Module instance_handle 

InstanceHandle — opaque, local identifier for entities and sample instances (DDS DCPS 1.4 §2.3.3 IDL-PSM, §2.2.2.5.1 SampleInfo.instance_handle).

In the spec, InstanceHandle_t is a builtin type with no fixed wire form — it is never placed on the wire, but serves solely for local identification (e.g. to address a sample stream in DataReader::read_instance()). The spec only guarantees that HANDLE_NIL has a reserved “no handle” value.

We encode it as an opaque u64:

• Unique per entity / sample instance within a runtime.
• HANDLE_NIL = 0 (spec convention).
• Created via InstanceHandleAllocator with a monotonically increasing counter — no reuse of dropped handles.

Structs

InstanceHandle

Opaque InstanceHandle_t (DDS-DCPS 1.4 §2.3.3).

InstanceHandleAllocator

Atomic counter for handing out unique InstanceHandle values.

Constants

HANDLE_NIL

Spec alias for the NIL handle (DDS-DCPS 1.4 §2.3.3).