westonpace commented on a change in pull request #9533:
URL: https://github.com/apache/arrow/pull/9533#discussion_r581464660
##########
File path: cpp/src/arrow/util/iterator_test.cc
##########
@@ -726,6 +730,142 @@ TEST(TestAsyncUtil, CompleteBackgroundStressTest) {
}
}
+template <typename T>
+class SlowSourcePreventingReentrant {
+ public:
+ explicit SlowSourcePreventingReentrant(AsyncGenerator<T> source)
+ : state_(std::make_shared<State>(std::move(source))) {}
+
+ Future<TestInt> operator()() {
+ if (state_->in.load()) {
+ state_->valid.store(false);
+ }
+ state_->in.store(true);
+ auto result = state_->source();
+ result.AddCallback(Callback{state_});
+ return result;
+ }
+
+ void AssertValid() {
+ EXPECT_EQ(true, state_->valid.load())
+ << "The generator was accessed in a reentrant manner";
+ }
+
+ private:
+ struct State {
+ explicit State(AsyncGenerator<T> source_)
+ : source(std::move(source_)), in(false), valid(true) {}
+
+ AsyncGenerator<T> source;
+ std::atomic<bool> in;
+ std::atomic<bool> valid;
+ };
+ struct Callback {
+ void operator()(const Result<T>& result) { state_->in.store(false); }
+ std::shared_ptr<State> state_;
+ };
+
+ std::shared_ptr<State> state_;
+};
+
+TEST(TestAsyncUtil, SerialReadaheadSlowProducer) {
+ AsyncGenerator<TestInt> it = BackgroundAsyncVectorIt({1, 2, 3, 4, 5});
+ SlowSourcePreventingReentrant<TestInt> tracker(std::move(it));
+ SerialReadaheadGenerator<TestInt> serial_readahead(tracker, 2);
+ AssertAsyncGeneratorMatch({1, 2, 3, 4, 5},
+
static_cast<AsyncGenerator<TestInt>>(serial_readahead));
+ tracker.AssertValid();
+}
+
+TEST(TestAsyncUtil, SerialReadaheadSlowConsumer) {
+ int num_delivered = 0;
+ auto source = [&num_delivered]() {
+ if (num_delivered < 5) {
+ return Future<TestInt>::MakeFinished(num_delivered++);
+ } else {
+ return Future<TestInt>::MakeFinished(IterationTraits<TestInt>::End());
+ }
+ };
+ SerialReadaheadGenerator<TestInt> serial_readahead(std::move(source), 3);
+ SleepABit();
+ ASSERT_EQ(0, num_delivered);
+ ASSERT_FINISHES_OK_AND_ASSIGN(auto next, serial_readahead());
+ ASSERT_EQ(0, next.value);
+ ASSERT_EQ(3, num_delivered);
+ AssertAsyncGeneratorMatch({1, 2, 3, 4},
+
static_cast<AsyncGenerator<TestInt>>(serial_readahead));
+}
+
+TEST(TestAsyncUtil, SerialReadaheadStress) {
+ constexpr int NTASKS = 20;
+ constexpr int NITEMS = 50;
+ constexpr int EXPECTED_SUM = (NITEMS * (NITEMS - 1)) / 2;
+ for (int i = 0; i < NTASKS; i++) {
+ AsyncGenerator<TestInt> it = BackgroundAsyncVectorIt(RangeVector(NITEMS));
+ SerialReadaheadGenerator<TestInt> serial_readahead(it, 2);
+ unsigned int sum = 0;
+ auto visit_fut = VisitAsyncGenerator<TestInt>(
+ serial_readahead, [&sum](TestInt test_int) -> Status {
+ sum += test_int.value;
+ // Normally sleeping in a visit function would be a faux-pas but we
want to slow
+ // the reader down to match the producer to maximize the stress
+ std::this_thread::sleep_for(kYieldDuration);
+ return Status::OK();
+ });
+ ASSERT_FINISHES_OK(visit_fut);
+ ASSERT_EQ(EXPECTED_SUM, sum);
+ }
+}
+
+TEST(TestAsyncUtil, SerialReadaheadStressFast) {
+ constexpr int NTASKS = 20;
+ constexpr int NITEMS = 50;
+ constexpr int EXPECTED_SUM = (NITEMS * (NITEMS - 1)) / 2;
+ for (int i = 0; i < NTASKS; i++) {
+ AsyncGenerator<TestInt> it = BackgroundAsyncVectorIt(RangeVector(NITEMS),
false);
+ SerialReadaheadGenerator<TestInt> serial_readahead(it, 2);
+ unsigned int sum = 0;
+ auto visit_fut = VisitAsyncGenerator<TestInt>(serial_readahead,
+ [&sum](TestInt test_int) ->
Status {
+ sum += test_int.value;
+ return Status::OK();
+ });
+ ASSERT_FINISHES_OK(visit_fut);
+ ASSERT_EQ(EXPECTED_SUM, sum);
Review comment:
It's more to check for race conditions. The background thread filling
callbacks and the visitor thread pulling the serial readahead both share a
pointer to State. Both of these tests were pretty useful in exposing issues
with the old AddCallback version. However, I added a reentrancy check in there
for good measure and got rid of the sum stuff.
##########
File path: cpp/src/arrow/util/queue_benchmark.cc
##########
@@ -0,0 +1,87 @@
+// 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.
+
+#include <algorithm>
+#include <iterator>
+#include <thread>
+#include <vector>
+
+#include <benchmark/benchmark.h>
+
+#include "arrow/buffer.h"
+#include "arrow/util/queue.h"
+
+namespace arrow {
+
+namespace util {
+
+static constexpr int64_t kSize = 100000;
+
+void throughput(benchmark::State& state) {
Review comment:
Done
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