org.h2.dev.store.btree
Class DataUtils

java.lang.Object
  org.h2.dev.store.btree.DataUtils

public class DataUtils
extends java.lang.Object

Utility methods

Field Summary

static int	MAX_VAR_INT_LEN The maximum length of a variable size int.
static int	MAX_VAR_LONG_LEN The maximum length of a variable size long.
static int	PAGE_COMPRESSED The bit mask for compressed pages.
static int	PAGE_TYPE_LEAF The type for leaf page.
static int	PAGE_TYPE_NODE The type for node page.

Constructor Summary

DataUtils()

Method Summary

static void	appendMap(java.lang.StringBuilder buff, java.lang.String key, java.lang.Object value) Append a key-value pair to the string buffer.
static void	copyExcept(java.lang.Object src, java.lang.Object dst, int oldSize, int removeIndex) Copy the elements of an array, and remove one element.
static void	copyWithGap(java.lang.Object src, java.lang.Object dst, int oldSize, int gapIndex) Copy the elements of an array, with a gap.
static int	encodeLength(int len) Convert the length to a length code 0..31. 31 means more than 1 MB.
static short	getCheckValue(int x) Calculate a check value for the given integer.
static int	getPageChunkId(long pos) Get the chunk id from the position.
static int	getPageMaxLength(long pos) Get the maximum length for the given code.
static int	getPageOffset(long pos) Get the offset from the position.
static long	getPagePos(int chunkId, int offset, int length, int type) Get the position of this page.
static int	getPageType(long pos) Get the page type from the position.
static int	getVarIntLen(int x) Get the length of the variable size int.
static int	getVarLongLen(long x) Get the length of the variable size long.
static java.util.HashMap<java.lang.String,java.lang.String>	parseMap(java.lang.String s) Parse a key-value pair list.
static void	readFully(java.nio.channels.FileChannel file, java.nio.ByteBuffer buff) Read from a file channel until the target buffer is full, or end-of-file has been reached.
static int	readVarInt(java.nio.ByteBuffer buff) Read a variable size int.
static long	readVarLong(java.nio.ByteBuffer buff) Read a variable size long.
static void	writeVarInt(java.nio.ByteBuffer buff, int x) Write a variable size int.
static void	writeVarLong(java.nio.ByteBuffer buff, long x) Write a variable size int.

Methods inherited from class java.lang.Object

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

Field Detail

PAGE_TYPE_LEAF

public static final int PAGE_TYPE_LEAF

The type for leaf page.

See Also:

Constant Field Values

PAGE_TYPE_NODE

public static final int PAGE_TYPE_NODE

The type for node page.

See Also:

Constant Field Values

PAGE_COMPRESSED

public static final int PAGE_COMPRESSED

The bit mask for compressed pages.

See Also:

Constant Field Values

MAX_VAR_INT_LEN

public static final int MAX_VAR_INT_LEN

The maximum length of a variable size int.

See Also:

Constant Field Values

MAX_VAR_LONG_LEN

public static final int MAX_VAR_LONG_LEN

The maximum length of a variable size long.

See Also:

Constant Field Values

Constructor Detail

DataUtils

public DataUtils()

Method Detail

getVarIntLen

public static int getVarIntLen(int x)

Get the length of the variable size int.

Parameters:

x - the value

Returns:

the length in bytes

getVarLongLen

public static int getVarLongLen(long x)

Get the length of the variable size long.

Parameters:

x - the value

Returns:

the length in bytes

readVarInt

public static int readVarInt(java.nio.ByteBuffer buff)

Read a variable size int.

Parameters:

buff - the source buffer

Returns:

the value

readVarLong

public static long readVarLong(java.nio.ByteBuffer buff)

Read a variable size long.

Parameters:

buff - the source buffer

Returns:

the value

writeVarInt

public static void writeVarInt(java.nio.ByteBuffer buff,
                               int x)

Write a variable size int.

Parameters:

buff - the target buffer

x - the value

writeVarLong

public static void writeVarLong(java.nio.ByteBuffer buff,
                                long x)

Write a variable size int.

Parameters:

buff - the target buffer

x - the value

copyWithGap

public static void copyWithGap(java.lang.Object src,
                               java.lang.Object dst,
                               int oldSize,
                               int gapIndex)

Copy the elements of an array, with a gap.

Parameters:

src - the source array

dst - the target array

oldSize - the size of the old array

gapIndex - the index of the gap

copyExcept

public static void copyExcept(java.lang.Object src,
                              java.lang.Object dst,
                              int oldSize,
                              int removeIndex)

Copy the elements of an array, and remove one element.

Parameters:

src - the source array

dst - the target array

oldSize - the size of the old array

removeIndex - the index of the entry to remove

readFully

public static void readFully(java.nio.channels.FileChannel file,
                             java.nio.ByteBuffer buff)
                      throws java.io.IOException

Read from a file channel until the target buffer is full, or end-of-file has been reached.

Parameters:

file - the file channel

buff - the target buffer

Throws:

java.io.IOException

encodeLength

public static int encodeLength(int len)

Convert the length to a length code 0..31. 31 means more than 1 MB.

Parameters:

len - the length

Returns:

the length code

getPageChunkId

public static int getPageChunkId(long pos)

Get the chunk id from the position.

Parameters:

pos - the position

Returns:

the chunk id

getPageMaxLength

public static int getPageMaxLength(long pos)

Get the maximum length for the given code. For the code 31, Integer.MAX_VALUE is returned.

Parameters:

pos - the position

Returns:

the maximum length

getPageOffset

public static int getPageOffset(long pos)

Get the offset from the position.

Parameters:

pos - the position

Returns:

the offset

getPageType

public static int getPageType(long pos)

Get the page type from the position.

Parameters:

pos - the position

Returns:

the page type (PAGE_TYPE_NODE or PAGE_TYPE_LEAF)

getPagePos

public static long getPagePos(int chunkId,
                              int offset,
                              int length,
                              int type)

Get the position of this page. The following information is encoded in the position: the chunk id, the offset, the maximum length, and the type (node or leaf).

Parameters:

chunkId - the chunk id

offset - the offset

length - the length

type - the page type (1 for node, 0 for leaf)

Returns:

the position

getCheckValue

public static short getCheckValue(int x)

Calculate a check value for the given integer. A check value is mean to verify the data is consistent with a high probability, but not meant to protect against media failure or deliberate changes.

Parameters:

x - the value

Returns:

the check value

appendMap

public static void appendMap(java.lang.StringBuilder buff,
                             java.lang.String key,
                             java.lang.Object value)

Append a key-value pair to the string buffer. Keys may not contain a colon. Values that contain a comma or a double quote are enclosed in double quotes, with special characters escaped using a backslash.

Parameters:

buff - the target buffer

key - the key

value - the value

parseMap

public static java.util.HashMap<java.lang.String,java.lang.String> parseMap(java.lang.String s)

Parse a key-value pair list.

Parameters:

s - the list

Returns:

the map