package peerstore import ( "sync" "time" "github.com/libp2p/go-libp2p/core/peer" ) // LatencyEWMASmoothing governs the decay of the EWMA (the speed // at which it changes). This must be a normalized (0-1) value. // 1 is 100% change, 0 is no change. var LatencyEWMASmoothing = 0.1 type metrics struct { mutex sync.RWMutex latmap map[peer.ID]time.Duration } func NewMetrics() *metrics { return &metrics{ latmap: make(map[peer.ID]time.Duration), } } // RecordLatency records a new latency measurement func (m *metrics) RecordLatency(p peer.ID, next time.Duration) { nextf := float64(next) s := LatencyEWMASmoothing if s > 1 || s < 0 { s = 0.1 // ignore the knob. it's broken. look, it jiggles. } m.mutex.Lock() ewma, found := m.latmap[p] ewmaf := float64(ewma) if !found { m.latmap[p] = next // when no data, just take it as the mean. } else { nextf = ((1.0 - s) * ewmaf) + (s * nextf) m.latmap[p] = time.Duration(nextf) } m.mutex.Unlock() } // LatencyEWMA returns an exponentially-weighted moving avg. // of all measurements of a peer's latency. func (m *metrics) LatencyEWMA(p peer.ID) time.Duration { m.mutex.RLock() defer m.mutex.RUnlock() return m.latmap[p] } func (m *metrics) RemovePeer(p peer.ID) { m.mutex.Lock() delete(m.latmap, p) m.mutex.Unlock() }