freenet.support.api

Interface LockableRandomAccessBuffer

All Superinterfaces:

java.lang.AutoCloseable, java.io.Closeable, RandomAccessBuffer

All Known Implementing Classes:

ByteArrayRandomAccessBuffer, DelayedFreeRandomAccessBuffer, EncryptedRandomAccessBuffer, FileRandomAccessBuffer, NullRandomAccessBuffer, PaddedRandomAccessBuffer, PooledFileRandomAccessBuffer, ReadOnlyRandomAccessBuffer

public interface LockableRandomAccessBuffer
extends RandomAccessBuffer

A RandomAccessBuffer which allows you to lock it open for a brief period to indicate that you are using it and it would be a bad idea to close the pooled fd. Locking the RAF open does not provide any concurrency guarantees but the implementation must guarantee to do the right thing, either using a mutex or supporting concurrent writes. Also has methods for persisting itself to a DataOutputStream. Implementations must register with BucketTools.restoreRAFFrom().

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	LockableRandomAccessBuffer.RAFLock

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object o) Must reimplement equals().
int	hashCode() Must reimplement hashCode() if we change equals().
LockableRandomAccessBuffer.RAFLock	lockOpen() Keep the RAF open.
void	onResume(ClientContext context) Called on resuming, i.e.
void	storeTo(java.io.DataOutputStream dos) Write enough data to reconstruct the Bucket, or throw UnsupportedOperationException.

Methods inherited from interface freenet.support.api.RandomAccessBuffer

close, free, pread, pwrite, size

Method Detail

lockOpen

LockableRandomAccessBuffer.RAFLock lockOpen()
                                     throws java.io.IOException

Keep the RAF open. Does not prevent others from writing to it. Will block until a slot is available if necessary. Hence can deadlock.

Throws:

java.io.IOException

onResume

void onResume(ClientContext context)
       throws ResumeFailedException

Called on resuming, i.e. after serialization. Use to e.g. register with the list of temporary files.

Throws:

ResumeFailedException

storeTo

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

Write enough data to reconstruct the Bucket, or throw UnsupportedOperationException. Used for recovering in emergencies, should be versioned if necessary. To make this work, write a fixed, unique integer magic value for the class, and add a clause to BucketTools.restoreRAFFrom().

Throws:

java.io.IOException

equals

boolean equals(java.lang.Object o)

Must reimplement equals(). Sometimes we will need to compare two RAFs to see if they represent the same stored object, notably during resuming a splitfile insert.

Overrides:

equals in class java.lang.Object

hashCode

int hashCode()

Must reimplement hashCode() if we change equals().

Overrides:

hashCode in class java.lang.Object