net.yacy.kelondro.blob

Interface BLOB

All Known Implementing Classes:

ArrayStack, Compressor, Heap, HeapModifier

public interface BLOB

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	BLOB.Reducer
static interface	BLOB.Rewriter

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() clears the content of the database
void	close(boolean writeIDX) close the BLOB table
boolean	containsKey(byte[] key) check if a specific key is in the database
void	delete(byte[] key) remove a BLOB
byte[]	get(byte[] key) retrieve the whole BLOB from the table
byte[]	get(java.lang.Object key)
void	insert(byte[] key, byte[] b) write a whole byte array as BLOB to the table
boolean	isEmpty() ask if the BLOB is empty
int	keylength() ask for the length of the primary key
CloneableIterator<byte[]>	keys(boolean up, boolean rotating) iterator over all keys
CloneableIterator<byte[]>	keys(boolean up, byte[] firstKey) iterate over all keys
long	length() retrieve the size of the database
long	length(byte[] key) retrieve the size of the BLOB
long	mem() calculate the memory in RAM that the BLOB occupies
java.lang.String	name() return a name of the BLOB; can be the file name
void	optimize() trim the index of the database: this releases memory not currently used
ByteOrder	ordering() return the underlying odering
int	reduce(byte[] key, BLOB.Reducer reducer) a reduce method is the same as the replace.
int	replace(byte[] key, BLOB.Rewriter rewriter) replace an existing entry in the BLOB with a new entry this method is similar to put, but it is necessary that a blob entry existed before and contains an entry of same size or bigger than the new entry.
int	size() ask for the number of entries

Method Detail

name

java.lang.String name()

return a name of the BLOB; can be the file name

Returns:

keylength

int keylength()

ask for the length of the primary key

Returns:

the length of the key

ordering

ByteOrder ordering()

return the underlying odering

Returns:

clear

void clear()
           throws java.io.IOException

clears the content of the database

Throws:

java.io.IOException

optimize

void optimize()

trim the index of the database: this releases memory not currently used

Throws:

java.io.IOException

mem

long mem()

calculate the memory in RAM that the BLOB occupies

Returns:

number of bytes that is used

size

int size()

ask for the number of entries

Returns:

the number of entries in the table

isEmpty

boolean isEmpty()

ask if the BLOB is empty

Returns:

true iff size() == 0

keys

CloneableIterator<byte[]> keys(boolean up,
                             boolean rotating)
                               throws java.io.IOException

iterator over all keys

Parameters:

up -

rotating -

Returns:

Throws:

java.io.IOException

keys

CloneableIterator<byte[]> keys(boolean up,
                             byte[] firstKey)
                               throws java.io.IOException

iterate over all keys

Parameters:

up -

firstKey -

Returns:

Throws:

java.io.IOException

containsKey

boolean containsKey(byte[] key)

check if a specific key is in the database

Parameters:

key - the primary key

Returns:

Throws:

java.io.IOException

get

byte[] get(byte[] key)
           throws java.io.IOException,
                  SpaceExceededException

retrieve the whole BLOB from the table

Parameters:

key - the primary key

Returns:

Throws:

java.io.IOException

SpaceExceededException

get

byte[] get(java.lang.Object key)

length

long length()
            throws java.io.IOException

retrieve the size of the database

Parameters:

-

Returns:

the size of the database in bytes

Throws:

java.io.IOException

length

long length(byte[] key)
            throws java.io.IOException

retrieve the size of the BLOB

Parameters:

key -

Returns:

the size of the BLOB or -1 if the BLOB does not exist

Throws:

java.io.IOException

insert

void insert(byte[] key,
          byte[] b)
            throws java.io.IOException

write a whole byte array as BLOB to the table

Parameters:

key - the primary key

b -

Throws:

java.io.IOException

SpaceExceededException

replace

int replace(byte[] key,
          BLOB.Rewriter rewriter)
            throws java.io.IOException,
                   SpaceExceededException

replace an existing entry in the BLOB with a new entry this method is similar to put, but it is necessary that a blob entry existed before and contains an entry of same size or bigger than the new entry. The old entry is then replaced by the new entry. This method throws a IOException if the new element is bigger than the old element. It is therefore necessary that it is known that the new entry will be smaller than the old entry before calling this method.

Parameters:

key - the primary key

rewriter -

Returns:

the number of bytes that the rewriter reduced the BLOB

Throws:

java.io.IOException

SpaceExceededException

reduce

int reduce(byte[] key,
         BLOB.Reducer reducer)
           throws java.io.IOException,
                  SpaceExceededException

a reduce method is the same as the replace. A replace subsumes a reduce method. A reduce method may be more simple.

Parameters:

key - the primary key

reducer -

Returns:

the number of bytes that the rewriter reduced the BLOB

Throws:

java.io.IOException

SpaceExceededException

delete

void delete(byte[] key)
            throws java.io.IOException

remove a BLOB

Parameters:

key - the primary key

Throws:

java.io.IOException

close

void close(boolean writeIDX)

close the BLOB table