RubyVM.stat

static VALUE
vm_stat(int argc, VALUE *argv, VALUE self)
{
    static VALUE sym_constant_cache_invalidations, sym_constant_cache_misses, sym_global_cvar_state, sym_next_shape_id;
    static VALUE sym_shape_cache_size;
    VALUE arg = Qnil;
    VALUE hash = Qnil, key = Qnil;

    if (rb_check_arity(argc, 0, 1) == 1) {
        arg = argv[0];
        if (SYMBOL_P(arg))
            key = arg;
        else if (RB_TYPE_P(arg, T_HASH))
            hash = arg;
        else
            rb_raise(rb_eTypeError, "non-hash or symbol given");
    }
    else {
        hash = rb_hash_new();
    }

#define S(s) sym_##s = ID2SYM(rb_intern_const(#s))
    S(constant_cache_invalidations);
    S(constant_cache_misses);
        S(global_cvar_state);
    S(next_shape_id);
    S(shape_cache_size);
#undef S

#define SET(name, attr) \
    if (key == sym_##name) \
        return SERIALT2NUM(attr); \
    else if (hash != Qnil) \
        rb_hash_aset(hash, sym_##name, SERIALT2NUM(attr));

    SET(constant_cache_invalidations, ruby_vm_constant_cache_invalidations);
    SET(constant_cache_misses, ruby_vm_constant_cache_misses);
    SET(global_cvar_state, ruby_vm_global_cvar_state);
    SET(next_shape_id, (rb_serial_t)GET_SHAPE_TREE()->next_shape_id);
    SET(shape_cache_size, (rb_serial_t)GET_SHAPE_TREE()->cache_size);
#undef SET

#if USE_DEBUG_COUNTER
    ruby_debug_counter_show_at_exit(FALSE);
    for (size_t i = 0; i < RB_DEBUG_COUNTER_MAX; i++) {
        const VALUE name = rb_sym_intern_ascii_cstr(rb_debug_counter_names[i]);
        const VALUE boxed_value = SIZET2NUM(rb_debug_counter[i]);

        if (key == name) {
            return boxed_value;
        }
        else if (hash != Qnil) {
            rb_hash_aset(hash, name, boxed_value);
        }
    }
#endif

    if (!NIL_P(key)) { /* matched key should return above */
        rb_raise(rb_eArgError, "unknown key: %"PRIsVALUE, rb_sym2str(key));
    }

    return hash;
}