com.bigdata.journal

Class DiskBackedBufferStrategy

java.lang.Object

com.bigdata.rawstore.AbstractRawStore

com.bigdata.rawstore.AbstractRawWormStore

com.bigdata.journal.AbstractBufferStrategy

com.bigdata.journal.BasicBufferStrategy

com.bigdata.journal.DiskBackedBufferStrategy

All Implemented Interfaces:

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

Direct Known Subclasses:

DirectBufferStrategy, MappedBufferStrategy

public abstract class DiskBackedBufferStrategy
extends BasicBufferStrategy
implements IDiskBasedStrategy

Abstract base class for implementations that use a direct buffer as a write through cache to an image on the disk. This covers both the BufferMode.Direct, where we use explicit IO operations, and the BufferMode.Mapped, where we memory-map the image. Common features shared by these implementations deal mainly with initialization of a new disk image.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
protected IReopenChannel<FileChannel>	opener Used to re-open the FileChannel in this class.

Fields inherited from class com.bigdata.journal.BasicBufferStrategy

extent, userExtent

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() Closes the file.
void	delete(long addr) The default is a NOP.
void	deleteResources() Deletes the backing file(s) (if any).
void	force(boolean metadata) Forces the data to disk.
FileChannel	getChannel() The channel used to read and write on the file.
File	getFile() The backing file.
int	getHeaderSize() The size of the file header in bytes.
RandomAccessFile	getRandomAccessFile() The object used to read and write on that file.
boolean	isStable() True iff backed by stable storage.
ByteBuffer	read(long addr) The backing file is fully buffered so it does not need to be open for a read to succeed.
ByteBuffer	readRootBlock(boolean rootBlock0) Read the specified root block from the backing file.
void	setNextOffset(long lastOffset) Protocol support for HAWrite
long	transferTo(RandomAccessFile out) Note: This is synchronized so that concurrent writers must block during this operation.
void	writeRootBlock(IRootBlockView rootBlock, ForceEnum forceOnCommit) Write the root block onto stable storage (ie, flush it through to disk).

Methods inherited from class com.bigdata.journal.BasicBufferStrategy

getBufferView, getCounters, getExtent, getUserExtent, truncate, write

Methods inherited from class com.bigdata.journal.AbstractBufferStrategy

abort, assertOpen, closeForWrites, commit, 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

abort, closeForWrites, commit, getAddressManager, getBufferMode, getCounters, getExtent, getInitialExtent, getMaximumExtent, getMaxRecordSize, getMetaBitsAddr, getMetaStartAddr, getNextOffset, getOffsetBits, getUserExtent, isDirty, requiresCommit, truncate, useChecksums

Methods inherited from interface com.bigdata.rawstore.IRawStore

destroy, getResourceMetadata, getUUID, isFullyBuffered, isOpen, isReadOnly, size, write

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

opener

protected final IReopenChannel<FileChannel> opener

Used to re-open the FileChannel in this class.

Method Detail

getHeaderSize

public final int getHeaderSize()

Description copied from interface: IDiskBasedStrategy

The size of the file header in bytes.

Specified by:

getHeaderSize in interface IBufferStrategy

Specified by:

getHeaderSize in interface IDiskBasedStrategy

getFile

public final File getFile()

Description copied from interface: IDiskBasedStrategy

The backing file.

Specified by:

getFile in interface IDiskBasedStrategy

Specified by:

getFile in interface IRawStore

getRandomAccessFile

public final RandomAccessFile getRandomAccessFile()

Description copied from interface: IDiskBasedStrategy

The object used to read and write on that file.

Specified by:

getRandomAccessFile in interface IDiskBasedStrategy

getChannel

public final FileChannel getChannel()

Description copied from interface: IDiskBasedStrategy

The channel used to read and write on the file.

Specified by:

getChannel in interface IDiskBasedStrategy

isStable

public final boolean isStable()

Description copied from interface: IRawStore

True iff backed by stable storage.

Specified by:

isStable in interface IRawStore

delete

public void delete(long addr)

Description copied from class: AbstractBufferStrategy

The default is a NOP.

Specified by:

delete in interface IRawStore

Overrides:

delete in class AbstractBufferStrategy

Parameters:

addr - A long integer formed using Addr that encodes both the offset at which the data was written and the #of bytes that were written.

force

public void force(boolean metadata)

Forces the data to disk.

Specified by:

force in interface IRawStore

Parameters:

metadata - If true, then force both the file contents and the file metadata to disk.

close

public void close()

Closes the file.

Specified by:

close in interface IRawStore

Overrides:

close in class BasicBufferStrategy

deleteResources

public void deleteResources()

Description copied from interface: IRawStore

Deletes the backing file(s) (if any).

Specified by:

deleteResources in interface IRawStore

readRootBlock

public ByteBuffer readRootBlock(boolean rootBlock0)

Description copied from interface: IBufferStrategy

Read the specified root block from the backing file.

Specified by:

readRootBlock in interface IBufferStrategy

writeRootBlock

public void writeRootBlock(IRootBlockView rootBlock,
                  ForceEnum forceOnCommit)

Description copied from interface: IBufferStrategy

Write the root block onto stable storage (ie, flush it through to disk).

Specified by:

writeRootBlock in interface IBufferStrategy

Parameters:

rootBlock - The root block. Which root block is indicated by IRootBlockView.isRootBlock0().

transferTo

public long transferTo(RandomAccessFile out)
                throws IOException

Description copied from class: BasicBufferStrategy

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

Specified by:

transferTo in interface IBufferStrategy

Overrides:

transferTo in class BasicBufferStrategy

Parameters:

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

Returns:

The #of bytes written.

Throws:

IOException

read

public ByteBuffer read(long addr)

The backing file is fully buffered so it does not need to be open for a read to succeed. However, we use this as an opportunity to transparently re-open the FileChannel if it has been closed asynchronously or in response to an interrupt (that is, if we discover that the channel is closed but AbstractBufferStrategy.isOpen() still returns true).

Specified by:

read in interface IRawStore

Overrides:

read in class BasicBufferStrategy

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).

setNextOffset

public void setNextOffset(long lastOffset)

Protocol support for HAWrite