Fix the bug when aggregation stops before a group is finished #3177
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| Original file line number | Diff line number | Diff line change |
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@@ -22,11 +22,14 @@ | |
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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.RecordCursor; | ||
| import com.apple.foundationdb.record.RecordCursorContinuation; | ||
| import com.apple.foundationdb.record.RecordCursorEndContinuation; | ||
| import com.apple.foundationdb.record.RecordCursorResult; | ||
| import com.apple.foundationdb.record.RecordCursorStartContinuation; | ||
| import com.apple.foundationdb.record.RecordCursorVisitor; | ||
| import com.apple.foundationdb.record.provider.foundationdb.KeyValueCursorBase; | ||
| import com.apple.foundationdb.record.query.plan.plans.QueryResult; | ||
| import com.google.common.base.Verify; | ||
| import com.google.protobuf.Message; | ||
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@@ -57,48 +60,77 @@ public class AggregateCursor<M extends Message> implements RecordCursor<QueryRes | |
| // Previous non-empty record processed by this cursor | ||
| @Nullable | ||
| private RecordCursorResult<QueryResult> previousValidResult; | ||
| // last row in last group, is null if the current group is the first group | ||
| @Nullable | ||
| private RecordCursorResult<QueryResult> lastInLastGroup; | ||
| byte[] continuation; | ||
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| public AggregateCursor(@Nonnull RecordCursor<QueryResult> inner, | ||
| @Nonnull final StreamGrouping<M> streamGrouping, | ||
| boolean isCreateDefaultOnEmpty, | ||
| byte[] continuation) { | ||
| this.inner = inner; | ||
| this.streamGrouping = streamGrouping; | ||
| this.isCreateDefaultOnEmpty = isCreateDefaultOnEmpty; | ||
| this.continuation = 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(previousResult.getContinuation(), | ||
| previousResult.getNoNextReason())); | ||
| } | ||
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| return AsyncUtil.whileTrue(() -> inner.onNext().thenApply(innerResult -> { | ||
| previousResult = innerResult; | ||
| if (!innerResult.hasNext()) { | ||
| if (!isNoRecords() || (isCreateDefaultOnEmpty && streamGrouping.isResultOnEmpty())) { | ||
| // the method streamGrouping.finalizeGroup() computes previousCompleteResult and resets the accumulator | ||
| streamGrouping.finalizeGroup(); | ||
| } | ||
| return false; | ||
| } else { | ||
| final QueryResult queryResult = Objects.requireNonNull(innerResult.get()); | ||
| boolean groupBreak = streamGrouping.apply(queryResult); | ||
| if (groupBreak) { | ||
| lastInLastGroup = previousValidResult; | ||
| } else { | ||
| previousValidResult = innerResult; | ||
| } | ||
| 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 | ||
| RecordCursorContinuation continuation = Verify.verifyNotNull(previousValidResult).getContinuation(); | ||
| previousValidResult = previousResult; | ||
| return RecordCursorResult.withNextValue(QueryResult.ofComputed(streamGrouping.getCompletedGroupResult()), continuation); | ||
| } else { | ||
| if (Verify.verifyNotNull(previousResult).getNoNextReason() == NoNextReason.SOURCE_EXHAUSTED) { | ||
| if (previousValidResult == null) { | ||
| return RecordCursorResult.exhausted(); | ||
|
There was a problem hiding this comment. Does this need to check to insert the empty result if Perhaps it would be simpler if there were fewer moving parts here. If we wait until 4.2, we could drop support entirely for |
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| } else { | ||
| RecordCursorContinuation continuation =previousValidResult.getContinuation(); | ||
| previousValidResult = previousResult; | ||
| return RecordCursorResult.withNextValue(QueryResult.ofComputed(streamGrouping.getCompletedGroupResult()), continuation); | ||
| } | ||
| } else { | ||
| RecordCursorContinuation currentContinuation; | ||
| // in the current scan, if current group is the first group, set the continuation to the start of the current scan | ||
| // otherwise set the continuation to the last row in the last group | ||
| if (lastInLastGroup == null) { | ||
| currentContinuation = continuation == null ? RecordCursorStartContinuation.START : ByteArrayContinuation.fromNullable(continuation); | ||
| } else { | ||
| currentContinuation = lastInLastGroup.getContinuation(); | ||
| } | ||
| previousValidResult = lastInLastGroup; | ||
| return RecordCursorResult.withoutNextValue(currentContinuation, Verify.verifyNotNull(previousResult).getNoNextReason()); | ||
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There was a problem hiding this comment. Should this also set That is: RecordCursor<T> aggCursor = getAggregateCursor();
RecordCursorResult<T> withValueResult = aggCursor.getNext(); // has a value
RecordCursorResult<T> withoutValueResult1 = aggCursor.getNext(); // first result with out-of-bound limit; continuation borrowed from withValueResult
RecordCursorResult<T> withoutValueResult2 = aggCursor.getNext(); // second result with out-of-bound limit; continuation may be greater than withoutValueResult1In general, once a cursor returns a |
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| } | ||
| } | ||
| }); | ||
| } | ||
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It looks like this still hasn't marked the
continuationfield as private. Is there a reason it needs package visibility?