[Tiered Caching] Segmented cache changes (#16047)

* Segmented cache changes for TieredCache Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Adding change log Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Allow segment number to be power of two Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Moving common tiered cache IT methods to a common base class Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Adding disk took time IT test with multiple segment Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Correcting changelog Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Addressing comments Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Fixing invalid segment count variable name Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Introducing new settings for size for respective cache tier Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Changing the default segmentCount logic Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> * Fixing missing java doc issue Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> --------- Signed-off-by: Sagar Upadhyaya <sagar.upadhyaya.121@gmail.com> Signed-off-by: Sagar <99425694+sgup432@users.noreply.github.com>
opensearch-project · Oct 8, 2024 · 266bdd3 · 266bdd3
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fallback to Remote cluster-state on Term-Version check mismatch - ([#15424](https://github.com/opensearch-project/OpenSearch/pull/15424))
 - Implement WithFieldName interface in ValuesSourceAggregationBuilder & FieldSortBuilder ([#15916](https://github.com/opensearch-project/OpenSearch/pull/15916))
 - Add successfulSearchShardIndices in searchRequestContext ([#15967](https://github.com/opensearch-project/OpenSearch/pull/15967))
+- [Tiered Caching] Segmented cache changes ([#16047](https://github.com/opensearch-project/OpenSearch/pull/16047))
 - Add support for msearch API to pass search pipeline name - ([#15923](https://github.com/opensearch-project/OpenSearch/pull/15923))
 - Add _list/indices API as paginated alternate to _cat/indices ([#14718](https://github.com/opensearch-project/OpenSearch/pull/14718))
 - Add success and failure metrics for async shard fetch ([#15976](https://github.com/opensearch-project/OpenSearch/pull/15976))

diff --git a/...internalClusterTest/java/org/opensearch/cache/common/tier/TieredSpilloverCacheBaseIT.java b/...internalClusterTest/java/org/opensearch/cache/common/tier/TieredSpilloverCacheBaseIT.java
@@ -0,0 +1,57 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.cache.common.tier;
+
+import org.opensearch.common.cache.CacheType;
+import org.opensearch.common.cache.settings.CacheSettings;
+import org.opensearch.common.cache.store.OpenSearchOnHeapCache;
+import org.opensearch.common.settings.Settings;
+import org.opensearch.common.util.FeatureFlags;
+import org.opensearch.test.OpenSearchIntegTestCase;
+
+public class TieredSpilloverCacheBaseIT extends OpenSearchIntegTestCase {
+
+    public Settings defaultSettings(String onHeapCacheSizeInBytesOrPercentage, int numberOfSegments) {
+        return Settings.builder()
+            .put(FeatureFlags.PLUGGABLE_CACHE, "true")
+            .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
+            )
+            .put(
+                TieredSpilloverCacheSettings.TIERED_SPILLOVER_SEGMENTS.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                numberOfSegments
+            )
+            .put(
+                TieredSpilloverCacheSettings.TIERED_SPILLOVER_ONHEAP_STORE_SIZE.getConcreteSettingForNamespace(
+                    CacheType.INDICES_REQUEST_CACHE.getSettingPrefix()
+                ).getKey(),
+                onHeapCacheSizeInBytesOrPercentage
+            )
+            .build();
+    }
+
+    public int getNumberOfSegments() {
+        return randomFrom(1, 2, 4, 8, 16, 64, 128, 256);
+    }
+}
diff --git a/...src/internalClusterTest/java/org/opensearch/cache/common/tier/TieredSpilloverCacheIT.java b/...src/internalClusterTest/java/org/opensearch/cache/common/tier/TieredSpilloverCacheIT.java
@@ -22,12 +22,8 @@
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.common.cache.CacheType;
 import org.opensearch.common.cache.ICache;
-import org.opensearch.common.cache.settings.CacheSettings;
-import org.opensearch.common.cache.store.OpenSearchOnHeapCache;
-import org.opensearch.common.cache.store.settings.OpenSearchOnHeapCacheSettings;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.common.unit.TimeValue;
-import org.opensearch.common.util.FeatureFlags;
 import org.opensearch.index.cache.request.RequestCacheStats;
 import org.opensearch.index.query.QueryBuilders;
 import org.opensearch.indices.IndicesRequestCache;
@@ -43,13 +39,15 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
+import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import static org.opensearch.common.cache.store.settings.OpenSearchOnHeapCacheSettings.MAXIMUM_SIZE_IN_BYTES_KEY;
+import static org.opensearch.common.cache.settings.CacheSettings.INVALID_SEGMENT_COUNT_EXCEPTION_MESSAGE;
 import static org.opensearch.indices.IndicesService.INDICES_CACHE_CLEAN_INTERVAL_SETTING;
 import static org.opensearch.search.aggregations.AggregationBuilders.dateHistogram;
 import static org.opensearch.test.hamcrest.OpenSearchAssertions.assertAcked;
@@ -58,43 +56,15 @@
 import static org.hamcrest.Matchers.greaterThan;
 
 @OpenSearchIntegTestCase.ClusterScope(numDataNodes = 0, scope = OpenSearchIntegTestCase.Scope.TEST)
-public class TieredSpilloverCacheIT extends OpenSearchIntegTestCase {
+public class TieredSpilloverCacheIT extends TieredSpilloverCacheBaseIT {
 
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {
         return Arrays.asList(TieredSpilloverCachePlugin.class, MockDiskCachePlugin.class);
     }
 
-    static Settings defaultSettings(String onHeapCacheSizeInBytesOrPercentage) {
-        return Settings.builder()
-            .put(FeatureFlags.PLUGGABLE_CACHE, "true")
-            .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
-            )
-            .put(
-                OpenSearchOnHeapCacheSettings.getSettingListForCacheType(CacheType.INDICES_REQUEST_CACHE)
-                    .get(MAXIMUM_SIZE_IN_BYTES_KEY)
-                    .getKey(),
-                onHeapCacheSizeInBytesOrPercentage
-            )
-            .build();
-    }
-
     public void testPluginsAreInstalled() {
-        internalCluster().startNode(Settings.builder().put(defaultSettings("1%")).build());
+        internalCluster().startNode(Settings.builder().put(defaultSettings("1%", getNumberOfSegments())).build());
         NodesInfoRequest nodesInfoRequest = new NodesInfoRequest();
         nodesInfoRequest.addMetric(NodesInfoRequest.Metric.PLUGINS.metricName());
         NodesInfoResponse nodesInfoResponse = OpenSearchIntegTestCase.client().admin().cluster().nodesInfo(nodesInfoRequest).actionGet();
@@ -111,7 +81,8 @@ public void testPluginsAreInstalled() {
     }
 
     public void testSanityChecksWithIndicesRequestCache() throws InterruptedException {
-        internalCluster().startNodes(3, Settings.builder().put(defaultSettings("1%")).build());
+        int numberOfSegments = getNumberOfSegments();
+        internalCluster().startNodes(3, Settings.builder().put(defaultSettings("1%", numberOfSegments)).build());
         Client client = client();
         assertAcked(
             client.admin()
@@ -147,9 +118,97 @@ public void testSanityChecksWithIndicesRequestCache() throws InterruptedExceptio
         );
     }
 
+    public void testWithDynamicTookTimePolicyWithMultiSegments() throws Exception {
+        int numberOfSegments = getNumberOfSegments();
+        int onHeapCacheSizePerSegmentInBytes = 800; // Per cache entry below is around ~700 bytes, so keeping this
+        // just a bit higher so that each segment can atleast hold 1 entry.
+        int onHeapCacheSizeInBytes = onHeapCacheSizePerSegmentInBytes * numberOfSegments;
+        internalCluster().startNode(Settings.builder().put(defaultSettings(onHeapCacheSizeInBytes + "b", numberOfSegments)).build());
+        Client client = client();
+        assertAcked(
+            client.admin()
+                .indices()
+                .prepareCreate("index")
+                .setMapping("k", "type=keyword")
+                .setSettings(
+                    Settings.builder()
+                        .put(IndicesRequestCache.INDEX_CACHE_REQUEST_ENABLED_SETTING.getKey(), true)
+                        .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
+                        .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0)
+                        .put("index.refresh_interval", -1)
+                )
+                .get()
+        );
+        // Set a very high value for took time policy so that no items evicted from onHeap cache are spilled
+        // to disk. And then hit requests so that few items are cached into cache.
+        ClusterUpdateSettingsRequest updateSettingsRequest = new ClusterUpdateSettingsRequest().transientSettings(
+            Settings.builder()
+                .put(
+                    TieredSpilloverCacheSettings.TOOK_TIME_POLICY_CONCRETE_SETTINGS_MAP.get(CacheType.INDICES_REQUEST_CACHE).getKey(),
+                    new TimeValue(100, TimeUnit.SECONDS)
+                )
+                .build()
+        );
+        assertAcked(internalCluster().client().admin().cluster().updateSettings(updateSettingsRequest).get());
+        int numberOfIndexedItems = numberOfSegments + 1; // Best case if all keys are distributed among different
+        // segment, atleast one of the segment will have 2 entries and we will see evictions.
+        for (int iterator = 0; iterator < numberOfIndexedItems; iterator++) {
+            indexRandom(true, client.prepareIndex("index").setSource("k" + iterator, "hello" + iterator));
+        }
+        ensureSearchable("index");
+        refreshAndWaitForReplication();
+        // Force merge the index to ensure there can be no background merges during the subsequent searches that would invalidate the cache
+        ForceMergeResponse forceMergeResponse = client.admin().indices().prepareForceMerge("index").setFlush(true).get();
+        OpenSearchAssertions.assertAllSuccessful(forceMergeResponse);
+        long perQuerySizeInCacheInBytes = -1;
+        for (int iterator = 0; iterator < numberOfIndexedItems; iterator++) {
+            SearchResponse resp = client.prepareSearch("index")
+                .setRequestCache(true)
+                .setQuery(QueryBuilders.termQuery("k" + iterator, "hello" + iterator))
+                .get();
+            if (perQuerySizeInCacheInBytes == -1) {
+                RequestCacheStats requestCacheStats = getRequestCacheStats(client, "index");
+                perQuerySizeInCacheInBytes = requestCacheStats.getMemorySizeInBytes();
+            }
+            assertSearchResponse(resp);
+        }
+        RequestCacheStats requestCacheStats = getRequestCacheStats(client, "index");
+        // Considering disk cache won't be used due to took time policy having a high value, we expect overall cache
+        // size to be less than or equal to onHeapCache size.
+        assertTrue(requestCacheStats.getMemorySizeInBytes() <= onHeapCacheSizeInBytes);
+        assertEquals(numberOfIndexedItems, requestCacheStats.getMissCount());
+        // We should atleast one eviction considering disk cache isn't able to hold anything due to policy.
+        assertTrue(requestCacheStats.getEvictions() > 0);
+        assertEquals(0, requestCacheStats.getHitCount());
+        long lastEvictionSeen = requestCacheStats.getEvictions();
+
+        // Decrease took time policy to zero so that disk cache also comes into play. Now we should be able
+        // to cache all entries.
+        updateSettingsRequest = new ClusterUpdateSettingsRequest().transientSettings(
+            Settings.builder()
+                .put(
+                    TieredSpilloverCacheSettings.TOOK_TIME_POLICY_CONCRETE_SETTINGS_MAP.get(CacheType.INDICES_REQUEST_CACHE).getKey(),
+                    new TimeValue(0, TimeUnit.MILLISECONDS)
+                )
+                .build()
+        );
+        assertAcked(internalCluster().client().admin().cluster().updateSettings(updateSettingsRequest).get());
+        for (int iterator = 0; iterator < numberOfIndexedItems * 2; iterator++) {
+            SearchResponse resp = client.prepareSearch("index")
+                .setRequestCache(true)
+                .setQuery(QueryBuilders.termQuery(UUID.randomUUID().toString(), UUID.randomUUID().toString()))
+                .get();
+            assertSearchResponse(resp);
+        }
+
+        requestCacheStats = getRequestCacheStats(client, "index");
+        // We shouldn't see any new evictions now.
+        assertEquals(lastEvictionSeen, requestCacheStats.getEvictions());
+    }
+
     public void testWithDynamicTookTimePolicy() throws Exception {
         int onHeapCacheSizeInBytes = 2000;
-        internalCluster().startNode(Settings.builder().put(defaultSettings(onHeapCacheSizeInBytes + "b")).build());
+        internalCluster().startNode(Settings.builder().put(defaultSettings(onHeapCacheSizeInBytes + "b", 1)).build());
         Client client = client();
         assertAcked(
             client.admin()
@@ -271,9 +330,10 @@ public void testWithDynamicTookTimePolicy() throws Exception {
 
     public void testInvalidationWithIndicesRequestCache() throws Exception {
         int onHeapCacheSizeInBytes = 2000;
+        int numberOfSegments = getNumberOfSegments();
         internalCluster().startNode(
             Settings.builder()
-                .put(defaultSettings(onHeapCacheSizeInBytes + "b"))
+                .put(defaultSettings(onHeapCacheSizeInBytes + "b", numberOfSegments))
                 .put(INDICES_CACHE_CLEAN_INTERVAL_SETTING.getKey(), new TimeValue(1))
                 .build()
         );
@@ -354,10 +414,11 @@ public void testInvalidationWithIndicesRequestCache() throws Exception {
     }
 
     public void testWithExplicitCacheClear() throws Exception {
+        int numberOfSegments = getNumberOfSegments();
         int onHeapCacheSizeInBytes = 2000;
         internalCluster().startNode(
             Settings.builder()
-                .put(defaultSettings(onHeapCacheSizeInBytes + "b"))
+                .put(defaultSettings(onHeapCacheSizeInBytes + "b", numberOfSegments))
                 .put(INDICES_CACHE_CLEAN_INTERVAL_SETTING.getKey(), new TimeValue(1))
                 .build()
         );
@@ -426,10 +487,13 @@ public void testWithExplicitCacheClear() throws Exception {
     }
 
     public void testWithDynamicDiskCacheSetting() throws Exception {
-        int onHeapCacheSizeInBytes = 10; // Keep it low so that all items are cached onto disk.
+        int numberOfSegments = getNumberOfSegments();
+        int onHeapCacheSizeInBytes = randomIntBetween(numberOfSegments + 1, numberOfSegments * 2); // Keep it low so
+        // that all items are
+        // cached onto disk.
         internalCluster().startNode(
             Settings.builder()
-                .put(defaultSettings(onHeapCacheSizeInBytes + "b"))
+                .put(defaultSettings(onHeapCacheSizeInBytes + "b", numberOfSegments))
                 .put(INDICES_CACHE_CLEAN_INTERVAL_SETTING.getKey(), new TimeValue(1))
                 .build()
         );
@@ -540,6 +604,27 @@ public void testWithDynamicDiskCacheSetting() throws Exception {
         assertEquals(0, lastKnownHitCount - requestCacheStats.getHitCount());
     }
 
+    public void testWithInvalidSegmentNumberSetting() throws Exception {
+        int numberOfSegments = getNumberOfSegments();
+        int onHeapCacheSizeInBytes = randomIntBetween(numberOfSegments + 1, numberOfSegments * 2); // Keep it low so
+        // that all items are
+        // cached onto disk.
+        assertThrows(
+            String.format(
+                Locale.ROOT,
+                INVALID_SEGMENT_COUNT_EXCEPTION_MESSAGE,
+                TieredSpilloverCache.TieredSpilloverCacheFactory.TIERED_SPILLOVER_CACHE_NAME
+            ),
+            IllegalArgumentException.class,
+            () -> internalCluster().startNode(
+                Settings.builder()
+                    .put(defaultSettings(onHeapCacheSizeInBytes + "b", 300))
+                    .put(INDICES_CACHE_CLEAN_INTERVAL_SETTING.getKey(), new TimeValue(1))
+                    .build()
+            )
+        );
+    }
+
     private RequestCacheStats getRequestCacheStats(Client client, String indexName) {
         return client.admin().indices().prepareStats(indexName).setRequestCache(true).get().getTotal().getRequestCache();
     }
@@ -550,7 +635,7 @@ public MockDiskCachePlugin() {}
 
         @Override
         public Map<String, ICache.Factory> getCacheFactoryMap() {
-            return Map.of(MockDiskCache.MockDiskCacheFactory.NAME, new MockDiskCache.MockDiskCacheFactory(0, 1000, false));
+            return Map.of(MockDiskCache.MockDiskCacheFactory.NAME, new MockDiskCache.MockDiskCacheFactory(0, 10000, false, 1));
         }
 
         @Override