cmd/trace,internal/trace,runtime: refactor to access frames via range over func

Change-Id: Id0be0eb35ae8560bd5338ec296a086aaf4617db0
Reviewed-on: https://go-review.googlesource.com/c/go/+/608856
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

9 files changed, 42 insertions, 68 deletions

diff --git a/src/cmd/trace/gstate.go b/src/cmd/trace/gstate.go
index 76c58073b3..ea501ef57d 100644
--- a/src/cmd/trace/gstate.go
+++ b/src/cmd/trace/gstate.go
@@ -362,11 +362,9 @@ func (gs *gState[R]) rangeEnd(ts trace.Time, name string, stack trace.Stack, ctx
 	delete(gs.activeRanges, name)
 }
 
-func lastFunc(s trace.Stack) string {
-	var last trace.StackFrame
-	s.Frames()(func(f trace.StackFrame) bool {
-		last = f
-		return true
-	})
-	return last.Func
+func lastFunc(s trace.Stack) (fn string) {
+	for frame := range s.Frames() {
+		fn = frame.Func
+	}
+	return
 }
diff --git a/src/cmd/trace/pprof.go b/src/cmd/trace/pprof.go
index 856b97b75f..d27dfa7aa3 100644
--- a/src/cmd/trace/pprof.go
+++ b/src/cmd/trace/pprof.go
@@ -306,19 +306,19 @@ func (m *stackMap) profile() []traceviewer.ProfileRecord {
 	prof := make([]traceviewer.ProfileRecord, 0, len(m.stacks))
 	for stack, record := range m.stacks {
 		rec := *record
-		i := 0
-		stack.Frames()(func(frame trace.StackFrame) bool {
+		for i, frame := range slices.Collect(stack.Frames()) {
 			rec.Stack = append(rec.Stack, &trace.Frame{
 				PC:   frame.PC,
 				Fn:   frame.Func,
 				File: frame.File,
 				Line: int(frame.Line),
 			})
-			i++
 			// Cut this off at pprofMaxStack because that's as far
 			// as our deduplication goes.
-			return i < pprofMaxStack
-		})
+			if i >= pprofMaxStack {
+				break
+			}
+		}
 		prof = append(prof, rec)
 	}
 	return prof
@@ -326,10 +326,10 @@ func (m *stackMap) profile() []traceviewer.ProfileRecord {
 
 // pcsForStack extracts the first pprofMaxStack PCs from stack into pcs.
 func pcsForStack(stack trace.Stack, pcs *[pprofMaxStack]uint64) {
-	i := 0
-	stack.Frames()(func(frame trace.StackFrame) bool {
+	for i, frame := range slices.Collect(stack.Frames()) {
 		pcs[i] = frame.PC
-		i++
-		return i < len(pcs)
-	})
+		if i >= len(pcs) {
+			break
+		}
+	}
 }
diff --git a/src/cmd/trace/regions.go b/src/cmd/trace/regions.go
index cae38355a5..4073b6b07d 100644
--- a/src/cmd/trace/regions.go
+++ b/src/cmd/trace/regions.go
@@ -72,10 +72,9 @@ func fingerprintRegion(r *trace.UserRegionSummary) regionFingerprint {
 func regionTopStackFrame(r *trace.UserRegionSummary) trace.StackFrame {
 	var frame trace.StackFrame
 	if r.Start != nil && r.Start.Stack() != trace.NoStack {
-		r.Start.Stack().Frames()(func(f trace.StackFrame) bool {
+		for f := range r.Start.Stack().Frames() {
 			frame = f
-			return false
-		})
+		}
 	}
 	return frame
 }
diff --git a/src/cmd/trace/viewer.go b/src/cmd/trace/viewer.go
index c367c7d636..6ce74b75b8 100644
--- a/src/cmd/trace/viewer.go
+++ b/src/cmd/trace/viewer.go
@@ -15,15 +15,14 @@ import (
 // used to store the frames to reduce allocations.
 func viewerFrames(stk trace.Stack) []*trace.Frame {
 	var frames []*trace.Frame
-	stk.Frames()(func(f trace.StackFrame) bool {
+	for f := range stk.Frames() {
 		frames = append(frames, &trace.Frame{
 			PC:   f.PC,
 			Fn:   f.Func,
 			File: f.File,
 			Line: int(f.Line),
 		})
-		return true
-	})
+	}
 	return frames
 }
 
diff --git a/src/internal/trace/event.go b/src/internal/trace/event.go
index 90effce653..a5c5aec2f8 100644
--- a/src/internal/trace/event.go
+++ b/src/internal/trace/event.go
@@ -798,11 +798,10 @@ func (e Event) String() string {
 		if s.Stack != NoStack {
 			fmt.Fprintln(&sb)
 			fmt.Fprintln(&sb, "TransitionStack=")
-			s.Stack.Frames()(func(f StackFrame) bool {
+			for f := range s.Stack.Frames() {
 				fmt.Fprintf(&sb, "\t%s @ 0x%x\n", f.Func, f.PC)
 				fmt.Fprintf(&sb, "\t\t%s:%d\n", f.File, f.Line)
-				return true
-			})
+			}
 		}
 	case EventExperimental:
 		r := e.Experimental()
@@ -811,11 +810,10 @@ func (e Event) String() string {
 	if stk := e.Stack(); stk != NoStack {
 		fmt.Fprintln(&sb)
 		fmt.Fprintln(&sb, "Stack=")
-		stk.Frames()(func(f StackFrame) bool {
+		for f := range stk.Frames() {
 			fmt.Fprintf(&sb, "\t%s @ 0x%x\n", f.Func, f.PC)
 			fmt.Fprintf(&sb, "\t\t%s:%d\n", f.File, f.Line)
-			return true
-		})
+		}
 	}
 	return sb.String()
 }
diff --git a/src/internal/trace/summary.go b/src/internal/trace/summary.go
index 1cd506ac5a..f31439feb8 100644
--- a/src/internal/trace/summary.go
+++ b/src/internal/trace/summary.go
@@ -390,24 +390,14 @@ func (s *Summarizer) Event(ev *Event) {
 			// This root frame will be identical for all transitions on this
 			// goroutine, because it represents its immutable start point.
 			if g.Name == "" {
-				stk := st.Stack
-				if stk != NoStack {
-					var frame StackFrame
-					var ok bool
-					stk.Frames()(func(f StackFrame) bool {
-						frame = f
-						ok = true
-						return true
-					})
-					if ok {
-						// NB: this PC won't actually be consistent for
-						// goroutines which existed at the start of the
-						// trace. The UI doesn't use it directly; this
-						// mainly serves as an indication that we
-						// actually saw a call stack for the goroutine
-						g.PC = frame.PC
-						g.Name = frame.Func
-					}
+				for frame := range st.Stack.Frames() {
+					// NB: this PC won't actually be consistent for
+					// goroutines which existed at the start of the
+					// trace. The UI doesn't use it directly; this
+					// mainly serves as an indication that we
+					// actually saw a call stack for the goroutine
+					g.PC = frame.PC
+					g.Name = frame.Func
 				}
 			}
 
diff --git a/src/internal/trace/testtrace/validation.go b/src/internal/trace/testtrace/validation.go
index 42a561f1f0..59ff19e610 100644
--- a/src/internal/trace/testtrace/validation.go
+++ b/src/internal/trace/testtrace/validation.go
@@ -350,20 +350,17 @@ func (v *Validator) getOrCreateThread(e *errAccumulator, ev trace.Event, m trace
 
 func checkStack(e *errAccumulator, stk trace.Stack) {
 	// Check for non-empty values, but we also check for crashes due to incorrect validation.
-	i := 0
-	stk.Frames()(func(f trace.StackFrame) bool {
+	for i, f := range slices.Collect(stk.Frames()) {
 		if i == 0 {
 			// Allow for one fully zero stack.
 			//
 			// TODO(mknyszek): Investigate why that happens.
-			return true
+			continue
 		}
 		if f.Func == "" || f.File == "" || f.PC == 0 || f.Line == 0 {
 			e.Errorf("invalid stack frame %#v: missing information", f)
 		}
-		i++
-		return true
-	})
+	}
 }
 
 type errAccumulator struct {
diff --git a/src/internal/trace/trace_test.go b/src/internal/trace/trace_test.go
index dcf9d05fb4..facac47eef 100644
--- a/src/internal/trace/trace_test.go
+++ b/src/internal/trace/trace_test.go
@@ -16,6 +16,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"slices"
 	"strings"
 	"testing"
 )
@@ -148,12 +149,11 @@ func TestTraceCPUProfile(t *testing.T) {
 				if hogRegion != nil && ev.Goroutine() == hogRegion.Goroutine() {
 					traceSamples++
 					var fns []string
-					ev.Stack().Frames()(func(frame trace.StackFrame) bool {
+					for frame := range ev.Stack().Frames() {
 						if frame.Func != "runtime.goexit" {
 							fns = append(fns, fmt.Sprintf("%s:%d", frame.Func, frame.Line))
 						}
-						return true
-					})
+					}
 					stack := strings.Join(fns, "|")
 					traceStacks[stack]++
 				}
@@ -436,21 +436,15 @@ func TestTraceStacks(t *testing.T) {
 			}...)
 		}
 		stackMatches := func(stk trace.Stack, frames []frame) bool {
-			i := 0
-			match := true
-			stk.Frames()(func(f trace.StackFrame) bool {
+			for i, f := range slices.Collect(stk.Frames()) {
 				if f.Func != frames[i].fn {
-					match = false
 					return false
 				}
 				if line := uint64(frames[i].line); line != 0 && line != f.Line {
-					match = false
 					return false
 				}
-				i++
-				return true
-			})
-			return match
+			}
+			return true
 		}
 		r, err := trace.NewReader(bytes.NewReader(tb))
 		if err != nil {
diff --git a/src/runtime/trace_cgo_test.go b/src/runtime/trace_cgo_test.go
index 28b6f7833e..871698f8b4 100644
--- a/src/runtime/trace_cgo_test.go
+++ b/src/runtime/trace_cgo_test.go
@@ -94,10 +94,9 @@ func mustFindLogV2(t *testing.T, trc io.Reader, category string) trace.Event {
 // 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 {
+	for f := range e.Stack().Frames() {
 		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()
 }