From efc101be12387868566faf4c11dbfc87938f17c0 Mon Sep 17 00:00:00 2001
From: Ferenc Toth <feri@gawker.com>
Date: Thu, 20 Aug 2015 09:41:53 +0200
Subject: + system-metrics: Add memory pool metrics

---
 .../kamon/system/SystemMetricsExtension.scala      |  1 +
 .../scala/kamon/system/jmx/MemoryPoolMetrics.scala | 80 ++++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100644 kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryPoolMetrics.scala

diff --git a/kamon-system-metrics/src/main/scala/kamon/system/SystemMetricsExtension.scala b/kamon-system-metrics/src/main/scala/kamon/system/SystemMetricsExtension.scala
index 3f67b518..9d2a5b94 100644
--- a/kamon-system-metrics/src/main/scala/kamon/system/SystemMetricsExtension.scala
+++ b/kamon-system-metrics/src/main/scala/kamon/system/SystemMetricsExtension.scala
@@ -55,6 +55,7 @@ class SystemMetricsExtension(system: ExtendedActorSystem) extends Kamon.Extensio
 
   // JMX Metrics
   if (jmxEnabled) {
+    MemoryPoolMetrics.register(metricsExtension)
     ClassLoadingMetrics.register(metricsExtension)
     GarbageCollectionMetrics.register(metricsExtension)
     HeapMemoryMetrics.register(metricsExtension)
diff --git a/kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryPoolMetrics.scala b/kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryPoolMetrics.scala
new file mode 100644
index 00000000..8c2d2293
--- /dev/null
+++ b/kamon-system-metrics/src/main/scala/kamon/system/jmx/MemoryPoolMetrics.scala
@@ -0,0 +1,80 @@
+/*
+ * =========================================================================================
+ * Copyright © 2013-2015 the kamon project <http://kamon.io/>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ * =========================================================================================
+ */
+
+package kamon.system.jmx
+
+import java.lang.management.{ ManagementFactory, MemoryPoolMXBean }
+
+import kamon.metric.GenericEntityRecorder
+import kamon.metric.instrument.{ InstrumentFactory, Memory }
+
+import scala.collection.convert.WrapAsScala
+
+/**
+ * Generic memory pool stat recorder.
+ * Records the amount of used, max, and committed memory in bytes for each passed MemoryPoolMXBean.
+ * @param instrumentFactory Helpers for metric recording.
+ * @param beansWithNames Data sources with metric name prefixes.
+ */
+class MemoryPoolMetrics(instrumentFactory: InstrumentFactory,
+    beansWithNames: Iterable[MemoryBeanWithMetricName]) extends GenericEntityRecorder(instrumentFactory) {
+  beansWithNames.foreach {
+    case MemoryBeanWithMetricName(name, bean) ⇒
+      gauge(name + "-used", Memory.Bytes, () ⇒ {
+        bean.getUsage.getUsed
+      })
+
+      gauge(name + "-max", Memory.Bytes, () ⇒ {
+        val max = bean.getUsage.getMax
+
+        // .getMax can return -1 if the max is not defined.
+        if (max >= 0) max
+        else 0
+      })
+
+      gauge(name + "-committed", Memory.Bytes, () ⇒ {
+        bean.getUsage.getCommitted
+      })
+  }
+}
+
+/**
+ * Objects of this kind may be passed to [[MemoryPoolMetrics]] for data collection.
+ * @param metricName The sanitized name of a [[MemoryPoolMXBean]].
+ * @param bean The data source for metrics.
+ */
+private[jmx] final case class MemoryBeanWithMetricName(metricName: String, bean: MemoryPoolMXBean)
+
+/**
+ *  Memory Pool metrics, as reported by JMX:
+ *    - @see [[http://docs.oracle.com/javase/7/docs/api/java/lang/management/MemoryMXBean.html "MemoryMXBean"]]
+ *  Pools in HotSpot Java 8:
+ *  code-cache, metaspace, compressed-class-space, ps-eden-space, ps-survivor-space, ps-old-gen
+ */
+object MemoryPoolMetrics extends JmxSystemMetricRecorderCompanion("memory-pool") with WrapAsScala {
+
+  private val invalidChars = """[^a-z0-9]""".r
+
+  private def sanitizedName(memoryPoolMXBean: MemoryPoolMXBean) =
+    invalidChars.replaceAllIn(memoryPoolMXBean.getName.toLowerCase, "-")
+
+  private val beansWithNames = ManagementFactory.getMemoryPoolMXBeans.toIterable.map { bean ⇒
+    MemoryBeanWithMetricName(sanitizedName(bean), bean)
+  }
+
+  def apply(instrumentFactory: InstrumentFactory): MemoryPoolMetrics =
+    new MemoryPoolMetrics(instrumentFactory, beansWithNames)
+}
-- 
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