Show route churn as a whole count per minute (closes #160)

The status page showed route churn per second as a one-minute moving
average, so a quiet feed gave a fraction such as 0.1. The average was
correct.

The metrics tracker now also counts prefix announcements and
withdrawals, from all peers, in each clock minute. /api/v1/stats
reports the count for the last full minute as route_churn_per_min in
stream, in place of route_churn_per_sec. The status page shows it as
"Route Churn/min".

The status and home pages round messages and updates per second to
whole numbers.

Model: opus-5-5

README.md

@@ -81,7 +81,9 @@ Every route answers `HEAD` as it answers `GET`, without the body.
 ### API v1
 
 - `GET /api/v1/stats` - The `/status.json` figures plus connection, garbage
-  collector, stream and handler queue statistics
+  collector, stream and handler queue statistics. `stream.route_churn_per_min`
+  is the number of prefix announcements and withdrawals, from all peers, in the
+  last full clock minute.
 - `GET /api/v1/ip/{ip}` - Looks up each address: its most specific live route
   (`netblock`), that route's origin AS with its WHOIS details, and the address's
   PTR names. `{ip}` is an IP address, a host name, or a comma-separated list of

TODO.md

@@ -33,6 +33,11 @@ tested.
 
 # Completed Steps
 
+- 2026-10-26: the status page shows "Route Churn/min", the number of prefix
+  announcements and withdrawals, from all peers, in the last full clock minute.
+  `/api/v1/stats` reports it as `route_churn_per_min` in `stream`, which
+  replaces the moving average `route_churn_per_sec`. The messages and updates
+  per second on `/` and `/status` are whole numbers (closes #160)
 - 2026-10-26: the WHOIS fetcher backs off more slowly. A failure makes its wait
   1.5 times as long, up to one minute instead of five. Its queries to RIPE,
   APNIC and AFRINIC leave out person and role objects, which RIPE counts against

internal/metrics/metrics.go

@@ -34,7 +34,7 @@ type Tracker struct {
 	// Announcement/withdrawal metrics
 	announcementCounter metrics.Counter
 	withdrawalCounter   metrics.Counter
-	churnRate           metrics.Meter // combined announcements + withdrawals per second
+	churnPerMinute      minuteCounter // prefix announcements and withdrawals
 
 	// BGP peer tracking
 	bgpPeerCount atomic.Int32
@@ -56,7 +56,7 @@ func New() *Tracker {
 		ipv6UpdateRate:      metrics.NewMeter(),
 		announcementCounter: metrics.NewCounter(),
 		withdrawalCounter:   metrics.NewCounter(),
-		churnRate:           metrics.NewMeter(),
+		churnPerMinute:      minuteCounter{now: time.Now},
 	}
 }
 
@@ -156,13 +156,13 @@ func (t *Tracker) RecordIPv6Update() {
 // RecordAnnouncement records a route announcement
 func (t *Tracker) RecordAnnouncement() {
 	t.announcementCounter.Inc(1)
-	t.churnRate.Mark(1)
+	t.churnPerMinute.add()
 }
 
 // RecordWithdrawal records a route withdrawal
 func (t *Tracker) RecordWithdrawal() {
 	t.withdrawalCounter.Inc(1)
-	t.churnRate.Mark(1)
+	t.churnPerMinute.add()
 }
 
 // SetBGPPeerCount updates the current BGP peer count
@@ -198,9 +198,10 @@ func (t *Tracker) GetWithdrawalCount() uint64 {
 	return uint64(count)
 }
 
-// GetChurnRate returns the route churn rate per second
-func (t *Tracker) GetChurnRate() float64 {
-	return t.churnRate.Rate1()
+// GetChurnPerMinute returns the number of prefix announcements and
+// withdrawals, from all peers, in the last full clock minute.
+func (t *Tracker) GetChurnPerMinute() int {
+	return t.churnPerMinute.lastFullMinute()
 }
 
 // GetRouteMetrics returns current route update metrics

internal/metrics/minutecounter.go

@@ -0,0 +1,59 @@
+package metrics
+
+import (
+	"sync"
+	"time"
+)
+
+// minuteCounter counts events in each clock minute and reports the count of
+// the last full minute. It is safe for concurrent use.
+type minuteCounter struct {
+	mu  sync.Mutex
+	now func() time.Time
+
+	// minute is the start of the minute that count belongs to.
+	minute time.Time
+	count  int
+	// lastMinuteCount is the count of the minute just before minute.
+	lastMinuteCount int
+}
+
+// add counts one event in the current minute.
+func (c *minuteCounter) add() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.moveToCurrentMinute()
+	c.count++
+}
+
+// lastFullMinute returns the number of events in the minute that ended most
+// recently.
+func (c *minuteCounter) lastFullMinute() int {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.moveToCurrentMinute()
+
+	return c.lastMinuteCount
+}
+
+// moveToCurrentMinute starts a new count when the clock has moved into
+// another minute. The count it ends becomes the last full minute's count when
+// its minute is the one just before the current minute. Otherwise the last
+// full minute had no events. The caller holds mu.
+func (c *minuteCounter) moveToCurrentMinute() {
+	minute := c.now().Truncate(time.Minute)
+	if minute.Equal(c.minute) {
+		return
+	}
+
+	if minute.Sub(c.minute) == time.Minute {
+		c.lastMinuteCount = c.count
+	} else {
+		c.lastMinuteCount = 0
+	}
+
+	c.minute = minute
+	c.count = 0
+}

internal/metrics/minutecounter_internal_test.go

@@ -0,0 +1,86 @@
+package metrics
+
+import (
+	"sync"
+	"testing"
+	"time"
+)
+
+// TestChurnPerMinuteCountsLastFullMinute announces and withdraws prefixes on
+// an injected clock and expects each minute's whole count once that minute
+// has ended, and 0 for a minute with none.
+func TestChurnPerMinuteCountsLastFullMinute(t *testing.T) {
+	t.Parallel()
+
+	now := time.Date(2026, 10, 26, 12, 0, 30, 0, time.UTC)
+	tracker := New()
+	tracker.churnPerMinute.now = func() time.Time { return now }
+
+	expectChurn := func(want int, why string) {
+		t.Helper()
+
+		got := tracker.GetChurnPerMinute()
+		if got != want {
+			t.Fatalf("at %s churn = %d, want %d: %s",
+				now.Format(time.TimeOnly), got, want, why)
+		}
+	}
+
+	const firstMinuteChurn = 2
+
+	tracker.RecordAnnouncement()
+	tracker.RecordWithdrawal()
+	expectChurn(0, "12:00 has not ended")
+
+	now = time.Date(2026, 10, 26, 12, 1, 59, 0, time.UTC)
+
+	tracker.RecordAnnouncement()
+	expectChurn(firstMinuteChurn, "12:00 had one announcement and one withdrawal")
+
+	now = time.Date(2026, 10, 26, 12, 2, 0, 0, time.UTC)
+
+	expectChurn(1, "12:01 had one announcement")
+
+	now = time.Date(2026, 10, 26, 12, 4, 0, 0, time.UTC)
+
+	expectChurn(0, "12:03 had none")
+
+	tracker.RecordWithdrawal()
+
+	now = time.Date(2026, 10, 26, 12, 6, 0, 0, time.UTC)
+
+	expectChurn(0, "12:05 had none, though 12:04 had one withdrawal")
+}
+
+// TestChurnPerMinuteCountsConcurrentRecords announces prefixes from several
+// goroutines at once and expects every one counted.
+func TestChurnPerMinuteCountsConcurrentRecords(t *testing.T) {
+	t.Parallel()
+
+	const (
+		goroutines          = 8
+		recordsPerGoroutine = 1000
+	)
+
+	now := time.Date(2026, 10, 26, 12, 0, 0, 0, time.UTC)
+	tracker := New()
+	tracker.churnPerMinute.now = func() time.Time { return now }
+
+	var wg sync.WaitGroup
+	for range goroutines {
+		wg.Go(func() {
+			for range recordsPerGoroutine {
+				tracker.RecordAnnouncement()
+			}
+		})
+	}
+
+	wg.Wait()
+
+	now = now.Add(time.Minute)
+
+	want := goroutines * recordsPerGoroutine
+	if got := tracker.GetChurnPerMinute(); got != want {
+		t.Fatalf("churn = %d, want %d", got, want)
+	}
+}

internal/server/handlers.go

@@ -443,7 +443,7 @@ type GCStats struct {
 type StreamStats struct {
 	Announcements    uint64 `json:"announcements"`
 	Withdrawals      uint64 `json:"withdrawals"`
-	RouteChurnPerSec float64 `json:"route_churn_per_sec"`
+	RouteChurnPerMin int    `json:"route_churn_per_min"`
 	BGPPeerCount     int    `json:"bgp_peer_count"`
 }
 
@@ -545,7 +545,7 @@ func (s *Server) streamStats() StreamStats {
 	return StreamStats{
 		Announcements:    metricsTracker.GetAnnouncementCount(),
 		Withdrawals:      metricsTracker.GetWithdrawalCount(),
-		RouteChurnPerSec: metricsTracker.GetChurnRate(),
+		RouteChurnPerMin: metricsTracker.GetChurnPerMinute(),
 		BGPPeerCount:     metricsTracker.GetBGPPeerCount(),
 	}
 }

internal/server/handlers_internal_test.go

@@ -195,6 +195,51 @@ func TestStatsHandlersAnswerFromMemory(t *testing.T) {
 	}
 }
 
+// TestStatsAnswerCarriesChurnPerMinute checks that the stream object of the
+// /api/v1/stats answer holds route_churn_per_min as a whole number, and no
+// longer route_churn_per_sec, the moving average it replaces
+// (https://git.eeqj.de/sneak/routewatch/issues/160).
+func TestStatsAnswerCarriesChurnPerMinute(t *testing.T) {
+	t.Parallel()
+
+	s := newServerWithTestRoutes(t)
+
+	rec := httptest.NewRecorder()
+	s.handleStats()(rec,
+		httptest.NewRequestWithContext(t.Context(), http.MethodGet, statsPath, nil))
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status %d, want %d; body %s", rec.Code, http.StatusOK, rec.Body)
+	}
+
+	var body struct {
+		Data struct {
+			Stream map[string]json.RawMessage `json:"stream"`
+		} `json:"data"`
+	}
+
+	err := json.Unmarshal(rec.Body.Bytes(), &body)
+	if err != nil {
+		t.Fatalf("decoding the answer: %v", err)
+	}
+
+	churn, ok := body.Data.Stream["route_churn_per_min"]
+	if !ok {
+		t.Fatalf("stream has no route_churn_per_min: %s", rec.Body)
+	}
+
+	var count int
+
+	err = json.Unmarshal(churn, &count)
+	if err != nil {
+		t.Errorf("route_churn_per_min = %s, want a whole number: %v", churn, err)
+	}
+
+	if _, ok := body.Data.Stream["route_churn_per_sec"]; ok {
+		t.Errorf("stream still has route_churn_per_sec: %s", rec.Body)
+	}
+}
+
 // newServerWithTestRoutes returns a server on a new database that holds a
 // route for testPrefixV4 and one for testPrefixV6.
 func newServerWithTestRoutes(t *testing.T) *Server {

internal/templates/index.html

@@ -400,7 +400,7 @@
                     }
 
                     const totalUpdates = data.ipv4_updates_per_sec + data.ipv6_updates_per_sec;
-                    document.getElementById('stat-updates').textContent = totalUpdates.toFixed(1);
+                    document.getElementById('stat-updates').textContent = Math.round(totalUpdates).toLocaleString();
                 })
                 .catch(() => {
                     document.getElementById('stat-status').textContent = 'Error';

internal/templates/status.html

@@ -231,8 +231,8 @@
                 <span class="metric-value" id="withdrawals">-</span>
             </div>
             <div class="metric">
-                <span class="metric-label">Route Churn/sec</span>
-                <span class="metric-value" id="route_churn_per_sec">-</span>
+                <span class="metric-label">Route Churn/min</span>
+                <span class="metric-value" id="route_churn_per_min">-</span>
             </div>
             <div class="metric">
                 <span class="metric-label">Total Data</span>
@@ -511,7 +511,7 @@
             document.getElementById('messages_per_sec').textContent = '-';
             document.getElementById('announcements').textContent = '-';
             document.getElementById('withdrawals').textContent = '-';
-            document.getElementById('route_churn_per_sec').textContent = '-';
+            document.getElementById('route_churn_per_min').textContent = '-';
             document.getElementById('total_wire_bytes').textContent = '-';
             document.getElementById('wire_mbits_per_sec').textContent = '-';
             document.getElementById('gc_num').textContent = '-';
@@ -578,7 +578,7 @@
                     document.getElementById('connection_duration').textContent = data.connection_duration;
                     document.getElementById('reconnect_count').textContent = formatNumber(data.reconnect_count);
                     document.getElementById('total_messages').textContent = formatNumber(data.total_messages);
-                    document.getElementById('messages_per_sec').textContent = data.messages_per_sec.toFixed(1);
+                    document.getElementById('messages_per_sec').textContent = formatNumber(Math.round(data.messages_per_sec));
                     document.getElementById('total_wire_bytes').textContent = formatBytes(data.total_wire_bytes);
                     document.getElementById('wire_mbits_per_sec').textContent = data.wire_mbits_per_sec.toFixed(2) + ' Mbps';
                     document.getElementById('asns').textContent = formatNumber(data.asns);
@@ -591,8 +591,8 @@
                     document.getElementById('live_routes').textContent = formatNumber(data.live_routes);
                     document.getElementById('ipv4_routes').textContent = formatNumber(data.ipv4_routes);
                     document.getElementById('ipv6_routes').textContent = formatNumber(data.ipv6_routes);
-                    document.getElementById('ipv4_updates_per_sec').textContent = data.ipv4_updates_per_sec.toFixed(1);
-                    document.getElementById('ipv6_updates_per_sec').textContent = data.ipv6_updates_per_sec.toFixed(1);
+                    document.getElementById('ipv4_updates_per_sec').textContent = formatNumber(Math.round(data.ipv4_updates_per_sec));
+                    document.getElementById('ipv6_updates_per_sec').textContent = formatNumber(Math.round(data.ipv6_updates_per_sec));
                     document.getElementById('oldest_route').textContent = formatRelativeTime(data.oldest_route);
                     document.getElementById('newest_route').textContent = formatRelativeTime(data.newest_route);
 
@@ -601,7 +601,7 @@
                         document.getElementById('bgp_peer_count').textContent = formatNumber(data.stream.bgp_peer_count);
                         document.getElementById('announcements').textContent = formatNumber(data.stream.announcements);
                         document.getElementById('withdrawals').textContent = formatNumber(data.stream.withdrawals);
-                        document.getElementById('route_churn_per_sec').textContent = data.stream.route_churn_per_sec.toFixed(1);
+                        document.getElementById('route_churn_per_min').textContent = formatNumber(data.stream.route_churn_per_min);
                     }
 
                     // Update GC stats