feat: add executable multiplayer SLO checks

server/observability/slo.go

@@ -0,0 +1,70 @@
+package observability
+
+import (
+	"sort"
+	"time"
+)
+
+type SLOWindow struct {
+	RegionalRTT []time.Duration
+	Assignment  []time.Duration
+	Connection  []time.Duration
+	APILatency  []time.Duration
+	Matches     []bool
+	TickBacklog bool
+	Headroom    float64
+}
+
+type SLOViolation struct {
+	Metric string
+	Reason string
+}
+
+func EvaluateSLO(window SLOWindow) []SLOViolation {
+	violations := make([]SLOViolation, 0)
+	if percentile(window.RegionalRTT, .95) > 80*time.Millisecond {
+		violations = append(violations, SLOViolation{"regional_rtt_p95", "exceeds 80ms"})
+	}
+	if percentile(window.Assignment, .95) > 5*time.Second || percentile(window.Assignment, .99) > 10*time.Second {
+		violations = append(violations, SLOViolation{"assignment_latency", "p95/p99 threshold exceeded"})
+	}
+	if percentile(window.Connection, .95) > 5*time.Second {
+		violations = append(violations, SLOViolation{"connection_latency_p95", "exceeds 5s"})
+	}
+	if ratio(window.Matches) < .999 {
+		violations = append(violations, SLOViolation{"allocation_result_success", "below 99.9%"})
+	}
+	if percentile(window.APILatency, .95) > 250*time.Millisecond {
+		violations = append(violations, SLOViolation{"api_latency_p95", "exceeds 250ms"})
+	}
+	if window.TickBacklog {
+		violations = append(violations, SLOViolation{"tick_health", "physics backlog detected"})
+	}
+	if window.Headroom > 0 && window.Headroom < .30 {
+		violations = append(violations, SLOViolation{"resource_headroom", "below 30%"})
+	}
+	return violations
+}
+
+func percentile(values []time.Duration, p float64) time.Duration {
+	if len(values) == 0 {
+		return 0
+	}
+	ordered := append([]time.Duration(nil), values...)
+	sort.Slice(ordered, func(i, j int) bool { return ordered[i] < ordered[j] })
+	index := int(float64(len(ordered)-1) * p)
+	return ordered[index]
+}
+
+func ratio(values []bool) float64 {
+	if len(values) == 0 {
+		return 1
+	}
+	success := 0
+	for _, value := range values {
+		if value {
+			success++
+		}
+	}
+	return float64(success) / float64(len(values))
+}

server/observability/slo_test.go

@@ -0,0 +1,27 @@
+package observability
+
+import (
+	"testing"
+	"time"
+)
+
+func TestEvaluateSLOAcceptsHealthyWindow(t *testing.T) {
+	window := SLOWindow{RegionalRTT: []time.Duration{20 * time.Millisecond, 40 * time.Millisecond}, Assignment: []time.Duration{time.Second}, Connection: []time.Duration{time.Second}, APILatency: []time.Duration{100 * time.Millisecond}, Matches: []bool{true, true, true}, Headroom: .50}
+	if violations := EvaluateSLO(window); len(violations) != 0 {
+		t.Fatalf("healthy window violations = %+v", violations)
+	}
+}
+
+func TestEvaluateSLOFlagsEveryLaunchGate(t *testing.T) {
+	window := SLOWindow{RegionalRTT: []time.Duration{101 * time.Millisecond}, Assignment: []time.Duration{11 * time.Second}, Connection: []time.Duration{6 * time.Second}, APILatency: []time.Duration{251 * time.Millisecond}, Matches: []bool{true, false}, TickBacklog: true, Headroom: .29}
+	violations := EvaluateSLO(window)
+	if len(violations) != 7 {
+		t.Fatalf("violations = %+v", violations)
+	}
+}
+
+func TestEvaluateSLODoesNotInventFailureForEmptyOptionalWindows(t *testing.T) {
+	if violations := EvaluateSLO(SLOWindow{}); len(violations) != 0 {
+		t.Fatalf("empty window violations = %+v", violations)
+	}
+}