com.sun.sgs.impl.service.data.store.db.bdb
Class BdbDatabase

java.lang.Object
  com.sun.sgs.impl.service.data.store.db.bdb.BdbDatabase

All Implemented Interfaces:

DbDatabase

public class BdbDatabase
extends Object
implements DbDatabase

Provides a database implementation using Berkeley DB.

Constructor Summary

BdbDatabase(com.sleepycat.db.Environment env, com.sleepycat.db.Transaction txn, String fileName, boolean create)
Creates an instance of this class.

Method Summary

void	close() Closes this database, releasing any associated resources.
(package private) static byte[]	convertData(byte[] bytes) Converts a Berkeley DB DatabaseEntry data value, replacing the null that BDB uses if the data is empty with an empty array.
boolean	delete(DbTransaction txn, byte[] key) Removes the value associated with a key in this database.
byte[]	get(DbTransaction txn, byte[] key, boolean forUpdate) Gets the value associated with a key in this database.
void	markForUpdate(DbTransaction txn, byte[] key) Locks the key and associated value for update.
DbCursor	openCursor(DbTransaction txn) Returns a cursor for iterating over the contents of this database.
void	put(DbTransaction txn, byte[] key, byte[] value) Sets the value associated with a key in this database, regardless of whether the key already has an associated value.
boolean	putNoOverwrite(DbTransaction txn, byte[] key, byte[] value) Sets the value associated with a key in this database, but only if the key does not already have an associated value.

Methods inherited from class java.lang.Object

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

Constructor Detail

BdbDatabase

BdbDatabase(com.sleepycat.db.Environment env,
            com.sleepycat.db.Transaction txn,
            String fileName,
            boolean create)
      throws FileNotFoundException

Creates an instance of this class.

Parameters:

env - the Berkeley DB environment

txn - the Berkeley DB transaction

fileName - the name of the file containing the database

create - whether to create the database if it does not exist

Throws:

FileNotFoundException - if the database file is not found

DbDatabaseException - if an unexpected database problem occurs

Method Detail

convertData

static byte[] convertData(byte[] bytes)

Converts a Berkeley DB DatabaseEntry data value, replacing the null that BDB uses if the data is empty with an empty array.

get

public byte[] get(DbTransaction txn,
                  byte[] key,
                  boolean forUpdate)

Gets the value associated with a key in this database. Returns null if the key is not found.

Specified by:

get in interface DbDatabase

Parameters:

txn - the transaction for this operation

key - the key

forUpdate - whether the object should be locked for update

Returns:

the associated value, or null if the key was not found

markForUpdate

public void markForUpdate(DbTransaction txn,
                          byte[] key)

Locks the key and associated value for update.

Specified by:

markForUpdate in interface DbDatabase

Parameters:

txn - the transaction for this operation

key - the key

put

public void put(DbTransaction txn,
                byte[] key,
                byte[] value)

Sets the value associated with a key in this database, regardless of whether the key already has an associated value.

Specified by:

put in interface DbDatabase

Parameters:

txn - the transaction for this operation

key - the key

value - the value

putNoOverwrite

public boolean putNoOverwrite(DbTransaction txn,
                              byte[] key,
                              byte[] value)

Sets the value associated with a key in this database, but only if the key does not already have an associated value.

Specified by:

putNoOverwrite in interface DbDatabase

Parameters:

txn - the transaction for this operation

key - the key

value - the value

Returns:

true if a value was stored for the key, and false if the key already had a value

delete

public boolean delete(DbTransaction txn,
                      byte[] key)

Removes the value associated with a key in this database.

Specified by:

delete in interface DbDatabase

Parameters:

txn - the transaction for this operation

key - the key

Returns:

true if the value was removed, and false if the key had no associated value

openCursor

public DbCursor openCursor(DbTransaction txn)

Returns a cursor for iterating over the contents of this database. The cursor needs to be closed before the associated transaction ends.

Specified by:

openCursor in interface DbDatabase

Parameters:

txn - the transaction for this operation

Returns:

the cursor

close

public void close()

Closes this database, releasing any associated resources. This database should not be used after this method is called. This method should not be called if the transactions associated with any operations performed on this database are still open. This method should be called before closing the associated environment.

Specified by:

close in interface DbDatabase