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Ehcache is an open source, standards-based cache used to boost performance, offload the database and simplify scalability. Ehcache is robust, proven and full-featured and this has made it the most widely-used Java-based cache.

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/**
 *  Copyright Terracotta, Inc.
 *
 *  Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/**
 *
 */
package net.sf.ehcache.store.disk;

import net.sf.ehcache.pool.sizeof.annotations.IgnoreSizeOf;
import net.sf.ehcache.store.disk.DiskStorageFactory.DiskSubstitute;

import java.util.concurrent.atomic.AtomicBoolean;

/**
 * Internal entry structure used by the {@link net.sf.ehcache.store.disk.Segment} class.
 *
 * @author Chris Dennis
 * @author Ludovic Orban
 */
final class HashEntry {

    /**
     * Key instance for this mapping.
     */
    @IgnoreSizeOf
    protected final Object key;

    /**
     * Spread hash value for they key.
     */
    protected final int hash;

    /**
     * Reference to the next HashEntry in this chain.
     */
    @IgnoreSizeOf
    protected final HashEntry next;

    /**
     * Reference to the DiskSubstitute for this entry.
     */
    protected volatile DiskSubstitute element;

    /**
     * marks the entry as faulted, can't evict faulted things
     */
    protected final AtomicBoolean faulted;

    /**
     * Constructs a HashEntry instance mapping the supplied key, value pair
     * and linking it to the supplied HashEntry
     *
     * @param key     key for this entry
     * @param hash    spread-hash for this entry
     * @param next    next HashEntry in the chain
     * @param element initial value for this entry
     */
    HashEntry(Object key, int hash, HashEntry next, DiskSubstitute element, AtomicBoolean faulted) {
        this.key = key;
        this.hash = hash;
        this.next = next;
        this.element = element;
        this.faulted = faulted;
    }
}