org.ctoolkit.restapi.client.adapter.GetCachedResourceProvider Maven / Gradle / Ivy

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/*
 * Copyright (c) 2017 Comvai, s.r.o. All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

package org.ctoolkit.restapi.client.adapter;

import net.sf.jsr107cache.Cache;
import org.ctoolkit.restapi.client.Identifier;
import org.ctoolkit.restapi.client.provider.LocalResourceProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.inject.Inject;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Map;

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

/**
 * The provider caching the single (GET) resource.
 *
 * @author Aurel Medvegy
 * @see Cache
 */
public class GetCachedResourceProvider
        implements LocalResourceProvider
{
    private static final Logger logger = LoggerFactory.getLogger( GetCachedResourceProvider.class );

    private final Cache cache;

    @Inject
    public GetCachedResourceProvider( Cache cache )
    {
        this.cache = cache;
    }

    @SuppressWarnings( "unchecked" )
    @Override
    public final T get( @Nonnull Identifier identifier,
                        @Nullable Map parameters,
                        @Nullable Locale locale )
    {
        checkNotNull( identifier );

        String key = composeKey( identifier, parameters, locale );

        try
        {
            if ( !cache.containsKey( key ) )
            {
                return null;
            }

            return ( T ) cache.get( key );
        }
        catch ( Exception e )
        {
            logger.warn( "Retrieval of the resource with key: " + key + " has failed.", e );
            return null;
        }
    }

    @SuppressWarnings( "unchecked" )
    @Override
    public final void persist( @Nonnull T instance,
                               @Nonnull Identifier identifier,
                               @Nullable Map parameters,
                               @Nullable Locale locale,
                               @Nullable Long lastFor )
    {
        checkNotNull( instance );
        checkNotNull( identifier );

        Object key = null;
        try
        {
            key = composeKey( identifier, parameters, locale );
            cache.put( key, instance );
            logger.info( "The " + instance.getClass().getSimpleName() + " has been cached with key: " + key );
        }
        catch ( Exception e )
        {
            logger.warn( "Caching of the value with key: " + key + " has failed.", e );
        }
    }

    @Override
    public List list( @Nullable Map parameters,
                         @Nullable Locale locale,
                         @Nullable Date lastModifiedDate )
    {
        return null;
    }

    @Override
    public void persistList( @Nonnull List list,
                             @Nullable Map parameters,
                             @Nullable Locale locale,
                             @Nullable Long lastFor )
    {
    }

    protected String composeKey( @Nonnull Identifier identifier,
                                 @Nullable Map parameters,
                                 @Nullable Locale locale )
    {
        checkNotNull( identifier );

        String prefix = keyPrefix();
        if ( prefix == null )
        {
            prefix = identifier.key();
        }
        else
        {
            prefix = prefix + ":" + identifier.key();
        }

        StringBuilder builder = new StringBuilder( prefix );

        if ( locale != null )
        {
            builder.append( "." );
            builder.append( locale.getLanguage().toLowerCase() );
        }

        return builder.toString();
    }

    /**
     * Returns a prefix to be prepended to the cache key.
     * By default returns {@code null}, override to provide your own prefix.
     *
     * @return the key prefix
     */
    protected String keyPrefix()
    {
        return null;
    }

    /**
     * Removes a resource from the cache identified by the input arguments (GET).
     *
     * @param identifier the unique identifier of the resource
     * @param parameters the optional resource parameters of the retrieval
     * @param locale     the language the client has configured
     * @return true if the resource has been deleted from the cache
     */
    public boolean removeFromCache( @Nonnull Identifier identifier,
                                    @Nullable Map parameters,
                                    @Nullable Locale locale )
    {
        Object key = composeKey( identifier, parameters, locale );

        try
        {
            if ( cache.containsKey( key ) )
            {
                cache.remove( key );
                return true;
            }
            return false;
        }
        catch ( Exception e )
        {
            logger.warn( "Removing of the resource from the cache with key: " + key + " has failed.", e );
            return false;
        }
    }
}