Method release

src/common/buffer.cc:459–486

  }

  void buffer::ptr::release()
  {
    // BE CAREFUL: this is called also for hypercombined ptr_node. After
    // freeing underlying raw, `*this` can become inaccessible as well!
    //
    // cache the pointer to avoid unncecessary reloads and repeated
    // checks.
    if (auto* const cached_raw = std::exchange(_raw, nullptr);
	cached_raw) {
      bdout << "ptr " << this << " release " << cached_raw << bendl;
      // optimize the common case where a particular `buffer::raw` has
      // only a single reference. Altogether with initializing `nref` of
      // freshly fabricated one with `1` through the std::atomic's ctor
      // (which doesn't impose a memory barrier on the strongly-ordered
      // x86), this allows to avoid all atomical operations in such case.
      const bool last_one = \
        (1 == cached_raw->nref.load(std::memory_order_acquire));
      if (likely(last_one) || --cached_raw->nref == 0) {
	bdout << "deleting raw " << static_cast<void*>(cached_raw)
	      << " len " << cached_raw->get_len() << bendl;
	ANNOTATE_HAPPENS_AFTER(&cached_raw->nref);
	ANNOTATE_HAPPENS_BEFORE_FORGET_ALL(&cached_raw->nref);
	delete cached_raw;  // dealloc old (if any)
      } else {
	ANNOTATE_HAPPENS_BEFORE(&cached_raw->nref);
      }
    }
  }

  int buffer::ptr::get_mempool() const {
    if (_raw) {