void	free() Free the bucket, if supported.
java.io.InputStream	getInputStream() Returns an InputStream that reads data from this Bucket.
java.io.InputStream	getInputStreamUnbuffered()
java.lang.String	getName() Returns the name of this NullBucket.
java.io.OutputStream	getOutputStream() Returns an OutputStream that is used to put data in this Bucket.
java.io.OutputStream	getOutputStreamUnbuffered() Get an OutputStream which is not buffered.
boolean	isReadOnly() Is the bucket read-only?
void	onResume(ClientContext context) Called after restarting.
void	setReadOnly() Make the bucket read-only.
long	size() Returns the amount of data currently in this bucket.
void	storeTo(java.io.DataOutputStream dos) Write enough data to reconstruct the Bucket, or throw UnsupportedOperationException.
LockableRandomAccessBuffer	toRandomAccessBuffer() Convert the Bucket to a LockableRandomAccessBuffer.

Methods inherited from class java.lang.Object

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

Field Detail

nullOut

public static final java.io.OutputStream nullOut

nullIn

public static final java.io.InputStream nullIn

length

public final long length

Constructor Detail

NullBucket

public NullBucket()

NullBucket

public NullBucket(long length)

Method Detail

getOutputStream

public java.io.OutputStream getOutputStream()

Returns an OutputStream that is used to put data in this Bucket.

Specified by:

getOutputStream in interface Bucket

getOutputStreamUnbuffered

public java.io.OutputStream getOutputStreamUnbuffered()

Description copied from interface: Bucket

Get an OutputStream which is not buffered. Should be called when we will buffer the stream at a higher level or when we will only be doing large writes (e.g. copying data from one Bucket to another). Does not make any more persistence guarantees than getOutputStream() does, this is just to save memory.

Specified by:

getOutputStreamUnbuffered in interface Bucket

getInputStream

public java.io.InputStream getInputStream()

Returns an InputStream that reads data from this Bucket. If there is no data in this bucket, null is returned.

Specified by:

getInputStream in interface Bucket

getInputStreamUnbuffered

public java.io.InputStream getInputStreamUnbuffered()

Specified by:

getInputStreamUnbuffered in interface Bucket

size

public long size()

Returns the amount of data currently in this bucket.

Specified by:

size in interface Bucket

getName

public java.lang.String getName()

Returns the name of this NullBucket.

Specified by:

getName in interface Bucket

isReadOnly

public boolean isReadOnly()

Description copied from interface: Bucket

Is the bucket read-only?

Specified by:

isReadOnly in interface Bucket

setReadOnly

public void setReadOnly()

Description copied from interface: Bucket

Make the bucket read-only. Irreversible.

Specified by:

setReadOnly in interface Bucket

free

public void free()

Description copied from interface: Bucket

Free the bucket, if supported. Note that you must call free() even if you haven't used the Bucket (haven't called getOutputStream()) for some kinds of Bucket's, as they may have allocated space (e.g. created a temporary file).

Specified by:

free in interface Bucket

createShadow

public RandomAccessBucket createShadow()

Description copied from interface: Bucket

Create a shallow read-only copy of this bucket, using different objects but using the same external storage. If this is not possible, return null. Note that if the underlying bucket is deleted, the copy will become invalid and probably throw an IOException on read, or possibly return too-short data etc. In some use cases e.g. on fproxy, this is acceptable.

Specified by:

createShadow in interface Bucket

Specified by:

createShadow in interface RandomAccessBucket

onResume

public void onResume(ClientContext context)

Description copied from interface: Bucket

Called after restarting. The Bucket should do any necessary housekeeping after resuming, e.g. registering itself with the appropriate persistent bucket tracker to avoid being garbage-collected. May be called twice, so the Bucket may need to track this internally.

Specified by:

onResume in interface Bucket

Parameters:

context - All the necessary runtime support will be on this object.

storeTo

public void storeTo(java.io.DataOutputStream dos)
             throws java.io.IOException

Description copied from interface: Bucket

Write enough data to reconstruct the Bucket, or throw UnsupportedOperationException. Used for recovering in emergencies, should be versioned if necessary.

Specified by:

storeTo in interface Bucket

Throws:

java.io.IOException

toRandomAccessBuffer

public LockableRandomAccessBuffer toRandomAccessBuffer()
                                                throws java.io.IOException

Description copied from interface: RandomAccessBucket

Convert the Bucket to a LockableRandomAccessBuffer. Must be efficient, i.e. will not copy the data. Freeing the Bucket is unnecessary if you free the LockableRandomAccessBuffer. Both the parent Bucket and the return value will be made read only.

Specified by:

toRandomAccessBuffer in interface RandomAccessBucket

Throws:

java.io.IOException