Add partial result to AggregateCursor continuation #3254
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@@ -22,12 +22,19 @@ | |
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| import com.apple.foundationdb.annotation.API; | ||
| import com.apple.foundationdb.async.AsyncUtil; | ||
| import com.apple.foundationdb.record.ByteArrayContinuation; | ||
| import com.apple.foundationdb.record.RecordCoreException; | ||
| import com.apple.foundationdb.record.RecordCursor; | ||
| import com.apple.foundationdb.record.RecordCursorContinuation; | ||
| import com.apple.foundationdb.record.RecordCursorProto; | ||
| import com.apple.foundationdb.record.RecordCursorResult; | ||
| import com.apple.foundationdb.record.RecordCursorVisitor; | ||
| import com.apple.foundationdb.record.query.plan.plans.QueryResult; | ||
| import com.apple.foundationdb.record.query.plan.plans.RecordQueryStreamingAggregationPlan; | ||
| import com.apple.foundationdb.tuple.ByteArrayUtil2; | ||
| import com.google.common.base.Verify; | ||
| import com.google.protobuf.ByteString; | ||
| import com.google.protobuf.InvalidProtocolBufferException; | ||
| import com.google.protobuf.Message; | ||
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| import javax.annotation.Nonnull; | ||
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@@ -55,26 +62,37 @@ public class AggregateCursor<M extends Message> implements RecordCursor<QueryRes | |
| // Previous non-empty record processed by this cursor | ||
| @Nullable | ||
| private RecordCursorResult<QueryResult> previousValidResult; | ||
| @Nonnull | ||
| private RecordCursorContinuation previousContinuationInGroup; | ||
| @Nullable | ||
| private RecordCursorProto.PartialAggregationResult partialAggregationResult; | ||
| @Nonnull | ||
| private final RecordQueryStreamingAggregationPlan.SerializationMode serializationMode; | ||
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| public AggregateCursor(@Nonnull RecordCursor<QueryResult> inner, | ||
| @Nonnull final StreamGrouping<M> streamGrouping, | ||
| @Nonnull RecordCursorContinuation continuation, | ||
| @Nonnull final RecordQueryStreamingAggregationPlan.SerializationMode serializationMode) { | ||
| this.inner = inner; | ||
| this.streamGrouping = streamGrouping; | ||
| this.serializationMode = serializationMode; | ||
| this.previousContinuationInGroup = continuation; | ||
| } | ||
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| @Nonnull | ||
| @Override | ||
| public CompletableFuture<RecordCursorResult<QueryResult>> onNext() { | ||
| if (previousResult != null && !previousResult.hasNext()) { | ||
| // we are done | ||
| return CompletableFuture.completedFuture(RecordCursorResult.withoutNextValue(new AggregateCursorContinuation(previousResult.getContinuation(), streamGrouping.getPartialAggregationResult(), serializationMode), | ||
| previousResult.getNoNextReason())); | ||
| } | ||
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| return AsyncUtil.whileTrue(() -> inner.onNext().thenApply(innerResult -> { | ||
| previousResult = innerResult; | ||
| if (!innerResult.hasNext()) { | ||
| if (!isNoRecords()) { | ||
| partialAggregationResult = streamGrouping.finalizeGroup(); | ||
| } | ||
| return false; | ||
| } else { | ||
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@@ -83,45 +101,73 @@ public CompletableFuture<RecordCursorResult<QueryResult>> onNext() { | |
| if (!groupBreak) { | ||
| // previousValidResult is the last row before group break, it sets the continuation | ||
| previousValidResult = innerResult; | ||
| previousContinuationInGroup = previousValidResult.getContinuation(); | ||
| } | ||
| return (!groupBreak); | ||
| } | ||
| }), getExecutor()).thenApply(vignore -> { | ||
| // either innerResult.hasNext() = false; or groupBreak = true | ||
| if (Verify.verifyNotNull(previousResult).hasNext()) { | ||
| // in this case groupBreak = true, return aggregated result and continuation, partialAggregationResult = null | ||
| // previousValidResult = null happens when 1st row of current scan != last row of last scan, results in groupBreak = true and previousValidResult = null | ||
| RecordCursorContinuation c = new AggregateCursorContinuation(previousContinuationInGroup, serializationMode); | ||
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| /* | ||
| * Update the previousValidResult to the next continuation even though it hasn't been returned. This is to return the correct continuation when there are single-element groups. | ||
| * Below is an example that shows how continuation(previousValidResult) moves: | ||
| * Initial: previousResult = null, previousValidResult = null | ||
| row0 groupKey0 groupBreak = False previousValidResult = row0 previousResult = row0 | ||
| row1 groupKey0 groupBreak = False previousValidResult = row1 previousResult = row1 | ||
| row2 groupKey1 groupBreak = True previousValidResult = row1 previousResult = row2 | ||
| * returns result (groupKey0, continuation = row1), and set previousValidResult = row2 | ||
| * | ||
| * Now there are 2 scenarios, 1) the current iteration continues; 2) the current iteration stops | ||
| * In scenario 1, the iteration continues, it gets to row3: | ||
| row3 groupKey2 groupBreak = True previousValidResult = row2 previousResult = row3 | ||
| * returns result (groupKey1, continuation = row2), and set previousValidResult = row3 | ||
| * | ||
| * In scenario 2, a new iteration starts from row2 (because the last returned continuation = row1), and set initial previousResult = null, previousValidResult = null: | ||
| row2 groupKey1 groupBreak = False previousValidResult = row2 previousResult = row2 | ||
| * (Note that because a new iteration starts, groupBreak = False for row2.) | ||
| row3 groupKey2 groupBreak = True previousValidResult = row2 previousResult = row3 | ||
| * returns result (groupKey1, continuation = row2), and set previousValidResult = row3 | ||
| * | ||
| * Both scenarios returns the correct result, and continuation are both set to row3 in the end, row2 is scanned twice if a new iteration starts. | ||
| */ | ||
| previousValidResult = previousResult; | ||
| previousContinuationInGroup = Verify.verifyNotNull(previousValidResult).getContinuation(); | ||
| return RecordCursorResult.withNextValue(QueryResult.ofComputed(streamGrouping.getCompletedGroupResult()), c); | ||
| } else { | ||
| // innerResult.hasNext() = false | ||
| if (Verify.verifyNotNull(previousResult).getNoNextReason() == NoNextReason.SOURCE_EXHAUSTED) { | ||
| // exhausted | ||
| if (previousValidResult == null && partialAggregationResult == null) { | ||
| return RecordCursorResult.exhausted(); | ||
| } else { | ||
| RecordCursorContinuation c = new AggregateCursorContinuation(previousContinuationInGroup, serializationMode); | ||
| previousValidResult = previousResult; | ||
| previousContinuationInGroup = Verify.verifyNotNull(previousValidResult).getContinuation(); | ||
| return RecordCursorResult.withNextValue(QueryResult.ofComputed(streamGrouping.getCompletedGroupResult()), c); | ||
| } | ||
| } else { | ||
| // stopped in the middle of a group | ||
| RecordCursorContinuation currentContinuation = new AggregateCursorContinuation(Verify.verifyNotNull(previousResult).getContinuation(), partialAggregationResult, serializationMode); | ||
| previousValidResult = previousResult; | ||
| previousContinuationInGroup = Verify.verifyNotNull(previousValidResult).getContinuation(); | ||
| if (serializationMode == RecordQueryStreamingAggregationPlan.SerializationMode.TO_NEW) { | ||
| return RecordCursorResult.withoutNextValue(currentContinuation, Verify.verifyNotNull(previousResult).getNoNextReason()); | ||
| } else { | ||
| // for TO_OLD, return {groupKey: partialResult from row x to y}, next time will return {groupKey: partialResult from y+1 to next stop point} | ||
| return RecordCursorResult.withNextValue(QueryResult.ofComputed(streamGrouping.getCompletedGroupResult()), currentContinuation); | ||
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| } | ||
| } | ||
| } | ||
| }); | ||
| } | ||
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| private boolean isNoRecords() { | ||
| return ((previousValidResult == null) && (!Verify.verifyNotNull(previousResult).hasNext()) && (streamGrouping.getPartialAggregationResult() == null)); | ||
| } | ||
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| @Override | ||
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@@ -147,4 +193,84 @@ public boolean accept(@Nonnull RecordCursorVisitor visitor) { | |
| } | ||
| return visitor.visitLeave(this); | ||
| } | ||
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| public static class AggregateCursorContinuation implements RecordCursorContinuation { | ||
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There was a problem hiding this comment. A comment generally about the approach: this isn't quite the way that I thought this was going to go. My assumption had been that we were going to modify the continuation here so that we always return an I do think the alternative presented here (that is, the inner continuation is associated with the last value in a group that was returned and It would be nice if we were a little forward looking and could handle a future continuation of that format. I could also see us wanting to transition to that approach in this PR now is I suppose debatable. |
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| @Nonnull | ||
| private final RecordCursorContinuation innerContinuation; | ||
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| @Nullable | ||
| private final RecordCursorProto.PartialAggregationResult partialAggregationResult; | ||
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| @Nullable | ||
| private RecordCursorProto.AggregateCursorContinuation cachedProto; | ||
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| private final RecordQueryStreamingAggregationPlan.SerializationMode serializationMode; | ||
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| public AggregateCursorContinuation(@Nonnull RecordCursorContinuation innerContinuation, @Nullable RecordCursorProto.PartialAggregationResult partialAggregationResult, final RecordQueryStreamingAggregationPlan.SerializationMode serializationMode) { | ||
| this.innerContinuation = innerContinuation; | ||
| this.partialAggregationResult = partialAggregationResult; | ||
| this.serializationMode = serializationMode; | ||
| } | ||
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| public AggregateCursorContinuation(@Nonnull RecordCursorContinuation other, RecordQueryStreamingAggregationPlan.SerializationMode serializationMode) { | ||
| this(other, null, serializationMode); | ||
| } | ||
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| @Nonnull | ||
| @Override | ||
| public ByteString toByteString() { | ||
| if (serializationMode == RecordQueryStreamingAggregationPlan.SerializationMode.TO_OLD) { | ||
| return innerContinuation.toByteString(); | ||
| } else { | ||
| return isEnd() ? ByteString.EMPTY : toProto().toByteString(); | ||
| } | ||
| } | ||
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| @Nullable | ||
| @Override | ||
| public byte[] toBytes() { | ||
| ByteString byteString = toByteString(); | ||
| return byteString.isEmpty() ? null : byteString.toByteArray(); | ||
| } | ||
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| @Override | ||
| public boolean isEnd() { | ||
| return innerContinuation.isEnd(); | ||
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| } | ||
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| @Nullable | ||
| public byte[] getInnerContinuation() { | ||
| return innerContinuation.toBytes(); | ||
| } | ||
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| @Nullable | ||
| public RecordCursorProto.PartialAggregationResult getPartialAggregationResult() { | ||
| return partialAggregationResult; | ||
| } | ||
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| @Nonnull | ||
| private RecordCursorProto.AggregateCursorContinuation toProto() { | ||
| if (cachedProto == null) { | ||
| RecordCursorProto.AggregateCursorContinuation.Builder cachedProtoBuilder = RecordCursorProto.AggregateCursorContinuation.newBuilder().setContinuation(innerContinuation.toByteString()); | ||
| if (partialAggregationResult != null) { | ||
| cachedProtoBuilder.setPartialAggregationResults(partialAggregationResult); | ||
| } | ||
| cachedProto = cachedProtoBuilder.build(); | ||
| } | ||
| return cachedProto; | ||
| } | ||
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| public static AggregateCursorContinuation fromRawBytes(@Nonnull byte[] rawBytes, RecordQueryStreamingAggregationPlan.SerializationMode serializationMode) { | ||
| if (serializationMode == RecordQueryStreamingAggregationPlan.SerializationMode.TO_OLD) { | ||
| return new AggregateCursorContinuation(ByteArrayContinuation.fromNullable(rawBytes), serializationMode); | ||
| } | ||
| try { | ||
| RecordCursorProto.AggregateCursorContinuation continuationProto = RecordCursorProto.AggregateCursorContinuation.parseFrom(rawBytes); | ||
| return new AggregateCursorContinuation(ByteArrayContinuation.fromNullable(continuationProto.getContinuation().toByteArray()), continuationProto.hasPartialAggregationResults() ? continuationProto.getPartialAggregationResults() : null, serializationMode); | ||
| } catch (InvalidProtocolBufferException ipbe) { | ||
| throw new RecordCoreException("error parsing continuation", ipbe) | ||
| .addLogInfo("raw_bytes", ByteArrayUtil2.loggable(rawBytes)); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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