Reduce peak client recalculation overhead

internal/dnstt/collector.go

@@ -167,9 +167,12 @@ func (c *Collector) RecordQueryFrom(domain string, clientID string, resolverIP n
 
 	now := c.now()
 	client, exists := tunnel.clients[clientID]
+	updatePeak := !exists
 	if !exists {
 		client = &clientState{firstSeen: now, firstKey: key}
 		tunnel.clients[clientID] = client
+	} else if now.Sub(client.lastSeen) >= ClientTimeout || client.lastKey != key {
+		updatePeak = true
 	}
 	client.lastSeen = now
 	client.lastKey = key
@@ -178,7 +181,9 @@ func (c *Collector) RecordQueryFrom(domain string, clientID string, resolverIP n
 		client.bytesIn += uint64(size)
 	}
 
-	updatePeaks(tunnel, now)
+	if updatePeak {
+		updatePeaks(tunnel, now)
+	}
 }
 
 // RecordResponse records an observed DNSTT DNS response.
@@ -211,7 +216,6 @@ func (c *Collector) Snapshot() Snapshot {
 	snapshot := Snapshot{Tunnels: make(map[string]TunnelSnapshot, len(c.tunnels))}
 	for _, domain := range c.domains {
 		tunnel := c.tunnels[domain]
-		updatePeaks(tunnel, now)
 		series := c.seriesSnapshotsLocked(domain, tunnel, now)
 
 		tunnelSnapshot := TunnelSnapshot{Domain: domain, Series: series}