review

versioned/storage/cache/src/main/java/org/projectnessie/versioned/storage/cache/CacheBackend.java

@@ -31,14 +31,35 @@
  * repositories. It is adviseable to have one {@link CacheBackend} per {@link Backend}.
  */
 public interface CacheBackend {
+  /**
+   * Special sentinel reference instance to indicate that a referenc object has been marked as "not
+   * found". This object is only for cache-internal purposes.
+   */
   Reference NON_EXISTENT_REFERENCE_SENTINEL =
       reference("NON_EXISTENT", zeroLengthObjId(), false, -1L, null);
 
+  /**
+   * Special sentinel object instance to indicate that an object has been marked as "not found".
+   * This object is only for cache-internal purposes.
+   */
+  Obj NOT_FOUND_OBJ_SENTINEL =
+      new Obj() {
+        @Override
+        public ObjType type() {
+          throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public ObjId id() {
+          throw new UnsupportedOperationException();
+        }
+      };
+
   /**
    * Returns the {@link Obj} for the given {@link ObjId id}.
    *
    * @return One of these alternatives: the cached object if present, the {@link
-   *     ObjCache#NOT_FOUND_OBJ_SENTINEL} indicating that the object does <em>not</em> exist as
+   *     CacheBackend#NOT_FOUND_OBJ_SENTINEL} indicating that the object does <em>not</em> exist as
    *     previously marked via {@link #putNegative(String, ObjId, ObjType)}, or {@code null}.
    */
   Obj get(@Nonnull String repositoryId, @Nonnull ObjId id);
@@ -79,7 +100,7 @@ public interface CacheBackend {
    */
   void putReferenceLocal(@Nonnull String repositoryId, @Nonnull Reference r);
 
-  void putNegative(@Nonnull String repositoryId, @Nonnull String name);
+  void putReferenceNegative(@Nonnull String repositoryId, @Nonnull String name);
 
   static CacheBackend noopCacheBackend() {
     return NoopCacheBackend.INSTANCE;

versioned/storage/cache/src/main/java/org/projectnessie/versioned/storage/cache/CachingPersistImpl.java

@@ -16,7 +16,7 @@
 package org.projectnessie.versioned.storage.cache;
 
 import static org.projectnessie.versioned.storage.cache.CacheBackend.NON_EXISTENT_REFERENCE_SENTINEL;
-import static org.projectnessie.versioned.storage.cache.ObjCache.NOT_FOUND_OBJ_SENTINEL;
+import static org.projectnessie.versioned.storage.cache.CacheBackend.NOT_FOUND_OBJ_SENTINEL;
 
 import jakarta.annotation.Nonnull;
 import java.util.Set;
@@ -90,7 +90,7 @@ public <T extends Obj> T fetchTypedObj(
         o = persist.fetchTypedObj(id, type, typeClass);
         cache.putLocal(o);
       } catch (ObjNotFoundException e) {
-        cache.putNegative(id, type);
+        cache.putReferenceNegative(id, type);
         throw e;
       }
     }
@@ -164,7 +164,7 @@ private <T extends Obj> T[] fetchObjsPost(
           r[i] = o;
           cache.putLocal(o);
         } else {
-          cache.putNegative(id, type);
+          cache.putReferenceNegative(id, type);
         }
       }
     }
@@ -398,7 +398,7 @@ private Reference fetchReferenceInternal(@Nonnull String name, boolean bypassCac
     if (r == null) {
       r = persist.fetchReferenceForUpdate(name);
       if (r == null) {
-        cache.putNegative(name);
+        cache.putReferenceNegative(name);
       } else {
         cache.putReferenceLocal(r);
       }
@@ -453,7 +453,7 @@ private Reference[] fetchReferencesInternal(@Nonnull String[] names, boolean byp
             r[i] = ref;
             cache.putReferenceLocal(ref);
           } else {
-            cache.putNegative(name);
+            cache.putReferenceNegative(name);
           }
         }
       }

versioned/storage/cache/src/main/java/org/projectnessie/versioned/storage/cache/CaffeineCacheBackend.java

@@ -19,7 +19,6 @@
 import static java.util.Collections.singletonList;
 import static java.util.concurrent.TimeUnit.MICROSECONDS;
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
-import static org.projectnessie.versioned.storage.cache.ObjCache.NOT_FOUND_OBJ_SENTINEL;
 import static org.projectnessie.versioned.storage.common.persist.ObjType.CACHE_UNLIMITED;
 import static org.projectnessie.versioned.storage.common.persist.ObjType.NOT_CACHED;
 import static org.projectnessie.versioned.storage.serialize.ProtoSerialization.deserializeReference;
@@ -227,7 +226,7 @@ public void putReferenceLocal(@Nonnull String repositoryId, @Nonnull Reference r
   }
 
   @Override
-  public void putNegative(@Nonnull String repositoryId, @Nonnull String name) {
+  public void putReferenceNegative(@Nonnull String repositoryId, @Nonnull String name) {
     if (refCacheNegativeTtlNanos <= 0L) {
       return;
     }

versioned/storage/cache/src/main/java/org/projectnessie/versioned/storage/cache/DistributedInvalidationsCacheBackend.java

@@ -113,7 +113,7 @@ public void putReference(@Nonnull String repositoryId, @Nonnull Reference r) {
   }
 
   @Override
-  public void putNegative(@Nonnull String repositoryId, @Nonnull String name) {
-    local.putNegative(repositoryId, name);
+  public void putReferenceNegative(@Nonnull String repositoryId, @Nonnull String name) {
+    local.putReferenceNegative(repositoryId, name);
   }
 }

versioned/storage/cache/src/main/java/org/projectnessie/versioned/storage/cache/NoopCacheBackend.java

@@ -34,7 +34,7 @@ public Persist wrap(@Nonnull Persist perist) {
   }
 
   @Override
-  public void putNegative(@Nonnull String repositoryId, @Nonnull String name) {}
+  public void putReferenceNegative(@Nonnull String repositoryId, @Nonnull String name) {}
 
   @Override
   public void putReference(@Nonnull String repositoryId, @Nonnull Reference r) {}

versioned/storage/cache/src/main/java/org/projectnessie/versioned/storage/cache/ObjCache.java

@@ -29,8 +29,8 @@ public interface ObjCache {
    * Returns the {@link Obj} for the given {@link ObjId id}.
    *
    * @return One of these alternatives: the cached object if present, the {@link
-   *     #NOT_FOUND_OBJ_SENTINEL} indicating that the object does <em>not</em> exist as previously
-   *     marked via {@link #putNegative(ObjId, ObjType)}, or {@code null}.
+   *     CacheBackend#NOT_FOUND_OBJ_SENTINEL} indicating that the object does <em>not</em> exist as
+   *     previously marked via {@link #putReferenceNegative(ObjId, ObjType)}, or {@code null}.
    */
   Obj get(@Nonnull ObjId id);
 
@@ -47,7 +47,7 @@ public interface ObjCache {
    * Record the "not found" sentinel for the given {@link ObjId id} and {@link ObjType type}.
    * Behaves like {@link #remove(ObjId)}, if {@code type} is {@code null}.
    */
-  void putNegative(ObjId id, ObjType type);
+  void putReferenceNegative(ObjId id, ObjType type);
 
   void remove(@Nonnull ObjId id);
 
@@ -68,23 +68,5 @@ public interface ObjCache {
    */
   void putReferenceLocal(@Nonnull Reference r);
 
-  void putNegative(@Nonnull String name);
-
-  /**
-   * Special sentinel object instance to indicate that an object has been marked as "not found" via
-   * {@link #putNegative(ObjId, ObjType)}, returned from {@link #get(ObjId)}. This object is only
-   * for cache-internal purposes.
-   */
-  Obj NOT_FOUND_OBJ_SENTINEL =
-      new Obj() {
-        @Override
-        public ObjType type() {
-          throw new UnsupportedOperationException();
-        }
-
-        @Override
-        public ObjId id() {
-          throw new UnsupportedOperationException();
-        }
-      };
+  void putReferenceNegative(@Nonnull String name);
 }

versioned/storage/cache/src/main/java/org/projectnessie/versioned/storage/cache/ObjCacheImpl.java

@@ -47,7 +47,7 @@ public void putLocal(@Nonnull Obj obj) {
   }
 
   @Override
-  public void putNegative(ObjId id, ObjType type) {
+  public void putReferenceNegative(ObjId id, ObjType type) {
     if (type != null) {
       backend.putNegative(repositoryId, id, type);
     } else {
@@ -86,7 +86,7 @@ public Reference getReference(@Nonnull String name) {
   }
 
   @Override
-  public void putNegative(@Nonnull String name) {
-    backend.putNegative(repositoryId, name);
+  public void putReferenceNegative(@Nonnull String name) {
+    backend.putReferenceNegative(repositoryId, name);
   }
 }