Class memStack

include/fastgrind.h:1145–1223

* @class memStack * @brief Thread-local logical call stack used to synthesize frame identifiers. * * The stack is explicitly manipulated via fastgrind RAII objects (FAST_GRIND macro) * rather than relying on platform unwinding. Each push/pop updates a rolling id * so that the same textual sequence of function names maps to a deterministic * frameId across time slices. */

 * frameId across time slices.
 */
class memStack
{
  public:
    MEM_NO_INSTRUMENT memStack()
    {
        _offset = 0;
        _stackId = 0;
    }

    MEM_NO_INSTRUMENT ~memStack()
    {
    }

    /** @brief Push function name onto stack and update frame id hash. */
    MEM_NO_INSTRUMENT void push(const char *v)
    {
        if (_offset >= __MEM_MAX_STACK_DEPTH) {
            static bool warned_stack = false;
            if (!warned_stack) {
                fprintf(stderr, "[FASTGRIND] WARNING: Call stack depth exceeded %d\n", __MEM_MAX_STACK_DEPTH);
                warned_stack = true;
            }

            return;
        }

        assert(_offset < __MEM_MAX_STACK_DEPTH);

        _stack[_offset++] = v;
        _stackId += size_t(v);
    }

    /** @brief Pop top of stack (must not be empty). */
    MEM_NO_INSTRUMENT const char *pop()
    {
        if (_offset == 0)
            return nullptr;

        auto v = _stack[--_offset];
        _stackId -= size_t(v);
        return v;
    }

    /** @return Current stack depth. */
    MEM_NO_INSTRUMENT unsigned depth() const
    {
        return _offset;
    }

    /** @return Top function name (undefined if empty). */
    MEM_NO_INSTRUMENT const char *top() const
    {
        return _stack[_offset - 1];
    }

    /** @return Synthetic frame id composed from top symbol pointer plus cumulative hash. */
    MEM_NO_INSTRUMENT size_t frameId() const
    {