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/*
 * Copyright (c) 2008-2016, Hazelcast, Inc. All Rights Reserved.
 *
 * 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 com.hazelcast.hibernate.access;

import com.hazelcast.hibernate.region.HazelcastRegion;
import org.hibernate.cache.CacheException;
import org.hibernate.cache.spi.access.SoftLock;

import java.util.Properties;

/**
 * Guarantees that view is read-only and no updates can be made
 *
 * @author Leo Kim ([email protected])
 * @param  implementation type of HazelcastRegion
 */
public class ReadOnlyAccessDelegate extends NonStrictReadWriteAccessDelegate {

    public ReadOnlyAccessDelegate(T hazelcastRegion, final Properties props) {
        super(hazelcastRegion, props);
    }

    @Override
    public boolean afterInsert(final Object key, final Object value, final Object version) throws CacheException {
        return cache.insert(key, value, version);
    }

    /**
     * @throws UnsupportedOperationException Always thrown as we cannot update an item in a read-only cache
     */
    @Override
    public boolean afterUpdate(final Object key, final Object value, final Object currentVersion,
                               final Object previousVersion, final SoftLock lock) throws CacheException {
        throw new UnsupportedOperationException("Cannot update an item in a read-only cache: "
                + getHazelcastRegion().getName());
    }

    /**
     * {@inheritDoc}
     * 
     * This cache is asynchronous hence a no-op
     * 
     */
    @Override
    public boolean insert(final Object key, final Object value, final Object version) throws CacheException {
        return false;
    }

    @Override
    public SoftLock lockItem(final Object key, final Object version) throws CacheException {
        return null;
    }

    /**
     * @throws UnsupportedOperationException Thrown always because a read-only cache region cannot be locked
     */
    @Override
    public SoftLock lockRegion() throws CacheException {
        throw new UnsupportedOperationException("Attempting to lock a read-only cache region: "
                + getHazelcastRegion().getName());
    }

    @Override
    public void removeAll() throws CacheException {
        cache.clear();
    }

    /**
     * {@inheritDoc}
     * 
     * Should be a no-op since this cache is read-only
     * 
     */
    @Override
    public void unlockItem(final Object key, final SoftLock lock) throws CacheException {
        /*
         * To err on the safe side though, follow ReadOnlyEhcacheEntityRegionAccessStrategy which nevertheless evicts
         * the key.
         */
        evict(key);
    }

    /**
     * This will issue a log warning stating that an attempt was made to unlock a read-only cache region.
     */
    @Override
    public void unlockRegion(final SoftLock lock) throws CacheException {
        log.warning("Attempting to unlock a read-only cache region");
    }

    /**
     * @throws UnsupportedOperationException Thrown always because update is not possible on a read-only cache
     */
    @Override
    public boolean update(final Object key, final Object value, final Object currentVersion,
                          final Object previousVersion) throws CacheException {
        throw new UnsupportedOperationException("Attempting to update an item in a read-only cache: "
                + getHazelcastRegion().getName());
    }
}