Set stack to cache since BPF_F_REUSE_STACKID is not set by default (#14)

ebpf/event_handler.go

@@ -27,9 +27,9 @@ type eventHandler struct {
 func (h *eventHandler) run(ctx context.Context) {
  var event bpfEvent
  // To delete stack_addresses that is not used recently.
- stackIdCache := expirable.NewLRU[int32, struct{}](
+ stackIdCache := expirable.NewLRU[int32, []*proc.Function](
  32, // cache size
- func(key int32, _ struct{}) {
+ func(key int32, _ []*proc.Function) {
  slog.Debug("delete stack_addresses", slog.Int("stack_id", int(key)))
  if err := h.objs.StackAddresses.Delete(key); err != nil {
  slog.Debug("Failed to delete stack_addresses", slog.Any("error", err))
@@ -46,18 +46,24 @@ func (h *eventHandler) run(ctx context.Context) {
  slog.Warn("Failed to read bpf ring buffer", slog.Any("error", err))
  continue
  }
- stack, err := h.lookupStack(ctx, event.StackId)
- if err != nil {
- slog.Warn(err.Error())
- continue
+ var stack []*proc.Function
+ var ok bool
+ var err error
+ stack, ok = stackIdCache.Get(event.StackId)
+ if !ok {
+ stack, err = h.lookupStack(ctx, event.StackId)
+ if err != nil {
+ slog.Warn(err.Error())
+ continue
+ }
  }
  h.sendGoroutine(goroutine{
  Id: event.GoroutineId,
  ObservedAt: time.Now(),
  Stack: stack,
  Exit: event.Exit,
  })
- _ = stackIdCache.Add(event.StackId, struct{}{})
+ _ = stackIdCache.Add(event.StackId, stack)
  }
 }