*Display* aggregates only. (#665)

There is a flag 
https://github.com/google/benchmark/blob/d9cab612e40017af10bddaa5b60c7067032a9e1c/src/benchmark.cc#L75-L78
and a call
https://github.com/google/benchmark/blob/d9cab612e40017af10bddaa5b60c7067032a9e1c/include/benchmark/benchmark.h#L837-L840
But that affects everything, every reporter, destination:
https://github.com/google/benchmark/blob/d9cab612e40017af10bddaa5b60c7067032a9e1c/src/benchmark.cc#L316


It would be quite useful to have an ability to be more picky.


More specifically, i would like to be able to only see the aggregates in the on-screen output,
but for the file output to still contain everything. The former is useful in case of a lot of repetition
(or even more so if every iteration is reported separately), while the former is **great** for tooling.

Fixes #664

README.md

@@ -545,12 +545,20 @@ The number of runs of each benchmark is specified globally by the
 `Repetitions` on the registered benchmark object. When a benchmark is run more
 than once the mean, median and standard deviation of the runs will be reported.
 
-Additionally the `--benchmark_report_aggregates_only={true|false}` flag or
-`ReportAggregatesOnly(bool)` function can be used to change how repeated tests
-are reported. By default the result of each repeated run is reported. When this
-option is `true` only the mean, median and standard deviation of the runs is reported.
-Calling `ReportAggregatesOnly(bool)` on a registered benchmark object overrides
-the value of the flag for that benchmark.
+Additionally the `--benchmark_report_aggregates_only={true|false}`,
+`--benchmark_display_aggregates_only={true|false}` flags or
+`ReportAggregatesOnly(bool)`, `DisplayAggregatesOnly(bool)` functions can be
+used to change how repeated tests are reported. By default the result of each
+repeated run is reported. When `report aggregates only` option is `true`,
+only the aggregates (i.e. mean, median and standard deviation, maybe complexity
+measurements if they were requested) of the runs is reported, to both the
+reporters - standard output (console), and the file.
+However when only the `display aggregates only` option is `true`,
+only the aggregates are displayed in the standard output, while the file
+output still contains everything.
+Calling `ReportAggregatesOnly(bool)` / `DisplayAggregatesOnly(bool)` on a
+registered benchmark object overrides the value of the appropriate flag for that
+benchmark.
 
 ## User-defined statistics for repeated benchmarks
 While having mean, median and standard deviation is nice, this may not be

include/benchmark/benchmark.h

@@ -438,9 +438,21 @@ enum AggregationReportMode
     : unsigned
 #else
 #endif
-{ ARM_Unspecified,  // The mode has not been manually specified
-  ARM_Default,      // The mode is user-specified as default.
-  ARM_ReportAggregatesOnly };
+{
+  // The mode has not been manually specified
+  ARM_Unspecified = 0,
+  // The mode is user-specified.
+  // This may or may not be set when the following bit-flags are set.
+  ARM_Default = 1U << 0U,
+  // File reporter should only output aggregates.
+  ARM_FileReportAggregatesOnly = 1U << 1U,
+  // Display reporter should only output aggregates
+  ARM_DisplayReportAggregatesOnly = 1U << 2U,
+  // Both reporters should only display aggregates.
+  ARM_ReportAggregatesOnly =
+      ARM_FileReportAggregatesOnly | ARM_DisplayReportAggregatesOnly
+};
+
 }  // namespace internal
 
 // State is passed to a running Benchmark and contains state for the
@@ -862,8 +874,12 @@ class Benchmark {
   // Specify if each repetition of the benchmark should be reported separately
   // or if only the final statistics should be reported. If the benchmark
   // is not repeated then the single result is always reported.
+  // Applies to *ALL* reporters (display and file).
   Benchmark* ReportAggregatesOnly(bool value = true);
 
+  // Same as ReportAggregatesOnly(), but applies to display reporter only.
+  Benchmark* DisplayAggregatesOnly(bool value = true);
+
   // If a particular benchmark is I/O bound, runs multiple threads internally or
   // if for some reason CPU timings are not representative, call this method. If
   // called, the elapsed time will be used to control how many iterations are

src/benchmark.cc

@@ -34,6 +34,7 @@
 #include <memory>
 #include <string>
 #include <thread>
+#include <utility>
 
 #include "check.h"
 #include "colorprint.h"
@@ -72,10 +73,19 @@ DEFINE_int32(benchmark_repetitions, 1,
              "The number of runs of each benchmark. If greater than 1, the "
              "mean and standard deviation of the runs will be reported.");
 
-DEFINE_bool(benchmark_report_aggregates_only, false,
-            "Report the result of each benchmark repetitions. When 'true' is "
-            "specified only the mean, standard deviation, and other statistics "
-            "are reported for repeated benchmarks.");
+DEFINE_bool(
+    benchmark_report_aggregates_only, false,
+    "Report the result of each benchmark repetitions. When 'true' is specified "
+    "only the mean, standard deviation, and other statistics are reported for "
+    "repeated benchmarks. Affects all reporters.");
+
+DEFINE_bool(
+    benchmark_display_aggregates_only, false,
+    "Display the result of each benchmark repetitions. When 'true' is "
+    "specified only the mean, standard deviation, and other statistics are "
+    "displayed for repeated benchmarks. Unlike "
+    "benchmark_report_aggregates_only, only affects the display reporter, but "
+    "*NOT* file reporter, which will still contain all the output.");
 
 DEFINE_string(benchmark_format, "console",
               "The format to use for console output. Valid values are "
@@ -193,22 +203,39 @@ void RunInThread(const benchmark::internal::Benchmark::Instance* b,
   manager->NotifyThreadComplete();
 }
 
-std::vector<BenchmarkReporter::Run> RunBenchmark(
+struct RunResults {
+  std::vector<BenchmarkReporter::Run> non_aggregates;
+  std::vector<BenchmarkReporter::Run> aggregates_only;
+
+  bool display_report_aggregates_only = false;
+  bool file_report_aggregates_only = false;
+};
+
+RunResults RunBenchmark(
     const benchmark::internal::Benchmark::Instance& b,
     std::vector<BenchmarkReporter::Run>* complexity_reports) {
-  std::vector<BenchmarkReporter::Run> reports;  // return value
+  RunResults run_results;
 
   const bool has_explicit_iteration_count = b.iterations != 0;
   size_t iters = has_explicit_iteration_count ? b.iterations : 1;
   std::unique_ptr<internal::ThreadManager> manager;
   std::vector<std::thread> pool(b.threads - 1);
   const int repeats =
       b.repetitions != 0 ? b.repetitions : FLAGS_benchmark_repetitions;
-  const bool report_aggregates_only =
-      repeats != 1 &&
-      (b.aggregation_report_mode == internal::ARM_Unspecified
-           ? FLAGS_benchmark_report_aggregates_only
-           : b.aggregation_report_mode == internal::ARM_ReportAggregatesOnly);
+  if (repeats != 1) {
+    run_results.display_report_aggregates_only =
+        (FLAGS_benchmark_report_aggregates_only ||
+         FLAGS_benchmark_display_aggregates_only);
+    run_results.file_report_aggregates_only =
+        FLAGS_benchmark_report_aggregates_only;
+    if (b.aggregation_report_mode != internal::ARM_Unspecified) {
+      run_results.display_report_aggregates_only =
+          (b.aggregation_report_mode &
+           internal::ARM_DisplayReportAggregatesOnly);
+      run_results.file_report_aggregates_only =
+          (b.aggregation_report_mode & internal::ARM_FileReportAggregatesOnly);
+    }
+  }
   for (int repetition_num = 0; repetition_num < repeats; repetition_num++) {
     for (;;) {
       // Try benchmark
@@ -281,7 +308,7 @@ std::vector<BenchmarkReporter::Run> RunBenchmark(
             b, results, memory_iterations, memory_result, seconds);
         if (!report.error_occurred && b.complexity != oNone)
           complexity_reports->push_back(report);
-        reports.push_back(report);
+        run_results.non_aggregates.push_back(report);
         break;
       }
 
@@ -304,18 +331,20 @@ std::vector<BenchmarkReporter::Run> RunBenchmark(
       iters = static_cast<int>(next_iters + 0.5);
     }
   }
+
   // Calculate additional statistics
-  auto stat_reports = ComputeStats(reports);
+  run_results.aggregates_only = ComputeStats(run_results.non_aggregates);
+
+  // Maybe calculate complexity report
   if ((b.complexity != oNone) && b.last_benchmark_instance) {
     auto additional_run_stats = ComputeBigO(*complexity_reports);
-    stat_reports.insert(stat_reports.end(), additional_run_stats.begin(),
-                        additional_run_stats.end());
+    run_results.aggregates_only.insert(run_results.aggregates_only.end(),
+                                       additional_run_stats.begin(),
+                                       additional_run_stats.end());
     complexity_reports->clear();
   }
 
-  if (report_aggregates_only) reports.clear();
-  reports.insert(reports.end(), stat_reports.begin(), stat_reports.end());
-  return reports;
+  return run_results;
 }
 
 }  // namespace
@@ -462,11 +491,25 @@ void RunBenchmarks(const std::vector<Benchmark::Instance>& benchmarks,
       (!file_reporter || file_reporter->ReportContext(context))) {
     flushStreams(display_reporter);
     flushStreams(file_reporter);
+
     for (const auto& benchmark : benchmarks) {
-      std::vector<BenchmarkReporter::Run> reports =
-          RunBenchmark(benchmark, &complexity_reports);
-      display_reporter->ReportRuns(reports);
-      if (file_reporter) file_reporter->ReportRuns(reports);
+      RunResults run_results = RunBenchmark(benchmark, &complexity_reports);
+
+      auto report = [&run_results](BenchmarkReporter* reporter,
+                                   bool report_aggregates_only) {
+        assert(reporter);
+        assert(
+            !(report_aggregates_only && run_results.aggregates_only.empty()));
+        if (!report_aggregates_only)
+          reporter->ReportRuns(run_results.non_aggregates);
+        if (!run_results.aggregates_only.empty())
+          reporter->ReportRuns(run_results.aggregates_only);
+      };
+
+      report(display_reporter, run_results.display_report_aggregates_only);
+      if (file_reporter)
+        report(file_reporter, run_results.file_report_aggregates_only);
+
       flushStreams(display_reporter);
       flushStreams(file_reporter);
     }
@@ -596,6 +639,7 @@ void PrintUsageAndExit() {
           "          [--benchmark_min_time=<min_time>]\n"
           "          [--benchmark_repetitions=<num_repetitions>]\n"
           "          [--benchmark_report_aggregates_only={true|false}]\n"
+          "          [--benchmark_display_aggregates_only={true|false}]\n"
           "          [--benchmark_format=<console|json|csv>]\n"
           "          [--benchmark_out=<filename>]\n"
           "          [--benchmark_out_format=<json|console|csv>]\n"
@@ -619,6 +663,8 @@ void ParseCommandLineFlags(int* argc, char** argv) {
                        &FLAGS_benchmark_repetitions) ||
         ParseBoolFlag(argv[i], "benchmark_report_aggregates_only",
                       &FLAGS_benchmark_report_aggregates_only) ||
+        ParseBoolFlag(argv[i], "benchmark_display_aggregates_only",
+                      &FLAGS_benchmark_display_aggregates_only) ||
         ParseStringFlag(argv[i], "benchmark_format", &FLAGS_benchmark_format) ||
         ParseStringFlag(argv[i], "benchmark_out", &FLAGS_benchmark_out) ||
         ParseStringFlag(argv[i], "benchmark_out_format",

src/benchmark_register.cc

@@ -373,6 +373,22 @@ Benchmark* Benchmark::ReportAggregatesOnly(bool value) {
   return this;
 }
 
+Benchmark* Benchmark::DisplayAggregatesOnly(bool value) {
+  // If we were called, the report mode is no longer 'unspecified', in any case.
+  aggregation_report_mode_ = static_cast<AggregationReportMode>(
+      aggregation_report_mode_ | ARM_Default);
+
+  if (value) {
+    aggregation_report_mode_ = static_cast<AggregationReportMode>(
+        aggregation_report_mode_ | ARM_DisplayReportAggregatesOnly);
+  } else {
+    aggregation_report_mode_ = static_cast<AggregationReportMode>(
+        aggregation_report_mode_ & ~ARM_DisplayReportAggregatesOnly);
+  }
+
+  return this;
+}
+
 Benchmark* Benchmark::UseRealTime() {
   CHECK(!use_manual_time_)
       << "Cannot set UseRealTime and UseManualTime simultaneously.";

test/CMakeLists.txt

@@ -125,6 +125,12 @@ add_test(templated_fixture_test templated_fixture_test --benchmark_min_time=0.01
 compile_output_test(user_counters_test)
 add_test(user_counters_test user_counters_test --benchmark_min_time=0.01)
 
+compile_output_test(report_aggregates_only_test)
+add_test(report_aggregates_only_test report_aggregates_only_test --benchmark_min_time=0.01)
+
+compile_output_test(display_aggregates_only_test)
+add_test(display_aggregates_only_test display_aggregates_only_test --benchmark_min_time=0.01)
+
 compile_output_test(user_counters_tabular_test)
 add_test(user_counters_tabular_test user_counters_tabular_test --benchmark_counters_tabular=true --benchmark_min_time=0.01)
 

test/display_aggregates_only_test.cc

@@ -0,0 +1,40 @@
+
+#undef NDEBUG
+#include <cstdio>
+#include <string>
+
+#include "benchmark/benchmark.h"
+#include "output_test.h"
+
+// Ok this test is super ugly. We want to check what happens with the file
+// reporter in the presence of DisplayAggregatesOnly().
+// We do not care about console output, the normal tests check that already.
+
+void BM_SummaryRepeat(benchmark::State& state) {
+  for (auto _ : state) {
+  }
+}
+BENCHMARK(BM_SummaryRepeat)->Repetitions(3)->DisplayAggregatesOnly();
+
+int main(int argc, char* argv[]) {
+  const std::string output = GetFileReporterOutput(argc, argv);
+
+  if (SubstrCnt(output, "BM_SummaryRepeat/repeats:3") != 6 ||
+      SubstrCnt(output, "\"BM_SummaryRepeat/repeats:3\"") != 3 ||
+      SubstrCnt(output, "\"BM_SummaryRepeat/repeats:3_mean\"") != 1 ||
+      SubstrCnt(output, "\"BM_SummaryRepeat/repeats:3_median\"") != 1 ||
+      SubstrCnt(output, "\"BM_SummaryRepeat/repeats:3_stddev\"") != 1) {
+    std::cout << "Precondition mismatch. Expected to only find 6 "
+                 "occurrences of \"BM_SummaryRepeat/repeats:3\" substring:\n"
+                 "\"BM_SummaryRepeat/repeats:3\", "
+                 "\"BM_SummaryRepeat/repeats:3\", "
+                 "\"BM_SummaryRepeat/repeats:3\", "
+                 "\"BM_SummaryRepeat/repeats:3_mean\", "
+                 "\"BM_SummaryRepeat/repeats:3_median\", "
+                 "\"BM_SummaryRepeat/repeats:3_stddev\"\nThe entire output:\n";
+    std::cout << output;
+    return 1;
+  }
+
+  return 0;
+}

test/output_test.h

@@ -60,6 +60,13 @@ int SetSubstitutions(
 // Run all output tests.
 void RunOutputTests(int argc, char* argv[]);
 
+// Count the number of 'pat' substrings in the 'haystack' string.
+int SubstrCnt(const std::string& haystack, const std::string& pat);
+
+// Run registered benchmarks with file reporter enabled, and return the content
+// outputted by the file reporter.
+std::string GetFileReporterOutput(int argc, char* argv[]);
+
 // ========================================================================= //
 // ------------------------- Results checking ------------------------------ //
 // ========================================================================= //

test/output_test_helper.cc

@@ -1,8 +1,11 @@
+#include <cstdio>
 #include <cstring>
+#include <fstream>
 #include <iostream>
 #include <map>
 #include <memory>
 #include <sstream>
+#include <streambuf>
 
 #include "../src/benchmark_api_internal.h"
 #include "../src/check.h"  // NOTE: check.h is for internal use only!
@@ -423,3 +426,37 @@ void RunOutputTests(int argc, char* argv[]) {
   CHECK(std::strcmp(csv.name, "CSVReporter") == 0);
   internal::GetResultsChecker().CheckResults(csv.out_stream);
 }
+
+int SubstrCnt(const std::string& haystack, const std::string& pat) {
+  if (pat.length() == 0) return 0;
+  int count = 0;
+  for (size_t offset = haystack.find(pat); offset != std::string::npos;
+       offset = haystack.find(pat, offset + pat.length()))
+    ++count;
+  return count;
+}
+
+std::string GetFileReporterOutput(int argc, char* argv[]) {
+  std::vector<char*> new_argv(argv, argv + argc);
+  assert(static_cast<decltype(new_argv)::size_type>(argc) == new_argv.size());
+
+  std::string tmp_file_name = std::tmpnam(nullptr);
+  std::cout << "Will be using this as the tmp file: " << tmp_file_name << '\n';
+
+  std::string tmp = "--benchmark_out=";
+  tmp += tmp_file_name;
+  new_argv.emplace_back(const_cast<char*>(tmp.c_str()));
+
+  argc = int(new_argv.size());
+
+  benchmark::Initialize(&argc, new_argv.data());
+  benchmark::RunSpecifiedBenchmarks();
+
+  // Read the output back from the file, and delete the file.
+  std::ifstream tmp_stream(tmp_file_name);
+  std::string output = std::string((std::istreambuf_iterator<char>(tmp_stream)),
+                                   std::istreambuf_iterator<char>());
+  std::remove(tmp_file_name.c_str());
+
+  return output;
+}