From 60bf4e92ffddc4deb1c108482af8407d4e5acfa0 Mon Sep 17 00:00:00 2001
From: Oliver Drotbohm <odrotbohm@pivotal.io>
Date: Wed, 20 Jan 2021 20:30:30 +0100
Subject: [PATCH] #1405 - Use ConcurrentLruCache for affordances.

We now use a ConcurrentLruCache limited to 256 entries instead of a ConcurrentReferenceHashMap to cache Affordance instances to prevent the cache from growing unboundedly before GC kicks in.
---
 .../hateoas/server/core/WebHandler.java                | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/main/java/org/springframework/hateoas/server/core/WebHandler.java b/src/main/java/org/springframework/hateoas/server/core/WebHandler.java
index 79c7791c..adec03b2 100644
--- a/src/main/java/org/springframework/hateoas/server/core/WebHandler.java
+++ b/src/main/java/org/springframework/hateoas/server/core/WebHandler.java
@@ -38,7 +38,7 @@ import org.springframework.hateoas.TemplateVariables;
 import org.springframework.hateoas.server.LinkBuilder;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
-import org.springframework.util.ConcurrentReferenceHashMap;
+import org.springframework.util.ConcurrentLruCache;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.ObjectUtils;
@@ -63,7 +63,8 @@ public class WebHandler {
 	public static final MappingDiscoverer DISCOVERER = CachingMappingDiscoverer
 			.of(new PropertyResolvingMappingDiscoverer(new AnnotationMappingDiscoverer(RequestMapping.class)));
 
-	private static final Map<AffordanceKey, List<Affordance>> AFFORDANCES_CACHE = new ConcurrentReferenceHashMap<>();
+	private static final ConcurrentLruCache<AffordanceKey, List<Affordance>> AFFORDANCES_CACHE = new ConcurrentLruCache<>(
+			256, key -> SpringAffordanceBuilder.create(key.type, key.method, key.href.toUriString(), DISCOVERER));
 
 	public interface LinkBuilderCreator<T extends LinkBuilder> {
 		T createBuilder(UriComponents components, TemplateVariables variables, List<Affordance> affordances);
@@ -160,9 +161,8 @@ public class WebHandler {
 				variables = variables.concat(variable);
 			}
 
-			List<Affordance> affordances = AFFORDANCES_CACHE.computeIfAbsent(
-					new AffordanceKey(invocation.getTargetType(), invocation.getMethod(), components),
-					key -> SpringAffordanceBuilder.create(key.type, key.method, key.href.toUriString(), DISCOVERER));
+			List<Affordance> affordances = AFFORDANCES_CACHE
+					.get(new AffordanceKey(invocation.getTargetType(), invocation.getMethod(), components));
 
 			return creator.createBuilder(components, variables, affordances);
 		};