From 7c893a79ac87ebf1e35a325282934b4efebb9275 Mon Sep 17 00:00:00 2001
From: Gavin King <gavin@hibernate.org>
Date: Thu, 25 Sep 2025 11:53:07 +0200
Subject: [PATCH] avoid unnecessarily holding onto Region in
 CacheRegionStatisticsImpl

---
 .../internal/CacheRegionStatisticsImpl.java   | 53 +++++++++++--------
 1 file changed, 31 insertions(+), 22 deletions(-)

diff --git a/hibernate-core/src/main/java/org/hibernate/stat/internal/CacheRegionStatisticsImpl.java b/hibernate-core/src/main/java/org/hibernate/stat/internal/CacheRegionStatisticsImpl.java
index e39fc0fd8d04..9f814ebcf119 100644
--- a/hibernate-core/src/main/java/org/hibernate/stat/internal/CacheRegionStatisticsImpl.java
+++ b/hibernate-core/src/main/java/org/hibernate/stat/internal/CacheRegionStatisticsImpl.java
@@ -7,6 +7,7 @@
 import java.io.Serializable;
 import java.util.concurrent.atomic.LongAdder;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.hibernate.cache.spi.ExtendedStatisticsSupport;
 import org.hibernate.cache.spi.Region;
 import org.hibernate.stat.CacheRegionStatistics;
@@ -17,7 +18,8 @@
  * @author Alex Snaps
  */
 public class CacheRegionStatisticsImpl implements CacheRegionStatistics, Serializable {
-	private final transient Region region;
+	private final String regionName;
+	private final transient @Nullable ExtendedStatisticsSupport extendedStatisticsSupport;
 
 	private final LongAdder hitCount = new LongAdder();
 	private final LongAdder missCount = new LongAdder();
@@ -25,12 +27,16 @@ public class CacheRegionStatisticsImpl implements CacheRegionStatistics, Seriali
 	private final LongAdder removeCount = new LongAdder();
 
 	CacheRegionStatisticsImpl(Region region) {
-		this.region = region;
+		regionName = region.getName();
+		extendedStatisticsSupport =
+				region instanceof ExtendedStatisticsSupport extended
+						? extended
+						: null;
 	}
 
 	@Override
 	public String getRegionName() {
-		return region.getName();
+		return regionName;
 	}
 
 	@Override
@@ -55,23 +61,23 @@ public long getRemoveCount() {
 
 	@Override
 	public long getElementCountInMemory() {
-		return region instanceof ExtendedStatisticsSupport extended
-				? extended.getElementCountInMemory()
-				: NO_EXTENDED_STAT_SUPPORT_RETURN;
+		return extendedStatisticsSupport == null
+				? NO_EXTENDED_STAT_SUPPORT_RETURN
+				: extendedStatisticsSupport.getElementCountInMemory();
 	}
 
 	@Override
 	public long getElementCountOnDisk() {
-		return region instanceof ExtendedStatisticsSupport extended
-				? extended.getElementCountOnDisk()
-				: NO_EXTENDED_STAT_SUPPORT_RETURN;
+		return extendedStatisticsSupport == null
+				? NO_EXTENDED_STAT_SUPPORT_RETURN
+				: extendedStatisticsSupport.getElementCountOnDisk();
 	}
 
 	@Override
 	public long getSizeInMemory() {
-		return region instanceof ExtendedStatisticsSupport extended
-				? extended.getSizeInMemory()
-				: NO_EXTENDED_STAT_SUPPORT_RETURN;
+		return extendedStatisticsSupport == null
+				? NO_EXTENDED_STAT_SUPPORT_RETURN
+				: extendedStatisticsSupport.getSizeInMemory();
 	}
 
 	void incrementHitCount() {
@@ -93,15 +99,18 @@ public void incrementRemoveCount() {
 
 	@Override
 	public String toString() {
-		return "CacheRegionStatistics"
-			+ "[region=" + region.getName()
-			+ ",hitCount=" + hitCount
-			+ ",missCount=" + missCount
-			+ ",putCount=" + putCount
-			+ ",removeCount=" + removeCount
-			+ ",elementCountInMemory=" + getElementCountInMemory()
-			+ ",elementCountOnDisk=" + getElementCountOnDisk()
-			+ ",sizeInMemory=" + getSizeInMemory()
-			+ ']';
+		final var string =
+				new StringBuilder("CacheRegionStatistics")
+						.append( "[region=" ).append( regionName )
+						.append( ",hitCount=" ).append( hitCount )
+						.append( ",missCount=" ).append( missCount )
+						.append( ",putCount=" ).append( putCount )
+						.append( ",removeCount=" ).append( removeCount );
+		if ( extendedStatisticsSupport != null ) {
+			string.append( ",elementCountInMemory=" ).append( getElementCountInMemory() )
+					.append( ",elementCountOnDisk=" ).append( getElementCountOnDisk() )
+					.append( ",sizeInMemory=" ).append( getSizeInMemory() );
+		}
+		return string.append( ']' ).toString();
 	}
 }