Introduces a new eth/peerstats package as the single home for per-peer
quality metrics consumed by the dropper. txtracker shrinks to a pure
tx-lifecycle role: it maps tx hash to deliverer, subscribes to chain
heads, computes per-block per-peer inclusion and finalization deltas,
and emits them to a StatsConsumer.
peerstats owns the aggregates: inclusion EMA, finalized counter,
latency EMA, sample counter, and the MinLatencySamples bootstrap
constant the dropper uses to filter under-sampled peers. It's a
plain struct with a mutex — no goroutine of its own, no lifecycle
management. The fetcher's onRequestLatency callback now flows to
peerStats.NotifyRequestLatency, the handler's unregisterPeer cleans
up via peerStats.NotifyPeerDrop, and the dropper reads its snapshot
via peerStats.GetAllPeerStats.
txtracker.handleChainHead computes deltas under its own lock, then
releases the lock before calling the consumer, which avoids any
cross-package lock ordering. Tests are split along the same line:
tracker tests use a mock consumer to assert what signals are emitted,
peerstats tests cover EMA math and aggregation semantics directly.
Adds NotifyRequestLatency(peer, latency) and a slow per-peer EMA
(alpha=0.01, ~70-sample half-life) that the dropper will use as a
new protection signal. The first sample seeds the EMA directly so
fresh peers don't ramp up from zero. RequestSamples is exposed
alongside the EMA so consumers can apply a minimum-samples bootstrap
guard before trusting the value.
Includes design notes for the broader peerdrop-latency feature.
The total-finalized protection category ranked peers by a monotonic
cumulative count, so a peer that had been productive in the past kept
a high score forever — even if they had since gone silent — and held
a protected slot without contributing.
Replace txtracker.PeerStats.Finalized (int64 cumulative) with
RecentFinalized (float64 EMA). On each chain head, finalization
credits accumulated over the newly-finalized range are folded into a
slow EMA (alpha=0.0001, half-life ~6930 blocks ≈ 23 hours on 12s
mainnet blocks). Peers that continue contributing keep a high score;
peers that stop decay toward zero over roughly a day.
The dropper category renames to "recent-finalized" accordingly. The
type's docstring is rewritten to describe both categories as EMAs
with different time horizons (slow finalized, fast included).
Refactors checkFinalization to return a per-peer credits map rather
than mutating state directly, so both EMAs update in the same loop
over tracked peers.
Tests used time.Sleep(50ms) to wait for async chain head processing,
making the suite slow (~2s) and flaky under CI load.
Add a step channel (buffered 1) to the Tracker, sent after each
event in the loop. Tests wait on the channel with a 1s timeout.
Suite now completes in <10ms.
NotifyPeerDrop deleted t.peers[peer] but left t.txs entries pointing
to that peer. When those txs later finalized, checkFinalization
recreated the peer entry, and the EMA loop decayed it forever.
Fix: create peer entries in NotifyAccepted (when txs are first
accepted), not in handleChainHead or checkFinalization. Both chain
event handlers now skip peers with no entry — disconnected peers
whose entries were deleted by NotifyPeerDrop stay deleted.
order = order[1:] reslices without releasing the backing array.
After N total insertions the array retains N hashes (32 bytes each)
but only the last maxTracked are live. On a long-running node
processing ~100 txs/s this leaks ~275 MB/day.
Compact by copying to a fresh array when capacity exceeds 2×maxTracked.
Peer stats were never pruned, so the peers map grew with every peer
ever seen. The EMA decay loop and stats copy iterated all historical
peers on every block/query.
Add NotifyPeerDrop(peer) that deletes the peer's stats entry. Called
from handler.unregisterPeer alongside txFetcher.Drop.
handleChainHead fetched the block by number only. If the tracker
goroutine lagged and that height was reorged before processing,
the EMA was computed from the wrong canonical block.
Use GetBlock(hash, number) with the header hash from the event to
fetch the exact block the event refers to, not whatever is currently
canonical at that height.
NotifyReceived was called before pool validation, allowing a peer
to claim deliverer credit by replaying already-included txs or
sending invalid packets.
Rename to NotifyAccepted (takes hashes, not full txs). Call it from
a new enqueueAndTrack helper in handler_eth.go that runs after
Enqueue and checks pool.Has to identify accepted txs. Only accepted
txs are credited to the delivering peer.
lastFinalNum started at 0, so the first checkFinalization after
startup iterated from block 1 to the current finalized head (~20M
blocks on mainnet) under the mutex, stalling the tracker and
potentially awarding bogus credit for ancient txs whose hashes
happened to match recently-received ones.
Seed lastFinalNum from chain.CurrentFinalBlock() in Start() so only
blocks finalized after startup are processed.
txtracker tests (7 tests):
- NotifyReceived: stats empty before chain events
- InclusionEMA: EMA increases on inclusion, decays on empty blocks
- Finalization: Finalized counter credited after finalization
- MultiplePeers: each peer credited for own txs only
- FirstDelivererWins: duplicate delivery ignored
- NoFinalizationCredit: no credit without finalization
- EMADecay: EMA approaches zero after 30 empty blocks
dropper tests (6 tests):
- FilterProtectedNoStats: nil stats → all droppable
- FilterProtectedEmptyStats: empty map → all droppable
- FilterProtectedTopPeer: top-scored peers removed from droppable
- FilterProtectedZeroScore: zero scores → no protection
- FilterProtectedOverlap: peer top in both categories → counted once
- FilterProtectedAllProtected: all droppable protected → empty list
Also fix: create peer entries during EMA update for peers with
inclusions in the current block (previously only created during
finalization, so EMA was not tracked before first finalization).
Expand the txtracker package doc to describe the tracking flow
(NotifyReceived → chain head → finalization → peer credit) and its
role as stats provider for the dropper.
Rewrite the dropper struct comment to document the full behavior
including the inclusion-based peer protection: two scoring categories
(total finalized + recent EMA), top 10% per pool, union of protected
sets.
Change the long-term protection category from total inclusions to
total finalized inclusions. Finalized txs are harder to game (require
actual block finality, not just inclusion) and represent confirmed
on-chain value.
The recent-inclusion EMA stays on chain head inclusions for
responsiveness — a peer delivering txs that appear in the latest
blocks gets quick protection without waiting for finalization.
The tracker now checks CurrentFinalBlock() on each chain head event
and credits delivering peers for all newly finalized blocks since
the last check.
Minimal txtracker that records which peer delivered each transaction
and credits peers when their transactions appear on chain. Provides
the PeerInclusionStats needed by the dropper's protection logic.
Design:
- NotifyReceived(peer, txs): records deliverer per tx hash (called
from handler_eth.go when tx bodies arrive via P2P)
- Subscribes to ChainHeadEvent, fetches block txs, credits the
delivering peer for each included tx
- Per-peer EMA of recent inclusions (alpha=0.05), updated every block
- LRU eviction at 262K entries to bound memory
- Mutex-based (not channel-based) for simplicity — the hot path
(NotifyReceived) is a fast map insert
Wired into the dropper via an adapter callback in backend.go that
converts txtracker.PeerStats to the dropper's PeerInclusionStats.
