net.craftforge.commons.database.memory
Class InMemoryDb

java.lang.Object
  java.lang.Thread
      net.craftforge.commons.database.memory.InMemoryDb

All Implemented Interfaces:

Runnable

public class InMemoryDb
extends Thread

An in-memory db is a wrapper for holding derby in-memory database instances. An in-memory db will be destroyed after a certain timeout has been reached, so it acts as temporary database which is only used for a certain time. The timeout is reset to its initial value with entity manager factory call. So an in-memory database keeps alive as long as it is frequently used.

Since:

08.08.11

Author:

Christian Bick

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

static long	DEFAULT_INITIAL_TIMEOUT Default maximum idle time before a database is dropped: 1 hour.
static long	DEFAULT_TIMEOUT_CHECK_INTERVAL Default update interval to check if the database should be dropped: 10 seconds.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

protected

InMemoryDb(InMemoryDbManager manager, String databaseName, long timeout, long timeoutCheckInterval) Create a new in memory-db with the given database name.

Method Summary

protected javax.persistence.EntityManagerFactory	buildEntityManagerFactory() Builds an entity manager factory associated to this in-memory database using the EJB configuration of the in-memory database manager.
protected org.hibernate.SessionFactory	buildSessionFactory() Builds a hibernate session factory associated to this in-memory database for the database setup.
protected void	destroyDatabase() Destroys an associated Derby in-memory database instance.
protected void	executeStatements(org.hibernate.Session session, String[] statements) Executes all given SQL statements using the given hibernate session.
javax.persistence.EntityManagerFactory	getEntityManagerFactory() Gets the entity-manager factory creating entity-managers for entities persisted in this database.
void	run() Sets up the database and then waits until the timeout is reached
protected void	setupDatabase() Sets up an associated Derby in-memory database instance and executes the SQL setup script of the in-memory database manager.
protected boolean	waitForCreationCompleted() The first process calling this method will trigger the creation of a Derby in-memory database.
protected void	waitForTimeout() Waits for the timeout to be reaches by frequently checking if the timeout has already been reached an decreasing the remaining time.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_INITIAL_TIMEOUT

public static final long DEFAULT_INITIAL_TIMEOUT

Default maximum idle time before a database is dropped: 1 hour.

See Also:

Constant Field Values

DEFAULT_TIMEOUT_CHECK_INTERVAL

public static final long DEFAULT_TIMEOUT_CHECK_INTERVAL

Default update interval to check if the database should be dropped: 10 seconds.

See Also:

Constant Field Values

Constructor Detail

InMemoryDb

protected InMemoryDb(InMemoryDbManager manager,
                     String databaseName,
                     long timeout,
                     long timeoutCheckInterval)

Create a new in memory-db with the given database name. Intended to be called by the managing in-memory manager only. The database will be destroyed after the no new entity manager was called within the given timeout. If the timeout has already been reached is checked in the given interval.

Parameters:

manager - The in-memory database manager for this database

databaseName - The database name

timeout - The timeout in milliseconds

timeoutCheckInterval - The interval to check for timeout in milliseconds

Method Detail

run

public void run()

Sets up the database and then waits until the timeout is reached

Specified by:

run in interface Runnable

Overrides:

run in class Thread

getEntityManagerFactory

public javax.persistence.EntityManagerFactory getEntityManagerFactory()

Gets the entity-manager factory creating entity-managers for entities persisted in this database. Calling this method resets the remaining timeout its initial value.

Returns:

The entity manager factory

waitForCreationCompleted

protected boolean waitForCreationCompleted()

The first process calling this method will trigger the creation of a Derby in-memory database. All following database will be queued for waiting until the creation process completed.

Returns:

Whether the database has already been created or not

setupDatabase

protected void setupDatabase()

Sets up an associated Derby in-memory database instance and executes the SQL setup script of the in-memory database manager.

waitForTimeout

protected void waitForTimeout()

Waits for the timeout to be reaches by frequently checking if the timeout has already been reached an decreasing the remaining time.

destroyDatabase

protected void destroyDatabase()

Destroys an associated Derby in-memory database instance.

buildEntityManagerFactory

protected javax.persistence.EntityManagerFactory buildEntityManagerFactory()

Builds an entity manager factory associated to this in-memory database using the EJB configuration of the in-memory database manager.

Returns:

The entity manager factory

buildSessionFactory

protected org.hibernate.SessionFactory buildSessionFactory()

Builds a hibernate session factory associated to this in-memory database for the database setup.

Returns:

The hibernate session factory

executeStatements

protected void executeStatements(org.hibernate.Session session,
                                 String[] statements)

Executes all given SQL statements using the given hibernate session.

Parameters:

session - The hibernate session

statements - The SQL statements