Restore lost comment

rmw_zenoh_cpp/src/detail/zenoh_utils.cpp

@@ -100,6 +100,14 @@ std::chrono::nanoseconds::rep ZenohReply::get_received_timestamp() const
 ///=============================================================================
 Payload::Payload(const zenoh::Bytes & bytes)
 {
+  // NOTE(fuzzypixelz): `zenoh::Bytes` is an list of reference-couted buffers. When the list of
+  // buffers contains exactly one element, it is not necessary to concatenate the list of buffers.
+  // In this case, we store a clone of the bytes object to maintain a non-zero reference-count on
+  // the buffer. This ensures that the slice into said buffer stays valid until we drop our copy
+  // of the bytes object (at the very least). This case corresponds to the `Contiguous`
+  // alternative of the `bytes_` variant and aims to optimize away a memcpy during "session-local"
+  // communication.
+
   zenoh::Bytes::SliceIterator slices = bytes.slice_iter();
   std::optional<zenoh::Slice> slice = slices.next();
   if (!slice.has_value()) {