const val HEADER_TABLE_SIZE = 1

    /** HTTP/2: The peer must not send a PUSH_PROMISE frame when this is 0. */
    const val ENABLE_PUSH = 2

    /** Sender's maximum number of concurrent streams. */
    const val MAX_CONCURRENT_STREAMS = 4

    /** HTTP/2: Size in bytes of the largest frame payload the sender will accept. */
    const val MAX_FRAME_SIZE = 5

// of a goroutine.
type stackScanState struct {
	// stack limits
	stack stack

	// conservative indicates that the next frame must be scanned conservatively.
	// This applies only to the innermost frame at an async safe-point.
	conservative bool

	// buf contains the set of possible pointers to stack objects.
	// Organized as a LIFO linked list of buffers.

		t.Fatalf("found more than one log with category: %q", category)
	}
	return candidates[0]
}

// dumpStack returns e.Stack() as a string.
func dumpStackV2(e *trace.Event) string {
	var buf bytes.Buffer
	e.Stack().Frames(func(f trace.StackFrame) bool {
		file := strings.TrimPrefix(f.File, runtime.GOROOT())
		fmt.Fprintf(&buf, "%s\n\t%s:%d\n", f.Func, file, f.Line)
		return true
	})
	return buf.String()

	// The idea is to do the compile with a trace option turned
	// on and then pick up on the frame offsets of specific
	// variables.
	//
	// Stack slot merging is a greedy algorithm, and there can
	// be many possible ways to overlap a given set of candidate
	// variables, all of them legal. Rather than locking down
	// a specific set of overlappings or frame offsets, this
	// tests just verifies that there is a decent-sized clump of 4+ vars that

}

//go:generate go run mkpreempt.go

// asyncPreempt saves all user registers and calls asyncPreempt2.
//
// When stack scanning encounters an asyncPreempt frame, it scans that
// frame and its parent frame conservatively.
//
// asyncPreempt is implemented in assembly.
func asyncPreempt()

//go:nosplit
func asyncPreempt2() {
	gp := getg()
	gp.asyncSafePoint = true

	// if tlsConfig != nil {
	// 	trhttp2, _ := http2.ConfigureTransports(tr)
	// 	if trhttp2 != nil {
	// 		// ReadIdleTimeout is the timeout after which a health check using ping
	// 		// frame will be carried out if no frame is received on the
	// 		// connection. 5 minutes is sufficient time for any idle connection.
	// 		trhttp2.ReadIdleTimeout = 5 * time.Minute

					stk = stk[i:]
					break
				}
			}
			locs = b.appendLocsForStack(locs[:0], stk)
			if len(locs) > 0 {
				break
			}
			hideRuntime = false // try again, and show all frames next time.
		}

		values[0], values[1] = scaleHeapSample(r.AllocObjects, r.AllocBytes, rate)
		values[2], values[3] = scaleHeapSample(r.InUseObjects(), r.InUseBytes(), rate)
		var blockSize int64
		if r.AllocObjects > 0 {

				return Event{}, fmt.Errorf("unexpected EOF while reading stack: args=%v", args)
			}
			if err != nil {
				return Event{}, err
			}
			frame, err := readArgs(line, frameFields)
			if err != nil {
				return Event{}, err
			}
			args = append(args, frame...)
		}
	}
	var data []byte
	if spec.HasData {
		line, err := r.nextLine()
		if err == io.EOF {

    const std::string& var_name,
    const tensorflow::FrameAndIter& control_frame) {
  if (control_frame.frame_id != tensorflow::kIllegalFrameId &&
      control_frame.iter_id != tensorflow::kIllegalIterId) {
    return tensorflow::strings::StrCat(var_name,
                                       "/frame:", control_frame.frame_id,
                                       "/iter:", control_frame.iter_id);
  }
  return var_name;
}

	// the "frame" to cgocallback and on to callbackWrap.
	SUBQ	$(24+callbackArgs__size), SP
	MOVQ	AX, (24+callbackArgs_index)(SP) 	// callback index
	MOVQ	R8, (24+callbackArgs_args)(SP)  	// address of args vector
	MOVQ	$0, (24+callbackArgs_result)(SP)	// result
	LEAQ	24(SP), AX
	// Call cgocallback, which will call callbackWrap(frame).
	MOVQ	$0, 16(SP)	// context