Package org.h2.mvstore
Class FileStore
java.lang.Object
org.h2.mvstore.FileStore
- Direct Known Subclasses:
OffHeapStore
The default storage mechanism of the MVStore. This implementation persists
data to a file. The file store is responsible to persist data and for free
space management.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate FileChannel
The encrypted file (if encryption is used).private FileChannel
The file.private FileLock
The file lock.private String
The file name.protected long
The file size (cached).protected final FreeSpaceBitSet
The free spaces between the chunks.protected final AtomicLong
The number of read bytes.protected final AtomicLong
The number of read operations.private boolean
Whether this store is read-only.protected final AtomicLong
The number of written bytes.protected final AtomicLong
The number of write operations. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescription(package private) long
allocate
(int length, long reservedLow, long reservedHigh) Allocate a number of blocks and mark them as used.void
clear()
Mark the file as empty.void
close()
Close this store.void
free
(long pos, int length) Mark the space as free.(package private) long
int
Get the default retention time for this store in milliseconds.Get the encrypted file instance, if encryption is used.getFile()
Get the file instance in use.(package private) long
Get the file name.int
(package private) long
(package private) int
getMovePriority
(int block) Calculates relative "priority" for chunk to be moved.int
getProjectedFillRate
(int vacatedBlocks) Calculates a prospective fill rate, which store would have after rewrite of sparsely populated chunk(s) and evacuation of still live data into a new chunk.long
Get the number of read bytes since this store was opened.long
Get the number of read operations since this store was opened.long
Get the number of written bytes since this store was opened.long
Get the number of write operations since this store was opened.(package private) boolean
boolean
void
markUsed
(long pos, int length) Mark the space as in use.void
Try to open the file.(package private) long
predictAllocation
(int blocks, long reservedLow, long reservedHigh) Calculate starting position of the prospective allocation.readFully
(long pos, int len) Read from the file.long
size()
Get the file size.void
sync()
Flush all changes.toString()
void
truncate
(long size) Truncate the file.void
writeFully
(long pos, ByteBuffer src) Write to the file.
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Field Details
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readCount
The number of read operations. -
readBytes
The number of read bytes. -
writeCount
The number of write operations. -
writeBytes
The number of written bytes. -
freeSpace
The free spaces between the chunks. The first block to use is block 2 (the first two blocks are the store header). -
fileName
The file name. -
readOnly
private boolean readOnlyWhether this store is read-only. -
fileSize
protected long fileSizeThe file size (cached). -
file
The file. -
encryptedFile
The encrypted file (if encryption is used). -
fileLock
The file lock.
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Constructor Details
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FileStore
public FileStore()
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Method Details
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toString
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readFully
Read from the file.- Parameters:
pos
- the write positionlen
- the number of bytes to read- Returns:
- the byte buffer
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writeFully
Write to the file.- Parameters:
pos
- the write positionsrc
- the source buffer
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open
Try to open the file.- Parameters:
fileName
- the file namereadOnly
- whether the file should only be opened in read-only mode, even if the file is writableencryptionKey
- the encryption key, or null if encryption is not used
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close
public void close()Close this store. -
sync
public void sync()Flush all changes. -
size
public long size()Get the file size.- Returns:
- the file size
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truncate
public void truncate(long size) Truncate the file.- Parameters:
size
- the new file size
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getFile
Get the file instance in use.The application may read from the file (for example for online backup), but not write to it or truncate it.
- Returns:
- the file
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getEncryptedFile
Get the encrypted file instance, if encryption is used.The application may read from the file (for example for online backup), but not write to it or truncate it.
- Returns:
- the encrypted file, or null if encryption is not used
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getWriteCount
public long getWriteCount()Get the number of write operations since this store was opened. For file based stores, this is the number of file write operations.- Returns:
- the number of write operations
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getWriteBytes
public long getWriteBytes()Get the number of written bytes since this store was opened.- Returns:
- the number of write operations
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getReadCount
public long getReadCount()Get the number of read operations since this store was opened. For file based stores, this is the number of file read operations.- Returns:
- the number of read operations
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getReadBytes
public long getReadBytes()Get the number of read bytes since this store was opened.- Returns:
- the number of write operations
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isReadOnly
public boolean isReadOnly() -
getDefaultRetentionTime
public int getDefaultRetentionTime()Get the default retention time for this store in milliseconds.- Returns:
- the retention time
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markUsed
public void markUsed(long pos, int length) Mark the space as in use.- Parameters:
pos
- the position in byteslength
- the number of bytes
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allocate
long allocate(int length, long reservedLow, long reservedHigh) Allocate a number of blocks and mark them as used.- Parameters:
length
- the number of bytes to allocatereservedLow
- start block index of the reserved area (inclusive)reservedHigh
- end block index of the reserved area (exclusive), special value -1 means beginning of the infinite free area- Returns:
- the start position in bytes
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predictAllocation
long predictAllocation(int blocks, long reservedLow, long reservedHigh) Calculate starting position of the prospective allocation.- Parameters:
blocks
- the number of blocks to allocatereservedLow
- start block index of the reserved area (inclusive)reservedHigh
- end block index of the reserved area (exclusive), special value -1 means beginning of the infinite free area- Returns:
- the starting block index
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isFragmented
boolean isFragmented() -
free
public void free(long pos, int length) Mark the space as free.- Parameters:
pos
- the position in byteslength
- the number of bytes
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getFillRate
public int getFillRate() -
getProjectedFillRate
public int getProjectedFillRate(int vacatedBlocks) Calculates a prospective fill rate, which store would have after rewrite of sparsely populated chunk(s) and evacuation of still live data into a new chunk.- Parameters:
vacatedBlocks
- number of blocks vacated- Returns:
- prospective fill rate (0 - 100)
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getFirstFree
long getFirstFree() -
getFileLengthInUse
long getFileLengthInUse() -
getMovePriority
int getMovePriority(int block) Calculates relative "priority" for chunk to be moved.- Parameters:
block
- where chunk starts- Returns:
- priority, bigger number indicate that chunk need to be moved sooner
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getAfterLastBlock
long getAfterLastBlock() -
clear
public void clear()Mark the file as empty. -
getFileName
Get the file name.- Returns:
- the file name
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