GH-39664: [C++][Acero] Ensure Acero benchmarks present a metric for i…

…dentifying throughput (#40884)

### Rationale for this change

Acero benchmarks sometimes output metrics such as `items/s`, `bytes/s`, `batches/s`, and `rows/s`. However, there is inconsistency in how these metrics are presented across different benchmarks. We are undertaking an effort to standardize the output of these metrics to ensure uniformity and clarity in performance measurement across all Acero benchmarks. 

### What changes are included in this PR?

`rows/s` has a similar meaning to `items/s`.

- `bytes/s` and `items/s`: aggregate
- `bytes/s` and `rows/s`: asof_join
- `batches/s` and `rows/s`: project, filter, expression

### Are these changes tested?

Yes.

### Are there any user-facing changes?

No.

* GitHub Issue: #39664

Authored-by: Hyunseok Seo <hsseo0501@gmail.com>
Signed-off-by: Weston Pace <weston.pace@gmail.com>

cpp/src/arrow/acero/aggregate_benchmark.cc

@@ -29,6 +29,7 @@
 #include "arrow/util/benchmark_util.h"
 #include "arrow/util/bit_util.h"
 #include "arrow/util/bitmap_reader.h"
+#include "arrow/util/byte_size.h"
 #include "arrow/util/string.h"
 
 namespace arrow {
@@ -50,6 +51,7 @@ namespace acero {
 #include <random>
 
 using arrow::internal::ToChars;
+using arrow::util::TotalBufferSize;
 
 #ifdef ARROW_WITH_BENCHMARKS_REFERENCE
 
@@ -371,9 +373,11 @@ static void BenchmarkGroupBy(benchmark::State& state, std::vector<Aggregate> agg
  for (std::size_t arg_idx = 0; arg_idx < arguments.size(); arg_idx++) {
  aggregates[arg_idx].target = {FieldRef(static_cast<int>(arg_idx))};
  }
+ int64_t total_bytes = TotalBufferSize(*batch);
  for (auto _ : state) {
  ABORT_NOT_OK(BatchGroupBy(batch, aggregates, key_refs));
  }
+ state.SetBytesProcessed(total_bytes * state.iterations());
 }
 
 #define GROUP_BY_BENCHMARK(Name, Impl) \
@@ -578,6 +582,8 @@ static void SumKernel(benchmark::State& state) {
  for (auto _ : state) {
  ABORT_NOT_OK(Sum(array).status());
  }
+
+ state.SetItemsProcessed(state.iterations() * array_size);
 }
 
 static void SumKernelArgs(benchmark::internal::Benchmark* bench) {
@@ -611,6 +617,8 @@ void ModeKernel(benchmark::State& state, int min, int max) {
  for (auto _ : state) {
  ABORT_NOT_OK(Mode(array).status());
  }
+
+ state.SetItemsProcessed(state.iterations() * array_size);
 }
 
 template <typename ArrowType>
@@ -625,13 +633,18 @@ void ModeKernelNarrow<Int8Type>(benchmark::State& state) {
 
 template <>
 void ModeKernelNarrow<BooleanType>(benchmark::State& state) {
+ using CType = typename TypeTraits<BooleanType>::CType;
+
  RegressionArgs args(state);
+ const int64_t array_size = args.size / sizeof(CType);
  auto rand = random::RandomArrayGenerator(1924);
  auto array = rand.Boolean(args.size * 8, 0.5, args.null_proportion);
 
  for (auto _ : state) {
  ABORT_NOT_OK(Mode(array).status());
  }
+
+ state.SetItemsProcessed(state.iterations() * array_size);
 }
 
 template <typename ArrowType>
@@ -668,6 +681,8 @@ static void MinMaxKernelBench(benchmark::State& state) {
  for (auto _ : state) {
  ABORT_NOT_OK(MinMax(array).status());
  }
+
+ state.SetItemsProcessed(state.iterations() * array_size);
 }
 
 static void MinMaxKernelBenchArgs(benchmark::internal::Benchmark* bench) {
@@ -698,6 +713,8 @@ static void CountKernelBenchInt64(benchmark::State& state) {
  for (auto _ : state) {
  ABORT_NOT_OK(Count(array->Slice(1, array_size)).status());
  }
+
+ state.SetItemsProcessed(state.iterations() * array_size);
 }
 BENCHMARK(CountKernelBenchInt64)->Args({1 * 1024 * 1024, 2}); // 1M with 50% null.
 
@@ -718,6 +735,8 @@ void VarianceKernelBench(benchmark::State& state) {
  for (auto _ : state) {
  ABORT_NOT_OK(Variance(array, options).status());
  }
+
+ state.SetItemsProcessed(state.iterations() * array_size);
 }
 
 static void VarianceKernelBenchArgs(benchmark::internal::Benchmark* bench) {

cpp/src/arrow/acero/asof_join_benchmark.cc

@@ -91,7 +91,7 @@ static void TableJoinOverhead(benchmark::State& state,
  ASSERT_OK(DeclarationToStatus(std::move(join_node), /*use_threads=*/false));
  }
 
- state.counters["input_rows_per_second"] = benchmark::Counter(
+ state.counters["rows_per_second"] = benchmark::Counter(
  static_cast<double>(state.iterations() * (left_table_stats.rows + right_hand_rows)),
  benchmark::Counter::kIsRate);