DPDK ring observable semantics

This example records semantic design knowledge as ordinary documentation. It is not a Bridge artifact and does not establish that any evidence ran.

Reserve producer head

Property	Design
Source	artifact/lib/ring/rte_ring_elem_pvt.h, move_prod_head return site
Trigger	After reservation
Capture timing	Post-state
Snapshot strength	Weak
Collection	Instrumentation
Semantic scope	Base and trace semantics
Captures	Thread ID, batch size, prodHead, consHead
Maps to	MPMCReserveProd, HTSReserveProd, RTSReserveProd
Used by	Trace validation and differential tests

The weak snapshot at reservation is acceptable because the opposing tail may be stabilized later by acquire semantics inside the CAS loop.

Publish tail

Property	Design
Source	artifact/lib/ring/rte_ring_c11_pvt.h, __rte_ring_update_tail and mode-specific update_tail return sites
Trigger	After publication
Capture timing	Post-state
Snapshot strength	Strong
Collection	Instrumentation
Semantic scope	Base and trace semantics
Captures	prodHead, prodTail, consHead, consTail, prodCnt, prodTailCnt
Maps to	MPMCPublishTail, HTSPublishTail, RTSPublishTail, TailProgress
Used by	Trace validation, runtime assertions, and differential tests

PublishTail is the linearization point for visibility of produced elements.

Concurrent trace ordering

Property	Design
Source	harness/traces/concurrent_mpmc.ndjson, derived from timestamp order
Trigger	Derived
Capture timing	Mixed
Snapshot strength	Derived
Collection	Replay
Semantic scope	Trace semantics
Captures	Timestamp and event order
Maps to	Trace-ordering assumption
Used by	Trace validation

Concurrent trace consumers trust timestamp ordering over mutex-serialized emission order when the two conflict. Any change to timestamp generation, buffering, or emission serialization requires review of this rule and rerunning the registered trace evidence.