From c4b58f26f43f3767633d9c06c9a65d6549093e35 Mon Sep 17 00:00:00 2001
From: Alexey Noskov <alexey.noskov@gmail.com>
Date: Sat, 26 Sep 2015 18:03:15 +0300
Subject: ! system-metrics: Fix heap metrics update

Don't store reference to MemoryUsage object: it's immutable, instead store function extracting it from MemoryMXBean
---
 .../main/scala/kamon/system/jmx/MemoryUsageMetrics.scala | 16 ++++++++--------
 .../src/test/scala/kamon/metrics/SystemMetricsSpec.scala | 14 ++++++++++++++
 2 files changed, 22 insertions(+), 8 deletions(-)

(limited to 'kamon-system-metrics')

diff --git a/kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryUsageMetrics.scala b/kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryUsageMetrics.scala
index ef9d47a6..41681459 100644
--- a/kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryUsageMetrics.scala
+++ b/kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryUsageMetrics.scala
@@ -32,13 +32,13 @@ import scala.collection.convert.WrapAsScala
 class MemoryUsageMetrics(instrumentFactory: InstrumentFactory,
     beansWithNames: Iterable[MemoryUsageWithMetricName]) extends GenericEntityRecorder(instrumentFactory) {
   beansWithNames.foreach {
-    case MemoryUsageWithMetricName(name, bean) ⇒
+    case MemoryUsageWithMetricName(name, beanFun) ⇒
       gauge(name + "-used", Memory.Bytes, () ⇒ {
-        bean.getUsed
+        beanFun().getUsed
       })
 
       gauge(name + "-max", Memory.Bytes, () ⇒ {
-        val max = bean.getMax
+        val max = beanFun().getMax
 
         // .getMax can return -1 if the max is not defined.
         if (max >= 0) max
@@ -46,7 +46,7 @@ class MemoryUsageMetrics(instrumentFactory: InstrumentFactory,
       })
 
       gauge(name + "-committed", Memory.Bytes, () ⇒ {
-        bean.getCommitted
+        beanFun().getCommitted
       })
   }
 }
@@ -54,9 +54,9 @@ class MemoryUsageMetrics(instrumentFactory: InstrumentFactory,
 /**
  * Objects of this kind may be passed to instances of [[MemoryUsageMetrics]] for data collection.
  * @param metricName The sanitized name for a metric.
- * @param bean The data source for metrics.
+ * @param beanFun Function returning the data source for metrics.
  */
-private[jmx] final case class MemoryUsageWithMetricName(metricName: String, bean: MemoryUsage)
+private[jmx] final case class MemoryUsageWithMetricName(metricName: String, beanFun: () ⇒ MemoryUsage)
 
 /**
  *  Memory Pool metrics, as reported by JMX:
@@ -79,7 +79,7 @@ object MemoryUsageMetrics extends JmxSystemMetricRecorderCompanion("jmx-memory")
 
   def apply(instrumentFactory: InstrumentFactory): MemoryUsageMetrics =
     new MemoryUsageMetrics(instrumentFactory,
-      MemoryUsageWithMetricName("non-heap", memoryMXBean.getNonHeapMemoryUsage) ::
-        MemoryUsageWithMetricName("heap", memoryMXBean.getHeapMemoryUsage) ::
+      MemoryUsageWithMetricName("non-heap", () ⇒ memoryMXBean.getNonHeapMemoryUsage) ::
+        MemoryUsageWithMetricName("heap", () ⇒ memoryMXBean.getHeapMemoryUsage) ::
         usagesWithNames)
 }
diff --git a/kamon-system-metrics/src/test/scala/kamon/metrics/SystemMetricsSpec.scala b/kamon-system-metrics/src/test/scala/kamon/metrics/SystemMetricsSpec.scala
index 7af704d5..452ee0c7 100644
--- a/kamon-system-metrics/src/test/scala/kamon/metrics/SystemMetricsSpec.scala
+++ b/kamon-system-metrics/src/test/scala/kamon/metrics/SystemMetricsSpec.scala
@@ -74,6 +74,20 @@ class SystemMetricsSpec extends BaseKamonSpec("system-metrics-spec") with Redire
       memoryMetrics.gauge("non-heap-committed").get.numberOfMeasurements should be > 0L
     }
 
+    "record correctly updatable values for heap metrics" in {
+      Thread.sleep(3000)
+
+      val data = new Array[Byte](20 * 1024 * 1024) // 20 Mb of data
+
+      Thread.sleep(3000)
+
+      val memoryMetrics = takeSnapshotOf("jmx-memory", "system-metric")
+      val heapUsed = memoryMetrics.gauge("heap-used").get
+
+      heapUsed.max should be > heapUsed.min
+      data.size should be > 0 // Just for data usage
+    }
+
     "record daemon, count and peak jvm threads metrics" in {
       val threadsMetrics = takeSnapshotOf("threads", "system-metric")
 
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