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import static com.sun.btrace.BTraceUtils.*;

import java.lang.reflect.Field;

import com.sun.btrace.BTraceUtils.Sys;
import com.sun.btrace.annotations.BTrace;
import com.sun.btrace.annotations.OnMethod;
import com.sun.btrace.annotations.Self;

@BTrace
public class DbcpMonitor {

        private static final String DS_CLASS = "org.apache.commons.dbcp.BasicDataSource";

        @OnMethod(clazz = DS_CLASS, method = "getConnection")
        public static void onGetConnection(@Self Object basicDataSource) {

                Class<?> dsClass = classOf(basicDataSource);
                printTitle(dsClass, basicDataSource);
                printFields(basicDataSource);
                printNumberOfActive(basicDataSource, dsClass);
                println("=======================================");
                Sys.exit(0);
        }

        private static void printTitle(Class<?> dsClass, Object basicDataSource) {
                Field urlField = field(dsClass, "url");
                Object url = get(urlField, basicDataSource);
                print("=====DBCP BasicDataSource info (");
                print(url);
                println(" ) ========");
        }

        private static void printNumberOfActive(Object basicDataSource, Class<?> dsClass) {
                Field poolField = field(dsClass, "connectionPool");
                Object numActive = getNumActive(basicDataSource, poolField);
                println(concat("===== number of Active : ", str(numActive)));
        }

        private static Object getNumActive(Object basicDataSource, Field poolField) {
                Object pool = get(poolField, basicDataSource);
                Field numActiveField = field(classOf(pool), "_numActive");
                Object numActive = get(numActiveField, pool);
                return numActive;
        }

}