net: window catch-up getdata to the serve cap - #272
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Connecting headers of 20 asked GetData for the whole path. The peer serves at most MAX_SERVE_BLOCKS (16), so extra hashes stuck in requested and sync_blocks timed out (minchainwork 50, createmultisig 149, bip68 CSV). Co-authored-by: Cursor <cursoragent@cursor.com>
Asking the whole header path left hashes in requested while the peer reconstructed at most 16. First ask and drain continuation share fetchable_header_path_bodies so leftover heights are re-asked after the window connects. Co-authored-by: Cursor <cursoragent@cursor.com>
Node-to-node getdata is MSG_CMPCT_BLOCK. Accepting CmpctBlock left the hash in requested, so drain's serve window stayed full and the rest of the header path was never asked. Co-authored-by: Cursor <cursoragent@cursor.com>
MSG_CMPCT_BLOCK replies never left requested, so drain truncated the next window to zero. Also cap compact ancestor getdata at MAX_SERVE_BLOCKS like the headers path. Co-authored-by: Cursor <cursoragent@cursor.com>
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Writer fetch_sub on every CmpctBlock wrapped 0 to usize::MAX when tip announce used queue_out, so later reconstruct was skipped (sync_blocks 60s). Count announce on the same counter, saturating-sub on write, and fill coinbase-only compact without a mempool. Co-authored-by: Cursor <cursoragent@cursor.com>
Counting tip announce on serve_inflight filled the reconstruct cap during a generate burst, so later getdata was skipped (bip68 activateCSV sync_blocks). Announce uses queue_out; writer still saturating-subs so an unpaired CmpctBlock cannot wrap the counter. Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
Overnight core-functional (
sync_blocks60s) stalled when a catch-up node asked the whole header path while the serving peer reconstructs at most 16 bodies (MAX_SERVE_BLOCKS). Extra hashes stayed inrequested/note_asked_blockand were never re-asked.Node-to-node getdata is
MSG_CMPCT_BLOCK. AcceptingCmpctBlockalso left the hash inrequested, so drain's window stayed full even after the 16 bodies connected.Writer
fetch_subon everyBlock/CmpctBlockwrappedserve_inflight0 →usize::MAXwhen compact tip announce usedqueue_out(no matchingfetch_add). Later reconstruct then saw the cap and skipped serve. Saturating-sub fixes the wrap. Counting announce on the same cap then starved getdata during a generate burst (feature_bip68_sequenceactivateCSV 432 blocks). Coinbase-only compact used to bail when the hub had no mempool.catchup_headers_getdata_stays_in_serve_window— 20 connecting headers must GetData 16, then the remaining 4 after those bodies connect (failed: got 20).drain_pendingcontinuation sharefetchable_header_path_bodies, truncated toMAX_SERVE_BLOCKS. Weaker / below-minwork paths stay header-only.catchup_compact_getdata_clears_requested_for_next_window— same 20-header catch-up answered withCmpctBlock(failed:requestedstill 16).blocktxn/ already-have drop the hash fromrequested. Compact ancestor getdata is also capped at 16. Serve-inflight cap test is unchanged.compact_tip_announce_must_not_wrap_serve_inflight— unpaired writer decrement after announce must leave inflight at 0.queue_out.compact_tip_announce_must_not_consume_serve_slots— 16 queued announces must leave inflight at 0 so a laterMSG_CMPCT_BLOCKgetdata still serves.fetch_add. Coinbase-only compact fills from prefilled txs without a mempool.Overnight run: https://github.com/reardencode/rbitcoin/actions/runs/32941780319
Green core-functional: https://github.com/reardencode/rbitcoin/actions/runs/32995598334
Test plan
cargo test -p rbitcoin-net --lib catchup_headers_getdatacargo test -p rbitcoin-net --lib catchup_compact_getdatacargo test -p rbitcoin-net --lib compact_tip_announcecargo test -p rbitcoin-net --lib coinbase_compact_fills_without_mempoolcargo test -p rbitcoin-net --lib(worktree)core-functional