Dart: Async queries to realtime servers. (#18241)

* Dart: Async queries to realtime servers.

Prior to this patch, queries from MSQ workers to data servers would
be initiated in the processing pool, and would block the processing
pool until results started coming in. This patch addresses it with
the strategy:

1) Update DataServerClient to return a future that resolves when the
   response starts being written.

2) Split DataServerQueryHandler into DartDataServerQueryHandler and
   IndexerDataServerQueryHandler. The Dart version doesn't do retries
   and doesn't follow segments to other data servers. It just returns
   the async future from DataServerClient. The Indexer (tasks) version
   retains the prior logic and isn't really async. I didn't attempt to
   asyncify its retry logic in this patch.

3) Add ReturnOrAwait.awaitAllFutures, which allows processors to wait
   for a future to resolve.

4) Update ScanQueryFrameProcessor and GroupByPreShuffleFrameProcessor
   to give up the processing thread when waiting for a data server query
   to come back.

Additionally, to simplify DataServerClient, cancellations are now
issued without using a scheduled executor. There should be no need for
this, because the service client is async.

* Fix tests and checkstyle.

* Fix exception checking.

Author: gianm

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/dart/guice/DartWorkerModule.java

@@ -19,6 +19,7 @@
 
 package org.apache.druid.msq.dart.guice;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.jsontype.NamedType;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import com.google.common.util.concurrent.MoreExecutors;
@@ -35,8 +36,10 @@
 import org.apache.druid.guice.LifecycleModule;
 import org.apache.druid.guice.ManageLifecycle;
 import org.apache.druid.guice.ManageLifecycleAnnouncements;
+import org.apache.druid.guice.annotations.EscalatedGlobal;
 import org.apache.druid.guice.annotations.LoadScope;
 import org.apache.druid.guice.annotations.Self;
+import org.apache.druid.guice.annotations.Smile;
 import org.apache.druid.initialization.DruidModule;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.java.util.common.concurrent.Execs;
@@ -50,6 +53,7 @@
 import org.apache.druid.msq.dart.controller.messages.ControllerMessage;
 import org.apache.druid.msq.dart.controller.sql.DartSqlEngine;
 import org.apache.druid.msq.dart.worker.DartDataSegmentProvider;
+import org.apache.druid.msq.dart.worker.DartDataServerQueryHandlerFactory;
 import org.apache.druid.msq.dart.worker.DartWorkerContextFactory;
 import org.apache.druid.msq.dart.worker.DartWorkerContextFactoryImpl;
 import org.apache.druid.msq.dart.worker.DartWorkerRunner;
@@ -58,6 +62,8 @@
 import org.apache.druid.msq.querykit.DataSegmentProvider;
 import org.apache.druid.msq.rpc.ResourcePermissionMapper;
 import org.apache.druid.query.DruidProcessingConfig;
+import org.apache.druid.query.QueryToolChestWarehouse;
+import org.apache.druid.rpc.ServiceClientFactory;
 import org.apache.druid.server.DruidNode;
 import org.apache.druid.server.security.AuthorizerMapper;
 
@@ -156,6 +162,20 @@ public Outbox<ControllerMessage> createOutbox()
     {
       return new OutboxImpl<>();
     }
+
+    @Provides
+    public DartDataServerQueryHandlerFactory createDataServerQueryHandlerFactory(
+        @EscalatedGlobal ServiceClientFactory serviceClientFactory,
+        @Smile ObjectMapper smileMapper,
+        QueryToolChestWarehouse queryToolChestWarehouse
+    )
+    {
+      return new DartDataServerQueryHandlerFactory(
+          serviceClientFactory,
+          smileMapper,
+          queryToolChestWarehouse
+      );
+    }
   }
 
   @Override

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/dart/worker/DartDataServerQueryHandler.java

@@ -0,0 +1,153 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.msq.dart.worker;
+
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.util.concurrent.ListenableFuture;
+import org.apache.druid.common.guava.FutureUtils;
+import org.apache.druid.discovery.DataServerClient;
+import org.apache.druid.error.DruidException;
+import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.java.util.common.guava.Sequence;
+import org.apache.druid.java.util.common.guava.Yielder;
+import org.apache.druid.java.util.common.io.Closer;
+import org.apache.druid.msq.counters.ChannelCounters;
+import org.apache.druid.msq.exec.DataServerQueryHandler;
+import org.apache.druid.msq.exec.DataServerQueryHandlerUtils;
+import org.apache.druid.msq.exec.DataServerQueryResult;
+import org.apache.druid.msq.input.table.DataServerRequestDescriptor;
+import org.apache.druid.msq.input.table.RichSegmentDescriptor;
+import org.apache.druid.query.Queries;
+import org.apache.druid.query.Query;
+import org.apache.druid.query.QueryToolChest;
+import org.apache.druid.query.QueryToolChestWarehouse;
+import org.apache.druid.query.SegmentDescriptor;
+import org.apache.druid.query.aggregation.MetricManipulatorFns;
+import org.apache.druid.query.context.DefaultResponseContext;
+import org.apache.druid.query.context.ResponseContext;
+import org.apache.druid.rpc.ServiceClientFactory;
+import org.apache.druid.rpc.ServiceLocation;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ * Dart implementation of {@link DataServerQueryHandler}. Issues queries asynchronously, with no retries.
+ */
+public class DartDataServerQueryHandler implements DataServerQueryHandler
+{
+  private final String dataSource;
+  private final ChannelCounters channelCounters;
+  private final ServiceClientFactory serviceClientFactory;
+  private final ObjectMapper objectMapper;
+  private final QueryToolChestWarehouse warehouse;
+  private final DataServerRequestDescriptor requestDescriptor;
+
+  public DartDataServerQueryHandler(
+      String dataSource,
+      ChannelCounters channelCounters,
+      ServiceClientFactory serviceClientFactory,
+      ObjectMapper objectMapper,
+      QueryToolChestWarehouse warehouse,
+      DataServerRequestDescriptor requestDescriptor
+  )
+  {
+    this.dataSource = dataSource;
+    this.channelCounters = channelCounters;
+    this.serviceClientFactory = serviceClientFactory;
+    this.objectMapper = objectMapper;
+    this.warehouse = warehouse;
+    this.requestDescriptor = requestDescriptor;
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * This method returns immediately. The returned future resolves when the server has started sending back
+   * its response.
+   *
+   * Queries are issued once, without retries.
+   */
+  @Override
+  public <RowType, QueryType> ListenableFuture<DataServerQueryResult<RowType>> fetchRowsFromDataServer(
+      Query<QueryType> query,
+      Function<Sequence<QueryType>, Sequence<RowType>> mappingFunction,
+      Closer closer
+  )
+  {
+    final Query<QueryType> preparedQuery =
+        Queries.withSpecificSegments(
+            DataServerQueryHandlerUtils.prepareQuery(query, dataSource),
+            requestDescriptor.getSegments()
+                             .stream()
+                             .map(RichSegmentDescriptor::toPlainDescriptor)
+                             .collect(Collectors.toList())
+        );
+
+    final ServiceLocation serviceLocation =
+        ServiceLocation.fromDruidServerMetadata(requestDescriptor.getServerMetadata());
+    final DataServerClient dataServerClient = makeDataServerClient(serviceLocation);
+    final QueryToolChest<QueryType, Query<QueryType>> toolChest = warehouse.getToolChest(query);
+    final Function<QueryType, QueryType> preComputeManipulatorFn =
+        toolChest.makePreComputeManipulatorFn(query, MetricManipulatorFns.deserializing());
+    final JavaType queryResultType = toolChest.getBaseResultType();
+    final ResponseContext responseContext = new DefaultResponseContext();
+
+    return FutureUtils.transform(
+        dataServerClient.run(preparedQuery, responseContext, queryResultType, closer),
+        resultSequence -> {
+          final Yielder<RowType> yielder = DataServerQueryHandlerUtils.createYielder(
+              resultSequence.map(preComputeManipulatorFn),
+              mappingFunction,
+              channelCounters
+          );
+
+          final List<SegmentDescriptor> missingSegments =
+              DataServerQueryHandlerUtils.getMissingSegments(responseContext);
+
+          if (!missingSegments.isEmpty()) {
+            throw DruidException
+                .forPersona(DruidException.Persona.USER)
+                .ofCategory(DruidException.Category.RUNTIME_FAILURE)
+                .build(
+                    "Segment[%s]%s not found on server[%s]. Please retry your query.",
+                    missingSegments.get(0),
+                    missingSegments.size() > 1 ? StringUtils.format(" and[%d] others", missingSegments.size() - 1) : "",
+                    serviceLocation.getHostAndPort()
+                );
+          }
+
+          return new DataServerQueryResult<>(
+              Collections.singletonList(yielder),
+              Collections.emptyList(),
+              dataSource
+          );
+        }
+    );
+  }
+
+  private DataServerClient makeDataServerClient(ServiceLocation serviceLocation)
+  {
+    return new DataServerClient(serviceClientFactory, serviceLocation, objectMapper);
+  }
+}

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/dart/worker/DartDataServerQueryHandlerFactory.java

@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.msq.dart.worker;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.druid.msq.counters.ChannelCounters;
+import org.apache.druid.msq.exec.DataServerQueryHandlerFactory;
+import org.apache.druid.msq.input.table.DataServerRequestDescriptor;
+import org.apache.druid.query.QueryToolChestWarehouse;
+import org.apache.druid.rpc.ServiceClientFactory;
+
+/**
+ * Factory for {@link DartDataServerQueryHandler}.
+ */
+public class DartDataServerQueryHandlerFactory implements DataServerQueryHandlerFactory
+{
+  private final ServiceClientFactory serviceClientFactory;
+  private final ObjectMapper objectMapper;
+  private final QueryToolChestWarehouse warehouse;
+
+  public DartDataServerQueryHandlerFactory(
+      ServiceClientFactory serviceClientFactory,
+      ObjectMapper objectMapper,
+      QueryToolChestWarehouse warehouse
+  )
+  {
+    this.serviceClientFactory = serviceClientFactory;
+    this.objectMapper = objectMapper;
+    this.warehouse = warehouse;
+  }
+
+  @Override
+  public DartDataServerQueryHandler createDataServerQueryHandler(
+      String dataSource,
+      ChannelCounters channelCounters,
+      DataServerRequestDescriptor requestDescriptor
+  )
+  {
+    return new DartDataServerQueryHandler(
+        dataSource,
+        channelCounters,
+        serviceClientFactory,
+        objectMapper,
+        warehouse,
+        requestDescriptor
+    );
+  }
+}

extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/dart/worker/DartWorkerContextFactoryImpl.java

@@ -22,7 +22,6 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.inject.Inject;
 import com.google.inject.Injector;
-import org.apache.druid.client.coordinator.CoordinatorClient;
 import org.apache.druid.guice.annotations.EscalatedGlobal;
 import org.apache.druid.guice.annotations.Json;
 import org.apache.druid.guice.annotations.Self;
@@ -31,14 +30,12 @@
 import org.apache.druid.messages.server.Outbox;
 import org.apache.druid.msq.dart.Dart;
 import org.apache.druid.msq.dart.controller.messages.ControllerMessage;
-import org.apache.druid.msq.exec.DataServerQueryHandlerFactory;
 import org.apache.druid.msq.exec.MemoryIntrospector;
 import org.apache.druid.msq.exec.ProcessingBuffersProvider;
 import org.apache.druid.msq.exec.WorkerContext;
 import org.apache.druid.msq.querykit.DataSegmentProvider;
 import org.apache.druid.query.DruidProcessingConfig;
 import org.apache.druid.query.QueryContext;
-import org.apache.druid.query.QueryToolChestWarehouse;
 import org.apache.druid.query.groupby.GroupingEngine;
 import org.apache.druid.query.policy.PolicyEnforcer;
 import org.apache.druid.rpc.ServiceClientFactory;
@@ -65,8 +62,7 @@ public class DartWorkerContextFactoryImpl implements DartWorkerContextFactory
   private final MemoryIntrospector memoryIntrospector;
   private final ProcessingBuffersProvider processingBuffersProvider;
   private final Outbox<ControllerMessage> outbox;
-  private final CoordinatorClient coordinatorClient;
-  private final QueryToolChestWarehouse warehouse;
+  private final DartDataServerQueryHandlerFactory dataServerQueryHandlerFactory;
   private final ServiceEmitter emitter;
 
   @Inject
@@ -84,8 +80,7 @@ public DartWorkerContextFactoryImpl(
       MemoryIntrospector memoryIntrospector,
       @Dart ProcessingBuffersProvider processingBuffersProvider,
       Outbox<ControllerMessage> outbox,
-      CoordinatorClient coordinatorClient,
-      QueryToolChestWarehouse warehouse,
+      DartDataServerQueryHandlerFactory dataServerQueryHandlerFactory,
       ServiceEmitter emitter
   )
   {
@@ -102,8 +97,7 @@ public DartWorkerContextFactoryImpl(
     this.memoryIntrospector = memoryIntrospector;
     this.processingBuffersProvider = processingBuffersProvider;
     this.outbox = outbox;
-    this.coordinatorClient = coordinatorClient;
-    this.warehouse = warehouse;
+    this.dataServerQueryHandlerFactory = dataServerQueryHandlerFactory;
     this.emitter = emitter;
   }
 
@@ -132,12 +126,7 @@ public WorkerContext build(
         outbox,
         tempDir,
         queryContext,
-        new DataServerQueryHandlerFactory(
-            coordinatorClient,
-            serviceClientFactory,
-            jsonMapper,
-            warehouse
-        ),
+        dataServerQueryHandlerFactory,
         emitter
     );
   }