peteralfonsi
diff --git a/‎DEVELOPER_GUIDE.md
+7-1 b/‎DEVELOPER_GUIDE.md
+7-1
diff --git a/‎distribution/src/config/opensearch.yml
+3 b/‎distribution/src/config/opensearch.yml
+3
diff --git a/‎gradle/run.gradle
+6 b/‎gradle/run.gradle
+6
diff --git a/‎libs/core/src/main/java/org/opensearch/core/common/bytes/BytesReference.java
+5 b/‎libs/core/src/main/java/org/opensearch/core/common/bytes/BytesReference.java
+5
diff --git a/‎libs/core/src/main/java/org/opensearch/core/common/io/stream/StreamInput.java
+39-1 b/‎libs/core/src/main/java/org/opensearch/core/common/io/stream/StreamInput.java
+39-1
diff --git a/‎libs/core/src/main/java/org/opensearch/core/index/shard/ShardId.java
+7 b/‎libs/core/src/main/java/org/opensearch/core/index/shard/ShardId.java
+7
diff --git a/‎modules/cache-common/build.gradle
+19 b/‎modules/cache-common/build.gradle
+19
@@ -183,6 +183,12 @@ Run OpenSearch using `gradlew run`.
 ./gradlew run
 ```
 
+[Plugins](plugins/) may be installed by passing a `-PinstalledPlugins` property:
+
+```bash
+./gradlew run -PinstalledPlugins="['plugin1', 'plugin2']"
+```
+
 That will build OpenSearch and start it, writing its log above Gradle's status message. We log a lot of stuff on startup, specifically these lines tell you that OpenSearch is ready.
 
 ```
@@ -578,7 +584,7 @@ explicitly marked by an annotation should not be extended by external implementa
 any time. The `@DeprecatedApi` annotation could also be added to any classes annotated with `@PublicApi` (or documented as `@opensearch.api`) or their methods that
 are either changed (with replacement) or planned to be removed across major versions.
 
-The APIs which are designated to be public but have not been stabilized yet should be marked with `@ExperimentalApi` (or documented as `@opensearch.experimental`) 
+The APIs which are designated to be public but have not been stabilized yet should be marked with `@ExperimentalApi` (or documented as `@opensearch.experimental`)
 annotation. The presence of this annotation signals that API may change at any time (major, minor or even patch releases). In general, the classes annotated with
 `@PublicApi` may expose other classes or methods annotated with `@ExperimentalApi`, in such cases the backward compatibility guarantees would not apply to latter
 (see please [Experimental Development](#experimental-development) for more details).
 
@@ -121,3 +121,6 @@ ${path.logs}
 # index searcher threadpool.
 #
 #opensearch.experimental.feature.concurrent_segment_search.enabled: false
+# Gates the functionality of enabling Opensearch to use pluggable caches with respective store names via setting.
+#
+#opensearch.experimental.feature.pluggable.caching.enabled: false
@@ -34,6 +34,12 @@ apply plugin: 'opensearch.testclusters'
 testClusters {
   runTask {
     testDistribution = 'archive'
+    if (findProperty("installedPlugins")) {
+      installedPlugins = Eval.me(installedPlugins)
+      for (String p : installedPlugins) {
+        plugin('plugins:'.concat(p))
+      }
+    }
   }
 }
 
 
@@ -82,6 +82,11 @@ static byte[] toBytes(BytesReference reference) {
         return ArrayUtil.copyOfSubArray(bytesRef.bytes, bytesRef.offset, bytesRef.offset + bytesRef.length);
     }
 
+    static byte[] toBytesWithoutCompact(BytesReference reference) {
+        final BytesRef bytesRef = reference.toBytesRef();
+        return bytesRef.bytes;
+    }
+
     /**
      * Returns an array of byte buffers from the given BytesReference.
      */
 
@@ -79,6 +79,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Date;
 import java.util.EnumSet;
 import java.util.HashMap;
@@ -89,6 +90,8 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
+import java.util.SortedMap;
+import java.util.TreeMap;
 import java.util.concurrent.TimeUnit;
 import java.util.function.IntFunction;
 
@@ -641,12 +644,47 @@ public <K, V> Map<K, V> readMap(Writeable.Reader<K> keyReader, Writeable.Reader<
             return Collections.emptyMap();
         }
         Map<K, V> map = new HashMap<>(size);
+        readIntoMap(keyReader, valueReader, map, size);
+        return map;
+    }
+
+    /**
+     * Read a serialized map into a SortedMap using the default ordering for the keys. If the result is empty it might be immutable.
+     */
+    public <K extends Comparable<K>, V> SortedMap<K, V> readOrderedMap(Writeable.Reader<K> keyReader, Writeable.Reader<V> valueReader)
+        throws IOException {
+        return readOrderedMap(keyReader, valueReader, null);
+    }
+
+    /**
+     * Read a serialized map into a SortedMap, specifying a Comparator for the keys. If the result is empty it might be immutable.
+     */
+    public <K extends Comparable<K>, V> SortedMap<K, V> readOrderedMap(
+        Writeable.Reader<K> keyReader,
+        Writeable.Reader<V> valueReader,
+        @Nullable Comparator<K> keyComparator
+    ) throws IOException {
+        int size = readArraySize();
+        if (size == 0) {
+            return Collections.emptySortedMap();
+        }
+        SortedMap<K, V> sortedMap;
+        if (keyComparator == null) {
+            sortedMap = new TreeMap<>();
+        } else {
+            sortedMap = new TreeMap<>(keyComparator);
+        }
+        readIntoMap(keyReader, valueReader, sortedMap, size);
+        return sortedMap;
+    }
+
+    private <K, V> void readIntoMap(Writeable.Reader<K> keyReader, Writeable.Reader<V> valueReader, Map<K, V> map, int size)
+        throws IOException {
         for (int i = 0; i < size; i++) {
             K key = keyReader.read(this);
             V value = valueReader.read(this);
             map.put(key, value);
         }
-        return map;
     }
 
     /**
 
@@ -32,6 +32,7 @@
 
 package org.opensearch.core.index.shard;
 
+import org.apache.lucene.util.RamUsageEstimator;
 import org.opensearch.common.annotation.PublicApi;
 import org.opensearch.core.common.Strings;
 import org.opensearch.core.common.io.stream.StreamInput;
@@ -55,6 +56,8 @@ public class ShardId implements Comparable<ShardId>, ToXContentFragment, Writeab
     private final int shardId;
     private final int hashCode;
 
+    private final static long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(ShardId.class);
+
     /**
      * Constructs a new shard id.
      * @param index the index name
@@ -88,6 +91,10 @@ public ShardId(StreamInput in) throws IOException {
         hashCode = computeHashCode();
     }
 
+    public long getBaseRamBytesUsed() {
+        return BASE_RAM_BYTES_USED;
+    }
+
     /**
      * Writes this shard id to a stream.
      * @param out the stream to write to
 
@@ -0,0 +1,19 @@
+/*
+ * 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.
+ */
+
+apply plugin: 'opensearch.internal-cluster-test'
+
+opensearchplugin {
+  description 'Module for caches which are optional and do not require additional security permission'
+  classname 'org.opensearch.cache.common.tier.TieredSpilloverCachePlugin'
+}
+
+test {
+  // TODO: Adding permission in plugin-security.policy doesn't seem to work.
+  systemProperty 'tests.security.manager', 'false'
+}
Original file line number	Diff line number	Diff line change
`@@ -121,3 +121,6 @@ ${path.logs}`
`121`	`121`	`# index searcher threadpool.`
`122`	`122`	`#`
`123`	`123`	`#opensearch.experimental.feature.concurrent_segment_search.enabled: false`
	`124`	`+# Gates the functionality of enabling Opensearch to use pluggable caches with respective store names via setting.`
	`125`	`+#`
	`126`	`+#opensearch.experimental.feature.pluggable.caching.enabled: false`
Original file line number	Diff line number	Diff line change
`@@ -34,6 +34,12 @@ apply plugin: 'opensearch.testclusters'`
`34`	`34`	`testClusters {`
`35`	`35`	`runTask {`
`36`	`36`	`testDistribution = 'archive'`
	`37`	`+ if (findProperty("installedPlugins")) {`
	`38`	`+ installedPlugins = Eval.me(installedPlugins)`
	`39`	`+ for (String p : installedPlugins) {`
	`40`	`+ plugin('plugins:'.concat(p))`
	`41`	`+ }`
	`42`	`+ }`
`37`	`43`	`}`
`38`	`44`	`}`
`39`	`45`