dimied/access_profiler

a tool to count accesses to member variables in c++ programs

access_profiler

access_profiler is a heavy-weight class field access profiler, implemented as C++ library.

to use this profiler, include "access_profiler.hpp" and make the types you want to instrument derive from access_profiler::instrument_type< your-type > (i.e. you need to specify your type as the template argument).

in you Jamfile, add a dependency to the access_profiler library.

When you terminate your program, the access counters for your types fields will be printed to "access_profile.out" in current working directory. This file lists all instrumented types and the access counters for offsets into those types.

To combine this information with the debug information for more user-friendly output, use the struct_layout tool and use the profile as input.

Note

access_profiler is currently not compatible with std::make_shared or similar functions, since those won't invoke the new operator. To profile such types, convert them to regular std::shared_ptr constructor which still allocates the object with new.

output format

Each instrumented type has its fully qualified name printed on a single line preceded by a blank line (even the first type).

After each instrumented type follows a list of offsets into that type, colon, and the number of times that offset was accessed. The counter does not distinguish between reads and writes. These lines are indented by at least 3 spaces, but the offset is right adjusted and may contain some leading spaces too.

The general outline looks like this:

<blank line>
<fully qualified name of instrumented type>
   <offset>:<hit count>
   <offset>:<hit count>

example usage

#include "access_profiler.hpp"
#include <stdio.h>

struct test : access_profiler::instrument_type<test>
{
        test() : a(0), b(0) {}
        char array[50];
        int a;
        int b;
};

int main(int argc, char* argv[])
{
        test* t1 = new test;

        for (int i = 0; i < 10; ++i)
        {
                ++t1->a;
                t1->b += t1->a;
        }

        printf("%d\n", t1->b);

        delete t1;
}

example output

output from a debug build:

test
     52: 31
     56: 22

output from a release build:

test
     52: 1