Refactor GetTimeUnitAndMultiplier and add example

README.md

@@ -190,6 +190,14 @@ static void BM_test(benchmark::State& state) {
 }
 ```
 
+If a benchmark runs a few milliseconds it may be hard to visually compare the
+measured times, since the output data is given in nanoseconds per default. In
+order to manually set the time unit, you can specify it manually:
+
+```c++
+BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
+```
+
 Benchmark Fixtures
 ------------------
 Fixture tests are created by

include/benchmark/benchmark_api.h

@@ -137,6 +137,13 @@ static void BM_MultiThreaded(benchmark::State& state) {
   }
 }
 BENCHMARK(BM_MultiThreaded)->Threads(4);
+
+
+If a benchmark runs a few milliseconds it may be hard to visually compare the
+measured times, since the output data is given in nanoseconds per default. In
+order to manually set the time unit, you can specify it manually:
+
+BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
 */
 
 #ifndef BENCHMARK_BENCHMARK_API_H_

include/benchmark/reporter.h

@@ -22,6 +22,8 @@
 
 namespace benchmark {
 
+typedef std::pair<const char*,double> TimeUnitMultiplier;
+
 // Interface for custom benchmark result printers.
 // By default, benchmark reports are printed to stdout. However an application
 // can control the destination of the reports by calling
@@ -83,11 +85,10 @@ class BenchmarkReporter {
 
   virtual ~BenchmarkReporter();
 protected:
-    static void ComputeStats(std::vector<Run> const& reports, Run* mean, Run* stddev);
+  static void ComputeStats(std::vector<Run> const& reports, Run* mean, Run* stddev);
+  static TimeUnitMultiplier GetTimeUnitAndMultiplier(TimeUnit unit);
 };
 
-typedef std::pair<const char*,double> TimeUnitMultiplier;
-
 // Simple reporter that outputs benchmark data to the console. This is the
 // default reporter used by RunSpecifiedBenchmarks().
 class ConsoleReporter : public BenchmarkReporter {
@@ -98,9 +99,6 @@ class ConsoleReporter : public BenchmarkReporter {
  protected:
   virtual void PrintRunData(const Run& report);
 
- private:
-  TimeUnitMultiplier getTimeUnitAndMultiplier(TimeUnit unit);
-
   size_t name_field_width_;
 };
 

src/console_reporter.cc

@@ -95,7 +95,7 @@ void ConsoleReporter::PrintRunData(const Run& result) {
 
   double multiplier;
   const char* timeLabel;
-  std::tie(timeLabel, multiplier) = getTimeUnitAndMultiplier(result.time_unit);
+  std::tie(timeLabel, multiplier) = GetTimeUnitAndMultiplier(result.time_unit);
 
   ColorPrintf(COLOR_GREEN, "%-*s ",
               name_field_width_, result.benchmark_name.c_str());
@@ -121,16 +121,4 @@ void ConsoleReporter::PrintRunData(const Run& result) {
               result.report_label.c_str());
 }
 
-TimeUnitMultiplier ConsoleReporter::getTimeUnitAndMultiplier(TimeUnit unit) {
-  switch (unit) {
-    case kMillisecond:
-      return std::make_pair("ms", 1e3);
-    case kMicrosecond:
-      return std::make_pair("us", 1e6);
-    case kNanosecond:
-    default:
-      return std::make_pair("ns", 1e9);
-  }
-}
-
 }  // end namespace benchmark

src/reporter.cc

@@ -77,6 +77,18 @@ void BenchmarkReporter::ComputeStats(
   stddev_data->items_per_second = items_per_second_stat.StdDev();
 }
 
+TimeUnitMultiplier BenchmarkReporter::GetTimeUnitAndMultiplier(TimeUnit unit) {
+  switch (unit) {
+    case kMillisecond:
+      return std::make_pair("ms", 1e3);
+    case kMicrosecond:
+      return std::make_pair("us", 1e6);
+    case kNanosecond:
+    default:
+      return std::make_pair("ns", 1e9);
+  }
+}
+
 void BenchmarkReporter::Finalize() {
 }