[Bugfix] Fix cache maximum size settings not working properly with pluggable caching

CHANGELOG.md

@@ -43,6 +43,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Support retrieving doc values of unsigned long field ([#16543](https://github.com/opensearch-project/OpenSearch/pull/16543))
 - Fix rollover alias supports restored searchable snapshot index([#16483](https://github.com/opensearch-project/OpenSearch/pull/16483))
 - Fix permissions error on scripted query against remote snapshot ([#16544](https://github.com/opensearch-project/OpenSearch/pull/16544))
+- Fix max request cache size settings not working properly with pluggable caching ([#16636](https://github.com/opensearch-project/OpenSearch/pull/16636))
 
 ### Security
 

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

@@ -85,6 +85,9 @@ public class TieredSpilloverCacheSettings {
 
     /**
      * Setting which defines the onHeap cache size to be used within tiered cache.
+     * This setting overrides size settings from the heap tier implementation.
+     * For example, if OpenSearchOnHeapCache is the heap tier in the request cache, and
+     * indices.requests.cache.opensearch_onheap.size is set, that value will be ignored in favor of this setting.
      *
      * Pattern: {cache_type}.tiered_spillover.onheap.store.size
      * Example: indices.request.cache.tiered_spillover.onheap.store.size
@@ -96,6 +99,7 @@ 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.
      */
     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

@@ -128,6 +128,10 @@ public void close() {
 
     }
 
+    long getMaxSize() {
+        return maxSize;
+    }
+
     public static class MockDiskCacheFactory implements Factory {
 
         public static final String NAME = "mockDiskCache";

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

@@ -58,6 +58,7 @@
 
 import static org.opensearch.cache.common.tier.TieredSpilloverCache.ZERO_SEGMENT_COUNT_EXCEPTION_MESSAGE;
 import static org.opensearch.cache.common.tier.TieredSpilloverCacheSettings.DISK_CACHE_ENABLED_SETTING_MAP;
+import static org.opensearch.cache.common.tier.TieredSpilloverCacheSettings.MIN_DISK_CACHE_SIZE_IN_BYTES;
 import static org.opensearch.cache.common.tier.TieredSpilloverCacheSettings.TIERED_SPILLOVER_ONHEAP_STORE_SIZE;
 import static org.opensearch.cache.common.tier.TieredSpilloverCacheSettings.TIERED_SPILLOVER_SEGMENTS;
 import static org.opensearch.cache.common.tier.TieredSpilloverCacheSettings.TOOK_TIME_POLICY_CONCRETE_SETTINGS_MAP;
@@ -2112,6 +2113,139 @@ public void testTieredCacheDefaultSegmentCount() {
         assertTrue(VALID_SEGMENT_COUNT_VALUES.contains(tieredSpilloverCache.getNumberOfSegments()));
     }
 
+    public void testSegmentSizesWhenUsingFactory() {
+        // The TSC's tier size settings, TIERED_SPILLOVER_ONHEAP_STORE_SIZE and TIERED_SPILLOVER_DISK_STORE_SIZE,
+        // should always be respected, overriding the individual implementation's size settings if present
+        long expectedHeapSize = 256L * between(10, 20);
+        long expectedDiskSize = MIN_DISK_CACHE_SIZE_IN_BYTES + 256L * between(30, 40);
+        long heapSizeFromImplSetting = 50;
+        int diskSizeFromImplSetting = 50;
+        int numSegments = getNumberOfSegments();
+
+        int keyValueSize = 1;
+        MockCacheRemovalListener<String, String> removalListener = new MockCacheRemovalListener<>();
+        Settings settings = Settings.builder()
+            .put(
+                CacheSettings.getConcreteStoreNameSettingForCacheType(CacheType.INDICES_REQUEST_CACHE).getKey(),
+                TieredSpilloverCache.TieredSpilloverCacheFactory.TIERED_SPILLOVER_CACHE_NAME
+            )
+            .put(
+                TieredSpilloverCacheSettings.TIERED_SPILLOVER_ONHEAP_STORE_NAME.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                OpenSearchOnHeapCache.OpenSearchOnHeapCacheFactory.NAME
+            )
+            .put(
+                TieredSpilloverCacheSettings.TIERED_SPILLOVER_DISK_STORE_NAME.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                MockDiskCache.MockDiskCacheFactory.NAME
+            )
+            // These two size settings should be honored
+            .put(
+                TieredSpilloverCacheSettings.TIERED_SPILLOVER_ONHEAP_STORE_SIZE.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                expectedHeapSize + "b"
+            )
+            .put(
+                TieredSpilloverCacheSettings.TIERED_SPILLOVER_DISK_STORE_SIZE.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                expectedDiskSize
+            )
+            // The size setting from the OpenSearchOnHeap implementation should not be honored
+            .put(
+                OpenSearchOnHeapCacheSettings.MAXIMUM_SIZE_IN_BYTES.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                heapSizeFromImplSetting + "b"
+            )
+            .put(FeatureFlags.PLUGGABLE_CACHE, "true")
+            .put(
+                TIERED_SPILLOVER_SEGMENTS.getConcreteSettingForNamespace(CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()).getKey(),
+                numSegments
+            )
+            .build();
+        String storagePath = getStoragePath(settings);
+
+        TieredSpilloverCache<String, String> tieredSpilloverCache = (TieredSpilloverCache<
+            String,
+            String>) new TieredSpilloverCache.TieredSpilloverCacheFactory().create(
+                new CacheConfig.Builder<String, String>().setKeyType(String.class)
+                    .setKeyType(String.class)
+                    .setWeigher((k, v) -> keyValueSize)
+                    .setRemovalListener(removalListener)
+                    .setKeySerializer(new StringSerializer())
+                    .setValueSerializer(new StringSerializer())
+                    .setSettings(settings)
+                    .setDimensionNames(dimensionNames)
+                    .setCachedResultParser(s -> new CachedQueryResult.PolicyValues(20_000_000L)) // Values will always appear to have taken
+                    // 20_000_000 ns = 20 ms to compute
+                    .setClusterSettings(clusterSettings)
+                    .setStoragePath(storagePath)
+                    .build(),
+                CacheType.INDICES_REQUEST_CACHE,
+                Map.of(
+                    OpenSearchOnHeapCache.OpenSearchOnHeapCacheFactory.NAME,
+                    new OpenSearchOnHeapCache.OpenSearchOnHeapCacheFactory(),
+                    MockDiskCache.MockDiskCacheFactory.NAME,
+                    // The size value passed in here acts as the "implementation setting" for the disk tier, and should also be ignored
+                    new MockDiskCache.MockDiskCacheFactory(0, diskSizeFromImplSetting, false, keyValueSize)
+                )
+            );
+        checkSegmentSizes(tieredSpilloverCache, expectedHeapSize, expectedDiskSize);
+    }
+
+    public void testSegmentSizesWhenNotUsingFactory() {
+        long expectedHeapSize = 256L * between(10, 20);
+        long expectedDiskSize = MIN_DISK_CACHE_SIZE_IN_BYTES + 256L * between(30, 40);
+        int heapSizeFromImplSetting = 50;
+        int diskSizeFromImplSetting = 50;
+
+        Settings settings = Settings.builder()
+            .put(
+                CacheSettings.getConcreteStoreNameSettingForCacheType(CacheType.INDICES_REQUEST_CACHE).getKey(),
+                TieredSpilloverCache.TieredSpilloverCacheFactory.TIERED_SPILLOVER_CACHE_NAME
+            )
+            .put(FeatureFlags.PLUGGABLE_CACHE, "true")
+            // The size setting from the OpenSearchOnHeapCache implementation should not be honored
+            .put(
+                OpenSearchOnHeapCacheSettings.MAXIMUM_SIZE_IN_BYTES.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                heapSizeFromImplSetting + "b"
+            )
+            .build();
+
+        int keyValueSize = 1;
+        MockCacheRemovalListener<String, String> removalListener = new MockCacheRemovalListener<>();
+        int numSegments = getNumberOfSegments();
+        CacheConfig<String, String> cacheConfig = getCacheConfig(1, settings, removalListener, numSegments);
+        TieredSpilloverCache<String, String> tieredSpilloverCache = getTieredSpilloverCache(
+            new OpenSearchOnHeapCache.OpenSearchOnHeapCacheFactory(),
+            new MockDiskCache.MockDiskCacheFactory(0, diskSizeFromImplSetting, true, keyValueSize),
+            cacheConfig,
+            null,
+            removalListener,
+            numSegments,
+            expectedHeapSize,
+            expectedDiskSize
+        );
+        checkSegmentSizes(tieredSpilloverCache, expectedHeapSize, expectedDiskSize);
+    }
+
+    private void checkSegmentSizes(TieredSpilloverCache<String, String> cache, long expectedHeapSize, long expectedDiskSize) {
+        OpenSearchOnHeapCache<String, String> segmentHeapCache = (OpenSearchOnHeapCache<
+            String,
+            String>) cache.tieredSpilloverCacheSegments[0].getOnHeapCache();
+        assertEquals(expectedHeapSize / cache.getNumberOfSegments(), segmentHeapCache.getMaximumWeight());
+
+        MockDiskCache<String, String> segmentDiskCache = (MockDiskCache<String, String>) cache.tieredSpilloverCacheSegments[0]
+            .getDiskCache();
+        assertEquals(expectedDiskSize / cache.getNumberOfSegments(), segmentDiskCache.getMaxSize());
+    }
+
     private List<String> getMockDimensions() {
         List<String> dims = new ArrayList<>();
         for (String dimensionName : dimensionNames) {
@@ -2401,9 +2535,9 @@ private void verifyComputeIfAbsentThrowsException(
         MockCacheRemovalListener<String, String> removalListener = new MockCacheRemovalListener<>();
         Settings settings = Settings.builder()
             .put(
-                OpenSearchOnHeapCacheSettings.getSettingListForCacheType(CacheType.INDICES_REQUEST_CACHE)
-                    .get(MAXIMUM_SIZE_IN_BYTES_KEY)
-                    .getKey(),
+                TieredSpilloverCacheSettings.TIERED_SPILLOVER_ONHEAP_STORE_SIZE.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
                 onHeapCacheSize * keyValueSize + "b"
             )
             .build();

plugins/cache-ehcache/src/main/java/org/opensearch/cache/EhcacheDiskCacheSettings.java

@@ -101,6 +101,7 @@ public class EhcacheDiskCacheSettings {
 
     /**
      * Disk cache max size setting.
+     * If this cache is used as a tier in a TieredSpilloverCache, this setting is ignored.
      */
     public static final Setting.AffixSetting<Long> DISK_CACHE_MAX_SIZE_IN_BYTES_SETTING = Setting.suffixKeySetting(
         EhcacheDiskCache.EhcacheDiskCacheFactory.EHCACHE_DISK_CACHE_NAME + ".max_size_in_bytes",

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

@@ -680,6 +680,11 @@ private V deserializeValue(ByteArrayWrapper binary) {
         return valueSerializer.deserialize(binary.value);
     }
 
+    // Pkg-private for testing.
+    long getMaxWeightInBytes() {
+        return maxWeightInBytes;
+    }
+
     /**
      * Factory to create an ehcache disk cache.
      */

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

@@ -20,11 +20,13 @@
 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.settings.CacheSettings;
 import org.opensearch.common.cache.stats.ImmutableCacheStats;
 import org.opensearch.common.cache.store.config.CacheConfig;
 import org.opensearch.common.metrics.CounterMetric;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.common.unit.TimeValue;
+import org.opensearch.common.util.FeatureFlags;
 import org.opensearch.common.util.io.IOUtils;
 import org.opensearch.core.common.bytes.BytesArray;
 import org.opensearch.core.common.bytes.BytesReference;
@@ -1201,6 +1203,65 @@ public void testEhcacheCloseWithDestroyCacheMethodThrowingException() throws Exc
         ehcacheDiskCache.close();
     }
 
+    public void testWithCacheConfigSizeSettings() throws Exception {
+        // The cache should get its size from the config if present, and otherwise should get it from the setting.
+        long maxSizeFromSetting = between(MINIMUM_MAX_SIZE_IN_BYTES + 1000, MINIMUM_MAX_SIZE_IN_BYTES + 2000);
+        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());
+
+        cache = setupMaxSizeTest(maxSizeFromSetting, maxSizeFromConfig, true);
+        assertEquals(maxSizeFromConfig, cache.getMaxWeightInBytes());
+    }
+
+    // Modified from OpenSearchOnHeapCacheTests. Can't reuse, as we can't add a dependency on the server.test module.
+    private EhcacheDiskCache<String, String> setupMaxSizeTest(long maxSizeFromSetting, long maxSizeFromConfig, boolean putSizeInConfig)
+        throws Exception {
+        MockRemovalListener<String, String> listener = new MockRemovalListener<>();
+        try (NodeEnvironment env = newNodeEnvironment(Settings.builder().build())) {
+            Settings settings = Settings.builder()
+                .put(FeatureFlags.PLUGGABLE_CACHE, true)
+                .put(
+                    CacheSettings.getConcreteStoreNameSettingForCacheType(CacheType.INDICES_REQUEST_CACHE).getKey(),
+                    EhcacheDiskCache.EhcacheDiskCacheFactory.EHCACHE_DISK_CACHE_NAME
+                )
+                .put(
+                    EhcacheDiskCacheSettings.getSettingListForCacheType(CacheType.INDICES_REQUEST_CACHE)
+                        .get(DISK_MAX_SIZE_IN_BYTES_KEY)
+                        .getKey(),
+                    maxSizeFromSetting
+                )
+                .put(
+                    EhcacheDiskCacheSettings.getSettingListForCacheType(CacheType.INDICES_REQUEST_CACHE)
+                        .get(DISK_STORAGE_PATH_KEY)
+                        .getKey(),
+                    env.nodePaths()[0].indicesPath.toString() + "/request_cache/" + 0
+                )
+                .build();
+
+            CacheConfig.Builder<String, String> cacheConfigBuilder = new CacheConfig.Builder<String, String>().setKeyType(String.class)
+                .setValueType(String.class)
+                .setKeySerializer(new StringSerializer())
+                .setValueSerializer(new StringSerializer())
+                .setWeigher(getWeigher())
+                .setRemovalListener(listener)
+                .setSettings(settings)
+                .setDimensionNames(List.of(dimensionName))
+                .setStatsTrackingEnabled(true);
+            if (putSizeInConfig) {
+                cacheConfigBuilder.setMaxSizeInBytes(maxSizeFromConfig);
+            }
+
+            ICache.Factory cacheFactory = new EhcacheDiskCache.EhcacheDiskCacheFactory();
+            return (EhcacheDiskCache<String, String>) cacheFactory.create(
+                cacheConfigBuilder.build(),
+                CacheType.INDICES_REQUEST_CACHE,
+                null
+            );
+        }
+    }
+
     static class MockEhcahceDiskCache extends EhcacheDiskCache<String, String> {
 
         public MockEhcahceDiskCache(Builder<String, String> builder) {

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

@@ -50,7 +50,7 @@ public <K, V> ICache<K, V> createCache(CacheConfig<K, V> config, CacheType cache
             cacheType.getSettingPrefix()
         );
         String storeName = cacheSettingForCacheType.get(settings);
-        if (!FeatureFlags.PLUGGABLE_CACHE_SETTING.get(settings) || (storeName == null || storeName.isBlank())) {
+        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
             // settings, so we again fallback to onHeap to maintain backward compatibility.
@@ -74,4 +74,15 @@ public NodeCacheStats stats(CommonStatsFlags flags) {
         }
         return new NodeCacheStats(statsMap, 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) {
+        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();
+    }
 }

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

@@ -17,6 +17,7 @@
 import org.opensearch.common.cache.RemovalListener;
 import org.opensearch.common.cache.RemovalNotification;
 import org.opensearch.common.cache.RemovalReason;
+import org.opensearch.common.cache.service.CacheService;
 import org.opensearch.common.cache.settings.CacheSettings;
 import org.opensearch.common.cache.stats.CacheStatsHolder;
 import org.opensearch.common.cache.stats.DefaultCacheStatsHolder;
@@ -80,8 +81,8 @@ public OpenSearchOnHeapCache(Builder<K, V> builder) {
         this.weigher = builder.getWeigher();
     }
 
-    // package private for testing
-    long getMaximumWeight() {
+    // public for testing
+    public long getMaximumWeight() {
         return this.maximumWeight;
     }
 
@@ -192,8 +193,12 @@ public <K, V> ICache<K, V> create(CacheConfig<K, V> config, CacheType cacheType,
             );
             long maxSizeInBytes = ((ByteSizeValue) settingList.get(MAXIMUM_SIZE_IN_BYTES_KEY).get(settings)).getBytes();
 
-            if (config.getMaxSizeInBytes() > 0) { // If this is passed from upstream(like tieredCache), then use this
-                // instead.
+            if (config.getMaxSizeInBytes() > 0) {
+                /*
+                Use the cache config value if present.
+                This can be passed down from the TieredSpilloverCache when creating individual segments,
+                but is not passed in from the IRC if pluggable caching is on.
+                 */
                 builder.setMaximumWeightInBytes(config.getMaxSizeInBytes());
             } else {
                 builder.setMaximumWeightInBytes(maxSizeInBytes);
@@ -204,8 +209,7 @@ public <K, V> ICache<K, V> create(CacheConfig<K, V> config, CacheType cacheType,
                 builder.setNumberOfSegments(-1); // By default it will use 256 segments.
             }
 
-            String storeName = cacheSettingForCacheType.get(settings);
-            if (!FeatureFlags.PLUGGABLE_CACHE_SETTING.get(settings) || (storeName == null || storeName.isBlank())) {
+            if (!CacheService.pluggableCachingEnabled(cacheType, settings)) {
                 // For backward compatibility as the user intent is to use older settings.
                 builder.setMaximumWeightInBytes(config.getMaxSizeInBytes());
                 builder.setExpireAfterAccess(config.getExpireAfterAccess());

server/src/main/java/org/opensearch/common/cache/store/settings/OpenSearchOnHeapCacheSettings.java

@@ -26,6 +26,7 @@ public class OpenSearchOnHeapCacheSettings {
 
     /**
      * Setting to define maximum size for the cache as a percentage of heap memory available.
+     * If this cache is used as a tier in a TieredSpilloverCache, this setting is ignored.
      *
      * Setting pattern: {cache_type}.opensearch_onheap.size
      */