Explain lifetime of Contiguous::slice

rmw_zenoh_cpp/src/detail/payload.hpp

@@ -29,6 +29,14 @@ class Payload
 public:
   explicit 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()) {