From f52f6f5052d8c610c38b8d6800821ea65fd61413 Mon Sep 17 00:00:00 2001
From: John Mazanec <jmazane@amazon.com>
Date: Wed, 16 Mar 2022 13:28:24 -0400
Subject: [PATCH] Add default for EnginePlugin.getEngineFactory (#2419)

Adds default implementation for getEngineFactory in EnginePlugin. The
default just returns Optional.empty(), allowing plugin developers to
implement this plugin without implementing this method.

Signed-off-by: John Mazanec <jmazane@amazon.com>
---
 .../java/org/opensearch/plugins/EnginePlugin.java |  4 +++-
 .../index/engine/EngineConfigFactoryTests.java    | 15 +++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/server/src/main/java/org/opensearch/plugins/EnginePlugin.java b/server/src/main/java/org/opensearch/plugins/EnginePlugin.java
index 4c3a07d7b98d9..31844dbdaec2b 100644
--- a/server/src/main/java/org/opensearch/plugins/EnginePlugin.java
+++ b/server/src/main/java/org/opensearch/plugins/EnginePlugin.java
@@ -56,7 +56,9 @@ public interface EnginePlugin {
      *
      * @return an optional engine factory
      */
-    Optional<EngineFactory> getEngineFactory(IndexSettings indexSettings);
+    default Optional<EngineFactory> getEngineFactory(IndexSettings indexSettings) {
+        return Optional.empty();
+    }
 
     /**
      * EXPERT:
diff --git a/server/src/test/java/org/opensearch/index/engine/EngineConfigFactoryTests.java b/server/src/test/java/org/opensearch/index/engine/EngineConfigFactoryTests.java
index a6bc87d53c004..8030619500278 100644
--- a/server/src/test/java/org/opensearch/index/engine/EngineConfigFactoryTests.java
+++ b/server/src/test/java/org/opensearch/index/engine/EngineConfigFactoryTests.java
@@ -146,6 +146,21 @@ public void testCreateCodecServiceFromFactory() {
         assertNotNull(config.getCodec());
     }
 
+    public void testGetEngineFactory() {
+        final EngineFactory engineFactory = config -> null;
+        EnginePlugin enginePluginThatImplementsGetEngineFactory = new EnginePlugin() {
+            @Override
+            public Optional<EngineFactory> getEngineFactory(IndexSettings indexSettings) {
+                return Optional.of(engineFactory);
+            }
+        };
+        assertEquals(engineFactory, enginePluginThatImplementsGetEngineFactory.getEngineFactory(null).orElse(null));
+
+        EnginePlugin enginePluginThatDoesNotImplementsGetEngineFactory = new EnginePlugin() {
+        };
+        assertFalse(enginePluginThatDoesNotImplementsGetEngineFactory.getEngineFactory(null).isPresent());
+    }
+
     private static class FooEnginePlugin extends Plugin implements EnginePlugin {
         @Override
         public Optional<EngineFactory> getEngineFactory(final IndexSettings indexSettings) {