From b3d31dd28979cd27652f7cc73cbd0fc9d653cb83 Mon Sep 17 00:00:00 2001
From: Ryan Fu <rfu+1@linkedin.com>
Date: Fri, 30 Aug 2024 17:59:11 -0700
Subject: [PATCH] Memoize toString() for MetricKey and MetricName (#32379)

(cherry picked from commit 64b4aa6fdde6a65b8157578036374623a47c18c2)
---
 .../src/main/java/org/apache/beam/sdk/metrics/MetricKey.java  | 4 +++-
 .../src/main/java/org/apache/beam/sdk/metrics/MetricName.java | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricKey.java b/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricKey.java
index e7dcebd14833..05f1d736d8a5 100644
--- a/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricKey.java
+++ b/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricKey.java
@@ -18,6 +18,7 @@
 package org.apache.beam.sdk.metrics;
 
 import com.google.auto.value.AutoValue;
+import com.google.auto.value.extension.memoized.Memoized;
 import java.io.Serializable;
 import org.apache.beam.sdk.annotations.Experimental;
 import org.apache.beam.sdk.annotations.Experimental.Kind;
@@ -35,7 +36,8 @@ public abstract class MetricKey implements Serializable {
   public abstract MetricName metricName();
 
   @Override
-  public final String toString() {
+  @Memoized
+  public String toString() {
     return stepName() + ":" + metricName();
   }
 
diff --git a/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricName.java b/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricName.java
index 329e44a5d714..258aa4827c50 100644
--- a/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricName.java
+++ b/sdks/java/core/src/main/java/org/apache/beam/sdk/metrics/MetricName.java
@@ -20,6 +20,7 @@
 import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkArgument;
 
 import com.google.auto.value.AutoValue;
+import com.google.auto.value.extension.memoized.Memoized;
 import java.io.Serializable;
 import org.apache.beam.sdk.annotations.Experimental;
 import org.apache.beam.sdk.annotations.Experimental.Kind;
@@ -42,6 +43,7 @@ public abstract class MetricName implements Serializable {
   public abstract String getName();
 
   @Override
+  @Memoized
   public String toString() {
     return getNamespace() + ":" + getName();
   }