Move get lifecycle API to Management thread pool and make cancellable (#97248)

* Move get lifecycle API to Management thread pool and make cancellable This commit moves the `TransportGetLifecycleAction` to execute on the `Management` thread pool, and to be cancellable so that wildcard requests looping through all or a subset of policies checks for cancellation while running. Resolves #96568

Author: dakrone

docs/changelog/97248.yaml

@@ -0,0 +1,6 @@
+pr: 97248
+summary: Move get lifecycle API to Management thread pool and make cancellable
+area: ILM+SLM
+type: enhancement
+issues:
+ - 96568

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ilm/action/GetLifecycleAction.java

@@ -16,13 +16,17 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.tasks.CancellableTask;
+import org.elasticsearch.tasks.Task;
+import org.elasticsearch.tasks.TaskId;
 import org.elasticsearch.xcontent.ToXContentObject;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xpack.core.ilm.LifecyclePolicy;
 
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 
 public class GetLifecycleAction extends ActionType<GetLifecycleAction.Response> {
@@ -113,6 +117,11 @@ public Request() {
  policyNames = Strings.EMPTY_ARRAY;
  }
 
+ @Override
+ public Task createTask(long id, String type, String action, TaskId parentTaskId, Map<String, String> headers) {
+ return new CancellableTask(id, type, action, "get-lifecycle-task", parentTaskId, headers);
+ }
+
  public String[] getPolicyNames() {
  return policyNames;
  }

x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/action/RestGetLifecycleAction.java

@@ -11,6 +11,7 @@
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.action.RestCancellableNodeClient;
 import org.elasticsearch.rest.action.RestToXContentListener;
 import org.elasticsearch.xpack.core.ilm.action.GetLifecycleAction;
 
@@ -37,6 +38,10 @@ protected RestChannelConsumer prepareRequest(RestRequest restRequest, NodeClient
  getLifecycleRequest.timeout(restRequest.paramAsTime("timeout", getLifecycleRequest.timeout()));
  getLifecycleRequest.masterNodeTimeout(restRequest.paramAsTime("master_timeout", getLifecycleRequest.masterNodeTimeout()));
 
- return channel -> client.execute(GetLifecycleAction.INSTANCE, getLifecycleRequest, new RestToXContentListener<>(channel));
+ return channel -> new RestCancellableNodeClient(client, restRequest.getHttpChannel()).execute(
+ GetLifecycleAction.INSTANCE,
+ getLifecycleRequest,
+ new RestToXContentListener<>(channel)
+ );
  }
 }

x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/action/TransportGetLifecycleAction.java

@@ -18,6 +18,7 @@
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.regex.Regex;
+import org.elasticsearch.tasks.CancellableTask;
 import org.elasticsearch.tasks.Task;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
@@ -55,12 +56,18 @@ public TransportGetLifecycleAction(
  Request::new,
  indexNameExpressionResolver,
  Response::new,
- ThreadPool.Names.SAME
+ ThreadPool.Names.MANAGEMENT
  );
  }
 
  @Override
  protected void masterOperation(Task task, Request request, ClusterState state, ActionListener<Response> listener) {
+ assert task instanceof CancellableTask : "get lifecycle requests should be cancellable";
+ final CancellableTask cancellableTask = (CancellableTask) task;
+ if (cancellableTask.notifyIfCancelled(listener)) {
+ return;
+ }
+
  IndexLifecycleMetadata metadata = clusterService.state().metadata().custom(IndexLifecycleMetadata.TYPE);
  if (metadata == null) {
  if (request.getPolicyNames().length == 0) {
@@ -88,6 +95,9 @@ protected void masterOperation(Task task, Request request, ClusterState state, A
  for (String name : names) {
  if (Regex.isSimpleMatchPattern(name)) {
  for (Map.Entry<String, LifecyclePolicyMetadata> entry : metadata.getPolicyMetadatas().entrySet()) {
+ if (cancellableTask.notifyIfCancelled(listener)) {
+ return;
+ }
  LifecyclePolicyMetadata policyMetadata = entry.getValue();
  if (Regex.simpleMatch(name, entry.getKey())) {
  policyResponseItemMap.put(