Package org.h2.store.fs.niomem

Class FileNioMemData

java.lang.Object

org.h2.store.fs.niomem.FileNioMemData

class FileNioMemData
extends java.lang.Object

This class contains the data of an in-memory random access file. Data compression using the LZF algorithm is supported as well.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	FileNioMemData.CompressItem	Represents a compressed item.
(package private) static class	FileNioMemData.CompressLaterCache<K,V>	This small cache compresses the data if an element leaves the cache.

Field Summary

Fields

Modifier and Type	Field	Description
private static int	BLOCK_SIZE
private static int	BLOCK_SIZE_MASK
private static int	BLOCK_SIZE_SHIFT
private java.util.concurrent.atomic.AtomicReference<java.nio.ByteBuffer>[]	buffers
private static int	CACHE_MIN_SIZE
private boolean	compress
private static java.lang.ThreadLocal<byte[]>	COMPRESS_OUT_BUF_THREAD_LOCAL	the output buffer when compressing
private static java.nio.ByteBuffer	COMPRESSED_EMPTY_BLOCK
private FileNioMemData.CompressLaterCache<FileNioMemData.CompressItem,FileNioMemData.CompressItem>	compressLaterCache
private float	compressLaterCachePercent
private boolean	isLockedExclusive
private boolean	isReadOnly
private long	lastModified
private long	length
private static java.lang.ThreadLocal<CompressLZF>	LZF_THREAD_LOCAL
private java.lang.String	name
(package private) int	nameHashCode	The hash code of the name.
private java.util.concurrent.locks.ReentrantReadWriteLock	rwLock
private int	sharedLockCount

Constructor Summary

Constructors

Constructor	Description
FileNioMemData(java.lang.String name, boolean compress, float compressLaterCachePercent)

Method Summary

Modifier and Type	Method	Description
private void	addToCompressLaterCache(int page)
(package private) boolean	canWrite()	Check whether writing is allowed.
private void	changeLength(long len)
(package private) void	compressPage(int page)	Compress the data in a byte array.
private java.nio.ByteBuffer	expandPage(int page)
(package private) long	getLastModified()	Get the last modified time.
(package private) java.lang.String	getName()	Get the file name
(package private) long	length()	Get the file length.
(package private) boolean	lockExclusive()	Lock the file in exclusive mode if possible.
(package private) boolean	lockShared()	Lock the file in shared mode if possible.
(package private) long	readWrite(long pos, java.nio.ByteBuffer b, int off, int len, boolean write)	Read or write.
(package private) void	setName(java.lang.String name)	Set the file name.
(package private) boolean	setReadOnly()	Set the read-only flag.
(package private) void	touch(boolean openReadOnly)	Update the last modified time.
(package private) void	truncate(long newLength)	Truncate the file.
(package private) void	unlock()	Unlock the file.

Methods inherited from class java.lang.Object

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

Field Detail

CACHE_MIN_SIZE

private static final int CACHE_MIN_SIZE

See Also:

Constant Field Values

BLOCK_SIZE_SHIFT

private static final int BLOCK_SIZE_SHIFT

See Also:

Constant Field Values

BLOCK_SIZE

private static final int BLOCK_SIZE

See Also:

Constant Field Values

BLOCK_SIZE_MASK

private static final int BLOCK_SIZE_MASK

See Also:

Constant Field Values

COMPRESSED_EMPTY_BLOCK

private static final java.nio.ByteBuffer COMPRESSED_EMPTY_BLOCK

LZF_THREAD_LOCAL

private static final java.lang.ThreadLocal<CompressLZF> LZF_THREAD_LOCAL

COMPRESS_OUT_BUF_THREAD_LOCAL

private static final java.lang.ThreadLocal<byte[]> COMPRESS_OUT_BUF_THREAD_LOCAL

the output buffer when compressing

nameHashCode

final int nameHashCode

The hash code of the name.

compressLaterCache

private final FileNioMemData.CompressLaterCache<FileNioMemData.CompressItem,FileNioMemData.CompressItem> compressLaterCache

name

private java.lang.String name

compress

private final boolean compress

compressLaterCachePercent

private final float compressLaterCachePercent

length

private volatile long length

buffers

private java.util.concurrent.atomic.AtomicReference<java.nio.ByteBuffer>[] buffers

lastModified

private long lastModified

isReadOnly

private boolean isReadOnly

isLockedExclusive

private boolean isLockedExclusive

sharedLockCount

private int sharedLockCount

rwLock

private final java.util.concurrent.locks.ReentrantReadWriteLock rwLock

Constructor Detail

FileNioMemData

FileNioMemData(java.lang.String name,
               boolean compress,
               float compressLaterCachePercent)

Method Detail

lockExclusive

boolean lockExclusive()

Lock the file in exclusive mode if possible.

Returns:

if locking was successful

lockShared

boolean lockShared()

Lock the file in shared mode if possible.

Returns:

if locking was successful

unlock

void unlock()

Unlock the file.

addToCompressLaterCache

private void addToCompressLaterCache(int page)

expandPage

private java.nio.ByteBuffer expandPage(int page)

compressPage

void compressPage(int page)

Compress the data in a byte array.

Parameters:

page - which page to compress

touch

void touch(boolean openReadOnly)

Update the last modified time.

Parameters:

openReadOnly - if the file was opened in read-only mode

length

long length()

Get the file length.

Returns:

the length

truncate

void truncate(long newLength)

Truncate the file.

Parameters:

newLength - the new length

changeLength

private void changeLength(long len)

readWrite

long readWrite(long pos,
               java.nio.ByteBuffer b,
               int off,
               int len,
               boolean write)

Read or write.

Parameters:

pos - the position

b - the byte array

off - the offset within the byte array

len - the number of bytes

write - true for writing

Returns:

the new position

setName

void setName(java.lang.String name)

Set the file name.

Parameters:

name - the name

getName

java.lang.String getName()

Get the file name

Returns:

the name

getLastModified

long getLastModified()

Get the last modified time.

Returns:

the time

canWrite

boolean canWrite()

Check whether writing is allowed.

Returns:

true if it is

setReadOnly

boolean setReadOnly()

Set the read-only flag.

Returns:

true