/Main/Source/Libraries/TSFJavaLibrary/src/org/gpa/tsf/transport/SignalIndexCache.java

//******************************************************************************************************

//  SignalIndexCache.java - Gbtc

//

//  Copyright Š 2010, Grid Protection Alliance.  All Rights Reserved.

//

//  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See

//  the NOTICE file distributed with this work for additional information regarding copyright ownership.

//  The GPA licenses this file to you under the Eclipse Public License -v 1.0 (the "License"); you may

//  not use this file except in compliance with the License. You may obtain a copy of the License at:

//

//      http://www.opensource.org/licenses/eclipse-1.0.php

//

//  Unless agreed to in writing, the subject software distributed under the License is distributed on an

//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the

//  License for the specific language governing permissions and limitations.

//

//  Code Modification History:

//  ----------------------------------------------------------------------------------------------------

//  04/12/2012 - Stephen C. Wills

//       Generated original version of source code.

//

//******************************************************************************************************



package org.gpa.tsf.transport;



import java.util.HashMap;

import java.util.Map;

import java.util.UUID;



import org.gpa.tsf.MeasurementKey;



/**

 * Represents a cache used to map 16-bit indexes to {@link MeasurementKey}s

 * in order to compact measurement IDs for the compact measurement format.

 */

public class SignalIndexCache

{

	private Map<Short, MeasurementKey> m_reference;

	private Map<UUID, Short> m_signalIdCache;

	

	/**

	 * Constructs a new signal index cache.

	 */

	public SignalIndexCache()

	{

		m_reference = new HashMap<Short, MeasurementKey>();

		m_signalIdCache = new HashMap<UUID, Short>();

	}



	/**

	 * Adds a measurement key to the signal index

	 * cache, identified by the given signal index.

	 * 

	 * @param signalIndex the 16-bit index by which the

	 *        measurement key can be retrieved from the cache

	 * @param signalId the measurement's globally unique identifier

	 * @param source the measurement's source

	 * @param id the measurement's simple numeric identifier

	 * @throws IllegalArgumentException if the given {@code signalID} is

	 *         {@code null} or the given {@code source} is {@code null} or

	 *         empty

	 */

	public void addMeasurementKey(short signalIndex, UUID signalId, String source, int id)

	{

		addMeasurementKey(signalIndex, new MeasurementKey(signalId, source, id));

	}

	

	/**

	 * Adds a measurement key to the signal index

	 * cache, identified by the given signal index.

	 * 

	 * @param signalIndex the 16-bit index by which the

	 *        measurement key can be retrieved from the cache

	 * @param key the measurement key to be placed in the cache

	 */

	public void addMeasurementKey(short signalIndex, MeasurementKey key)

	{

		m_reference.put(signalIndex, key);

		m_signalIdCache.put(key.getSignalId(), signalIndex);

	}

	

	/**

	 * Empties the signal index cache.

	 */

	public void clear()

	{

		m_reference.clear();

		m_signalIdCache.clear();

	}

	

	/**

	 * Determines whether a measurement key exists

	 * in the cache for the given signal index.

	 * 

	 * @param signalIndex the signal index to be searched for

	 * @return true if the signal index refers to

	 *         a measurement key; false otherwise

	 */

	public boolean contains(short signalIndex)

	{

		return m_reference.containsKey(signalIndex);

	}



	/**

	 * Gets the measurement key identified by the given signal index.

	 * 

	 * @param signalIndex the signal index which identifies the measurement key

	 * @return the measurement key identified by the given signal index,

	 *         or {@code null} if no mapping exists for the signal index

	 */

	public MeasurementKey getMeasurementKey(short signalIndex)

	{

		return m_reference.get(signalIndex);

	}

	

	/**

	 * Provides a backwards mapping from the globally unique identifiers

	 * of the measurements whose keys are stored in the cache to the

	 * signal indexes that refer to them.

	 * 

	 * @param signalId the measurement's globally unique identifier

	 * @return the signal index which identifies the measurement key 

	 */

	short getSignalIndex(UUID signalId)

	{

		return m_signalIdCache.get(signalId);

	}

}