JAVA-2934: Handle empty non-final pages in ReactiveResultSetSubscription by dssysolyatin · Pull Request #1544 · apache/cassandra-java-driver · GitHub
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JAVA-2934: Handle empty non-final pages in ReactiveResultSetSubscription #1544

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Merged
adutra merged 1 commit into from
Apr 28, 2021
Merged

JAVA-2934: Handle empty non-final pages in ReactiveResultSetSubscription #1544

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4 changes: 4 additions & 0 deletions changelog/README.md
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5 changes: 1 addition & 4 deletions ...ava/com/datastax/dse/driver/internal/core/cql/reactive/ReactiveResultSetSubscription.java
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Original file line number Diff line number Diff line change
Expand Up @@ -277,13 +277,10 @@ private Object tryNext() {
if (pages.poll() == null) {
throw new AssertionError("Queue is empty, this should not happen");
}
current = pages.peek();
// if the next page is readily available,
// serve its first row now, no need to wait
// for the next drain.
if (current != null && current.hasMoreRows()) {
return current.nextRow();
}
return tryNext();
}
}
// No items available right now.
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30 changes: 30 additions & 0 deletions ...com/datastax/dse/driver/internal/core/cql/reactive/ReactiveResultSetSubscriptionTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -145,4 +145,34 @@ public void should_report_error_on_intermediary_page() {
assertThat(wasAppliedSubscriber.getElements()).hasSize(1).containsExactly(true);
assertThat(wasAppliedSubscriber.getError()).isNull();
}

@Test
public void should_handle_empty_non_final_pages() {
CompletableFuture<AsyncResultSet> future1 = new CompletableFuture<>();
CompletableFuture<AsyncResultSet> future2 = new CompletableFuture<>();
CompletableFuture<AsyncResultSet> future3 = new CompletableFuture<>();
MockAsyncResultSet page1 = new MockAsyncResultSet(10, future2);
MockAsyncResultSet page2 = new MockAsyncResultSet(0, future3);
MockAsyncResultSet page3 = new MockAsyncResultSet(10, null);
TestSubscriber<ReactiveRow> mainSubscriber = new TestSubscriber<>(1);
TestSubscriber<ColumnDefinitions> colDefsSubscriber = new TestSubscriber<>();
TestSubscriber<ExecutionInfo> execInfosSubscriber = new TestSubscriber<>();
TestSubscriber<Boolean> wasAppliedSubscriber = new TestSubscriber<>();
ReactiveResultSetSubscription<AsyncResultSet> subscription =
new ReactiveResultSetSubscription<>(
mainSubscriber, colDefsSubscriber, execInfosSubscriber, wasAppliedSubscriber);
mainSubscriber.onSubscribe(subscription);
subscription.start(() -> future1);
future1.complete(page1);
future2.complete(page2);
// emulate backpressure
subscription.request(1);
future3.complete(page3);
subscription.request(Long.MAX_VALUE);
mainSubscriber.awaitTermination();
assertThat(mainSubscriber.getError()).isNull();
List<Row> expected = new ArrayList<>(page1.currentPage());
expected.addAll(page3.currentPage());
assertThat(mainSubscriber.getElements()).hasSize(20).extracting("row").isEqualTo(expected);
}
}
12 changes: 11 additions & 1 deletion core/src/test/java/com/datastax/dse/driver/internal/core/cql/reactive/TestSubscriber.java
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