Jackie-Jiang commented on code in PR #9808:
URL: https://github.com/apache/pinot/pull/9808#discussion_r1034106995
##########
pinot-common/src/main/java/org/apache/pinot/common/assignment/InstancePartitions.java:
##########
@@ -134,6 +134,10 @@ public InstancePartitions withName(String newName) {
return new InstancePartitions(newName, getPartitionToInstancesMap());
}
+ public InstancePartitions createCopy() {
Review Comment:
This is not needed (see the above comment). Also, this is creating a shallow
copy, which actually shares the underlying map
##########
pinot-broker/src/main/java/org/apache/pinot/broker/routing/instanceselector/MultiStageStrictReplicaGroupSelector.java:
##########
@@ -0,0 +1,150 @@
+/**
+ * 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.pinot.broker.routing.instanceselector;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import javax.annotation.Nullable;
+import org.apache.helix.model.ExternalView;
+import org.apache.helix.model.IdealState;
+import org.apache.helix.store.zk.ZkHelixPropertyStore;
+import org.apache.helix.zookeeper.datamodel.ZNRecord;
+import
org.apache.pinot.broker.routing.adaptiveserverselector.AdaptiveServerSelector;
+import org.apache.pinot.common.assignment.InstancePartitions;
+import org.apache.pinot.common.assignment.InstancePartitionsUtils;
+import org.apache.pinot.common.metrics.BrokerMetrics;
+import org.apache.pinot.spi.config.table.TableType;
+import org.apache.pinot.spi.config.table.assignment.InstancePartitionsType;
+import org.apache.pinot.spi.utils.builder.TableNameBuilder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * Instance selector for multi-stage queries which can ensure that Colocated
Tables always leverage Colocated Join
+ * whenever possible. To achieve this, this instance-selector uses
InstancePartitions (IP) to determine replica-groups,
+ * as opposed to IdealState used by other instance-selectors. Moreover, this
also uses the requestId generated by
+ * Pinot broker to determine the replica-group picked for each table involved
in the query, as opposed to using a
+ * member variable. There may be scenarios where an instance in the chosen
replica-group is down. In that case, this
+ * strategy will try to pick another replica-group. For realtime tables, this
strategy uses only CONSUMING partitions.
+ * This is feature is in <strong>Beta</strong>.
+ */
+public class MultiStageStrictReplicaGroupSelector extends BaseInstanceSelector
{
+ private static final Logger LOGGER =
LoggerFactory.getLogger(MultiStageStrictReplicaGroupSelector.class);
+
+ private final String _tableNameWithType;
+ private final ZkHelixPropertyStore<ZNRecord> _propertyStore;
+ private InstancePartitions _instancePartitions;
+
+ public MultiStageStrictReplicaGroupSelector(String tableNameWithType,
ZkHelixPropertyStore<ZNRecord> propertyStore,
+ BrokerMetrics brokerMetrics, @Nullable AdaptiveServerSelector
adaptiveServerSelector) {
+ super(tableNameWithType, brokerMetrics, adaptiveServerSelector);
+ _tableNameWithType = tableNameWithType;
+ _propertyStore = propertyStore;
+ }
+
+ @Override
+ public void init(Set<String> enabledInstances, IdealState idealState,
ExternalView externalView,
+ Set<String> onlineSegments) {
+ super.init(enabledInstances, idealState, externalView, onlineSegments);
+ _instancePartitions = getInstancePartitions();
+ }
+
+ @Override
+ public void onInstancesChange(Set<String> enabledInstances, List<String>
changedInstances) {
+ super.onInstancesChange(enabledInstances, changedInstances);
+ _instancePartitions = getInstancePartitions();
+ }
+
+ @Override
+ public void onAssignmentChange(IdealState idealState, ExternalView
externalView, Set<String> onlineSegments) {
+ super.onAssignmentChange(idealState, externalView, onlineSegments);
+ _instancePartitions = getInstancePartitions();
+ }
+
+ @Override
+ Map<String, String> select(List<String> segments, int requestId,
+ Map<String, List<String>> segmentToEnabledInstancesMap, Map<String,
String> queryOptions) {
+ // Create a copy of InstancePartitions to avoid race-condition with
event-listeners above.
+ InstancePartitions localInstancePartitions =
_instancePartitions.createCopy();
Review Comment:
We don't need to create a copy here. Instead, you may define
`_instancePartitions` as `volatile`, and assign it to a local variable
```suggestion
InstancePartitions instancePartitions = _instancePartitions;
```
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