com.sun.sgs.impl.service.data.store
Class DbUtilities

java.lang.Object
  com.sun.sgs.impl.service.data.store.DbUtilities

public final class DbUtilities
extends Object

Utility methods for database operations needed to implement a DataStore using the com.sun.sgs.service.store.db package. This class should not be instantiated.

Nested Class Summary

static class

DbUtilities.Databases Stores information about the databases that constitute the data store.

Method Summary

static int	getClassId(DbEnvironment env, DbDatabase classesDb, byte[] classInfo, long timeout) Returns the class ID to represent classes with the specified class information.
static byte[]	getClassInfo(DbEnvironment env, DbDatabase classesDb, int classId, long timeout) Returns the class information associated with the specified class ID.
static DbUtilities.Databases	getDatabases(DbEnvironment env, DbTransaction dbTxn, LoggerWrapper logger) Opens or creates the Berkeley DB databases for a data store.
static long	getNextNodeId(DbDatabase infoDb, DbTransaction dbTxn, int blockSize) Returns the next available node ID and increments the stored value by the specified amount.
static long	getNextObjectId(DbDatabase infoDb, DbTransaction dbTxn, int blockSize) Returns the next available object ID and increments the stored value by the specified amount.

Methods inherited from class java.lang.Object

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

Method Detail

getDatabases

public static DbUtilities.Databases getDatabases(DbEnvironment env,
                                                 DbTransaction dbTxn,
                                                 LoggerWrapper logger)

Opens or creates the Berkeley DB databases for a data store.

Parameters:

env - the database environment

dbTxn - the database transaction

logger - the logger for logging messages

Returns:

the databases

getNextObjectId

public static long getNextObjectId(DbDatabase infoDb,
                                   DbTransaction dbTxn,
                                   int blockSize)

Returns the next available object ID and increments the stored value by the specified amount.

Parameters:

infoDb - the info database

dbTxn - the transaction

blockSize - the number of items to allocate

Returns:

the next object ID

getNextNodeId

public static long getNextNodeId(DbDatabase infoDb,
                                 DbTransaction dbTxn,
                                 int blockSize)

Returns the next available node ID and increments the stored value by the specified amount.

Parameters:

infoDb - the info database

dbTxn - the transaction

blockSize - the number of node IDs to allocate

Returns:

the next node ID

getClassId

public static int getClassId(DbEnvironment env,
                             DbDatabase classesDb,
                             byte[] classInfo,
                             long timeout)

Returns the class ID to represent classes with the specified class information. Obtains an existing ID for the class information if present; otherwise, stores the information and returns the new ID associated with it. Class IDs are always greater than 0. The class information is the serialized form of the ObjectStreamClass instance that serialization uses to represent the class.

Parameters:

env - the database environment

classesDb - the classes database

classInfo - the class information

timeout - the timeout to use when creating a transaction

Returns:

the associated class ID

getClassInfo

public static byte[] getClassInfo(DbEnvironment env,
                                  DbDatabase classesDb,
                                  int classId,
                                  long timeout)

Returns the class information associated with the specified class ID. The class information is the serialized form of the ObjectStreamClass instance that serialization uses to represent the class.

Parameters:

env - the database environment

classesDb - the classes database

classId - the class ID

timeout - the transaction timeout for creating a transaction

Returns:

the associated class information or null if the ID is not found

Throws:

IllegalArgumentException - if classId is not greater than 0