gianm commented on code in PR #13506: URL: https://github.com/apache/druid/pull/13506#discussion_r1127471391
########## extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/querykit/common/SortMergeJoinFrameProcessor.java: ########## @@ -0,0 +1,1075 @@ +/* + * 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.querykit.common; + +import com.google.common.base.Preconditions; +import com.google.common.base.Predicate; +import com.google.common.collect.ImmutableList; +import it.unimi.dsi.fastutil.ints.IntOpenHashSet; +import it.unimi.dsi.fastutil.ints.IntSet; +import org.apache.druid.frame.Frame; +import org.apache.druid.frame.channel.FrameWithPartition; +import org.apache.druid.frame.channel.ReadableFrameChannel; +import org.apache.druid.frame.channel.WritableFrameChannel; +import org.apache.druid.frame.key.FrameComparisonWidget; +import org.apache.druid.frame.key.KeyColumn; +import org.apache.druid.frame.key.RowKey; +import org.apache.druid.frame.key.RowKeyReader; +import org.apache.druid.frame.processor.FrameProcessor; +import org.apache.druid.frame.processor.FrameProcessors; +import org.apache.druid.frame.processor.FrameRowTooLargeException; +import org.apache.druid.frame.processor.ReturnOrAwait; +import org.apache.druid.frame.read.FrameReader; +import org.apache.druid.frame.segment.FrameCursor; +import org.apache.druid.frame.write.FrameWriter; +import org.apache.druid.frame.write.FrameWriterFactory; +import org.apache.druid.java.util.common.ISE; +import org.apache.druid.msq.exec.Limits; +import org.apache.druid.msq.indexing.error.MSQException; +import org.apache.druid.msq.indexing.error.TooManyRowsWithSameKeyFault; +import org.apache.druid.msq.input.ReadableInput; +import org.apache.druid.query.dimension.DefaultDimensionSpec; +import org.apache.druid.query.dimension.DimensionSpec; +import org.apache.druid.query.filter.ValueMatcher; +import org.apache.druid.query.monomorphicprocessing.RuntimeShapeInspector; +import org.apache.druid.segment.ColumnSelectorFactory; +import org.apache.druid.segment.ColumnValueSelector; +import org.apache.druid.segment.Cursor; +import org.apache.druid.segment.DimensionSelector; +import org.apache.druid.segment.DimensionSelectorUtils; +import org.apache.druid.segment.IdLookup; +import org.apache.druid.segment.NilColumnValueSelector; +import org.apache.druid.segment.column.ColumnCapabilities; +import org.apache.druid.segment.column.RowSignature; +import org.apache.druid.segment.data.IndexedInts; +import org.apache.druid.segment.data.ZeroIndexedInts; +import org.apache.druid.segment.join.JoinPrefixUtils; +import org.apache.druid.segment.join.JoinType; + +import javax.annotation.Nullable; +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; + +/** + * Processor for a sort-merge join of two inputs. + * + * Prerequisites: + * + * 1) Two inputs, both of which are stages; i.e. {@link ReadableInput#hasChannel()}. + * + * 2) Conditions are all simple equalities. Validated by {@link SortMergeJoinFrameProcessorFactory#validateCondition} + * and then transformed to lists of key columns by {@link SortMergeJoinFrameProcessorFactory#toKeyColumns}. + * + * 3) Both inputs are comprised of {@link org.apache.druid.frame.FrameType#ROW_BASED} frames, are sorted by the same + * key, and that key can be used to check the provided condition. Validated by + * {@link SortMergeJoinFrameProcessorFactory#validateInputFrameSignatures}. + * + * Algorithm: + * + * 1) Read current key from each side of the join. + * + * 2) If there is no match, emit or skip the row for the earlier key, as appropriate, based on the join type. + * + * 3) If there is a match, identify a complete set on one side or the other. (It doesn't matter which side has the + * complete set, but we need it on one of them.) We mark the first row for the key using {@link Tracker#markCurrent()} + * and find complete sets using {@link Tracker#hasCompleteSetForMark()}. Once we find one, we store it in + * {@link #trackerWithCompleteSetForCurrentKey}. If both sides have a complete set, we break ties by choosing the + * left side. + * + * 4) Once a complete set for the current key is identified: for each row on the *other* side, loop through the entire + * set of rows on {@link #trackerWithCompleteSetForCurrentKey}, and emit that many joined rows. + * + * 5) Once we process the final row on the *other* side, reset both marks with {@link Tracker#markCurrent()} and + * continue the algorithm. + */ +public class SortMergeJoinFrameProcessor implements FrameProcessor<Long> +{ + private static final int LEFT = 0; + private static final int RIGHT = 1; + + /** + * Input channels for each side of the join. Two-element array: {@link #LEFT} and {@link #RIGHT}. + */ + private final List<ReadableFrameChannel> inputChannels; + + /** + * Trackers for each side of the join. Two-element array: {@link #LEFT} and {@link #RIGHT}. + */ + private final List<Tracker> trackers; + + private final WritableFrameChannel outputChannel; + private final FrameWriterFactory frameWriterFactory; + private final String rightPrefix; + private final JoinType joinType; + private final JoinColumnSelectorFactory joinColumnSelectorFactory = new JoinColumnSelectorFactory(); + private FrameWriter frameWriter = null; + + // Used by runIncrementally to defer certain logic to the next run. + private Runnable nextIterationRunnable = null; + + // Used by runIncrementally to remember which tracker has the complete set for the current key. + private int trackerWithCompleteSetForCurrentKey = -1; + + SortMergeJoinFrameProcessor( + ReadableInput left, + ReadableInput right, + WritableFrameChannel outputChannel, + FrameWriterFactory frameWriterFactory, + String rightPrefix, + List<List<KeyColumn>> keyColumns, + JoinType joinType + ) + { + this.inputChannels = ImmutableList.of(left.getChannel(), right.getChannel()); + this.outputChannel = outputChannel; + this.frameWriterFactory = frameWriterFactory; + this.rightPrefix = rightPrefix; + this.joinType = joinType; + this.trackers = ImmutableList.of( + new Tracker(left, keyColumns.get(LEFT)), + new Tracker(right, keyColumns.get(RIGHT)) + ); + } + + @Override + public List<ReadableFrameChannel> inputChannels() + { + return inputChannels; + } + + @Override + public List<WritableFrameChannel> outputChannels() + { + return Collections.singletonList(outputChannel); + } + + @Override + public ReturnOrAwait<Long> runIncrementally(IntSet readableInputs) throws IOException + { + // Fetch enough frames such that each tracker has one readable row. + for (int i = 0; i < inputChannels.size(); i++) { + final Tracker tracker = trackers.get(i); + if (tracker.isAtEndOfPushedData() && !pushNextFrame(i)) { + return nextAwait(); + } + } + + // Initialize new output frame, if needed. + startNewFrameIfNeeded(); + + while (!allTrackersAreAtEnd() + && !trackers.get(LEFT).needsMoreData() + && !trackers.get(RIGHT).needsMoreData()) { + // Algorithm can proceed: not all trackers are at the end of their streams, and no tracker needs more data to + // read the current cursor or move it forward. + if (nextIterationRunnable != null) { + final Runnable tmp = nextIterationRunnable; + nextIterationRunnable = null; + tmp.run(); + } + + final int markCmp = compareMarks(); + + // Two rows match if the keys compare equal _and_ neither key has a null component. (x JOIN y ON x.a = y.a does + // not match rows where "x.a" is null.) + final boolean match = markCmp == 0 && trackers.get(LEFT).hasCompletelyNonNullMark(); + + // If marked keys are equal on both sides ("match"), at least one side must have a complete set of rows + // for the marked key. + if (match && trackerWithCompleteSetForCurrentKey < 0) { + for (int i = 0; i < inputChannels.size(); i++) { + final Tracker tracker = trackers.get(i); + + // Fetch up to one frame from each tracker, to check if that tracker has a complete set. + // Can't fetch more than one frame, because channels are only guaranteed to have one frame per run. + if (tracker.hasCompleteSetForMark() || (pushNextFrame(i) && tracker.hasCompleteSetForMark())) { + trackerWithCompleteSetForCurrentKey = i; + break; + } + } + + if (trackerWithCompleteSetForCurrentKey < 0) { + // Algorithm cannot proceed; fetch more frames on the next run. + return nextAwait(); + } + } + + if (match || (markCmp <= 0 && joinType.isLefty()) || (markCmp >= 0 && joinType.isRighty())) { + // Emit row, if there's room in the current frameWriter. + joinColumnSelectorFactory.cmp = markCmp; + joinColumnSelectorFactory.match = match; + + if (!frameWriter.addSelection()) { + if (frameWriter.getNumRows() > 0) { + // Out of space in the current frame. Run again without moving cursors. + flushCurrentFrame(); + return ReturnOrAwait.runAgain(); + } else { + throw new FrameRowTooLargeException(frameWriterFactory.allocatorCapacity()); + } + } + } + + // Advance one or both trackers. + if (match) { + // Matching keys. First advance the tracker with the complete set. + final Tracker tracker = trackers.get(trackerWithCompleteSetForCurrentKey); + final Tracker otherTracker = trackers.get(trackerWithCompleteSetForCurrentKey == LEFT ? RIGHT : LEFT); + + tracker.advance(); + if (!tracker.isCurrentSameKeyAsMark()) { + // Reached end of complete set. Advance the other tracker. + otherTracker.advance(); + + // On next iteration (when we're sure to have data) either rewind the complete-set tracker, or update marks + // of both, as appropriate. + onNextIteration(() -> { + if (otherTracker.isCurrentSameKeyAsMark()) { + otherTracker.markCurrent(); // Set mark to enable cleanup of old frames. + tracker.rewindToMark(); + } else { + // Reached end of the other side too. Advance marks on both trackers. + tracker.markCurrent(); + otherTracker.markCurrent(); + trackerWithCompleteSetForCurrentKey = -1; + } + }); + } + } else { + final int trackerToAdvance; + + if (markCmp < 0) { + trackerToAdvance = LEFT; + } else if (markCmp > 0) { + trackerToAdvance = RIGHT; + } else { + // Key is null on both sides. Note that there is a preference for running through the left side first + // on a FULL join. It doesn't really matter which side we run through first, but we do need to be consistent + // for the benefit of the logic in "shouldEmitColumnValue". + trackerToAdvance = joinType.isLefty() ? LEFT : RIGHT; + } + + final Tracker tracker = trackers.get(trackerToAdvance); + + tracker.advance(); + + // On next iteration (when we're sure to have data), update mark if the key changed. + onNextIteration(() -> { + if (!tracker.isCurrentSameKeyAsMark()) { + tracker.markCurrent(); + trackerWithCompleteSetForCurrentKey = -1; + } + }); + } + } + + if (allTrackersAreAtEnd()) { + flushCurrentFrame(); + return ReturnOrAwait.returnObject(0L); + } else { + // Keep reading. + return nextAwait(); + } + } + + @Override + public void cleanup() throws IOException + { + FrameProcessors.closeAll(inputChannels(), outputChannels(), frameWriter, () -> trackers.forEach(Tracker::clear)); + } + + /** + * Returns a {@link ReturnOrAwait#awaitAll} for the channel numbers that need more data and have not yet hit their + * buffered-bytes limit, {@link Limits#MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN}. + * + * If all channels have hit their limit, throws {@link MSQException} with {@link TooManyRowsWithSameKeyFault}. + */ + private ReturnOrAwait<Long> nextAwait() + { + final IntSet awaitSet = new IntOpenHashSet(); + int trackerAtLimit = -1; + + for (int i = 0; i < inputChannels.size(); i++) { + final Tracker tracker = trackers.get(i); + if (tracker.needsMoreData()) { + if (tracker.totalBytesBuffered() < Limits.MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN) { + awaitSet.add(i); + } else if (trackerAtLimit < 0) { + trackerAtLimit = i; + } + } + } + + if (awaitSet.isEmpty() && trackerAtLimit > 0) { + // All trackers that need more data are at their max buffered bytes limit. Generate a nice exception. + final Tracker tracker = trackers.get(trackerAtLimit); + if (tracker.totalBytesBuffered() > Limits.MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN) { + // Generate a nice exception. + throw new MSQException( + new TooManyRowsWithSameKeyFault( + tracker.readMarkKey(), + tracker.totalBytesBuffered(), + Limits.MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN + ) + ); + } + } + + return ReturnOrAwait.awaitAll(awaitSet); + } + + /** + * Whether all trackers return true from {@link Tracker#isAtEnd()}. + */ + private boolean allTrackersAreAtEnd() + { + for (Tracker tracker : trackers) { + if (!tracker.isAtEnd()) { + return false; + } + } + + return true; + } + + /** + * Compares the marked rows of the two {@link #trackers}. + * + * @throws IllegalStateException if either tracker does not have a marked row and is not completely done + */ + private int compareMarks() + { + final Tracker leftTracker = trackers.get(LEFT); + final Tracker rightTracker = trackers.get(RIGHT); + + Preconditions.checkState(leftTracker.hasMark() || leftTracker.isAtEnd(), "left.hasMark || left.isAtEnd"); + Preconditions.checkState(rightTracker.hasMark() || rightTracker.isAtEnd(), "right.hasMark || right.isAtEnd"); + + if (!leftTracker.hasMark()) { + return rightTracker.markFrame < 0 ? 0 : 1; + } else if (!rightTracker.hasMark()) { + return -1; + } else { + final FrameHolder leftHolder = leftTracker.holders.get(leftTracker.markFrame); + final FrameHolder rightHolder = rightTracker.holders.get(rightTracker.markFrame); + return leftHolder.comparisonWidget.compare( + leftTracker.markRow, + rightHolder.comparisonWidget, + rightTracker.markRow + ); + } + } + + /** + * Pushes a frame from the indicated channel into the appropriate tracker. Returns true if a frame was pushed + * or if the channel is finished. + */ + private boolean pushNextFrame(final int channelNumber) + { + final ReadableFrameChannel channel = inputChannels.get(channelNumber); + final Tracker tracker = trackers.get(channelNumber); + + if (!channel.isFinished() && !channel.canRead()) { + return false; + } else if (channel.isFinished()) { + tracker.push(null); + return true; + } else { + final Frame frame = channel.read(); + + if (frame.numRows() == 0) { + // Skip, read next. + return false; + } else { + tracker.push(frame); + return true; + } + } + } + + private void onNextIteration(final Runnable runnable) + { + if (nextIterationRunnable != null) { + throw new ISE("postAdvanceRunnable already set"); Review Comment: Not that I can think of. If this ever happens, it's a bug in the class and someone's gonna have a fun time in the degbugger. ########## extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/querykit/common/SortMergeJoinFrameProcessor.java: ########## @@ -0,0 +1,1075 @@ +/* + * 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.querykit.common; + +import com.google.common.base.Preconditions; +import com.google.common.base.Predicate; +import com.google.common.collect.ImmutableList; +import it.unimi.dsi.fastutil.ints.IntOpenHashSet; +import it.unimi.dsi.fastutil.ints.IntSet; +import org.apache.druid.frame.Frame; +import org.apache.druid.frame.channel.FrameWithPartition; +import org.apache.druid.frame.channel.ReadableFrameChannel; +import org.apache.druid.frame.channel.WritableFrameChannel; +import org.apache.druid.frame.key.FrameComparisonWidget; +import org.apache.druid.frame.key.KeyColumn; +import org.apache.druid.frame.key.RowKey; +import org.apache.druid.frame.key.RowKeyReader; +import org.apache.druid.frame.processor.FrameProcessor; +import org.apache.druid.frame.processor.FrameProcessors; +import org.apache.druid.frame.processor.FrameRowTooLargeException; +import org.apache.druid.frame.processor.ReturnOrAwait; +import org.apache.druid.frame.read.FrameReader; +import org.apache.druid.frame.segment.FrameCursor; +import org.apache.druid.frame.write.FrameWriter; +import org.apache.druid.frame.write.FrameWriterFactory; +import org.apache.druid.java.util.common.ISE; +import org.apache.druid.msq.exec.Limits; +import org.apache.druid.msq.indexing.error.MSQException; +import org.apache.druid.msq.indexing.error.TooManyRowsWithSameKeyFault; +import org.apache.druid.msq.input.ReadableInput; +import org.apache.druid.query.dimension.DefaultDimensionSpec; +import org.apache.druid.query.dimension.DimensionSpec; +import org.apache.druid.query.filter.ValueMatcher; +import org.apache.druid.query.monomorphicprocessing.RuntimeShapeInspector; +import org.apache.druid.segment.ColumnSelectorFactory; +import org.apache.druid.segment.ColumnValueSelector; +import org.apache.druid.segment.Cursor; +import org.apache.druid.segment.DimensionSelector; +import org.apache.druid.segment.DimensionSelectorUtils; +import org.apache.druid.segment.IdLookup; +import org.apache.druid.segment.NilColumnValueSelector; +import org.apache.druid.segment.column.ColumnCapabilities; +import org.apache.druid.segment.column.RowSignature; +import org.apache.druid.segment.data.IndexedInts; +import org.apache.druid.segment.data.ZeroIndexedInts; +import org.apache.druid.segment.join.JoinPrefixUtils; +import org.apache.druid.segment.join.JoinType; + +import javax.annotation.Nullable; +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; + +/** + * Processor for a sort-merge join of two inputs. + * + * Prerequisites: + * + * 1) Two inputs, both of which are stages; i.e. {@link ReadableInput#hasChannel()}. + * + * 2) Conditions are all simple equalities. Validated by {@link SortMergeJoinFrameProcessorFactory#validateCondition} + * and then transformed to lists of key columns by {@link SortMergeJoinFrameProcessorFactory#toKeyColumns}. + * + * 3) Both inputs are comprised of {@link org.apache.druid.frame.FrameType#ROW_BASED} frames, are sorted by the same + * key, and that key can be used to check the provided condition. Validated by + * {@link SortMergeJoinFrameProcessorFactory#validateInputFrameSignatures}. + * + * Algorithm: + * + * 1) Read current key from each side of the join. + * + * 2) If there is no match, emit or skip the row for the earlier key, as appropriate, based on the join type. + * + * 3) If there is a match, identify a complete set on one side or the other. (It doesn't matter which side has the + * complete set, but we need it on one of them.) We mark the first row for the key using {@link Tracker#markCurrent()} + * and find complete sets using {@link Tracker#hasCompleteSetForMark()}. Once we find one, we store it in + * {@link #trackerWithCompleteSetForCurrentKey}. If both sides have a complete set, we break ties by choosing the + * left side. + * + * 4) Once a complete set for the current key is identified: for each row on the *other* side, loop through the entire + * set of rows on {@link #trackerWithCompleteSetForCurrentKey}, and emit that many joined rows. + * + * 5) Once we process the final row on the *other* side, reset both marks with {@link Tracker#markCurrent()} and + * continue the algorithm. + */ +public class SortMergeJoinFrameProcessor implements FrameProcessor<Long> +{ + private static final int LEFT = 0; + private static final int RIGHT = 1; + + /** + * Input channels for each side of the join. Two-element array: {@link #LEFT} and {@link #RIGHT}. + */ + private final List<ReadableFrameChannel> inputChannels; + + /** + * Trackers for each side of the join. Two-element array: {@link #LEFT} and {@link #RIGHT}. + */ + private final List<Tracker> trackers; + + private final WritableFrameChannel outputChannel; + private final FrameWriterFactory frameWriterFactory; + private final String rightPrefix; + private final JoinType joinType; + private final JoinColumnSelectorFactory joinColumnSelectorFactory = new JoinColumnSelectorFactory(); + private FrameWriter frameWriter = null; + + // Used by runIncrementally to defer certain logic to the next run. + private Runnable nextIterationRunnable = null; + + // Used by runIncrementally to remember which tracker has the complete set for the current key. + private int trackerWithCompleteSetForCurrentKey = -1; + + SortMergeJoinFrameProcessor( + ReadableInput left, + ReadableInput right, + WritableFrameChannel outputChannel, + FrameWriterFactory frameWriterFactory, + String rightPrefix, + List<List<KeyColumn>> keyColumns, + JoinType joinType + ) + { + this.inputChannels = ImmutableList.of(left.getChannel(), right.getChannel()); + this.outputChannel = outputChannel; + this.frameWriterFactory = frameWriterFactory; + this.rightPrefix = rightPrefix; + this.joinType = joinType; + this.trackers = ImmutableList.of( + new Tracker(left, keyColumns.get(LEFT)), + new Tracker(right, keyColumns.get(RIGHT)) + ); + } + + @Override + public List<ReadableFrameChannel> inputChannels() + { + return inputChannels; + } + + @Override + public List<WritableFrameChannel> outputChannels() + { + return Collections.singletonList(outputChannel); + } + + @Override + public ReturnOrAwait<Long> runIncrementally(IntSet readableInputs) throws IOException + { + // Fetch enough frames such that each tracker has one readable row. + for (int i = 0; i < inputChannels.size(); i++) { + final Tracker tracker = trackers.get(i); + if (tracker.isAtEndOfPushedData() && !pushNextFrame(i)) { + return nextAwait(); + } + } + + // Initialize new output frame, if needed. + startNewFrameIfNeeded(); + + while (!allTrackersAreAtEnd() + && !trackers.get(LEFT).needsMoreData() + && !trackers.get(RIGHT).needsMoreData()) { + // Algorithm can proceed: not all trackers are at the end of their streams, and no tracker needs more data to + // read the current cursor or move it forward. + if (nextIterationRunnable != null) { + final Runnable tmp = nextIterationRunnable; + nextIterationRunnable = null; + tmp.run(); + } + + final int markCmp = compareMarks(); + + // Two rows match if the keys compare equal _and_ neither key has a null component. (x JOIN y ON x.a = y.a does + // not match rows where "x.a" is null.) + final boolean match = markCmp == 0 && trackers.get(LEFT).hasCompletelyNonNullMark(); + + // If marked keys are equal on both sides ("match"), at least one side must have a complete set of rows + // for the marked key. + if (match && trackerWithCompleteSetForCurrentKey < 0) { + for (int i = 0; i < inputChannels.size(); i++) { + final Tracker tracker = trackers.get(i); + + // Fetch up to one frame from each tracker, to check if that tracker has a complete set. + // Can't fetch more than one frame, because channels are only guaranteed to have one frame per run. + if (tracker.hasCompleteSetForMark() || (pushNextFrame(i) && tracker.hasCompleteSetForMark())) { + trackerWithCompleteSetForCurrentKey = i; + break; + } + } + + if (trackerWithCompleteSetForCurrentKey < 0) { + // Algorithm cannot proceed; fetch more frames on the next run. + return nextAwait(); + } + } + + if (match || (markCmp <= 0 && joinType.isLefty()) || (markCmp >= 0 && joinType.isRighty())) { + // Emit row, if there's room in the current frameWriter. + joinColumnSelectorFactory.cmp = markCmp; + joinColumnSelectorFactory.match = match; + + if (!frameWriter.addSelection()) { + if (frameWriter.getNumRows() > 0) { + // Out of space in the current frame. Run again without moving cursors. + flushCurrentFrame(); + return ReturnOrAwait.runAgain(); + } else { + throw new FrameRowTooLargeException(frameWriterFactory.allocatorCapacity()); + } + } + } + + // Advance one or both trackers. + if (match) { + // Matching keys. First advance the tracker with the complete set. + final Tracker tracker = trackers.get(trackerWithCompleteSetForCurrentKey); + final Tracker otherTracker = trackers.get(trackerWithCompleteSetForCurrentKey == LEFT ? RIGHT : LEFT); + + tracker.advance(); + if (!tracker.isCurrentSameKeyAsMark()) { + // Reached end of complete set. Advance the other tracker. + otherTracker.advance(); + + // On next iteration (when we're sure to have data) either rewind the complete-set tracker, or update marks + // of both, as appropriate. + onNextIteration(() -> { + if (otherTracker.isCurrentSameKeyAsMark()) { + otherTracker.markCurrent(); // Set mark to enable cleanup of old frames. + tracker.rewindToMark(); + } else { + // Reached end of the other side too. Advance marks on both trackers. + tracker.markCurrent(); + otherTracker.markCurrent(); + trackerWithCompleteSetForCurrentKey = -1; + } + }); + } + } else { + final int trackerToAdvance; + + if (markCmp < 0) { + trackerToAdvance = LEFT; + } else if (markCmp > 0) { + trackerToAdvance = RIGHT; + } else { + // Key is null on both sides. Note that there is a preference for running through the left side first + // on a FULL join. It doesn't really matter which side we run through first, but we do need to be consistent + // for the benefit of the logic in "shouldEmitColumnValue". + trackerToAdvance = joinType.isLefty() ? LEFT : RIGHT; + } + + final Tracker tracker = trackers.get(trackerToAdvance); + + tracker.advance(); + + // On next iteration (when we're sure to have data), update mark if the key changed. + onNextIteration(() -> { + if (!tracker.isCurrentSameKeyAsMark()) { + tracker.markCurrent(); + trackerWithCompleteSetForCurrentKey = -1; + } + }); + } + } + + if (allTrackersAreAtEnd()) { + flushCurrentFrame(); + return ReturnOrAwait.returnObject(0L); + } else { + // Keep reading. + return nextAwait(); + } + } + + @Override + public void cleanup() throws IOException + { + FrameProcessors.closeAll(inputChannels(), outputChannels(), frameWriter, () -> trackers.forEach(Tracker::clear)); + } + + /** + * Returns a {@link ReturnOrAwait#awaitAll} for the channel numbers that need more data and have not yet hit their + * buffered-bytes limit, {@link Limits#MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN}. + * + * If all channels have hit their limit, throws {@link MSQException} with {@link TooManyRowsWithSameKeyFault}. + */ + private ReturnOrAwait<Long> nextAwait() + { + final IntSet awaitSet = new IntOpenHashSet(); + int trackerAtLimit = -1; + + for (int i = 0; i < inputChannels.size(); i++) { + final Tracker tracker = trackers.get(i); + if (tracker.needsMoreData()) { + if (tracker.totalBytesBuffered() < Limits.MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN) { + awaitSet.add(i); + } else if (trackerAtLimit < 0) { + trackerAtLimit = i; + } + } + } + + if (awaitSet.isEmpty() && trackerAtLimit > 0) { + // All trackers that need more data are at their max buffered bytes limit. Generate a nice exception. + final Tracker tracker = trackers.get(trackerAtLimit); + if (tracker.totalBytesBuffered() > Limits.MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN) { + // Generate a nice exception. + throw new MSQException( + new TooManyRowsWithSameKeyFault( + tracker.readMarkKey(), + tracker.totalBytesBuffered(), + Limits.MAX_BUFFERED_BYTES_FOR_SORT_MERGE_JOIN + ) + ); + } + } + + return ReturnOrAwait.awaitAll(awaitSet); + } + + /** + * Whether all trackers return true from {@link Tracker#isAtEnd()}. + */ + private boolean allTrackersAreAtEnd() + { + for (Tracker tracker : trackers) { + if (!tracker.isAtEnd()) { + return false; + } + } + + return true; + } + + /** + * Compares the marked rows of the two {@link #trackers}. + * + * @throws IllegalStateException if either tracker does not have a marked row and is not completely done + */ + private int compareMarks() + { + final Tracker leftTracker = trackers.get(LEFT); + final Tracker rightTracker = trackers.get(RIGHT); + + Preconditions.checkState(leftTracker.hasMark() || leftTracker.isAtEnd(), "left.hasMark || left.isAtEnd"); + Preconditions.checkState(rightTracker.hasMark() || rightTracker.isAtEnd(), "right.hasMark || right.isAtEnd"); + + if (!leftTracker.hasMark()) { + return rightTracker.markFrame < 0 ? 0 : 1; + } else if (!rightTracker.hasMark()) { + return -1; + } else { + final FrameHolder leftHolder = leftTracker.holders.get(leftTracker.markFrame); + final FrameHolder rightHolder = rightTracker.holders.get(rightTracker.markFrame); + return leftHolder.comparisonWidget.compare( + leftTracker.markRow, + rightHolder.comparisonWidget, + rightTracker.markRow + ); + } + } + + /** + * Pushes a frame from the indicated channel into the appropriate tracker. Returns true if a frame was pushed + * or if the channel is finished. + */ + private boolean pushNextFrame(final int channelNumber) + { + final ReadableFrameChannel channel = inputChannels.get(channelNumber); + final Tracker tracker = trackers.get(channelNumber); + + if (!channel.isFinished() && !channel.canRead()) { + return false; + } else if (channel.isFinished()) { + tracker.push(null); + return true; + } else { + final Frame frame = channel.read(); + + if (frame.numRows() == 0) { + // Skip, read next. + return false; + } else { + tracker.push(frame); + return true; + } + } + } + + private void onNextIteration(final Runnable runnable) + { + if (nextIterationRunnable != null) { + throw new ISE("postAdvanceRunnable already set"); Review Comment: Not that I can think of. If this ever happens, it's a bug in the class and someone's gonna have a fun time in the debugger. -- This is an automated message from the Apache Git Service. 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