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 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
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package org.apache.cayenne.cache;

import org.apache.cayenne.query.QueryMetadata;

import java.util.List;

/**
 * Defines API of a cache that stores query results.
 *
 * @since 3.0
 */
public interface QueryCache {

    /**
     * Returns a cached query result for the given QueryMetadata or null if the result is
     * not cached or is expired.
     */
    @SuppressWarnings("rawtypes")
    List get(QueryMetadata metadata);

    /**
     * Returns a cached query result for the given QueryMetadata. If the result is not
     * cached or is expired, cache will use provided factory to rebuild the value and
     * store it in the cache. A corollary is that this method never returns null.
     * <p>
     * Compared to {@link #get(QueryMetadata)}, this method allows the cache to do
     * appropriate synchronization when refreshing the entry, preventing multiple threads
     * from running the same query when a missing entry is requested by multiple threads
     * simultaneously.
     */
    @SuppressWarnings("rawtypes")
    List get(QueryMetadata metadata, QueryCacheEntryFactory factory);

    @SuppressWarnings("rawtypes")
    void put(QueryMetadata metadata, List results);

    /**
     * Removes a single entry from cache.
     */
    void remove(String key);

    /**
     * Removes a group of entries identified by group key. Note that depending on
     * implementation this method may either actively remove the entries belonging to the
     * group or just mark them as expired, so that they are refreshed on the next access.
     * In the former case the cache size would shrink, but in the later the cache size
     * will not change after calling this method.
     */
    void removeGroup(String groupKey);

    /**
     * Removes a group of entries identified by group key.
     * Can be used if cache provider supports strictly typed caches.
     * @see QueryCache#removeGroup(String)
     *
     * @since 4.0
     */
    void removeGroup(String groupKey, Class<?> keyType, Class<?> valueType);

    /**
     * Clears all cache entries.
     *
     * @deprecated since 4.0. Please use implementation specific methods to perform cache management tasks.
     */
    @Deprecated
    void clear();

    /**
     * Returns the number of entries currently in the cache, including expired but not
     * removed entries.
     *
     * @deprecated since 4.0. Please use implementation specific methods to perform cache management tasks.
     */
    @Deprecated
    int size();
}