com.bigdata.journal

Class BasicBufferStrategy

java.lang.Object

com.bigdata.rawstore.AbstractRawStore

com.bigdata.rawstore.AbstractRawWormStore

com.bigdata.journal.AbstractBufferStrategy

com.bigdata.journal.BasicBufferStrategy

All Implemented Interfaces:

ICounterSetAccess, IBufferStrategy, IAddressManager, IMRMW, IMROW, IRawStore, IStreamStore, IWORM

Direct Known Subclasses:

DiskBackedBufferStrategy, TransientBufferStrategy

public abstract class BasicBufferStrategy
extends AbstractBufferStrategy

Implements logic to read from and write on a buffer. This is sufficient for a BufferMode.Transient implementation or a BufferMode.Mapped implementation, but the BufferMode.Direct implementation needs to also implement write through to the disk.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
protected long	extent The current length of the backing file in bytes.
protected long	userExtent The size of the user data space in bytes.

Fields inherited from class com.bigdata.journal.AbstractBufferStrategy

bufferMode, commitOffset, ERR_ADDRESS_IS_NULL, ERR_ADDRESS_NOT_WRITTEN, ERR_BAD_RECORD_SIZE, ERR_BUFFER_EMPTY, ERR_BUFFER_NULL, ERR_BUFFER_OVERRUN, ERR_MAX_EXTENT, ERR_NOT_OPEN, ERR_OPEN, ERR_READ_ONLY, ERR_RECORD_LENGTH_ZERO, ERR_TRUNCATE, initialExtent, log, maximumExtent, nextOffset, WARN

Fields inherited from class com.bigdata.rawstore.AbstractRawWormStore

am

Fields inherited from interface com.bigdata.rawstore.IAddressManager

NULL

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Releases the buffer.
protected ByteBuffer	getBufferView(boolean readOnly)
CounterSet	getCounters() FIXME Counters need to be added here for the DirectBufferStrategy, MappedBufferStrategy, and TransientBufferStrategy.
long	getExtent() The current size of the journal in bytes.
long	getUserExtent() The size of the user data extent in bytes.
ByteBuffer	read(long addr) Read the data (unisolated).
long	transferTo(RandomAccessFile out) Note: This is synchronized so that concurrent writers must block during this operation.
void	truncate(long newExtent) Note: This is synchronized since it MAY be invoked directly while concurrent writers are running and not just from AbstractBufferStrategy.overflow(long).
long	write(ByteBuffer data) Write the data (unisolated).

Methods inherited from class com.bigdata.journal.AbstractBufferStrategy

abort, assertOpen, closeForWrites, commit, delete, destroy, getBufferMode, getInitialExtent, getMaximumExtent, getMaxRecordSize, getMetaBitsAddr, getMetaStartAddr, getMinimumExtension, getNextOffset, getResourceMetadata, getUUID, isDirty, isOpen, isReadOnly, overflow, requiresCommit, size, transferFromDiskTo, useChecksums

Methods inherited from class com.bigdata.rawstore.AbstractRawWormStore

getAddressManager, getByteCount, getOffset, getOffsetBits, getPhysicalAddress, toAddr, toString

Methods inherited from class com.bigdata.rawstore.AbstractRawStore

getInputStream, getOutputStream

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.bigdata.journal.IBufferStrategy

getAddressManager, getHeaderSize, getOffsetBits, readRootBlock, writeRootBlock

Methods inherited from interface com.bigdata.rawstore.IRawStore

deleteResources, force, getFile, isFullyBuffered, isStable

Methods inherited from interface com.bigdata.rawstore.IAddressManager

getByteCount, getOffset, getPhysicalAddress, toAddr, toString

Methods inherited from interface com.bigdata.rawstore.IStreamStore

getInputStream, getOutputStream

Field Detail

extent

protected long extent

The current length of the backing file in bytes.

userExtent

protected long userExtent

The size of the user data space in bytes.

Method Detail

getBufferView

protected ByteBuffer getBufferView(boolean readOnly)

Parameters:

readOnly -

Returns:

getExtent

public long getExtent()

Description copied from interface: IBufferStrategy

The current size of the journal in bytes. When the journal is backed by a disk file this is the actual size on disk of that file. The initial value for this property is set by Options.INITIAL_EXTENT.

getUserExtent

public long getUserExtent()

Description copied from interface: IBufferStrategy

The size of the user data extent in bytes.

Note: The size of the user extent is always generally smaller than the value reported by IBufferStrategy.getExtent() since the latter also reports the space allocated to the journal header and root blocks.

close

public void close()

Releases the buffer.

Specified by:

close in interface IRawStore

Overrides:

close in class AbstractBufferStrategy

write

public long write(ByteBuffer data)

Description copied from interface: IRawStore

Write the data (unisolated).

Parameters:

data - The data. The bytes from the current Buffer.position() to the Buffer.limit() will be written and the Buffer.position() will be advanced to the Buffer.limit() . The caller may subsequently modify the contents of the buffer without changing the state of the store (i.e., the data are copied into the store).

Returns:

A long integer formed that encodes both the offset from which the data may be read and the #of bytes to be read. See IAddressManager.

read

public ByteBuffer read(long addr)

Description copied from interface: IRawStore

Read the data (unisolated).

Parameters:

addr - A long integer that encodes both the offset from which the data will be read and the #of bytes to be read. See IAddressManager.toAddr(int, long).

Returns:

The data read. The buffer will be flipped to prepare for reading (the position will be zero and the limit will be the #of bytes read).

truncate

public void truncate(long newExtent)

Note: This is synchronized since it MAY be invoked directly while concurrent writers are running and not just from AbstractBufferStrategy.overflow(long).

Parameters:

newExtent - The new extent of the journal. This value represent the total extent of the journal, including any root blocks together with the user extent.

transferTo

public long transferTo(RandomAccessFile out)
                throws IOException

Note: This is synchronized so that concurrent writers must block during this operation.

Parameters:

out - The file to which the buffer contents will be transferred.

Returns:

The #of bytes written.

Throws:

IOException

getCounters

public CounterSet getCounters()

FIXME Counters need to be added here for the DirectBufferStrategy, MappedBufferStrategy, and TransientBufferStrategy.