freenet.support

Class SimpleReadOnlyArrayBucket

java.lang.Object

freenet.support.SimpleReadOnlyArrayBucket

All Implemented Interfaces:

Bucket, RandomAccessBucket

public class SimpleReadOnlyArrayBucket
extends java.lang.Object
implements Bucket, RandomAccessBucket

Simple read-only array bucket. Just an adapter class to save some RAM. Wraps a byte[], offset, length into a Bucket. Read-only. ArrayBucket on the other hand is a chain of byte[]'s. Not serializable as it doesn't copy. Should only be used for short-lived hacks for that reason.

Constructor Summary

Constructors

Constructor and Description
SimpleReadOnlyArrayBucket(byte[] buf)
SimpleReadOnlyArrayBucket(byte[] buf, int offset, int 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 a name for the bucket, may be used to identify them in certain in certain situations.
java.io.OutputStream	getOutputStream() Returns an OutputStream that is used to put data in this Bucket, from the beginning.
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 in bytes.
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

Constructor Detail

SimpleReadOnlyArrayBucket

public SimpleReadOnlyArrayBucket(byte[] buf,
                                 int offset,
                                 int length)

SimpleReadOnlyArrayBucket

public SimpleReadOnlyArrayBucket(byte[] buf)

Method Detail

getOutputStream

public java.io.OutputStream getOutputStream()
                                     throws java.io.IOException

Description copied from interface: Bucket

Returns an OutputStream that is used to put data in this Bucket, from the beginning. It is not possible to append data to a Bucket! This simplifies the code significantly for some classes. If you need to append, just pass the OutputStream around. Will be buffered if appropriate (e.g. byte array backed buckets don't need to be buffered).

Specified by:

getOutputStream in interface Bucket

Throws:

java.io.IOException

getOutputStreamUnbuffered

public java.io.OutputStream getOutputStreamUnbuffered()
                                               throws java.io.IOException

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

Throws:

java.io.IOException

getInputStreamUnbuffered

public java.io.InputStream getInputStreamUnbuffered()
                                             throws java.io.IOException

Specified by:

getInputStreamUnbuffered in interface Bucket

Throws:

java.io.IOException

getInputStream

public java.io.InputStream getInputStream()
                                   throws java.io.IOException

Description copied from interface: Bucket

Returns an InputStream that reads data from this Bucket. If there is no data in this bucket, null is returned. You have to call Closer.close(inputStream) on the obtained stream to prevent resource leakage.

Specified by:

getInputStream in interface Bucket

Throws:

java.io.IOException

getName

public java.lang.String getName()

Description copied from interface: Bucket

Returns a name for the bucket, may be used to identify them in certain in certain situations.

Specified by:

getName in interface Bucket

size

public long size()

Description copied from interface: Bucket

Returns the amount of data currently in this bucket in bytes.

Specified by:

size 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)

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

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