ankitsultana commented on code in PR #10570: URL: https://github.com/apache/pinot/pull/10570#discussion_r1160344962
########## pinot-query-runtime/src/main/java/org/apache/pinot/query/runtime/operator/SortedMailboxReceiveOperator.java: ########## @@ -0,0 +1,202 @@ +/** + * 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.query.runtime.operator; + +import com.google.common.base.Preconditions; +import java.util.ArrayList; +import java.util.List; +import java.util.Map; +import java.util.PriorityQueue; +import javax.annotation.Nullable; +import org.apache.calcite.rel.RelDistribution; +import org.apache.calcite.rel.RelFieldCollation; +import org.apache.commons.collections.CollectionUtils; +import org.apache.pinot.common.datablock.DataBlock; +import org.apache.pinot.common.exception.QueryException; +import org.apache.pinot.common.utils.DataSchema; +import org.apache.pinot.query.mailbox.MailboxIdentifier; +import org.apache.pinot.query.mailbox.ReceivingMailbox; +import org.apache.pinot.query.planner.logical.RexExpression; +import org.apache.pinot.query.routing.VirtualServer; +import org.apache.pinot.query.runtime.blocks.TransferableBlock; +import org.apache.pinot.query.runtime.blocks.TransferableBlockUtils; +import org.apache.pinot.query.runtime.operator.utils.SortUtils; +import org.apache.pinot.query.runtime.plan.OpChainExecutionContext; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +/** + * This {@code SortedMailboxReceiveOperator} receives data from a {@link ReceivingMailbox} and serve it out from the + * {@link MultiStageOperator#getNextBlock()}()} API in a sorted manner. + * + * TODO: Once sorting on the {@code MailboxSendOperator} is available, modify this to use a k-way merge instead of + * resorting via the PriorityQueue. + */ +public class SortedMailboxReceiveOperator extends BaseMailboxReceiveOperator { + private static final Logger LOGGER = LoggerFactory.getLogger(SortedMailboxReceiveOperator.class); + private static final String EXPLAIN_NAME = "SORTED_MAILBOX_RECEIVE"; + + private final List<RexExpression> _collationKeys; + private final List<RelFieldCollation.Direction> _collationDirections; + private final boolean _isSortOnSender; + private final boolean _isSortOnReceiver; + private final DataSchema _dataSchema; + private final PriorityQueue<Object[]> _priorityQueue; + private boolean _isSortedBlockConstructed; + + public SortedMailboxReceiveOperator(OpChainExecutionContext context, RelDistribution.Type exchangeType, + List<RexExpression> collationKeys, List<RelFieldCollation.Direction> collationDirections, boolean isSortOnSender, + boolean isSortOnReceiver, DataSchema dataSchema, int senderStageId, int receiverStageId) { + this(context, context.getMetadataMap().get(senderStageId).getServerInstances(), exchangeType, collationKeys, + collationDirections, isSortOnSender, isSortOnReceiver, dataSchema, senderStageId, + receiverStageId, context.getTimeoutMs()); + } + + // TODO: Move deadlineInNanoSeconds to OperatorContext. + // TODO: Remove boxed timeoutMs value from here and use long deadlineMs from context. + public SortedMailboxReceiveOperator(OpChainExecutionContext context, List<VirtualServer> sendingStageInstances, + RelDistribution.Type exchangeType, List<RexExpression> collationKeys, + List<RelFieldCollation.Direction> collationDirections, boolean isSortOnSender, boolean isSortOnReceiver, + DataSchema dataSchema, int senderStageId, int receiverStageId, Long timeoutMs) { + super(context, sendingStageInstances, exchangeType, senderStageId, receiverStageId, timeoutMs); + _collationKeys = collationKeys; + _collationDirections = collationDirections; + _isSortOnSender = isSortOnSender; + _isSortOnReceiver = isSortOnReceiver; + _dataSchema = dataSchema; + Preconditions.checkState(!CollectionUtils.isEmpty(collationKeys) && isSortOnReceiver, + "Collation keys should exist and sorting must be enabled otherwise use non-sorted MailboxReceiveOperator"); + // No need to switch the direction since all rows will be stored in the priority queue without applying limits + _priorityQueue = new PriorityQueue<>(new SortUtils.SortComparator(collationKeys, collationDirections, + dataSchema, false, false)); + _isSortedBlockConstructed = false; + } + + @Nullable + @Override + public String toExplainString() { + return EXPLAIN_NAME; + } + + @Override + protected TransferableBlock getNextBlock() { + if (_upstreamErrorBlock != null) { + return _upstreamErrorBlock; + } else if (System.nanoTime() >= _deadlineTimestampNano) { + return TransferableBlockUtils.getErrorTransferableBlock(QueryException.EXECUTION_TIMEOUT_ERROR); + } + + int startingIdx = _serverIdx; + int openMailboxCount = 0; + int eosMailboxCount = 0; + boolean foundNonNullTransferableBlock; + // For all non-singleton distribution, we poll from every instance to check mailbox content. + // Since this operator needs to wait for all incoming data before it can send the data to the + // upstream operators, this operator will keep trying to poll from all mailboxes until it only + // receives null blocks or EOS for all mailboxes. This operator does not need to yield itself + // for backpressure at the moment but once support is added for k-way merge when input data is + // sorted this operator will have to return some data blocks without waiting for all the data. + // TODO: Fix wasted CPU cycles on waiting for servers that are not supposed to give content. + do { + // Reset the following for each loop + foundNonNullTransferableBlock = false; + openMailboxCount = 0; + eosMailboxCount = 0; + for (int i = 0; i < _sendingMailbox.size(); i++) { + // this implements a round-robin mailbox iterator, so we don't starve any mailboxes + _serverIdx = (startingIdx + i) % _sendingMailbox.size(); + MailboxIdentifier mailboxId = _sendingMailbox.get(_serverIdx); + try { + ReceivingMailbox<TransferableBlock> mailbox = _mailboxService.getReceivingMailbox(mailboxId); + if (!mailbox.isClosed()) { + openMailboxCount++; + TransferableBlock block = mailbox.receive(); + // Get null block when pulling times out from mailbox. + if (block != null) { + foundNonNullTransferableBlock = true; + if (block.isErrorBlock()) { + _upstreamErrorBlock = + TransferableBlockUtils.getErrorTransferableBlock(block.getDataBlock().getExceptions()); + return _upstreamErrorBlock; + } + if (!block.isEndOfStreamBlock()) { + // Add rows to the PriorityQueue to order them + List<Object[]> container = block.getContainer(); + _priorityQueue.addAll(container); + } else { + if (_opChainStats != null && !block.getResultMetadata().isEmpty()) { + for (Map.Entry<String, OperatorStats> entry : block.getResultMetadata().entrySet()) { + _opChainStats.getOperatorStatsMap().compute(entry.getKey(), (_key, _value) -> entry.getValue()); + } + } + eosMailboxCount++; + } + } + } + } catch (Exception e) { + return TransferableBlockUtils.getErrorTransferableBlock( + new RuntimeException(String.format("Error polling mailbox=%s", mailboxId), e)); + } + } + } while (foundNonNullTransferableBlock && ((openMailboxCount > 0) && (openMailboxCount > eosMailboxCount))); + + if (((openMailboxCount == 0) || (openMailboxCount == eosMailboxCount)) + && (!CollectionUtils.isEmpty(_priorityQueue)) && !_isSortedBlockConstructed) { + // Some data is present in the PriorityQueue, these need to be sent upstream + List<Object[]> rows = new ArrayList<>(); + while (_priorityQueue.size() > 0) { + Object[] row = _priorityQueue.poll(); + rows.add(row); + } + _isSortedBlockConstructed = true; + return new TransferableBlock(rows, _dataSchema, DataBlock.Type.ROW); + } + + // there are two conditions in which we should return EOS: (1) there were + // no mailboxes to open (this shouldn't happen because the second condition + // should be hit first, but is defensive) (2) every mailbox that was opened + // returned an EOS block. in every other scenario, there are mailboxes that + // are not yet exhausted and we should wait for more data to be available + TransferableBlock block = + openMailboxCount > 0 && openMailboxCount > eosMailboxCount ? TransferableBlockUtils.getNoOpTransferableBlock() + : TransferableBlockUtils.getEndOfStreamTransferableBlock(); + return block; + } + + private void cleanUpResources() { + if (_priorityQueue != null) { + _priorityQueue.clear(); + } + } + + @Override + public void close() { + super.close(); + cleanUpResources(); + } + + @Override + public void cancel(Throwable t) { + super.cancel(t); + if (_upstreamErrorBlock != null) { + cleanUpResources(); Review Comment: I think we should call this everytime. For example in line 153 we don't set the upstream error-block, and in the future there may be a few more edge cases. ``` } catch (Exception e) { return TransferableBlockUtils.getErrorTransferableBlock( new RuntimeException(String.format("Error polling mailbox=%s", mailboxId), e)); } ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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