UsageEventCollection.java example

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atlas-lb-master
package org.openstack.atlas.usagerefactor.collection;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.openstack.atlas.service.domain.entities.Host;
import org.openstack.atlas.service.domain.entities.LoadBalancer;
import org.openstack.atlas.service.domain.exceptions.UsageEventCollectionException;
import org.openstack.atlas.usagerefactor.SnmpUsage;
import org.openstack.atlas.usagerefactor.processor.UsageEventProcessor;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;

public class UsageEventCollection extends AbstractUsageEventCollection {
    private final Log LOG = LogFactory.getLog(UsageEventCollection.class);

    public UsageEventCollection() throws UsageEventCollectionException {
    }

    @Override
    public List<Future<SnmpUsage>> collectUsageRecords(ExecutorService executorService,
                                                       UsageEventProcessor usageEventProcessor, List<Host> hosts,
                                                       LoadBalancer lb)
            throws UsageEventCollectionException {

        LOG.debug("Collecting SNMP Usages for load balancer: " + lb.getId());

        List<Future<SnmpUsage>> futures;
        List<Callable<SnmpUsage>> callables = new ArrayList<Callable<SnmpUsage>>();

        for (Host h : hosts) {
            callables.add(new SnmpUsageCollector(h, lb));
        }
        try {
            LOG.debug("Executing SNMP collection tasks for loadbalancer: " + lb.getId());
            futures = executorService.invokeAll(callables);
        } catch (InterruptedException e) {
            LOG.error("Error Executing SNMP: " + e);
            throw new UsageEventCollectionException("Error executing SNMP collection: ", e);
        }
        return futures;
    }

    @Override
    public List<SnmpUsage> getUsagesFromFutures(List<Future<SnmpUsage>> futures) throws UsageEventCollectionException{
        List<SnmpUsage> usages = new ArrayList<SnmpUsage>();

        for (Future<SnmpUsage> f : futures) {
            try {
                SnmpUsage usage = f.get();
                if(usage != null) {
                    usages.add(usage);
                } else {
                    LOG.info("A null snmp usage was encountered by will not be used for processing.");
                }
            } catch (InterruptedException e) {
                LOG.error("Error retrieving SNMP futures: " + e);
                throw new UsageEventCollectionException("Error retrieving SNMP futures: ", e);
            } catch (ExecutionException e) {
                LOG.error("Error retrieving SNMP futures: " + e);
                throw new UsageEventCollectionException("Error retrieving SNMP futures: ", e);
            }
        }
        return usages;
    }
}