Replace NotifyRequestLatency(peer, latency) with
NotifyRequestResult(peer, latency, timeout). The new timeout bool
tells peerstats whether the request was answered or timed out.
Per-peer RequestSuccesses and RequestTimeouts counters replace the
single RequestSamples field — any two of the three are derivable, so
we keep the two primary counters and derive the total
(successes + timeouts) where needed (e.g. the MinLatencySamples
guard in the dropper).
The latency EMA continues to use the timeout value for timed-out
requests, penalizing slow peers as before. The success/timeout
counters are exposed as statistics only — no protection category
uses them yet.
The request-latency category scores peers by the reciprocal of their
RequestLatencyEMA, but that EMA is only updated by NotifyRequestLatency
— which only fires when the tx fetcher sends a request to the peer.
A peer can serve a burst of fast replies to build a strong EMA, stop
announcing transactions so we never request from them again, and
retain latency protection indefinitely with a frozen score.
Record LastLatencySample (wall-clock time) per peer alongside the EMA
update. In the dropper's scoring function, return 0 when the last
sample is older than MaxLatencyStaleness (10 minutes). Fresh samples
reset the clock, so peers that resume activity become eligible again.
Timestamps rather than block counts: real-time is what we actually
care about (10 minutes idle), not a block count that varies with
chain pace, and the EMA itself is a time.Duration so measuring
staleness in the same domain stays consistent.
Tests cover the timestamp update on NotifyRequestLatency, the timestamp
advancing on successive samples, and the dropper rejecting a stale
peer whose EMA and sample count would otherwise qualify.
Require substantially more samples before a peer's request-latency EMA
becomes eligible for protection. A 10-sample floor was too low: a peer
hitting 10 fast replies in a short burst could earn protection before
the slow alpha=0.01 EMA had moved meaningfully away from the bootstrap
value. At ~70-sample EMA half-life, a 100-sample floor means the EMA
has been refined through several half-lives before it can affect
dropping decisions.
Updates the dropper tests that previously used RequestSamples=50 to
use peerstats.MinLatencySamples so they stay robust to future value
changes. Design notes and a test comment reference the new value.
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.
