Question

i am trying to find out a way in which i can write out run-time of selected number of functions when my tool runs. let say out of large list of functions which my tool have i need to write out the what is the time taken by individual calls y(), z() , a1() ….

X(){

 y();
 ..
 ..
 z();
 ..
 ..
 a1();
 ..
 ..
 b1();
 ..
 ..
}

I don’t want to use gprof because it need to be separately run , and there is no way customer can run gprof at there end. In many cases i don’t have access to the test which is producing long runtime. A way to log run time of high level function will be helpful. i dont’t want to wrap around each and every function call around time() system call and then print it. Can macro help in this.? any ideas?

Answer 1

You said you don’t want to wrap each call, but let me just show you how I handle timer calls so they can be removed at compile time, and maybe that can be wrapped up in another macro later:

#ifndef NOTIME
#  include <ctime>
#  define CLOCK_TICK(acc, ctr)  ctr = std::clock()
#  define CLOCK_TOCK(acc, ctr)  acc += (std::clock() - ctr)
#  define CLOCK_RESET(acc) acc = 0
#  define CLOCK_REPORT(acc) 1000. * double(acc) / double(CLOCKS_PER_SEC)

static clock_t t1a, t1c, t2a, t2c; // as many pairs as you need

#else
#  define CLOCK_TICK(acc, ctr)
#  define CLOCK_TOCK(acc, ctr)
#  define CLOCK_RESET(acc)
#  define CLOCK_REPORT(acc) 0
#endif

Now you can use it like this:

CLOCK_RESET(t1a);
for (int i = 0; i != 250000; ++i)
{
  CLOCK_TICK(t1a, t1c);
  some_expensive_function();
  CLOCK_TOCK(t1a, t1c);
}
std::cout << "Time spent in some_expensive_function(): " << CLOCK_REPORT(t1a) << "ms.\n";

With variadic macros you might even be able to wrap up the function call:

#define timed_call(ACC, CTR, func, ...) do { CLOCK_TICK(ACC, CTR); \
                                             func(__VA_ARGS__);    \
                                             CLOCK_TOCK(ACC,CTR);  \
                                           } while (false)