task 302: add stats engine orchestration and snapshots

1 files changed, 130 insertions, 0 deletions

diff --git a/internal/statsengine/engine_test.go b/internal/statsengine/engine_test.go
new file mode 100644
index 0000000..943fe9c
--- /dev/null
+++ b/internal/statsengine/engine_test.go
@@ -0,0 +1,130 @@
+package statsengine
+
+import (
+	"ior/internal/event"
+	"ior/internal/file"
+	"ior/internal/types"
+	"math"
+	"testing"
+	"time"
+)
+
+type fakeClock struct {
+	now time.Time
+}
+
+func (c *fakeClock) Now() time.Time {
+	return c.now
+}
+
+func (c *fakeClock) Advance(d time.Duration) {
+	c.now = c.now.Add(d)
+}
+
+func TestEngineIngestAndSnapshotIntegration(t *testing.T) {
+	clock := &fakeClock{now: time.Unix(1000, 0)}
+	engine := newEngineWithClock(2, clock.Now)
+
+	engine.Ingest(newEnginePair(types.SYS_ENTER_READ, 100, types.READ_CLASSIFIED, "proc-a", 1, "/tmp/a", 100, 10, 3))
+	clock.Advance(500 * time.Millisecond)
+	engine.Ingest(newEnginePair(types.SYS_ENTER_WRITE, -1, types.WRITE_CLASSIFIED, "proc-a", 1, "/tmp/a", 50, 20, 5))
+	clock.Advance(500 * time.Millisecond)
+	engine.Ingest(newEnginePair(types.SYS_ENTER_COPY_FILE_RANGE, 80, types.TRANSFER_CLASSIFIED, "proc-b", 2, "/tmp/b", 20, 40, 8))
+	clock.Advance(1 * time.Second)
+
+	snap := engine.Snapshot()
+	if snap == nil {
+		t.Fatalf("expected snapshot")
+	}
+
+	if snap.TotalSyscalls != 3 || snap.TotalErrors != 1 || snap.TotalBytes != 170 {
+		t.Fatalf("unexpected totals: syscalls=%d errors=%d bytes=%d", snap.TotalSyscalls, snap.TotalErrors, snap.TotalBytes)
+	}
+	if snap.LatencyMeanNs != (10+20+40)/3.0 {
+		t.Fatalf("unexpected latency mean: %v", snap.LatencyMeanNs)
+	}
+	if snap.GapMeanNs != (3+5+8)/3.0 {
+		t.Fatalf("unexpected gap mean: %v", snap.GapMeanNs)
+	}
+
+	if math.Abs(snap.SyscallRatePerSec-1.5) > 1e-9 {
+		t.Fatalf("unexpected syscall rate: %v", snap.SyscallRatePerSec)
+	}
+	if math.Abs(snap.ErrorRatePerSec-0.5) > 1e-9 {
+		t.Fatalf("unexpected error rate: %v", snap.ErrorRatePerSec)
+	}
+	if math.Abs(snap.ReadBytesPerSec-60.0) > 1e-9 {
+		t.Fatalf("unexpected read bytes rate: %v", snap.ReadBytesPerSec)
+	}
+	if math.Abs(snap.WriteBytesPerSec-35.0) > 1e-9 {
+		t.Fatalf("unexpected write bytes rate: %v", snap.WriteBytesPerSec)
+	}
+
+	if len(snap.Syscalls()) != 3 {
+		t.Fatalf("expected 3 syscall rows, got %d", len(snap.Syscalls()))
+	}
+	if len(snap.Files()) != 2 {
+		t.Fatalf("expected top 2 files due to topN=2, got %d", len(snap.Files()))
+	}
+	if len(snap.Processes()) != 2 {
+		t.Fatalf("expected 2 process rows, got %d", len(snap.Processes()))
+	}
+	if snap.LatencyHistogram.Total != 3 || snap.GapHistogram.Total != 3 {
+		t.Fatalf("unexpected histogram totals: latency=%d gap=%d", snap.LatencyHistogram.Total, snap.GapHistogram.Total)
+	}
+}
+
+func TestEngineSnapshotWithNoEvents(t *testing.T) {
+	clock := &fakeClock{now: time.Unix(2000, 0)}
+	engine := newEngineWithClock(10, clock.Now)
+
+	snap := engine.Snapshot()
+	if snap == nil {
+		t.Fatalf("expected snapshot")
+	}
+	if snap.TotalSyscalls != 0 || snap.TotalErrors != 0 || snap.TotalBytes != 0 {
+		t.Fatalf("expected zero totals, got %+v", snap)
+	}
+	if len(snap.Syscalls()) != 0 || len(snap.Files()) != 0 || len(snap.Processes()) != 0 {
+		t.Fatalf("expected empty rows in zero snapshot")
+	}
+}
+
+func TestEngineTrendDetection(t *testing.T) {
+	if got := detectTrend(make([]float64, trendWindowSlots*2)); got.Direction != TrendStable {
+		t.Fatalf("expected stable for flat data, got %+v", got)
+	}
+
+	series := make([]float64, trendWindowSlots*2)
+	for i := 0; i < trendWindowSlots; i++ {
+		series[i] = 10
+	}
+	for i := trendWindowSlots; i < trendWindowSlots*2; i++ {
+		series[i] = 30
+	}
+	if got := detectTrend(series); got.Direction != TrendRising {
+		t.Fatalf("expected rising trend, got %+v", got)
+	}
+
+	for i := 0; i < trendWindowSlots; i++ {
+		series[i] = 40
+	}
+	for i := trendWindowSlots; i < trendWindowSlots*2; i++ {
+		series[i] = 10
+	}
+	if got := detectTrend(series); got.Direction != TrendFalling {
+		t.Fatalf("expected falling trend, got %+v", got)
+	}
+}
+
+func newEnginePair(traceID types.TraceId, ret int64, retType uint32, comm string, pid uint32, path string, bytes uint64, duration uint64, gap uint64) *event.Pair {
+	return &event.Pair{
+		EnterEv:        &types.RetEvent{TraceId: traceID, Pid: pid},
+		ExitEv:         &types.RetEvent{TraceId: traceID, Pid: pid, Ret: ret, RetType: retType},
+		Comm:           comm,
+		Duration:       duration,
+		DurationToPrev: gap,
+		Bytes:          bytes,
+		File:           file.NewFd(3, path, -1),
+	}
+}