TriggerData.java

/*
 * Copyright (c) 2004, 2005, 2006 TADA AB - Taby Sweden
 * Distributed under the terms shown in the file COPYRIGHT
 * found in the root folder of this project or at
 * http://eng.tada.se/osprojects/COPYRIGHT.html
 */
package org.postgresql.pljava.internal;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.postgresql.pljava.jdbc.TriggerResultSet;

/**
 * The <code>TriggerData</code> correspons to the internal PostgreSQL <code>TriggerData</code>.
 * 
 * @author Thomas Hallgren
 */
public class TriggerData extends JavaWrapper implements org.postgresql.pljava.TriggerData
{
	private Relation m_relation;
	private TriggerResultSet m_old = null;
	private TriggerResultSet m_new = null;
	private Tuple m_newTuple;
	private Tuple m_triggerTuple;

	TriggerData(long pointer)
	{
		super(pointer);
	}

	/**
	 * Returns the ResultSet that represents the new row. This ResultSet will
	 * be null for delete triggers and for triggers that was fired for
	 * statement. <br>
	 * The returned set will be updateable and positioned on a
	 * valid row.
	 * 
	 * @return An updateable <code>ResultSet</code> containing one row or
	 *         <code>null</code>.
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public ResultSet getNew() throws SQLException
	{
		if (m_new != null)
			return m_new;

		if (this.isFiredByDelete() || this.isFiredForStatement())
			return null;

		// PostgreSQL uses the trigger tuple as the new tuple for inserts.
		//
		Tuple tuple =
			this.isFiredByInsert()
				? this.getTriggerTuple()
				: this.getNewTuple();
				
		// Triggers fired after will always have a read-only row
		//
		m_new = new TriggerResultSet(this.getRelation().getTupleDesc(), tuple, this.isFiredAfter());
		return m_new;
	}

	/**
	 * Returns the ResultSet that represents the old row. This ResultSet will
	 * be null for insert triggers and for triggers that was fired for
	 * statement. <br>
	 * The returned set will be read-only and positioned on a
	 * valid row.
	 * 
	 * @return A read-only <code>ResultSet</code> containing one row or
	 *         <code>null</code>.
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public ResultSet getOld() throws SQLException
	{
		if (m_old != null)
			return m_old;

		if (this.isFiredByInsert() || this.isFiredForStatement())
			return null;
		m_old = new TriggerResultSet(this.getRelation().getTupleDesc(), this.getTriggerTuple(), true);
		return m_old;
	}

	/**
	 * Commits the changes made on the <code>ResultSet</code> representing
	 * <code>new</code> and returns the native pointer of new tuple. This
	 * method is called automatically by the trigger handler and should not
	 * be called in any other way.
	 * 
	 * @return The modified tuple, or if no modifications have been made, the
	 *         original tuple.
	 */
	public long getTriggerReturnTuple() throws SQLException
	{
		if(this.isFiredForStatement() || this.isFiredAfter())
			//
			// Only triggers fired before each row can have a return
			// value.
			//
			return 0;

		if (m_new != null)
		{
			Object[] changes = m_new.getChangeIndexesAndValues();
			if (changes != null)
			{
				Tuple original = (Tuple)changes[0];
				int[] indexes = (int[])changes[1];
				Object[] values = (Object[])changes[2];
				return this.getRelation().modifyTuple(original, indexes, values).getNativePointer();
			}
		}

		// Return the original tuple.
		//
		return (this.isFiredByUpdate() ? this.getNewTuple() : this.getTriggerTuple()).getNativePointer();
	}

	public String getTableName()
	throws SQLException
	{
		return this.getRelation().getName();
	}

	public String getSchemaName() throws SQLException {
		return this.getRelation().getSchema();
	}

	/**
	 * Returns a descriptor for the Tuples exposed by this trigger.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public Relation getRelation()
	throws SQLException
	{
		if(m_relation == null)
		{
			synchronized(Backend.THREADLOCK)
			{
				m_relation = _getRelation(this.getNativePointer());
			}
		}
		return m_relation;
	}

	/**
	 * Returns a <code>Tuple</code> reflecting the row for which the trigger
	 * was fired. This is the row being inserted, updated, or deleted. If this
	 * trigger was fired for an <code>
	 * INSERT</code> or <code>DELETE</code>
	 * then this is what you should return to from the method if you don't want
	 * to replace the row with a different one (in the case of <code>INSERT
	 * </code>)
	 * or skip the operation.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public Tuple getTriggerTuple()
	throws SQLException
	{
		if(m_triggerTuple == null)
		{
			synchronized(Backend.THREADLOCK)
			{
				m_triggerTuple = _getTriggerTuple(this.getNativePointer());
			}
		}
		return m_triggerTuple;
	}

	/**
	 * Returns a <code>Tuple</code> reflecting the new version of the row, if
	 * the trigger was fired for an <code>UPDATE</code>, and <code>null</code>
	 * if it is for an <code>INSERT</code> or a <code>DELETE</code>. This
	 * is what you have to return from the function if the event is an <code>UPDATE</code>
	 * and you don't want to replace this row by a different one or skip the
	 * operation.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public Tuple getNewTuple()
	throws SQLException
	{
		if(m_newTuple == null)
		{
			synchronized(Backend.THREADLOCK)
			{
				m_newTuple = _getNewTuple(this.getNativePointer());
			}
		}
		return m_newTuple;
	}

	/**
	 * Returns the arguments for this trigger (as declared in the <code>CREATE TRIGGER</code>
	 * statement. If the trigger has no arguments, this method will return an
	 * array with size 0.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public String[] getArguments()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _getArguments(this.getNativePointer());
		}
	}

	/**
	 * Returns the name of the trigger (as declared in the <code>CREATE TRIGGER</code>
	 * statement).
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public String getName()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _getName(this.getNativePointer());
		}
	}

	/**
	 * Returns <code>true</code> if the trigger was fired after the statement
	 * or row action that it is associated with.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public boolean isFiredAfter()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _isFiredAfter(this.getNativePointer());
		}
	}

	/**
	 * Returns <code>true</code> if the trigger was fired before the
	 * statement or row action that it is associated with.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public boolean isFiredBefore()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _isFiredBefore(this.getNativePointer());
		}
	}

	/**
	 * Returns <code>true</code> if this trigger is fired once for each row
	 * (as opposed to once for the entire statement).
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public boolean isFiredForEachRow()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _isFiredForEachRow(this.getNativePointer());
		}
	}

	/**
	 * Returns <code>true</code> if this trigger is fired once for the entire
	 * statement (as opposed to once for each row).
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public boolean isFiredForStatement()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _isFiredForStatement(this.getNativePointer());
		}
	}

	/**
	 * Returns <code>true</code> if this trigger was fired by a <code>DELETE</code>.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public boolean isFiredByDelete()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _isFiredByDelete(this.getNativePointer());
		}
	}

	/**
	 * Returns <code>true</code> if this trigger was fired by an <code>INSERT</code>.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public boolean isFiredByInsert()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _isFiredByInsert(this.getNativePointer());
		}
	}

	/**
	 * Returns <code>true</code> if this trigger was fired by an <code>UPDATE</code>.
	 * 
	 * @throws SQLException
	 *             if the contained native buffer has gone stale.
	 */
	public boolean isFiredByUpdate()
	throws SQLException
	{
		synchronized(Backend.THREADLOCK)
		{
			return _isFiredByUpdate(this.getNativePointer());
		}
	}

	protected native void _free(long pointer);
	private static native Relation _getRelation(long pointer) throws SQLException;
	private static native Tuple _getTriggerTuple(long pointer) throws SQLException;
	private static native Tuple _getNewTuple(long pointer) throws SQLException;
	private static native String[] _getArguments(long pointer) throws SQLException;
	private static native String _getName(long pointer) throws SQLException;
	private static native boolean _isFiredAfter(long pointer) throws SQLException;
	private static native boolean _isFiredBefore(long pointer) throws SQLException;
	private static native boolean _isFiredForEachRow(long pointer) throws SQLException;
	private static native boolean _isFiredForStatement(long pointer) throws SQLException;
	private static native boolean _isFiredByDelete(long pointer) throws SQLException;
	private static native boolean _isFiredByInsert(long pointer) throws SQLException;
	private static native boolean _isFiredByUpdate(long pointer) throws SQLException;
}