From a39babaf4dcc2f690f65907adf92963d2308b65b Mon Sep 17 00:00:00 2001
From: Ajay Kumar Movva <movvaam@amazon.com>
Date: Mon, 4 Mar 2024 14:07:52 +0530
Subject: [PATCH] Enable IO Usage Tracker For Linux OS

Signed-off-by: Ajay Kumar Movva <movvaam@amazon.com>
---
 .../java/org/opensearch/node/IoUsageStats.java |  2 +-
 .../tracker/AverageIoUsageTracker.java         | 18 +++++++++++-------
 .../org/opensearch/node/IoUsageStatsTests.java |  4 ++--
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/server/src/main/java/org/opensearch/node/IoUsageStats.java b/server/src/main/java/org/opensearch/node/IoUsageStats.java
index 75cd93981f04d..ecb1ac1bb1de4 100644
--- a/server/src/main/java/org/opensearch/node/IoUsageStats.java
+++ b/server/src/main/java/org/opensearch/node/IoUsageStats.java
@@ -58,7 +58,7 @@ public void setIoUtilisationPercent(double ioUtilisationPercent) {
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject();
-        builder.field("io_utilization_percent", String.format(Locale.ROOT, "%.1f", this.ioUtilisationPercent));
+        builder.field("max_io_utilization_percent", String.format(Locale.ROOT, "%.1f", this.ioUtilisationPercent));
         return builder.endObject();
     }
 
diff --git a/server/src/main/java/org/opensearch/node/resource/tracker/AverageIoUsageTracker.java b/server/src/main/java/org/opensearch/node/resource/tracker/AverageIoUsageTracker.java
index 97df9e6511596..101f60f36c346 100644
--- a/server/src/main/java/org/opensearch/node/resource/tracker/AverageIoUsageTracker.java
+++ b/server/src/main/java/org/opensearch/node/resource/tracker/AverageIoUsageTracker.java
@@ -10,6 +10,7 @@
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.apache.lucene.util.Constants;
 import org.opensearch.common.unit.TimeValue;
 import org.opensearch.monitor.fs.FsInfo.DeviceStats;
 import org.opensearch.monitor.fs.FsService;
@@ -28,14 +29,14 @@ public class AverageIoUsageTracker extends AbstractAverageUsageTracker {
     private final FsService fsService;
     private final HashMap<String, Long> prevIoTimeDeviceMap;
     private long prevTimeInMillis;
-    private final IoUsageStats ioUsageStats;
+    private IoUsageStats ioUsageStats;
 
     public AverageIoUsageTracker(FsService fsService, ThreadPool threadPool, TimeValue pollingInterval, TimeValue windowDuration) {
         super(threadPool, pollingInterval, windowDuration);
         this.fsService = fsService;
         this.prevIoTimeDeviceMap = new HashMap<>();
         this.prevTimeInMillis = -1;
-        this.ioUsageStats = new IoUsageStats(-1);
+        this.ioUsageStats = null;
     }
 
     /**
@@ -67,11 +68,14 @@ public long getUsage() {
 
     @Override
     protected void doStart() {
-        scheduledFuture = threadPool.scheduleWithFixedDelay(() -> {
-            long usage = getUsage();
-            recordUsage(usage);
-            updateIoUsageStats();
-        }, pollingInterval, ThreadPool.Names.GENERIC);
+        if (Constants.LINUX) {
+            this.ioUsageStats = new IoUsageStats(-1);
+            scheduledFuture = threadPool.scheduleWithFixedDelay(() -> {
+                long usage = getUsage();
+                recordUsage(usage);
+                updateIoUsageStats();
+            }, pollingInterval, ThreadPool.Names.GENERIC);
+        }
     }
 
     private boolean preValidateFsStats() {
diff --git a/server/src/test/java/org/opensearch/node/IoUsageStatsTests.java b/server/src/test/java/org/opensearch/node/IoUsageStatsTests.java
index 30681df0361fb..4a4de44e3acea 100644
--- a/server/src/test/java/org/opensearch/node/IoUsageStatsTests.java
+++ b/server/src/test/java/org/opensearch/node/IoUsageStatsTests.java
@@ -39,12 +39,12 @@ public void testIoUsageStats() throws IOException {
         XContentBuilder builder = JsonXContent.contentBuilder();
         builder = ioUsageStats.toXContent(builder, ToXContent.EMPTY_PARAMS);
         String response = builder.toString();
-        assertEquals(response, "{\"io_utilization_percent\":\"10.0\"}");
+        assertEquals(response, "{\"max_io_utilization_percent\":\"10.0\"}");
         ioUsageStats.setIoUtilisationPercent(20);
         builder = JsonXContent.contentBuilder();
         builder = ioUsageStats.toXContent(builder, ToXContent.EMPTY_PARAMS);
         response = builder.toString();
-        assertEquals(response, "{\"io_utilization_percent\":\"20.0\"}");
+        assertEquals(response, "{\"max_io_utilization_percent\":\"20.0\"}");
     }
 
     public void testIoUsageStatsToString() {