bench.cpp

#include <cstdio>
#include <sys/time.h>
#include <unistd.h>
#include <stdarg.h>
using namespace std;

struct __bench__ {
  double start;
  char msg[100];
  __bench__(const char* format, ...)
  __attribute__((format(printf, 2, 3)))
  {
    va_list args;
    va_start(args, format);
    vsnprintf(msg, sizeof(msg), format, args);
    va_end(args);

    start = sec();
  }
  ~__bench__() {
    fprintf(stderr, "%s: %.6f sec\n", msg, sec() - start);
  }
  double sec() {
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return tv.tv_sec + tv.tv_usec * 1e-6;
  }
  operator bool() { return false; }
};

#define benchmark(...) if(__bench__ __b__ = __bench__(__VA_ARGS__));else

int main() {
    int i = 1;
    int j = 3;
    benchmark("sleep(%d) and %d", i, j) {
        benchmark("sleep(%d)", j) {
            sleep(j);
        }
        sleep(i);
    }
    return 0;
}