SimpleSpringMemcached.java

/*
 * Copyright 2013-2014 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 org.springframework.cloud.aws.cache.memcached;

import net.spy.memcached.MemcachedClientIF;
import org.springframework.cache.Cache;
import org.springframework.cache.support.SimpleValueWrapper;
import org.springframework.util.Assert;

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

/**
 * @author Agim Emruli
 */
public class SimpleSpringMemcached implements Cache {

    private final MemcachedClientIF memcachedClientIF;
    private final String cacheName;
    private int expiration;

    public SimpleSpringMemcached(MemcachedClientIF memcachedClientIF, String cacheName) {
        Assert.notNull(memcachedClientIF, "memcachedClient is mandatory");
        Assert.notNull(cacheName, "cacheName is mandatory");
        this.memcachedClientIF = memcachedClientIF;
        this.cacheName = cacheName;
    }

    @Override
    public String getName() {
        return this.cacheName;
    }

    @Override
    public Object getNativeCache() {
        return this.memcachedClientIF;
    }

    @Override
    public ValueWrapper get(Object key) {
        Assert.notNull(key, "key parameter is mandatory");
        Assert.isAssignable(String.class, key.getClass());
        Object result = this.memcachedClientIF.get((String) key);
        return result != null ? new SimpleValueWrapper(result) : null;
    }

    @Override
    public <T> T get(Object key, Class<T> type) {
        Assert.notNull(key, "key parameter is mandatory");
        Assert.isAssignable(String.class, key.getClass());
        Object result = this.memcachedClientIF.get((String) key);
        if (result == null) {
            return null;
        }
        Assert.isAssignable(type, result.getClass());
        return type.cast(result);
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T get(Object key, Callable<T> valueLoader) {
        ValueWrapper valueWrapper = get(key);
        if (valueWrapper != null) {
            return (T) valueWrapper.get();
        } else {
            T newValue;
            try {
                newValue = valueLoader.call();
            } catch (Throwable ex) {
                throw new ValueRetrievalException(key, valueLoader, ex);
            }
            put(key, newValue);
            return newValue;
        }
    }

    @Override
    public void put(Object key, Object value) {
        Assert.notNull(key, "key parameter is mandatory");
        Assert.isAssignable(String.class, key.getClass());
        try {
            this.memcachedClientIF.set((String) key, this.expiration, value).get();
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        } catch (ExecutionException e) {
            throw new IllegalArgumentException("Error writing key" + key, e);
        }
    }

    /**
     * <b>IMPORTANT:</b> This operation is not atomic as the underlying implementation (memcached) does not provide a
     * way to do it.
     */
    @Override
    public ValueWrapper putIfAbsent(Object key, Object value) {
        Assert.notNull(key, "key parameter is mandatory");
        Assert.isAssignable(String.class, key.getClass());

        ValueWrapper valueWrapper = get(key);
        if (valueWrapper == null) {
            try {
                this.memcachedClientIF.add((String) key, this.expiration, value).get();
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            } catch (ExecutionException e) {
                throw new IllegalArgumentException("Error writing key" + key, e);
            }
            return null;
        } else {
            return valueWrapper;
        }
    }

    @Override
    public void evict(Object key) {
        Assert.notNull(key, "key parameter is mandatory");
        Assert.isAssignable(String.class, key.getClass());
        try {
            this.memcachedClientIF.delete((String) key).get();
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        } catch (ExecutionException e) {
            throw new IllegalArgumentException("Error evicting items" + key);
        }
    }

    @Override
    public void clear() {
        this.memcachedClientIF.flush();
    }

    public void setExpiration(int expiration) {
        this.expiration = expiration;
    }
}