Task 8's port of retry/retransmit from localthings dropped the per-attempt
timeout/retry log lines (present in coap_dtls.py) — found while gathering
real-device pacing evidence, where the missing logs made retry frequency
impossible to see. Restores both the retry and final-timeout log lines.
pace() slept the entire rate-limit interval every call regardless of how
much of it had already elapsed since the last real send (e.g. spent
processing the previous block's response). Track the last send timestamp
and only sleep the remainder, recovering time already spent between
requests without changing the enforced minimum interval.
Verified against 10.0.0.129/10.0.0.254: multi-block /device/0 fetches
still complete cleanly, faster per sweep, with the same request spacing
guarantee (patch and measurement from QuiteYellow, PR #8 review).
Ported from localthings fork: bounded per-block retransmission
(_BLOCK_MAX_ATTEMPTS/_BLOCK_ACK_TIMEOUT) instead of a single attempt
per block, SZX renegotiation tracking, and a bugfix moving
conn.send(datagram) inside the try that catches its own SSL errors.
Marc Billow