Handle index deletion while querying in ES|QL (#137702)

If the index is deleted while querying, ES|QL might try to get the index 
routing from the latest cluster state. This could throw an
index-not-found exception, which is not handled properly, causing the
user to never receive a response, even though execution has completed.
This also results in a dangling task in the task manager.

Relates #126653
Closes #135863

Author: dnhatn

docs/changelog/137702.yaml

@@ -0,0 +1,6 @@
+pr: 137702
+summary: Handle index deletion while querying in ES|QL
+area: ES|QL
+type: bug
+issues:
+ - 135863

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/EsqlRetryIT.java

@@ -8,6 +8,9 @@
 package org.elasticsearch.xpack.esql.action;
 
 import org.elasticsearch.action.index.IndexRequestBuilder;
+import org.elasticsearch.cluster.ClusterState;
+import org.elasticsearch.cluster.metadata.IndexMetadata;
+import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.index.IndexService;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.indices.IndicesService;
@@ -20,11 +23,14 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import static org.elasticsearch.index.shard.IndexShardTestCase.closeShardNoCheck;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.not;
 
 public class EsqlRetryIT extends AbstractEsqlIntegTestCase {
 
@@ -59,6 +65,37 @@ public void testRetryOnShardFailures() throws Exception {
         }
     }
 
+    public void testQueryWhileDeletingIndices() {
+        populateIndices();
+        CountDownLatch waitForDeletion = new CountDownLatch(1);
+        try {
+            final AtomicBoolean deleted = new AtomicBoolean();
+            for (String node : internalCluster().getNodeNames()) {
+                MockTransportService.getInstance(node)
+                    .addRequestHandlingBehavior(ComputeService.DATA_ACTION_NAME, (handler, request, channel, task) -> {
+                        if (deleted.compareAndSet(false, true)) {
+                            deleteIndexCompletely("log-index-2");
+                            waitForDeletion.countDown();
+                        } else {
+                            assertTrue(waitForDeletion.await(10, TimeUnit.SECONDS));
+                        }
+                        handler.messageReceived(request, channel, task);
+                    });
+            }
+            EsqlQueryRequest request = new EsqlQueryRequest();
+            request.query("FROM log-* | STATS COUNT(timestamp) | LIMIT 1");
+            request.allowPartialResults(true);
+            try (var resp = run(request)) {
+                assertTrue(resp.isPartial());
+                assertThat(EsqlTestUtils.getValuesList(resp).getFirst().getFirst(), equalTo(4L));
+            }
+        } finally {
+            for (String node : internalCluster().getNodeNames()) {
+                MockTransportService.getInstance(node).clearAllRules();
+            }
+        }
+    }
+
     private void populateIndices() {
         internalCluster().ensureAtLeastNumDataNodes(2);
         assertAcked(prepareCreate("log-index-1").setSettings(indexSettings(between(1, 3), 1)).setMapping("timestamp", "type=date"));
@@ -88,4 +125,36 @@ private void closeOrFailShards(String nodeName) throws Exception {
             }
         }
     }
+
+    /**
+     * Deletes the given index and ensures it is completely removed from the cluster state and from all nodes
+     */
+    private void deleteIndexCompletely(String indexName) throws Exception {
+        assertAcked(indicesAdmin().prepareDelete(indexName));
+        String[] nodeNames = internalCluster().getNodeNames();
+        assertBusy(() -> {
+            for (String nodeName : nodeNames) {
+                ClusterState clusterState = internalCluster().getInstance(ClusterService.class, nodeName).state();
+                for (IndexMetadata imd : clusterState.metadata().indicesAllProjects()) {
+                    assertThat(
+                        "Index [" + indexName + "] still exists in the cluster state on [" + nodeName + "]",
+                        imd.getIndex().getName(),
+                        not(equalTo(indexName))
+                    );
+                }
+            }
+            for (String nodeName : nodeNames) {
+                final IndicesService indicesService = internalCluster().getInstance(IndicesService.class, nodeName);
+                for (IndexService indexService : indicesService) {
+                    for (IndexShard indexShard : indexService) {
+                        assertThat(
+                            "Index [" + indexName + "] still exists on node [" + nodeName + "]",
+                            indexShard.shardId().getIndexName(),
+                            not(equalTo(indexName))
+                        );
+                    }
+                }
+            }
+        });
+    }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/DataNodeRequestSender.java

@@ -30,6 +30,8 @@
 import org.elasticsearch.index.Index;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.shard.ShardId;
+import org.elasticsearch.logging.LogManager;
+import org.elasticsearch.logging.Logger;
 import org.elasticsearch.search.SearchShardTarget;
 import org.elasticsearch.search.internal.AliasFilter;
 import org.elasticsearch.tasks.CancellableTask;
@@ -67,6 +69,8 @@
  */
 abstract class DataNodeRequestSender {
 
+    private static final Logger LOGGER = LogManager.getLogger(DataNodeRequestSender.class);
+
     /**
      * Query order according to the
      * <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/node-roles-overview.html">node roles</a>.
@@ -283,38 +287,53 @@ private void sendOneNodeRequest(TargetShards targetShards, ComputeListener compu
         final ActionListener<DriverCompletionInfo> listener = computeListener.acquireCompute();
         sendRequest(request.node, request.shards, request.aliasFilters, new NodeListener() {
 
-            void onAfter(DriverCompletionInfo info) {
+            void onAfterRequest() {
                 nodePermits.get(request.node).release();
                 if (concurrentRequests != null) {
                     concurrentRequests.release();
                 }
                 trySendingRequestsForPendingShards(targetShards, computeListener);
-                listener.onResponse(info);
             }
 
             @Override
             public void onResponse(DataNodeComputeResponse response) {
-                // remove failures of successful shards
-                for (DataNodeRequest.Shard shard : request.shards()) {
-                    if (response.shardLevelFailures().containsKey(shard.shardId()) == false) {
-                        shardFailures.remove(shard.shardId());
+                try {
+                    // remove failures of successful shards
+                    for (var shard : request.shards) {
+                        ShardId shardId = shard.shardId();
+                        if (response.shardLevelFailures().containsKey(shardId) == false) {
+                            shardFailures.remove(shardId);
+                        }
                     }
+                    for (var entry : response.shardLevelFailures().entrySet()) {
+                        final ShardId shardId = entry.getKey();
+                        trackShardLevelFailure(shardId, false, entry.getValue());
+                        pendingShardIds.add(shardId);
+                    }
+                    onAfterRequest();
+                } catch (Exception ex) {
+                    expectNoFailure("expect no failure while handling data node response", ex);
+                    listener.onFailure(ex);
+                    return;
                 }
-                for (var entry : response.shardLevelFailures().entrySet()) {
-                    final ShardId shardId = entry.getKey();
-                    trackShardLevelFailure(shardId, false, entry.getValue());
-                    pendingShardIds.add(shardId);
-                }
-                onAfter(response.completionInfo());
+                listener.onResponse(response.completionInfo());
             }
 
             @Override
             public void onFailure(Exception e, boolean receivedData) {
-                for (DataNodeRequest.Shard shard : request.shards) {
-                    trackShardLevelFailure(shard.shardId(), receivedData, e);
-                    pendingShardIds.add(shard.shardId());
+                try {
+                    for (var shard : request.shards) {
+                        ShardId shardId = shard.shardId();
+                        trackShardLevelFailure(shardId, receivedData, e);
+                        pendingShardIds.add(shardId);
+                    }
+                    onAfterRequest();
+                } catch (Exception ex) {
+                    expectNoFailure("expect no failure while handling failure of data node request", ex);
+                    listener.onFailure(ex);
+                    return;
                 }
-                onAfter(DriverCompletionInfo.EMPTY);
+                listener.onResponse(DriverCompletionInfo.EMPTY);
             }
 
             @Override
@@ -326,6 +345,11 @@ public void onSkip() {
                     onResponse(new DataNodeComputeResponse(DriverCompletionInfo.EMPTY, Map.of()));
                 }
             }
+
+            private void expectNoFailure(String message, Exception e) {
+                LOGGER.error(message, e);
+                assert false : new AssertionError(message, e);
+            }
         });
     }
 
@@ -527,15 +551,20 @@ Map<ShardId, List<DiscoveryNode>> resolveShards(Set<ShardId> shardIds) {
         var project = projectResolver.getProjectState(clusterService.state());
         var nodes = Maps.<ShardId, List<DiscoveryNode>>newMapWithExpectedSize(shardIds.size());
         for (var shardId : shardIds) {
-            nodes.put(
-                shardId,
-                project.routingTable()
+            List<DiscoveryNode> allocatedNodes;
+            try {
+                allocatedNodes = project.routingTable()
                     .shardRoutingTable(shardId)
                     .allShards()
                     .filter(shard -> shard.active() && shard.isSearchable())
                     .map(shard -> project.cluster().nodes().get(shard.currentNodeId()))
-                    .toList()
-            );
+                    .toList();
+            } catch (Exception ignored) {
+                // If the target index is deleted or the target shard is not found after the query has started,
+                // we skip resolving its new shard routing, and that shard will not be retried.
+                continue;
+            }
+            nodes.put(shardId, allocatedNodes);
         }
         return nodes;
     }