[Tiered Caching] Add a memory-efficient key lookup store for use in tiered cache

.gitignore

@@ -64,4 +64,5 @@ testfixtures_shared/
 .ci/jobs/
 
 # build files generated
-doc-tools/missing-doclet/bin/
+doc-tools/missing-doclet/bin/
+server/src/main/java/org/opensearch/indices/KLSPerformanceTest.java

CHANGELOG.md

@@ -130,6 +130,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add match_only_text field that is optimized for storage by trading off positional queries performance ([#6836](https://github.com/opensearch-project/OpenSearch/pull/11039))
 - Add copy ingest processor ([#11870](https://github.com/opensearch-project/OpenSearch/pull/11870))
 - Introduce new feature flag "WRITEABLE_REMOTE_INDEX" to gate the writeable remote index functionality ([#11717](https://github.com/opensearch-project/OpenSearch/pull/11170))
+- [Tiered caching] Integrating ehcache as a disk cache option ([#11874](https://github.com/opensearch-project/OpenSearch/pull/11874))
 - Bump OpenTelemetry from 1.32.0 to 1.34.1 ([#11891](https://github.com/opensearch-project/OpenSearch/pull/11891))
 - Support index level allocation filtering for searchable snapshot index ([#11563](https://github.com/opensearch-project/OpenSearch/pull/11563))
 - Add `org.opensearch.rest.MethodHandlers` and `RestController#getAllHandlers` ([11876](https://github.com/opensearch-project/OpenSearch/pull/11876))

buildSrc/version.properties

@@ -72,3 +72,4 @@ resteasy          = 6.2.4.Final
 # opentelemetry dependencies
 opentelemetry         = 1.34.1
 opentelemetrysemconv  = 1.23.1-alpha
+ehcache = 3.10.8

plugins/cache-ehcache/build.gradle

@@ -0,0 +1,86 @@
+/*
+ * 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.
+ */
+
+import org.apache.tools.ant.taskdefs.condition.Os
+import org.opensearch.gradle.Architecture
+import org.opensearch.gradle.OS
+import org.opensearch.gradle.info.BuildParams
+
+opensearchplugin {
+  description 'Ehcache based cache implementation.'
+  classname 'org.opensearch.cache.EhcacheCachePlugin'
+  hasClientJar = true
+}
+
+dependencies {
+  // for ehcache
+  api "org.ehcache:ehcache:${versions.ehcache}"
+
+  // For roaring bitmaps
+  api 'org.roaringbitmap:RoaringBitmap:0.9.49'
+  runtimeOnly 'org.roaringbitmap:shims:0.9.49'
+}
+
+thirdPartyAudit {
+  ignoreViolations(
+    'org.ehcache.impl.internal.concurrent.ConcurrentHashMap',
+    'org.ehcache.impl.internal.concurrent.ConcurrentHashMap$CounterCell',
+    'org.ehcache.impl.internal.concurrent.ConcurrentHashMap$TreeBin',
+    'org.ehcache.impl.internal.concurrent.ThreadLocalRandomUtil',
+    'org.ehcache.sizeof.impl.UnsafeSizeOf'
+  )
+
+  ignoreMissingClasses(
+    'javax.cache.Cache',
+    'javax.cache.Cache$Entry',
+    'javax.cache.CacheException',
+    'javax.cache.CacheManager',
+    'javax.cache.configuration.CacheEntryListenerConfiguration',
+    'javax.cache.configuration.CompleteConfiguration',
+    'javax.cache.configuration.Configuration',
+    'javax.cache.configuration.Factory',
+    'javax.cache.configuration.OptionalFeature',
+    'javax.cache.event.CacheEntryCreatedListener',
+    'javax.cache.event.CacheEntryEvent',
+    'javax.cache.event.CacheEntryEventFilter',
+    'javax.cache.event.CacheEntryExpiredListener',
+    'javax.cache.event.CacheEntryListener',
+    'javax.cache.event.CacheEntryRemovedListener',
+    'javax.cache.event.CacheEntryUpdatedListener',
+    'javax.cache.event.EventType',
+    'javax.cache.expiry.Duration',
+    'javax.cache.expiry.EternalExpiryPolicy',
+    'javax.cache.expiry.ExpiryPolicy',
+    'javax.cache.integration.CacheLoader',
+    'javax.cache.integration.CacheLoaderException',
+    'javax.cache.integration.CacheWriter',
+    'javax.cache.integration.CacheWriterException',
+    'javax.cache.integration.CompletionListener',
+    'javax.cache.management.CacheMXBean',
+    'javax.cache.management.CacheStatisticsMXBean',
+    'javax.cache.processor.EntryProcessor',
+    'javax.cache.processor.EntryProcessorResult',
+    'javax.cache.processor.MutableEntry',
+    'javax.cache.spi.CachingProvider',
+    'javax.xml.bind.JAXBContext',
+    'javax.xml.bind.JAXBElement',
+    'javax.xml.bind.Marshaller',
+    'javax.xml.bind.Unmarshaller',
+    'javax.xml.bind.annotation.XmlElement',
+    'javax.xml.bind.annotation.XmlRootElement',
+    'javax.xml.bind.annotation.XmlSchema',
+    'javax.xml.bind.annotation.adapters.XmlAdapter',
+    'org.osgi.framework.BundleActivator',
+    'org.osgi.framework.BundleContext',
+    'org.osgi.framework.ServiceReference',
+    'org.slf4j.Logger',
+    'org.slf4j.LoggerFactory',
+    'org.slf4j.Marker',
+    'org.slf4j.event.Level'
+  )
+}

plugins/cache-ehcache/licenses/RoaringBitmap-0.9.49.jar.sha1

@@ -0,0 +1 @@
+b45b49c1ec5c5fc48580412d0ca635e1833110ea

plugins/cache-ehcache/licenses/RoaringBitmap-LICENSE.txt

@@ -0,0 +1,191 @@
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+http://www.apache.org/licenses/
+
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plugins/cache-ehcache/licenses/ehcache-3.10.8.jar.sha1

@@ -0,0 +1 @@
+f0d50ede46609db78413ca7f4250d348a597b101