Package org.h2.store.fs.niomem
Class FileNioMemData
- java.lang.Object
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- org.h2.store.fs.niomem.FileNioMemData
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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.
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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.
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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 compressingprivate 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
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Constructor Summary
Constructors Constructor Description FileNioMemData(java.lang.String name, boolean compress, float compressLaterCachePercent)
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Method Summary
All Methods Instance Methods Concrete Methods 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.
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Field Detail
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CACHE_MIN_SIZE
private static final int CACHE_MIN_SIZE
- See Also:
- Constant Field Values
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BLOCK_SIZE_SHIFT
private static final int BLOCK_SIZE_SHIFT
- See Also:
- Constant Field Values
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BLOCK_SIZE
private static final int BLOCK_SIZE
- See Also:
- Constant Field Values
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BLOCK_SIZE_MASK
private static final int BLOCK_SIZE_MASK
- See Also:
- Constant Field Values
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COMPRESSED_EMPTY_BLOCK
private static final java.nio.ByteBuffer COMPRESSED_EMPTY_BLOCK
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LZF_THREAD_LOCAL
private static final java.lang.ThreadLocal<CompressLZF> LZF_THREAD_LOCAL
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COMPRESS_OUT_BUF_THREAD_LOCAL
private static final java.lang.ThreadLocal<byte[]> COMPRESS_OUT_BUF_THREAD_LOCAL
the output buffer when compressing
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nameHashCode
final int nameHashCode
The hash code of the name.
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compressLaterCache
private final FileNioMemData.CompressLaterCache<FileNioMemData.CompressItem,FileNioMemData.CompressItem> compressLaterCache
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name
private java.lang.String name
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compress
private final boolean compress
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compressLaterCachePercent
private final float compressLaterCachePercent
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length
private volatile long length
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buffers
private java.util.concurrent.atomic.AtomicReference<java.nio.ByteBuffer>[] buffers
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lastModified
private long lastModified
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isReadOnly
private boolean isReadOnly
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isLockedExclusive
private boolean isLockedExclusive
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sharedLockCount
private int sharedLockCount
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rwLock
private final java.util.concurrent.locks.ReentrantReadWriteLock rwLock
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Method Detail
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lockExclusive
boolean lockExclusive()
Lock the file in exclusive mode if possible.- Returns:
- if locking was successful
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lockShared
boolean lockShared()
Lock the file in shared mode if possible.- Returns:
- if locking was successful
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unlock
void unlock()
Unlock the file.
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addToCompressLaterCache
private void addToCompressLaterCache(int page)
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expandPage
private java.nio.ByteBuffer expandPage(int page)
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compressPage
void compressPage(int page)
Compress the data in a byte array.- Parameters:
page
- which page to compress
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touch
void touch(boolean openReadOnly)
Update the last modified time.- Parameters:
openReadOnly
- if the file was opened in read-only mode
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length
long length()
Get the file length.- Returns:
- the length
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truncate
void truncate(long newLength)
Truncate the file.- Parameters:
newLength
- the new length
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changeLength
private void changeLength(long len)
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readWrite
long readWrite(long pos, java.nio.ByteBuffer b, int off, int len, boolean write)
Read or write.- Parameters:
pos
- the positionb
- the byte arrayoff
- the offset within the byte arraylen
- the number of byteswrite
- true for writing- Returns:
- the new position
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setName
void setName(java.lang.String name)
Set the file name.- Parameters:
name
- the name
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getName
java.lang.String getName()
Get the file name- Returns:
- the name
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getLastModified
long getLastModified()
Get the last modified time.- Returns:
- the time
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canWrite
boolean canWrite()
Check whether writing is allowed.- Returns:
- true if it is
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setReadOnly
boolean setReadOnly()
Set the read-only flag.- Returns:
- true
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