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/*
* Copyright (c) 2009-2012 jMonkeyEngine
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of 'jMonkeyEngine' nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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*/
package com.jme3.asset.cache;
import com.jme3.asset.AssetKey;
/**
* AssetCache is an interface for asset caches.
* Allowing storage of loaded resources in order to improve their access time
* if they are requested again in a short period of time.
* Depending on the asset type and how it is used, a specialized
* caching method can be selected that is most appropriate for that asset type.
* The asset cache must be thread safe.
*
* Some caches are used to manage cloneable assets, which track reachability
* based on a shared key in all instances exposed in user code.
* E.g. {@link WeakRefCloneAssetCache} uses this approach.
* For those particular caches, either {@link #registerAssetClone(com.jme3.asset.AssetKey, java.lang.Object) }
* or {@link #notifyNoAssetClone() } MUST be called to avoid memory
* leaking following a successful {@link #addToCache(com.jme3.asset.AssetKey, java.lang.Object) }
* or {@link #getFromCache(com.jme3.asset.AssetKey) } call!
*
* @author Kirill Vainer
*/
public interface AssetCache {
/**
* Adds an asset to the cache.
* Once added, it should be possible to retrieve the asset
* by using the {@link #getFromCache(com.jme3.asset.AssetKey) } method.
* However the caching criteria may at some point choose that the asset
* should be removed from the cache to save memory, in that case,
* {@link #getFromCache(com.jme3.asset.AssetKey) } will return null.
*
Thread-Safe
*
* @param The type of the asset to cache.
* @param key The asset key that can be used to look up the asset.
* @param obj The asset data to cache.
*/
public void addToCache(AssetKey key, T obj);
/**
* This should be called by the asset manager when it has successfully
* acquired a cached asset (with {@link #getFromCache(com.jme3.asset.AssetKey) })
* and cloned it for use.
* Thread-Safe
*
* @param The type of the asset to register.
* @param key The asset key of the loaded asset (used to retrieve from cache)
* @param clone The clone of the asset retrieved from
* the cache.
*/
public void registerAssetClone(AssetKey key, T clone);
/**
* Notifies the cache that even though the methods {@link #addToCache(com.jme3.asset.AssetKey, java.lang.Object) }
* or {@link #getFromCache(com.jme3.asset.AssetKey) } were used, there won't
* be a call to {@link #registerAssetClone(com.jme3.asset.AssetKey, java.lang.Object) }
* for some reason. For example, if an error occurred during loading
* or if the addToCache/getFromCache were used from user code.
*/
public void notifyNoAssetClone();
/**
* Retrieves an asset from the cache.
* It is possible to add an asset to the cache using
* {@link #addToCache(com.jme3.asset.AssetKey, java.lang.Object) }.
* The asset may be removed from the cache automatically even if
* it was added previously, in that case, this method will return null.
* Thread-Safe
*
* @param The type of the asset to retrieve
* @param key The key used to lookup the asset.
* @return The asset that was previously cached, or null if not found.
*/
public T getFromCache(AssetKey key);
/**
* Deletes an asset from the cache.
* Thread-Safe
*
* @param key The asset key to find the asset to delete.
* @return True if the asset was successfully found in the cache
* and removed.
*/
public boolean deleteFromCache(AssetKey key);
/**
* Deletes all assets from the cache.
*
Thread-Safe
*/
public void clearCache();
}