[MRESOLVER-450] Enhance RepositoryCache

maven-resolver-api/src/main/java/org/eclipse/aether/DefaultRepositoryCache.java

@@ -18,16 +18,16 @@
  */
 package org.eclipse.aether;
 
-import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Supplier;
 
 /**
  * A simplistic repository cache backed by a thread-safe map. The simplistic nature of this cache makes it only suitable
  * for use with short-lived repository system sessions where pruning of cache data is not required.
  */
 public final class DefaultRepositoryCache implements RepositoryCache {
 
-    private final Map<Object, Object> cache = new ConcurrentHashMap<>(256);
+    private final ConcurrentHashMap<Object, Object> cache = new ConcurrentHashMap<>(256);
 
     public Object get(RepositorySystemSession session, Object key) {
         return cache.get(key);
@@ -40,4 +40,9 @@ public void put(RepositorySystemSession session, Object key, Object data) {
             cache.remove(key);
         }
     }
+
+    @Override
+    public Object computeIfAbsent(RepositorySystemSession session, Object key, Supplier<Object> supplier) {
+        return cache.computeIfAbsent(key, k -> supplier.get());
+    }
 }

maven-resolver-api/src/main/java/org/eclipse/aether/RepositoryCache.java

@@ -18,12 +18,16 @@
  */
 package org.eclipse.aether;
 
+import java.util.function.Supplier;
+
 /**
  * Caches auxiliary data used during repository access like already processed metadata. The data in the cache is meant
  * for exclusive consumption by the repository system and is opaque to the cache implementation. <strong>Note:</strong>
  * Actual cache implementations must be thread-safe.
  *
  * @see RepositorySystemSession#getCache()
+ * @noimplement This interface is not intended to be implemented by clients.
+ * @noextend This interface is not intended to be extended by clients.
  */
 public interface RepositoryCache {
 
@@ -53,4 +57,14 @@ public interface RepositoryCache {
      * @return The requested data or {@code null} if none was present in the cache.
      */
     Object get(RepositorySystemSession session, Object key);
+
+    /**
+     * Retrieve or compute the data associated with the specified key.
+     *
+     * @param key The key for which to retrieve the session data, must not be {@code null}.
+     * @param supplier The supplier will compute the new value, must not be {@code null}.
+     * @return The cache data associated with the key.
+     * @since 2.0.0
+     */
+    Object computeIfAbsent(RepositorySystemSession session, Object key, Supplier<Object> supplier);
 }

pom.xml

@@ -299,6 +299,7 @@
               <configuration>
                 <parameter>
                   <excludes>
+                    <exclude>org.eclipse.aether.RepositoryCache</exclude>
                     <exclude>org.eclipse.aether.RepositoryListener</exclude>
                     <exclude>org.eclipse.aether.RepositorySystem</exclude>
                     <exclude>org.eclipse.aether.RepositorySystemSession</exclude>