Addressed Ankit's comments

Signed-off-by: Peter Alfonsi <[email protected]>

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

@@ -526,6 +526,14 @@ void updateStatsOnPut(String destinationTierValue, ICacheKey<K> key, V value) {
             statsHolder.incrementSizeInBytes(dimensionValues, weigher.applyAsLong(key, value));
         }
 
+        @Override
+        public long getMaximumWeight() {
+            if (caches.get(diskCache).isEnabled()) {
+                return onHeapCache.getMaximumWeight() + diskCache.getMaximumWeight();
+            }
+            return onHeapCache.getMaximumWeight();
+        }
+
         /**
          * A class which receives removal events from the heap tier.
          */
@@ -692,6 +700,11 @@ long diskCacheCount() {
         return diskCacheEntries;
     }
 
+    @Override
+    public long getMaximumWeight() {
+        return tieredSpilloverCacheSegments[0].getMaximumWeight() * numberOfSegments;
+    }
+
     /**
      * ConcatenatedIterables which combines cache iterables and supports remove() functionality as well if underlying
      * iterator supports it.

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

@@ -99,7 +99,9 @@ public class TieredSpilloverCacheSettings {
 
     /**
      * Setting which defines the disk cache size to be used within tiered cache.
-     * Similarly, this setting overrides the size setting from the disk tier implementation.
+     * This setting overrides the size setting from the disk tier implementation.
+     * For example, if EhcacheDiskCache is the disk tier in the request cache, and
+     * indices.requests.cache.ehcache_disk.max_size_in_bytes is set, that value will be ignored in favor of this setting.
      */
     public static final Setting.AffixSetting<Long> TIERED_SPILLOVER_DISK_STORE_SIZE = Setting.suffixKeySetting(
         TieredSpilloverCache.TieredSpilloverCacheFactory.TIERED_SPILLOVER_CACHE_NAME + ".disk.store.size",

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

@@ -128,7 +128,8 @@ public void close() {
 
     }
 
-    long getMaxSize() {
+    @Override
+    public long getMaximumWeight() {
         return maxSize;
     }
 

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

@@ -2297,7 +2297,12 @@ private void checkSegmentSizes(TieredSpilloverCache<String, String> cache, long
 
         MockDiskCache<String, String> segmentDiskCache = (MockDiskCache<String, String>) cache.tieredSpilloverCacheSegments[0]
             .getDiskCache();
-        assertEquals(expectedDiskSize / cache.getNumberOfSegments(), segmentDiskCache.getMaxSize());
+        assertEquals(expectedDiskSize / cache.getNumberOfSegments(), segmentDiskCache.getMaximumWeight());
+        assertEquals(
+            expectedHeapSize / cache.getNumberOfSegments() + expectedDiskSize / cache.getNumberOfSegments(),
+            cache.tieredSpilloverCacheSegments[0].getMaximumWeight()
+        );
+        assertEquals(expectedHeapSize + expectedDiskSize, cache.getMaximumWeight());
     }
 
     private List<String> getMockDimensions() {

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

@@ -681,7 +681,8 @@ private V deserializeValue(ByteArrayWrapper binary) {
     }
 
     // Pkg-private for testing.
-    long getMaxWeightInBytes() {
+    @Override
+    public long getMaximumWeight() {
         return maxWeightInBytes;
     }
 

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

@@ -1209,10 +1209,10 @@ public void testWithCacheConfigSizeSettings() throws Exception {
         long maxSizeFromConfig = between(MINIMUM_MAX_SIZE_IN_BYTES + 3000, MINIMUM_MAX_SIZE_IN_BYTES + 4000);
 
         EhcacheDiskCache<String, String> cache = setupMaxSizeTest(maxSizeFromSetting, maxSizeFromConfig, false);
-        assertEquals(maxSizeFromSetting, cache.getMaxWeightInBytes());
+        assertEquals(maxSizeFromSetting, cache.getMaximumWeight());
 
         cache = setupMaxSizeTest(maxSizeFromSetting, maxSizeFromConfig, true);
-        assertEquals(maxSizeFromConfig, cache.getMaxWeightInBytes());
+        assertEquals(maxSizeFromConfig, cache.getMaximumWeight());
     }
 
     // Modified from OpenSearchOnHeapCacheTests. Can't reuse, as we can't add a dependency on the server.test module.

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

@@ -53,6 +53,8 @@ default ImmutableCacheStatsHolder stats() {
     // Return stats aggregated by the provided levels. If levels is null or an empty array, return total stats only.
     ImmutableCacheStatsHolder stats(String[] levels);
 
+    long getMaximumWeight();
+
     /**
      * Factory to create objects.
      */

server/src/main/java/org/opensearch/common/cache/service/CacheService.java

@@ -46,10 +46,7 @@ public CacheService(Map<String, ICache.Factory> cacheStoreTypeFactories, Setting
     }
 
     public <K, V> ICache<K, V> createCache(CacheConfig<K, V> config, CacheType cacheType) {
-        Setting<String> cacheSettingForCacheType = CacheSettings.CACHE_TYPE_STORE_NAME.getConcreteSettingForNamespace(
-            cacheType.getSettingPrefix()
-        );
-        String storeName = cacheSettingForCacheType.get(settings);
+        String storeName = getStoreNameFromSetting(cacheType, settings);
         if (!pluggableCachingEnabled(cacheType, settings)) {
             // Condition 1: In case feature flag is off, we default to onHeap.
             // Condition 2: In case storeName is not explicitly mentioned, we assume user is looking to use older
@@ -79,10 +76,14 @@ public NodeCacheStats stats(CommonStatsFlags flags) {
      * Check if pluggable caching is on, and if a store type is present for this cache type.
      */
     public static boolean pluggableCachingEnabled(CacheType cacheType, Settings settings) {
+        String storeName = getStoreNameFromSetting(cacheType, settings);
+        return FeatureFlags.PLUGGABLE_CACHE_SETTING.get(settings) && storeName != null && !storeName.isBlank();
+    }
+
+    private static String getStoreNameFromSetting(CacheType cacheType, Settings settings) {
         Setting<String> cacheSettingForCacheType = CacheSettings.CACHE_TYPE_STORE_NAME.getConcreteSettingForNamespace(
             cacheType.getSettingPrefix()
         );
-        String storeName = cacheSettingForCacheType.get(settings);
-        return FeatureFlags.PLUGGABLE_CACHE_SETTING.get(settings) && storeName != null && !storeName.isBlank();
+        return cacheSettingForCacheType.get(settings);
     }
 }

server/src/main/java/org/opensearch/common/cache/store/OpenSearchOnHeapCache.java

@@ -81,7 +81,7 @@ public OpenSearchOnHeapCache(Builder<K, V> builder) {
         this.weigher = builder.getWeigher();
     }
 
-    // public for testing
+    @Override
     public long getMaximumWeight() {
         return this.maximumWeight;
     }