Renamed classes to make more sense, removed interface

Signed-off-by: Peter Alfonsi <petealft@amazon.com>

modules/cache-common/src/main/java/org/opensearch/cache/common/tier/TieredSpilloverCache.java

@@ -17,7 +17,7 @@
 import org.opensearch.common.cache.RemovalListener;
 import org.opensearch.common.cache.RemovalNotification;
 import org.opensearch.common.cache.policy.CachedQueryResult;
-import org.opensearch.common.cache.stats.CacheStats;
+import org.opensearch.common.cache.stats.ImmutableCacheStatsHolder;
 import org.opensearch.common.cache.store.config.CacheConfig;
 import org.opensearch.common.settings.Setting;
 import org.opensearch.common.settings.Settings;
@@ -195,7 +195,7 @@ public void close() throws IOException {
     }
 
     @Override
-    public CacheStats stats() {
+    public ImmutableCacheStatsHolder stats() {
         return null; // TODO: in TSC stats PR
     }
 

modules/cache-common/src/test/java/org/opensearch/cache/common/tier/MockDiskCache.java

@@ -16,7 +16,6 @@
 import org.opensearch.common.cache.RemovalNotification;
 import org.opensearch.common.cache.RemovalReason;
 import org.opensearch.common.cache.serializer.Serializer;
-import org.opensearch.common.cache.stats.CacheStats;
 import org.opensearch.common.cache.store.builders.ICacheBuilder;
 import org.opensearch.common.cache.store.config.CacheConfig;
 

plugins/cache-ehcache/src/main/java/org/opensearch/cache/store/disk/EhcacheDiskCache.java

@@ -24,8 +24,8 @@
 import org.opensearch.common.cache.RemovalReason;
 import org.opensearch.common.cache.serializer.ICacheKeySerializer;
 import org.opensearch.common.cache.serializer.Serializer;
-import org.opensearch.common.cache.stats.CacheStats;
-import org.opensearch.common.cache.stats.StatsHolder;
+import org.opensearch.common.cache.stats.CacheStatsHolder;
+import org.opensearch.common.cache.stats.ImmutableCacheStatsHolder;
 import org.opensearch.common.cache.store.builders.ICacheBuilder;
 import org.opensearch.common.cache.store.config.CacheConfig;
 import org.opensearch.common.collect.Tuple;
@@ -113,7 +113,7 @@ public class EhcacheDiskCache<K, V> implements ICache<K, V> {
     private final Class<K> keyType;
     private final Class<V> valueType;
     private final TimeValue expireAfterAccess;
-    private final StatsHolder statsHolder;
+    private final CacheStatsHolder cacheStatsHolder;
     private final EhCacheEventListener ehCacheEventListener;
     private final String threadPoolAlias;
     private final Settings settings;
@@ -162,7 +162,7 @@ private EhcacheDiskCache(Builder<K, V> builder) {
         this.ehCacheEventListener = new EhCacheEventListener(builder.getRemovalListener(), builder.getWeigher());
         this.cache = buildCache(Duration.ofMillis(expireAfterAccess.getMillis()), builder);
         List<String> dimensionNames = Objects.requireNonNull(builder.dimensionNames, "Dimension names can't be null");
-        this.statsHolder = new StatsHolder(dimensionNames);
+        this.cacheStatsHolder = new CacheStatsHolder(dimensionNames);
     }
 
     @SuppressWarnings({ "rawtypes" })
@@ -277,9 +277,9 @@ public V get(ICacheKey<K> key) {
             throw new OpenSearchException("Exception occurred while trying to fetch item from ehcache disk cache");
         }
         if (value != null) {
-            statsHolder.incrementHits(key.dimensions);
+            cacheStatsHolder.incrementHits(key.dimensions);
         } else {
-            statsHolder.incrementMisses(key.dimensions);
+            cacheStatsHolder.incrementMisses(key.dimensions);
         }
         return value;
     }
@@ -315,9 +315,9 @@ public V computeIfAbsent(ICacheKey<K> key, LoadAwareCacheLoader<ICacheKey<K>, V>
             value = compute(key, loader);
         }
         if (!loader.isLoaded()) {
-            statsHolder.incrementHits(key.dimensions);
+            cacheStatsHolder.incrementHits(key.dimensions);
         } else {
-            statsHolder.incrementMisses(key.dimensions);
+            cacheStatsHolder.incrementMisses(key.dimensions);
         }
         return value;
     }
@@ -383,7 +383,7 @@ private V compute(ICacheKey<K> key, LoadAwareCacheLoader<ICacheKey<K>, V> loader
     public void invalidate(ICacheKey<K> key) {
         try {
             if (key.getDropStatsForDimensions()) {
-                statsHolder.removeDimensions(key.dimensions);
+                cacheStatsHolder.removeDimensions(key.dimensions);
             }
             if (key.key != null) {
                 cache.remove(key);
@@ -398,7 +398,7 @@ public void invalidate(ICacheKey<K> key) {
     @Override
     public void invalidateAll() {
         cache.clear();
-        statsHolder.reset();
+        cacheStatsHolder.reset();
     }
 
     /**
@@ -416,7 +416,7 @@ public Iterable<ICacheKey<K>> keys() {
      */
     @Override
     public long count() {
-        return statsHolder.count();
+        return cacheStatsHolder.count();
     }
 
     @Override
@@ -448,8 +448,8 @@ public void close() {
      * @return CacheStats
      */
     @Override
-    public CacheStats stats() {
-        return statsHolder.getCacheStats();
+    public ImmutableCacheStatsHolder stats() {
+        return cacheStatsHolder.getImmutableCacheStatsHolder();
     }
 
     /**
@@ -508,39 +508,39 @@ private long getNewValuePairSize(CacheEvent<? extends ICacheKey<K>, ? extends By
         public void onEvent(CacheEvent<? extends ICacheKey<K>, ? extends ByteArrayWrapper> event) {
             switch (event.getType()) {
                 case CREATED:
-                    statsHolder.incrementEntries(event.getKey().dimensions);
-                    statsHolder.incrementSizeInBytes(event.getKey().dimensions, getNewValuePairSize(event));
+                    cacheStatsHolder.incrementEntries(event.getKey().dimensions);
+                    cacheStatsHolder.incrementSizeInBytes(event.getKey().dimensions, getNewValuePairSize(event));
                     assert event.getOldValue() == null;
                     break;
                 case EVICTED:
                     this.removalListener.onRemoval(
                         new RemovalNotification<>(event.getKey(), deserializeValue(event.getOldValue()), RemovalReason.EVICTED)
                     );
-                    statsHolder.decrementEntries(event.getKey().dimensions);
-                    statsHolder.decrementSizeInBytes(event.getKey().dimensions, getOldValuePairSize(event));
-                    statsHolder.incrementEvictions(event.getKey().dimensions);
+                    cacheStatsHolder.decrementEntries(event.getKey().dimensions);
+                    cacheStatsHolder.decrementSizeInBytes(event.getKey().dimensions, getOldValuePairSize(event));
+                    cacheStatsHolder.incrementEvictions(event.getKey().dimensions);
                     assert event.getNewValue() == null;
                     break;
                 case REMOVED:
                     this.removalListener.onRemoval(
                         new RemovalNotification<>(event.getKey(), deserializeValue(event.getOldValue()), RemovalReason.EXPLICIT)
                     );
-                    statsHolder.decrementEntries(event.getKey().dimensions);
-                    statsHolder.decrementSizeInBytes(event.getKey().dimensions, getOldValuePairSize(event));
+                    cacheStatsHolder.decrementEntries(event.getKey().dimensions);
+                    cacheStatsHolder.decrementSizeInBytes(event.getKey().dimensions, getOldValuePairSize(event));
                     assert event.getNewValue() == null;
                     break;
                 case EXPIRED:
                     this.removalListener.onRemoval(
                         new RemovalNotification<>(event.getKey(), deserializeValue(event.getOldValue()), RemovalReason.INVALIDATED)
                     );
-                    statsHolder.decrementEntries(event.getKey().dimensions);
-                    statsHolder.decrementSizeInBytes(event.getKey().dimensions, getOldValuePairSize(event));
+                    cacheStatsHolder.decrementEntries(event.getKey().dimensions);
+                    cacheStatsHolder.decrementSizeInBytes(event.getKey().dimensions, getOldValuePairSize(event));
                     assert event.getNewValue() == null;
                     break;
                 case UPDATED:
                     long newSize = getNewValuePairSize(event);
                     long oldSize = getOldValuePairSize(event);
-                    statsHolder.incrementSizeInBytes(event.getKey().dimensions, newSize - oldSize);
+                    cacheStatsHolder.incrementSizeInBytes(event.getKey().dimensions, newSize - oldSize);
                     break;
                 default:
                     break;

plugins/cache-ehcache/src/test/java/org/opensearch/cache/store/disk/EhCacheDiskCacheTests.java

@@ -20,8 +20,7 @@
 import org.opensearch.common.cache.RemovalNotification;
 import org.opensearch.common.cache.serializer.BytesReferenceSerializer;
 import org.opensearch.common.cache.serializer.Serializer;
-import org.opensearch.common.cache.stats.CacheStatsCounterSnapshot;
-import org.opensearch.common.cache.stats.MultiDimensionCacheStats;
+import org.opensearch.common.cache.stats.CacheStatsSnapshot;
 import org.opensearch.common.cache.store.config.CacheConfig;
 import org.opensearch.common.metrics.CounterMetric;
 import org.opensearch.common.settings.Settings;
@@ -829,17 +828,15 @@ public void testInvalidateWithDropDimensions() throws Exception {
 
             ICacheKey<String> keyToDrop = keysAdded.get(0);
 
-            CacheStatsCounterSnapshot snapshot = ((MultiDimensionCacheStats) ehCacheDiskCachingTier.stats()).getStatsForDimensionValues(
-                keyToDrop.dimensions
-            );
+            CacheStatsSnapshot snapshot = ehCacheDiskCachingTier.stats().getStatsForDimensionValues(keyToDrop.dimensions);
             assertNotNull(snapshot);
 
             keyToDrop.setDropStatsForDimensions(true);
             ehCacheDiskCachingTier.invalidate(keyToDrop);
 
             // Now assert the stats are gone for any key that has this combination of dimensions, but still there otherwise
             for (ICacheKey<String> keyAdded : keysAdded) {
-                snapshot = ((MultiDimensionCacheStats) ehCacheDiskCachingTier.stats()).getStatsForDimensionValues(keyAdded.dimensions);
+                snapshot = ehCacheDiskCachingTier.stats().getStatsForDimensionValues(keyAdded.dimensions);
                 if (keyAdded.dimensions.equals(keyToDrop.dimensions)) {
                     assertNull(snapshot);
                 } else {

server/src/main/java/org/opensearch/common/cache/ICache.java

@@ -9,7 +9,7 @@
 package org.opensearch.common.cache;
 
 import org.opensearch.common.annotation.ExperimentalApi;
-import org.opensearch.common.cache.stats.CacheStats;
+import org.opensearch.common.cache.stats.ImmutableCacheStatsHolder;
 import org.opensearch.common.cache.store.config.CacheConfig;
 
 import java.io.Closeable;
@@ -45,7 +45,7 @@ public interface ICache<K, V> extends Closeable {
 
     void refresh();
 
-    CacheStats stats();
+    ImmutableCacheStatsHolder stats();
 
     /**
      * Factory to create objects.

server/src/main/java/org/opensearch/common/cache/ICacheKey.java

@@ -14,7 +14,8 @@
 
 /**
  * A key wrapper used for ICache implementations, which carries dimensions with it.
- * @param <K> the type of the underlying key
+ * @param <K> the type of the underlying key. K must implement equals(), or else ICacheKey.equals()
+ *           won't work properly and cache behavior may be incorrect!
  *
  * @opensearch.experimental
  */

server/src/main/java/org/opensearch/common/cache/stats/CacheStats.java

@@ -8,28 +8,125 @@
 
 package org.opensearch.common.cache.stats;
 
-import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.common.metrics.CounterMetric;
+
+import java.util.Objects;
 
 /**
- * Interface for access to any cache stats. Allows accessing stats by dimension values.
- * Stores an immutable snapshot of stats for a cache. The cache maintains its own live counters.
- *
- * @opensearch.experimental
+ * A mutable class containing the 5 live metrics tracked by a StatsHolder object.
  */
-@ExperimentalApi
-public interface CacheStats { // TODO: also extends Writeable, ToXContentFragment (in API PR)
+public class CacheStats {
+    CounterMetric hits;
+    CounterMetric misses;
+    CounterMetric evictions;
+    CounterMetric sizeInBytes;
+    CounterMetric entries;
+
+    public CacheStats(long hits, long misses, long evictions, long sizeInBytes, long entries) {
+        this.hits = new CounterMetric();
+        this.hits.inc(hits);
+        this.misses = new CounterMetric();
+        this.misses.inc(misses);
+        this.evictions = new CounterMetric();
+        this.evictions.inc(evictions);
+        this.sizeInBytes = new CounterMetric();
+        this.sizeInBytes.inc(sizeInBytes);
+        this.entries = new CounterMetric();
+        this.entries.inc(entries);
+    }
+
+    public CacheStats() {
+        this(0, 0, 0, 0, 0);
+    }
+
+    private void internalAdd(long otherHits, long otherMisses, long otherEvictions, long otherSizeInBytes, long otherEntries) {
+        this.hits.inc(otherHits);
+        this.misses.inc(otherMisses);
+        this.evictions.inc(otherEvictions);
+        this.sizeInBytes.inc(otherSizeInBytes);
+        this.entries.inc(otherEntries);
+    }
+
+    public void add(CacheStats other) {
+        if (other == null) {
+            return;
+        }
+        internalAdd(other.getHits(), other.getMisses(), other.getEvictions(), other.getSizeInBytes(), other.getEntries());
+    }
+
+    public void add(CacheStatsSnapshot snapshot) {
+        if (snapshot == null) {
+            return;
+        }
+        internalAdd(snapshot.getHits(), snapshot.getMisses(), snapshot.getEvictions(), snapshot.getSizeInBytes(), snapshot.getEntries());
+    }
+
+    public void subtract(CacheStatsSnapshot other) {
+        if (other == null) {
+            return;
+        }
+        internalAdd(-other.getHits(), -other.getMisses(), -other.getEvictions(), -other.getSizeInBytes(), -other.getEntries());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(hits.count(), misses.count(), evictions.count(), sizeInBytes.count(), entries.count());
+    }
+
+    public void incrementHits() {
+        hits.inc();
+    }
+
+    public void incrementMisses() {
+        misses.inc();
+    }
+
+    public void incrementEvictions() {
+        evictions.inc();
+    }
+
+    public void incrementSizeInBytes(long amount) {
+        sizeInBytes.inc(amount);
+    }
+
+    public void decrementSizeInBytes(long amount) {
+        sizeInBytes.dec(amount);
+    }
+
+    public void incrementEntries() {
+        entries.inc();
+    }
+
+    public void decrementEntries() {
+        entries.dec();
+    }
+
+    public long getHits() {
+        return hits.count();
+    }
 
-    // Method to get all 5 values at once
-    CacheStatsCounterSnapshot getTotalStats();
+    public long getMisses() {
+        return misses.count();
+    }
 
-    // Methods to get total values.
-    long getTotalHits();
+    public long getEvictions() {
+        return evictions.count();
+    }
 
-    long getTotalMisses();
+    public long getSizeInBytes() {
+        return sizeInBytes.count();
+    }
 
-    long getTotalEvictions();
+    public long getEntries() {
+        return entries.count();
+    }
 
-    long getTotalSizeInBytes();
+    public void resetSizeAndEntries() {
+        sizeInBytes = new CounterMetric();
+        entries = new CounterMetric();
+    }
 
-    long getTotalEntries();
+    public CacheStatsSnapshot snapshot() {
+        return new CacheStatsSnapshot(hits.count(), misses.count(), evictions.count(), sizeInBytes.count(), entries.count());
+    }
 }