From 6646be8d946e4640628071e16426516a9b3f90ac Mon Sep 17 00:00:00 2001
From: Jon Chambers <jon@signal.org>
Date: Mon, 10 Aug 2020 11:52:03 -0400
Subject: [PATCH] Make CpuUsageGauge a CachedGauge.

---
 .../textsecuregcm/WhisperServerService.java            |  3 ++-
 .../textsecuregcm/metrics/CpuUsageGauge.java           | 10 +++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
index 106fe7562..fd59249f9 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
@@ -171,6 +171,7 @@ import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.concurrent.TimeUnit;
 
 import static com.codahale.metrics.MetricRegistry.name;
 
@@ -484,7 +485,7 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
     environment.healthChecks().register("directory", new RedisHealthCheck(directoryClient));
     environment.healthChecks().register("cacheCluster", new RedisClusterHealthCheck(cacheCluster));
 
-    environment.metrics().register(name(CpuUsageGauge.class, "cpu"), new CpuUsageGauge());
+    environment.metrics().register(name(CpuUsageGauge.class, "cpu"), new CpuUsageGauge(3, TimeUnit.SECONDS));
     environment.metrics().register(name(FreeMemoryGauge.class, "free_memory"), new FreeMemoryGauge());
     environment.metrics().register(name(NetworkSentGauge.class, "bytes_sent"), new NetworkSentGauge());
     environment.metrics().register(name(NetworkReceivedGauge.class, "bytes_received"), new NetworkReceivedGauge());
diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/metrics/CpuUsageGauge.java b/service/src/main/java/org/whispersystems/textsecuregcm/metrics/CpuUsageGauge.java
index 3deb90b86..0074a2509 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/metrics/CpuUsageGauge.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/metrics/CpuUsageGauge.java
@@ -1,21 +1,25 @@
 package org.whispersystems.textsecuregcm.metrics;
 
+import com.codahale.metrics.CachedGauge;
 import com.codahale.metrics.Gauge;
 import com.sun.management.OperatingSystemMXBean;
 
 import java.lang.management.ManagementFactory;
+import java.util.concurrent.TimeUnit;
 
-public class CpuUsageGauge implements Gauge<Integer> {
+public class CpuUsageGauge extends CachedGauge<Integer> {
 
   private final OperatingSystemMXBean operatingSystemMXBean;
 
-  public CpuUsageGauge() {
+  public CpuUsageGauge(final long timeout, final TimeUnit timeoutUnit) {
+    super(timeout, timeoutUnit);
+
     this.operatingSystemMXBean = (com.sun.management.OperatingSystemMXBean)
             ManagementFactory.getOperatingSystemMXBean();
   }
 
   @Override
-  public Integer getValue() {
+  protected Integer loadValue() {
     return (int) Math.ceil(operatingSystemMXBean.getSystemCpuLoad() * 100);
   }
 }