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/*******************************************************************************
* Copyright (c) 2014 Wind River Systems, Inc. and others. All rights reserved.
* This program and the accompanying materials are made available under the terms
* of the Eclipse Public License v1.0 which accompanies this distribution, and is
* available at http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Wind River Systems - initial API and implementation
*******************************************************************************/
package org.eclipse.tcf.debug.test.util;
/**
* The interface for a general purpose cache that caches the result of a single
* request. Implementations need to provide the logic to fetch data from an
* asynchronous data source.
* <p>
* This cache requires an executor to use. The executor is used to synchronize
* access to the cache state and data.
* </p>
* @since 2.2
*/
public interface ICache<V> {
/**
* Returns the current data value held by this cache. Clients should first
* call isValid() to determine if the data is up to date. Calling this when
* in the invalid state will throw an IllegalStateException
*/
public V getData();
/**
* Returns the status of the source request held by this cache. Clients
* should first call isValid() to determine if the data is up to date.
* Calling this when in the invalid state will throw an
* IllegalStateException
*/
public Throwable getError();
/**
* Asks the cache to update its value from the source. Typically, this
* method is called by a client after it discovers the cache is invalid
* via {@link #isValid()}.
*
* <p>If the cache is already valid, the cache is not updated again from
* source. Instead the callback is completed next time the cache state is
* changed. Clients can use this feature to be notified when the cache is
* being reset.
* </p>
* @param cb
* Callback that is called when cache becomes valid.
*/
public void wait(Callback cb);
/**
* Returns <code>true</code> if the cache is currently valid. I.e.
* whether the cache can return a value immediately without first
* retrieving it from the data source.
*/
public boolean isValid();
}
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