Fixing backward incompatibility check from #15473 (#15486)

* Fixing backward incompatibility check

Signed-off-by: Ankit Jain <[email protected]>

* Fixing spotless violations

Signed-off-by: Ankit Jain <[email protected]>

* Adding missing javadocs

Signed-off-by: Ankit Jain <[email protected]>

---------

Signed-off-by: Ankit Jain <[email protected]>

Author: jainankitk

server/src/main/java/org/opensearch/search/ResourceType.java

@@ -0,0 +1,66 @@
+/*
+ * 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.search;
+
+import org.opensearch.common.annotation.PublicApi;
+import org.opensearch.core.common.io.stream.StreamOutput;
+import org.opensearch.core.tasks.resourcetracker.ResourceStats;
+import org.opensearch.tasks.Task;
+
+import java.io.IOException;
+import java.util.function.Function;
+
+/**
+ * Enum to hold the resource type
+ */
+@PublicApi(since = "2.x")
+public enum ResourceType {
+    CPU("cpu", task -> task.getTotalResourceUtilization(ResourceStats.CPU)),
+    MEMORY("memory", task -> task.getTotalResourceUtilization(ResourceStats.MEMORY));
+
+    private final String name;
+    private final Function<Task, Long> getResourceUsage;
+
+    ResourceType(String name, Function<Task, Long> getResourceUsage) {
+        this.name = name;
+        this.getResourceUsage = getResourceUsage;
+    }
+
+    /**
+     * The string match here is case-sensitive
+     * @param s name matching the resource type name
+     * @return a {@link ResourceType}
+     */
+    public static ResourceType fromName(String s) {
+        for (ResourceType resourceType : values()) {
+            if (resourceType.getName().equals(s)) {
+                return resourceType;
+            }
+        }
+        throw new IllegalArgumentException("Unknown resource type: [" + s + "]");
+    }
+
+    public static void writeTo(StreamOutput out, ResourceType resourceType) throws IOException {
+        out.writeString(resourceType.getName());
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * Gets the resource usage for a given resource type and task.
+     *
+     * @param task the task for which to calculate resource usage
+     * @return the resource usage
+     */
+    public long getResourceUsage(Task task) {
+        return getResourceUsage.apply(task);
+    }
+}