Reset SettingsManager's instance when calling cleanup

[srstsavage]

SettingsManager provides the cleanup method:

/**
 * Clean up this SettingsManager. All subsequent calls to this class are
 * undefined.
 */
public abstract void cleanup();

This method is purely abstract and does not unset SettingsManager's instance property, used in getInstance():

    /**
     * Gets the singleton instance of the SettingsManager.
     * <p/>
     *
     * @return the settings manager
     *         <p/>
     * @throws ConfigurationException
     *             if no implementation can be found
     */
    public static SettingsManager getInstance() throws ConfigurationException {
        if (instance == null) {
            creationLock.lock();
            try {
                if (instance == null) {
                    instance = createInstance();
                }
            } finally {
                creationLock.unlock();
            }
        }
        return instance;
    }

I'm running into this problem when trying to create a second integration test suite. SOS40ComplianceTestSuite runs SettingsManager.getInstance().cleanup() in its @AfterClass, which invalidates the SettingsManager for any tests running after the suite.

    @AfterClass
    public static void cleanup() {
        SettingsManager.getInstance().cleanup();
    }

If SettingsManager.getInstance().cleanup() set instance = null then I believe future calls to SettingsManager.getInstance() would reinitialize the SettingsManager, allowing for further usage.

[srstsavage]

Just a note, if it's decided that SettingsManager shouldn't be able to reinitialize after cleanup() is called we should at least catch when getConnection() is called after cleanup(). Right now the message is confusing : Unknown service requested [org.hibernate.engine.jdbc.connections.spi.ConnectionProvider]

Example stacktrace:

java.lang.RuntimeException: org.n52.sos.ds.ConnectionProviderException: org.hibernate.service.UnknownServiceException: Unknown service requested [org.hibernate.engine.jdbc.connections.spi.ConnectionProvider]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:201)
    at org.hibernate.internal.AbstractSessionImpl.getJdbcConnectionAccess(AbstractSessionImpl.java:341)
    at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.<init>(JdbcCoordinatorImpl.java:114)
    at org.hibernate.engine.transaction.internal.TransactionCoordinatorImpl.<init>(TransactionCoordinatorImpl.java:89)
    at org.hibernate.internal.SessionImpl.<init>(SessionImpl.java:258)
    at org.hibernate.internal.SessionFactoryImpl$SessionBuilderImpl.openSession(SessionFactoryImpl.java:1589)
    at org.hibernate.internal.SessionFactoryImpl.openSession(SessionFactoryImpl.java:999)
    at org.n52.sos.config.sqlite.SQLiteSessionFactoryForTesting.getConnection(SQLiteSessionFactoryForTesting.java:72)
    at org.n52.sos.config.sqlite.SQLiteSessionFactoryForTesting.getConnection(SQLiteSessionFactoryForTesting.java:46)
    at org.n52.sos.config.sqlite.SQLiteManager.execute(SQLiteManager.java:81)
    at org.n52.sos.config.sqlite.SQLiteSettingsManager.execute(SQLiteSettingsManager.java:127)
    at org.n52.sos.config.sqlite.ExtensionEnabledSQLiteSettingsManager.execute(ExtensionEnabledSQLiteSettingsManager.java:86)
    at org.n52.sos.config.sqlite.ExtensionEnabledSQLiteSettingsManager.getActiveStaticCapabilities(ExtensionEnabledSQLiteSettingsManager.java:128)
    at org.n52.sos.config.sqlite.ExtensionEnabledSQLiteSettingsManager.isStaticCapabilitiesActive(ExtensionEnabledSQLiteSettingsManager.java:162)
    at org.n52.sos.ds.GetCapabilitiesDAO.getCapabilities(GetCapabilitiesDAO.java:204)
    at org.n52.sos.request.operator.SosGetCapabilitiesOperatorV20.receive(SosGetCapabilitiesOperatorV20.java:71)
    at org.n52.sos.request.operator.SosGetCapabilitiesOperatorV20.receive(SosGetCapabilitiesOperatorV20.java:53)