From 3f6629fae8f41fdf8c24b6ddd752b8cae7f74a74 Mon Sep 17 00:00:00 2001
From: Xiaodan <xsun@netflix.com>
Date: Tue, 23 Jul 2024 14:33:17 -0700
Subject: [PATCH] add cycle start time and end time to consumer metrics

---
 .../api/client/HollowClientUpdater.java       |  3 +++
 .../api/metrics/HollowConsumerMetrics.java    | 22 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/hollow/src/main/java/com/netflix/hollow/api/client/HollowClientUpdater.java b/hollow/src/main/java/com/netflix/hollow/api/client/HollowClientUpdater.java
index c70ce519d9..82590dd3f4 100644
--- a/hollow/src/main/java/com/netflix/hollow/api/client/HollowClientUpdater.java
+++ b/hollow/src/main/java/com/netflix/hollow/api/client/HollowClientUpdater.java
@@ -117,6 +117,7 @@ public synchronized boolean updateTo(long requestedVersion) throws Throwable {
         return updateTo(new HollowConsumer.VersionInfo(requestedVersion));
     }
     public synchronized boolean updateTo(HollowConsumer.VersionInfo requestedVersionInfo) throws Throwable {
+        metrics.setLastRefreshStartNs(System.nanoTime());
         long requestedVersion = requestedVersionInfo.getVersion();
         if (requestedVersion == getCurrentVersionId()) {
             if (requestedVersion == HollowConstants.VERSION_NONE && hollowDataHolderVolatile == null) {
@@ -205,6 +206,7 @@ public synchronized boolean updateTo(HollowConsumer.VersionInfo requestedVersion
                 metricsCollector.collect(metrics);
 
             initialLoad.complete(getCurrentVersionId()); // only set the first time
+            metrics.setLastRefreshEndNs(System.nanoTime());
             return getCurrentVersionId() == requestedVersion;
         } catch(Throwable th) {
             forceDoubleSnapshotNextUpdate();
@@ -216,6 +218,7 @@ public synchronized boolean updateTo(HollowConsumer.VersionInfo requestedVersion
 
             // intentionally omitting a call to initialLoad.completeExceptionally(th), for producers
             // that write often a consumer has a chance to try another snapshot that might succeed
+            metrics.setLastRefreshEndNs(System.nanoTime());
 
             throw th;
         }
diff --git a/hollow/src/main/java/com/netflix/hollow/api/metrics/HollowConsumerMetrics.java b/hollow/src/main/java/com/netflix/hollow/api/metrics/HollowConsumerMetrics.java
index 4cc2cb1da0..e63d993636 100644
--- a/hollow/src/main/java/com/netflix/hollow/api/metrics/HollowConsumerMetrics.java
+++ b/hollow/src/main/java/com/netflix/hollow/api/metrics/HollowConsumerMetrics.java
@@ -18,9 +18,31 @@
 
 import com.netflix.hollow.core.read.engine.HollowReadStateEngine;
 
+import java.util.concurrent.atomic.AtomicLong;
+
 public class HollowConsumerMetrics extends HollowMetrics {
     private int refreshFailed;      // TODO: Move these metrics over to com.netflix.hollow.api.consumer.metrics.AbstractRefreshMetricsListener
     private int refreshSucceeded;
+    private final AtomicLong lastRefreshStartNs = new AtomicLong(); //last time a refresh started
+    private final AtomicLong lastRefreshEndNs = new AtomicLong();
+
+    public void setLastRefreshStartNs(long startNs) {
+        lastRefreshStartNs.set(startNs);
+    }
+
+    public AtomicLong getLastRefreshStartNs() {
+        return lastRefreshStartNs;
+    }
+
+    public void setLastRefreshEndNs(long endNs) {
+        lastRefreshEndNs.set(endNs);
+    }
+
+    public AtomicLong getLastRefreshEndNs() {
+       return lastRefreshEndNs;
+    }
+
+
 
     /**
      * Updates the consumer metrics: