Merge commit '8e97373d883c06e1c73791849561d1311c880bc0' as 'libs/loguru'

libs/loguru/glog_bench/glog_bench.cpp

@@ -0,0 +1,93 @@
+#include <chrono>
+#include <cmath>
+#include <iomanip>
+#include <iostream>
+
+#include <glog/logging.h>
+#include <glog/raw_logging.h>
+
+const size_t kNumIterations = 50 * 1000;
+const size_t kNumRuns = 10;
+const double kPi = 3.1415926535897932384626433;
+
+static long long now_ns()
+{
+	using namespace std::chrono;
+	return duration_cast<nanoseconds>(high_resolution_clock::now().time_since_epoch()).count();
+}
+
+template<typename Function>
+double time_sec(const Function& function)
+{
+	auto start_ns = now_ns();
+	function();
+	return (now_ns() - start_ns) * 1e-9;
+}
+
+template<typename Function>
+void bench(const std::string& name, const Function& function)
+{
+	function(); // Warm-up
+
+	printf("%-30s ", name.c_str());
+	fflush(stdout);
+	std::vector<double> times;
+	double sum = 0;
+	for (size_t i = 0; i < kNumRuns; ++i)
+	{
+		times.push_back(time_sec(function) / kNumIterations);
+		sum += times.back();
+	}
+
+	double mean = sum / kNumRuns;
+	double std_dev_sum = 0;
+
+	for (double time : times) {
+		std_dev_sum += (time - mean) * (time - mean);
+	}
+
+	double variance = std::sqrt(std_dev_sum / kNumRuns);
+
+	printf("%6.3f +- %.3f us per call\n", mean * 1e6, variance * 1e6);
+	fflush(stdout);
+}
+
+// ----------------------------------------------------------------------------
+
+void stream_strings()
+{
+	for (size_t i = 0; i < kNumIterations; ++i) {
+		LOG(WARNING) << "Some long, complex message.";
+	}
+	google::FlushLogFiles(google::GLOG_INFO);
+}
+
+void stream_float()
+{
+	for (size_t i = 0; i < kNumIterations; ++i) {
+		LOG(WARNING) << std::setfill('0') << std::setw(6) << std::setprecision(3) << kPi;
+	}
+	google::FlushLogFiles(google::GLOG_INFO);
+}
+
+void raw_string_float()
+{
+	for (size_t i = 0; i < kNumIterations; ++i) {
+		RAW_LOG(WARNING, "Some long, complex message.");
+	}
+	google::FlushLogFiles(google::GLOG_INFO);
+}
+
+int main(int argc, char* argv[])
+{
+    FLAGS_alsologtostderr = true;
+    google::ParseCommandLineFlags(&argc, &argv, true);
+    google::InitGoogleLogging(argv[0]);
+
+    bench("LOG(WARNING) << string (buffered):", stream_strings);
+    bench("LOG(WARNING) << float  (buffered):", stream_float);
+
+    FLAGS_logbufsecs = 0; // Flush all output in realtime
+    bench("LOG(WARNING) << string (unbuffered):", stream_strings);
+    bench("LOG(WARNING) << float  (unbuffered):", stream_float);
+}