Profiling Results

System	CPU	Memory	Disk	ofstream prof.txt	ofstream /dev/null	ostringstream	“blackhole” streambuf	ofstream failbit	ConditionalOStream
WSL2 Debian	i7-8565U	32GB	Intel M.2 SSDPEKK- F512G8L	10.7935s	7.78622s	7.37819s	5.94589s	2.66578s	0.538241s
WSL2 Debian	Ryzen 7 3800X	32GB	Sabrent M.2 Rocket 4.0 500GB	7.74714s	6.69068s	5.84889s	4.17527s	2.11662s	0.550667s
NixOS 20.09	Ryzen 7 1700	32GB	PNY CS1311 240GB SSD	9.88139s	7.96852s	7.35156s	5.09152s	2.67259s	0.684588s

Test Function

tests/profiling/profile.h

#include <chrono>
#include <iostream>

// 100,000,000
constexpr unsigned iterations = 100000000;

template <typename StreamType>
void time_streaming(StreamType &stream) {
  auto value = "hello world\n";
  auto t0 = std::chrono::steady_clock::now();
  for (unsigned i = 0; i < iterations; ++i) {
    stream << i << ": " << value;
  }
  auto t1 = std::chrono::steady_clock::now();
  std::chrono::duration<long double> dt = t1 - t0;
  std::cout << "Streaming took " << dt.count() << "s\n";
}

Stream to a file

tests/profiling/ofstream.cpp

#include <iostream>
#include <fstream>

#include "conditional_ostream.h"
#include "profile.h"

int main() {
  auto stream = std::ofstream("ofstream.cpp.txt", std::ios::trunc);
  time_streaming(stream);
  return 0;
}

Stream to /dev/null

tests/profiling/devnull.cpp

#include <iostream>
#include <fstream>

#include "conditional_ostream.h"
#include "profile.h"

int main() {
  auto stream = std::ofstream("/dev/null", std::ios::out);
  time_streaming(stream);
  return 0;
}

Stream to a std::ostringstream

tests/profiling/ostringstream.cpp

#include <iostream>
#include <sstream>

#include "conditional_ostream.h"
#include "profile.h"

int main() {
  std::ostringstream stream;
  time_streaming(stream);
  return 0;
}

Stream to a “blackhole”

This includes an implementation of a std::streambuf that ignores all input, borrowed from Deduplicator on the Code Review Stack Exchange.

tests/profiling/nullbuffer.cpp

#include <iostream>
#include <iterator>
#include <streambuf>

#include "conditional_ostream.h"
#include "profile.h"


class blackhole_buf final : public std::streambuf {
    char_type target[64];
    std::streamsize xsputn(const char_type*, std::streamsize n) { return n; }
    int_type overflow(int_type = traits_type::eof()) {
        setp(target, std::end(target));
        return 0;
    }
};


int main() {
  blackhole_buf buf {};
  std::ostream stream { &buf };
  time_streaming(stream);
  return 0;
}

Stream with failbit set

tests/profiling/failbit.cpp

#include <iostream>
#include <fstream>

#include "conditional_ostream.h"
#include "profile.h"

int main() {
  auto stream = std::ofstream();
  stream.setstate(std::ios::failbit);
  time_streaming(stream);
  return 0;
}

Stream to a ConditionalOStream

tests/profiling/conditional.cpp

#include <iostream>

#include "conditional_ostream.h"
#include "profile.h"

int main() {
  ConditionalOStream stream {};
  time_streaming(stream);
  return 0;
}