Grails setup for using Apache Commons Pool to pool JAX-WS Port Proxy WS Stub objects because creating the connections can be an expensive operation

APoolHelper.groovy

import org.apache.commons.pool2.ObjectPool
import org.apache.log4j.Logger
class PoolHelper {
  static Logger log = Logger.getLogger(PoolHelper)

  /**
  * Executes a closure using the object from the passed
  * in Commons Pool, invalidating the object if an error is returned,
  * and always returning it to the pool. Similar to how Groovy Sql methods work.
  */
  static def withCommonsPool(ObjectPool pool, Closure closure) {
    def borrowedObject = pool.borrowObject()
    try {
      return closure.call(borrowedObject)
    } catch (Exception e) {
      log.warn "exception caught using pool, invalidating connection", e
      pool.invalidateObject(borrowedObject)
      borrowedObject = null
      throw e
    } finally {
      if (null != borrowedObject) {
        pool.returnObject(borrowedObject)
      }
    }
  }
}

BuildConfig.groovy

dependencies {
  compile "org.apache.commons:commons-pool2:2.2"
}

GridService.groovy

import static com.sheetsj.pool.PoolHelper.withCommonsPool
class GridService {
  /**
  * Improve JAX-WS performance by reusing connections.
  * Pool defined in resources.groovy
  */
  ObjectPool ruleConnectionPool

  /**
  * Gets rules using a free connection from the connection pool
  */
  def getGridRules(String gridName) {
    withCommonsPool(ruleConnectionPool) { ruleWSConn ->
      def request = new RequestWSDTO(gridName: gridName)
      ResponseWSDTO result = ruleWSConn.getGridMetaData(request)

      result.getGridMetaDataWSDTO()
    }
  }
}

JaxwsPortProxy.groovy

import java.util.UUID;
import groovy.util.Proxy
/**
 * Needed so each item in pool is unique via equals method,
 * but Jaxws Port calls use a Proxy that does not behave well for the equals method
 * @see http://stackoverflow.com/questions/22824889/apache-pool-cant-return-object-in-spring-controller-service
 */
class JaxwsPortProxy<T> extends Proxy {
  private final UUID poolId = UUID.randomUUID()

  @Override
  boolean equals(Object o) {
    if (this == o)
      return true
    if (!(o instanceof JaxwsPortProxy))
      return false

    JaxwsPortProxy that = (JaxwsPortProxy) o

    poolId == that.poolId
  }

  @Override
  int hashCode() {
    poolId?.hashCode() ?: 0
  }
}

resources.groovy

import org.apache.commons.pool2.impl.GenericObjectPool
import com.sheetsj.pool.RuleServiceFactory
beans = {
  ruleServiceFactory(RuleServiceFactory)

  ruleConnectionPool(GenericObjectPool, ruleServiceFactory) {
    maxTotal = 10
    maxIdle = 10

    //61 seconds to wait for object creation
    maxWaitMillis = 61000

    //10 minutes before an object is evicted for being idle
    minEvictableIdleTimeMillis = 10 * 60 * 1000

    //2 minutes between checks for evictions
    timeBetweenEvictionRunsMillis = 2 * 60 * 1000

    blockWhenExhausted = true
  }
}

RuleServiceFactory.groovy

import org.apache.commons.pool2.BasePooledObjectFactory
import org.apache.commons.pool2.PooledObject
import org.apache.commons.pool2.impl.DefaultPooledObject
class RuleServiceFactory extends BasePooledObjectFactory<JaxwsPortProxy<RuleServiceWS>> {

  @Override
  public JaxwsPortProxy<RuleServiceWS> create() throws Exception {
    // Used to get JAX-WS Port Proxy WS Stub object
    def ruleService = RuleServiceClientFactory.getRuleService()
    
    return new JaxwsPortProxy<RuleServiceWS>().wrap(ruleService)
  }

  @Override
  public PooledObject<JaxwsPortProxy<RuleServiceWS>> wrap(JaxwsPortProxy<RuleServiceWS> ruleService) {
    return new DefaultPooledObject<JaxwsPortProxy<RuleServiceWS>>(ruleService);
  }
}