POC for hollow shard

Author: kingherc

server/src/main/java/org/elasticsearch/index/IndexService.java

@@ -282,6 +282,11 @@ public IndexService(
     }
 
     static boolean needsMapperService(IndexSettings indexSettings, IndexCreationContext indexCreationContext) {
+        // if (indexSettings.getSettings().get("index.provided_name").equals(".ds-gharchive-2024.11.22-000025")) {
+        // return true;
+        // } else {
+        // return false;
+        // }
         return false == (indexSettings.getIndexMetadata().getState() == IndexMetadata.State.CLOSE
             && indexCreationContext == IndexCreationContext.CREATE_INDEX); // metadata verification needs a mapper service
     }

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -4263,6 +4263,28 @@ public void afterRefresh(boolean didRefresh) {
         }
     }
 
+    public void myReset(ActionListener<Void> listener) throws IOException {
+        ActionListener.run(ActionListener.<Void>wrap(ignored -> {
+            ActionListener.run(listener, l -> {
+                final EngineConfig config = newEngineConfig(replicationTracker);
+                config.setEnableGcDeletes(false);
+                synchronized (engineMutex) {
+                    IOUtils.close(currentEngineReference.get());
+                    final Engine newEngine = createEngine(config);
+                    currentEngineReference.set(newEngine);
+                    onNewEngine(newEngine);
+                    active.set(true);
+                }
+                onSettingsChanged();
+                checkAndCallWaitForEngineOrClosedShardListeners();
+
+                getEngine().skipTranslogRecovery();
+                getEngine().refresh("post_recovery");
+                indexEventListener.afterIndexShardRecovery(this, l);
+            });
+        }, e -> { listener.onFailure(e); }), l -> indexEventListener.beforeIndexShardRecovery(this, indexSettings, l));
+    }
+
     /**
      * Rollback the current engine to the safe commit, then replay local translog up to the global checkpoint.
      */

server/src/main/java/org/elasticsearch/node/NodeConstruction.java

@@ -221,6 +221,7 @@
 import java.io.Closeable;
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.lang.management.ManagementFactory;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -538,15 +539,17 @@ private SettingsModule validateSettings(Settings envSettings, Settings settings,
         // after settings validation.
         nodeEnvironment = new NodeEnvironment(envSettings, environment);
         logger.info(
-            "node name [{}], node ID [{}], cluster name [{}], roles {}",
+            "node name [{}], node ID [{}], cluster name [{}], roles {}, myPID {}",
             Node.NODE_NAME_SETTING.get(envSettings),
             nodeEnvironment.nodeId(),
             ClusterName.CLUSTER_NAME_SETTING.get(envSettings).value(),
             DiscoveryNode.getRolesFromSettings(settings)
                 .stream()
                 .map(DiscoveryNodeRole::roleName)
-                .collect(Collectors.toCollection(LinkedHashSet::new))
+                .collect(Collectors.toCollection(LinkedHashSet::new)),
+            ManagementFactory.getRuntimeMXBean().getName()
         );
+
         resourcesToClose.add(nodeEnvironment);
         modules.bindToInstance(NodeEnvironment.class, nodeEnvironment);