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package statsengine
import (
"math"
"math/rand/v2"
"testing"
"time"
"ior/internal/event"
"ior/internal/types"
)
func TestSyscallAccumulatorBasicStats(t *testing.T) {
acc := newSyscallAccumulatorWithConfig(10_000, rand.New(rand.NewPCG(1, 0)))
traceID := types.SYS_ENTER_READ
acc.Add(newPair(traceID, 10, 100, 0))
acc.Add(newPair(traceID, 20, 50, -1))
acc.Add(newPair(traceID, 30, 25, 5))
snap := acc.Snapshot(2 * time.Second)
if len(snap) != 1 {
t.Fatalf("expected 1 syscall snapshot, got %d", len(snap))
}
got := snap[0]
if got.TraceID != traceID {
t.Fatalf("wrong trace id: got %v want %v", got.TraceID, traceID)
}
if got.Name != traceID.Name() {
t.Fatalf("wrong name: got %q want %q", got.Name, traceID.Name())
}
if got.Count != 3 {
t.Fatalf("wrong count: got %d want 3", got.Count)
}
if got.Errors != 1 {
t.Fatalf("wrong errors: got %d want 1", got.Errors)
}
if got.Bytes != 175 {
t.Fatalf("wrong bytes: got %d want 175", got.Bytes)
}
if got.LatencyMinNs != 10 || got.LatencyMaxNs != 30 {
t.Fatalf("wrong min/max: got (%d,%d) want (10,30)", got.LatencyMinNs, got.LatencyMaxNs)
}
if got.LatencyMeanNs != 20 {
t.Fatalf("wrong mean: got %v want 20", got.LatencyMeanNs)
}
if got.LatencyP50Ns != 20 || got.LatencyP95Ns != 30 || got.LatencyP99Ns != 30 {
t.Fatalf("wrong percentiles: got p50=%d p95=%d p99=%d", got.LatencyP50Ns, got.LatencyP95Ns, got.LatencyP99Ns)
}
if math.Abs(got.RatePerSec-1.5) > 1e-9 {
t.Fatalf("wrong rate: got %v want 1.5", got.RatePerSec)
}
}
func TestSyscallAccumulatorSortsByCountThenName(t *testing.T) {
acc := newSyscallAccumulatorWithConfig(10_000, rand.New(rand.NewPCG(2, 0)))
idA := types.SYS_ENTER_OPENAT
idB := types.SYS_ENTER_READ
acc.Add(newPair(idA, 10, 0, 0))
acc.Add(newPair(idA, 11, 0, 0))
acc.Add(newPair(idB, 12, 0, 0))
snap := acc.Snapshot(1 * time.Second)
if len(snap) != 2 {
t.Fatalf("expected 2 syscall snapshots, got %d", len(snap))
}
if snap[0].TraceID != idA {
t.Fatalf("expected first id %v, got %v", idA, snap[0].TraceID)
}
if snap[1].TraceID != idB {
t.Fatalf("expected second id %v, got %v", idB, snap[1].TraceID)
}
}
func TestSyscallAccumulatorReservoirPercentilesAccuracy(t *testing.T) {
acc := newSyscallAccumulatorWithConfig(100, rand.New(rand.NewPCG(7, 0)))
traceID := types.SYS_ENTER_WRITE
for d := uint64(1); d <= 10_000; d++ {
acc.Add(newPair(traceID, d, 0, 0))
}
snap := acc.Snapshot(1 * time.Second)
if len(snap) != 1 {
t.Fatalf("expected 1 syscall snapshot, got %d", len(snap))
}
got := snap[0]
assertNearPercentile(t, "p50", got.LatencyP50Ns, 5_000, 1_500)
assertNearPercentile(t, "p95", got.LatencyP95Ns, 9_500, 800)
assertNearPercentile(t, "p99", got.LatencyP99Ns, 9_900, 500)
}
func TestSyscallAccumulatorZeroElapsedRate(t *testing.T) {
acc := newSyscallAccumulatorWithConfig(32, rand.New(rand.NewPCG(9, 0)))
acc.Add(newPair(types.SYS_ENTER_READ, 9, 0, 0))
snap := acc.Snapshot(0)
if len(snap) != 1 {
t.Fatalf("expected 1 syscall snapshot, got %d", len(snap))
}
if snap[0].RatePerSec != 0 {
t.Fatalf("expected zero rate, got %v", snap[0].RatePerSec)
}
}
func TestSyscallAccumulatorPercentilesRecomputeAfterThreshold(t *testing.T) {
acc := newSyscallAccumulatorWithConfig(10_000, rand.New(rand.NewPCG(11, 0)))
traceID := types.SYS_ENTER_READ
for i := 1; i <= 1000; i++ {
acc.Add(newPair(traceID, uint64(i), 0, 0))
}
_ = acc.Snapshot(1 * time.Second)
stats := acc.byID[traceID]
if stats == nil {
t.Fatalf("expected syscall stats")
}
initialVersion := stats.lastPercentileVersion
initialP50 := stats.cachedP50
if initialVersion == 0 {
t.Fatalf("expected initial percentile computation")
}
acc.Add(newPair(traceID, 50000, 0, 0))
_ = acc.Snapshot(1 * time.Second)
if stats.lastPercentileVersion != initialVersion {
t.Fatalf("expected percentile recompute to be deferred; got %d want %d", stats.lastPercentileVersion, initialVersion)
}
if stats.cachedP50 != initialP50 {
t.Fatalf("expected cached p50 to remain unchanged before threshold")
}
for i := 0; i < syscallPercentileRecomputeStepDefault; i++ {
acc.Add(newPair(traceID, uint64(60000+i), 0, 0))
}
_ = acc.Snapshot(1 * time.Second)
if stats.lastPercentileVersion != stats.sampleVersion {
t.Fatalf("expected percentile recompute after threshold, last=%d sample=%d", stats.lastPercentileVersion, stats.sampleVersion)
}
}
func newPair(traceID types.TraceId, duration uint64, bytes uint64, ret int64) *event.Pair {
return &event.Pair{
EnterEv: &types.RetEvent{TraceId: traceID},
ExitEv: &types.RetEvent{TraceId: traceID, Ret: ret},
Duration: duration,
Bytes: bytes,
}
}
func assertNearPercentile(t *testing.T, name string, got uint64, want uint64, tolerance uint64) {
t.Helper()
delta := absDiff(got, want)
if delta > tolerance {
t.Fatalf("%s too far from expected: got %d want %d (delta %d > %d)", name, got, want, delta, tolerance)
}
}
func absDiff(a, b uint64) uint64 {
if a > b {
return a - b
}
return b - a
}
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