com.ushahidi.swiftriver.core.rules.DropFilterQueueConsumer.java Source code

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Here is the source code for com.ushahidi.swiftriver.core.rules.DropFilterQueueConsumer.java

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/**
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/agpl.html>
 * 
 * Copyright (C) Ushahidi Inc. All Rights Reserved.
 */
package com.ushahidi.swiftriver.core.rules;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.amqp.AmqpException;
import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessagePostProcessor;
import org.springframework.amqp.rabbit.core.ChannelAwareMessageListener;
import org.springframework.util.ErrorHandler;

import com.rabbitmq.client.Channel;
import com.ushahidi.swiftriver.core.model.RawDrop;
import com.ushahidi.swiftriver.core.model.Rule;

/**
 * This class is an asynchronous consumer for consuming messages
 * from the DROP_FILTER_QUEUE queue. When a message is received, it is
 * marshalled into a {@link RawDrop} object before being passed to the 
 * {@link RulesExecutor} object for application of the rules
 *  
 * @author ekala
 *
 */
public class DropFilterQueueConsumer implements ChannelAwareMessageListener, ErrorHandler {

    private ObjectMapper objectMapper;

    private RulesRegistry rulesRegistry;

    private RulesExecutor rulesExecutor;

    private AmqpTemplate amqpTemplate;

    final static Logger logger = LoggerFactory.getLogger(DropFilterQueueConsumer.class);

    public DropFilterQueueConsumer() {
        rulesExecutor = new RulesExecutor();
    }

    public void setRulesRegistry(RulesRegistry rulesRegistry) {
        this.rulesRegistry = rulesRegistry;
    }

    public void setRulesExecutor(RulesExecutor rulesExecutor) {
        this.rulesExecutor = rulesExecutor;
    }

    public void setAmqpTemplate(AmqpTemplate amqpTemplate) {
        this.amqpTemplate = amqpTemplate;
    }

    public void setObjectMapper(ObjectMapper mapper) {
        this.objectMapper = mapper;
    }

    public synchronized void onMessage(Message message, Channel channel)
            throws JsonGenerationException, JsonMappingException, IOException {

        // Serialize the message into a Drop POJO
        RawDrop drop = objectMapper.readValue(new String(message.getBody()), RawDrop.class);

        ConcurrentMap<Long, Map<Long, Rule>> rulesMap = rulesRegistry.getRulesMap();

        // Send the drop for rules processing
        rulesExecutor.applyRules(drop, rulesMap);

        // Set the source to "rules"
        drop.setSource("rules");

        // Get he correlation id and callback queue name
        final String correlationId = new String(message.getMessageProperties().getCorrelationId());
        String routingKey = message.getMessageProperties().getReplyTo();
        long deliveryTag = message.getMessageProperties().getDeliveryTag();

        // Place drop on the publishing queue
        amqpTemplate.convertAndSend(routingKey, drop, new MessagePostProcessor() {
            public Message postProcessMessage(Message message) throws AmqpException {
                try {
                    message.getMessageProperties().setCorrelationId(correlationId.getBytes("UTF-8"));
                } catch (UnsupportedEncodingException e) {
                    logger.error("An error occurred while setting the correlation ID {}", correlationId, e);
                }

                return message;
            }

        });

        // Only acknowledge the current message
        channel.basicAck(deliveryTag, false);

        logger.debug("Drop with correlation id {} has completed rules processing", correlationId);
    }

    public void handleError(Throwable t) {
        logger.error("An error was encountered while processing the drop", t);
    }

}