net.derquinse.bocas.BocasServiceDecorator.java Source code

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Here is the source code for net.derquinse.bocas.BocasServiceDecorator.java

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/*
 * Copyright (C) the original author or authors.
 *
 * 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.derquinse.bocas;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;

import com.google.common.annotations.Beta;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

/**
 * Bocas service decorators.
 * @author Andres Rodriguez.
 */
@Beta
final class BocasServiceDecorator implements BocasService {
    /** Decorated service. */
    private final BocasService service;
    /** Bucket decorator. */
    private final BocasDecorator decorator;
    /** Decorated buckets. */
    private final Cache<String, Bocas> buckets;

    /** Constructor. */
    BocasServiceDecorator(BocasService service, BocasDecorator decorator) {
        this.service = checkNotNull(service, "The bocas service to decorate must be provided");
        this.decorator = checkNotNull(decorator, "The bocas decorator must be provided");
        this.buckets = CacheBuilder.newBuilder().build();
    }

    /*
     * (non-Javadoc)
     * @see net.derquinse.bocas.BocasService#getBucket(java.lang.String)
     */
    public Bocas getBucket(final String name) {
        checkNotNull(name, "The bucket name must be provided");
        Callable<Bocas> loader = new Callable<Bocas>() {
            @Override
            public Bocas call() throws Exception {
                Bocas original = service.getBucket(name);
                return decorator.decorate(name, original);
            }
        };
        try {
            return buckets.get(name, loader);
        } catch (ExecutionException e) {
            Throwable t = e.getCause();
            if (t instanceof BocasException) {
                throw (BocasException) t;
            }
            throw new BocasException(t);
        }
    }
}