dgb(#82): bind 5 won-block reconstruct seams to live tracker (decision (a), deadlock-safe) - #267
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frstrtr merged 1 commit intoJun 20, 2026
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…n a, deadlock-safe) Replace the interim nullopt reconstruct stub in main_dgb.cpp --run path with the faithful make_reconstruct_closure (#265), bound to the LIVE ShareTracker via 5 seams: share_fields / gentx_bytes / nth_parent / new_tx_hashes / known_txs. Adds a NON-LOCKING const-ref known_txs() accessor to dgb::NodeImpl (node.hpp). THREADING -- decision (a) (integrator + decisions, 2026-06-20): the prior approval assumed m_on_block_found fires lock-free on the IO thread and the seams would take a shared_lock snapshot. That premise was FALSIFIED: the callback fires on the COMPUTE thread, which ALREADY holds m_tracker_mutex EXCLUSIVELY (run_think node.cpp:1433 unique_lock -> think -> attempt_verify -> share_tracker.hpp:537). A shared_lock from the lock-owning thread on the non-recursive std::shared_mutex is UB/self-deadlock. Fix (a): drop the by-value snapshot_known_txs(), read chain + known-tx state DIRECTLY under the exclusive lock the compute thread already owns (non-locking accessor). HARD CONDITION verified (integrator): none of the 5 seam reads re-takes m_tracker_mutex -- grep confirms the mutex lives ONLY in NodeImpl (node.cpp/node.hpp); ShareTracker + ShareChain (chain.get_share, get_nth_parent_via_skip) and generate_share_transaction contain ZERO mutex/lock_guard/unique_lock/shared_lock. So (a) does NOT reintroduce the recursive self-deadlock one frame deeper. SHARE-VERSION GUARD: m_tx_info (new_transaction_hashes + transaction_hash_refs) is on-wire ONLY for share version < 34 (Share=17 / NewShare=33 -- the p2pool-dgb-scrypt oracle baseline). The generic ShareVariants::invoke must compile for all 5 variants, incl. v34+ segwit/merged which carry no tx refs in the DGB share format, so the two m_tx_info seams are if-constexpr requires-guarded and fail closed (throw -> caught -> nullopt, never a malformed broadcast) for any unexpected-for-DGB v34+ won share. Fenced to main_dgb.cpp + node.hpp. build_dgb green; #265 KAT 6/6 green; binary --help/selftest OK. The #82 dual-path broadcaster gate stays OPEN: the submitblock-RPC arm is still unarmed (coin_node rpc=nullptr, #163 seam guard = deferred-not-dropped, loud) and neither arm is verified until the live won-block-reaches-network test. HOLD merge (stacked on #265).
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#82 run-loop consume — bind the 5 reconstruct seams to the LIVE tracker (decision (a))
Stacked on #265 (base branch
dgb/won-block-reconstruct-closure). Fenced tomain_dgb.cpp+node.hpponly — no shared/bitcoin_family/cross-coin touch.What
Replaces the interim
return nulloptreconstruct stub inrun_node()with the faithfulmake_reconstruct_closure(#265), bound to the liveShareTrackervia 5 seams:share_fields→chain.get_share(h)→ {min_header, merkle_link, tx refs}gentx_bytes→generate_share_transaction(...)SSOT regennth_parent→chain.get_nth_parent_via_skipnew_tx_hashes→ sharem_new_transaction_hashesknown_txs→ new non-lockingNodeImpl::known_txs()const-ref accessorDecision (a) — deadlock-safe (integrator + decisions, 2026-06-20)
The earlier-approved shared_lock snapshot would self-deadlock:
m_on_block_foundfires on the COMPUTE thread, which already holdsm_tracker_mutexexclusively (run_thinknode.cpp:1433unique_lock→ think → attempt_verify → share_tracker.hpp:537). Ashared_lockfrom the lock-owning thread on the non-recursivestd::shared_mutexis UB. Fix (a): droppedsnapshot_known_txs(), read state directly under the held exclusive lock via the non-locking accessor.HARD CONDITION verified: none of the 5 seam reads re-takes
m_tracker_mutex.grepconfirms the mutex lives only inNodeImpl;ShareTracker+ShareChain+generate_share_transactioncontain zero mutex/lock usage. (a) does not reintroduce the recursive deadlock a frame deeper.Share-version guard
m_tx_info(tx refs) is on-wire only for share version < 34 (Share=17 / NewShare=33 — the p2pool-dgb-scrypt oracle baseline). The genericShareVariants::invokemust compile for all 5 variants, so the twom_tx_infoseams areif constexpr (requires {...})guarded and fail closed for any unexpected-for-DGB v34+ segwit/merged won share.Evidence
build_dgbgreen (only pre-existing warnings); binary--help/selftest OKGate status
The #82 dual-path broadcaster gate stays OPEN. The submitblock-RPC arm is still unarmed (
coin_noderpc=nullptr; #163 seam guard = deferred-not-dropped, loud). Neither arm is verified until the live won-block-reaches-network test. HOLD merge (lands after #265).