Remove twice add Source bug and code clean

core/src/main/scala/spark/metrics/MetricsSystem.scala

 package spark.metrics
 
-import scala.collection.mutable
-
 import com.codahale.metrics.{JmxReporter, MetricSet, MetricRegistry}
 
 import java.util.Properties
 import java.util.concurrent.TimeUnit
 
+import scala.collection.mutable
+
 import spark.Logging
-import spark.metrics.sink._
-import spark.metrics.source._
+import spark.metrics.sink.Sink
+import spark.metrics.source.Source
 
 private[spark] class MetricsSystem private (val instance: String) extends Logging {
   initLogging()
@@ -46,7 +46,6 @@ private[spark] class MetricsSystem private (val instance: String) extends Loggin
       val classPath = kv._2.getProperty("class")
       try {
         val source = Class.forName(classPath).newInstance()
-        sources += source.asInstanceOf[Source]
         registerSource(source.asInstanceOf[Source])
       } catch {
         case e: Exception => logError("source class " + classPath + " cannot be instantialized", e)
@@ -58,7 +57,6 @@ private[spark] class MetricsSystem private (val instance: String) extends Loggin
     val instConfig = metricsConfig.getInstance(instance)
     val sinkConfigs = MetricsConfig.subProperties(instConfig, MetricsSystem.SINK_REGEX)
     
-    // Register other sinks according to conf
     sinkConfigs.foreach { kv =>
       val classPath = if (MetricsSystem.DEFAULT_SINKS.contains(kv._1)) {
         MetricsSystem.DEFAULT_SINKS(kv._1)

core/src/main/scala/spark/metrics/source/JvmSource.scala

 package spark.metrics.source
 
-import java.util.{Map, HashMap => JHashMap}
-
 import com.codahale.metrics.MetricRegistry
 import com.codahale.metrics.jvm.{GarbageCollectorMetricSet, MemoryUsageGaugeSet}
 
+import java.util.{Map, HashMap => JHashMap}
+
 class JvmSource extends Source {
   val sourceName = "jvm"
   val metricRegistry = new MetricRegistry()
   
-    val gcMetricSet = new GarbageCollectorMetricSet
-    val memGaugeSet = new MemoryUsageGaugeSet
+  val gcMetricSet = new GarbageCollectorMetricSet
+  val memGaugeSet = new MemoryUsageGaugeSet
     
-    metricRegistry.registerAll(gcMetricSet)
-    metricRegistry.registerAll(memGaugeSet)
+  metricRegistry.registerAll(gcMetricSet)
+  metricRegistry.registerAll(memGaugeSet)
 }