perf: default-off in-app profiler + debug scroll jumps; verify scroll perf & clamping

internal/perf: single-goroutine profiler (no locks). When enabled by the
/storage/emulated/0/PadPerf/enable marker it records one CSV row per logic
frame (seq, ms, frame delta, page, scroll Dp, max-scroll Dp, total lines,
visible byte range), logs a rolling ~1/s summary, and on Stop reports
nearest-rank p50/p90/p99/max. Flushes per row-batch but never fsyncs per
flush (avoids periodic hitches in the logic path).

editor: PerfRecord package-level hook (nil when off) + ProbeRecord;
Logic.emitFrame() now centralizes every frame emission so the profiler sees
each logic frame exactly once, on the owner goroutine. State gains
VisibleStart/VisibleEnd so the probe can confirm shaping stays
viewport-bounded.

logic: optional debug cmd poller (off by default) watches <dir>/cmd as a
one-shot file (top/bottom/frac <0..1>/dp <int>) and the owner applies a
clamped [0,MaxScroll] jump + frame. Enables deterministic large-offset scroll
tests without pixel taps.

main: wires the profiler when the marker file exists; logs present-fps
every 2s; stops the profiler on Destroy.

docs: README package inventory (add internal/perf); architecture §11
profiler facility; spec §5 invariant 7 (scroll always clamped to
[0,maxScroll]) + §6 measured rows; development_plan v5 + Phase 6 results.

Verified: go build/vet + full -race green. On-device 10 MB file:
logic-frame cadence flat across offsets 0.02->1.0 (no large-offset
degradation), visible byte range <=4.3 KB at every offset, clamping exact
across 2->130,955-line files, PSS plateaus ~250 MB (bounded, no leak);
profiler overhead negligible.
This commit is contained in:
Greg Pomerantz 2026-08-16 16:53:28 -04:00
parent 5271092c21
commit be48ad8157
10 changed files with 627 additions and 46 deletions

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@ -6,17 +6,19 @@ import (
"os"
"path/filepath"
"sync"
"time"
"gioui.org/app"
"gioui.org/font/gofont"
"gioui.org/io/key"
"gioui.org/op"
"gioui.org/text"
"gioui.org/unit"
"gioui.org/font/gofont"
"gioui.org/io/key"
"gioui.org/widget"
"pad/internal/editor"
"pad/internal/io/pool/real"
"pad/internal/perf"
"pad/internal/ui"
)
@ -45,7 +47,7 @@ func run(w *app.Window) error {
// Initialize the real filesystem rooted at the system root "/"
// so that the browser can navigate the entire system.
fs := real.NewRealFileSystem("/")
// Get the absolute path of the startup directory
startAbs, err := filepath.Abs(*rootDir)
if err != nil {
@ -56,6 +58,32 @@ func run(w *app.Window) error {
logic := editor.NewLogic(fs, startAbs, OpenFile)
renderer := ui.New(ui.Theme{FontSize: 14}, shaper)
// In-app frame profiler (default off). Enabled by the presence of a marker
// file so the shipping APK needs no rebuild to toggle profiling. When on,
// it records logic-frame cadence plus scroll/visible-range context to a CSV
// and logs rolling percentiles; it also enables the scroll-jump debug poller.
const perfDir = "/storage/emulated/0/PadPerf"
var prof *perf.Profiler
var perfOn bool
var presentN int
var presentStart time.Time
if _, err := os.Stat(filepath.Join(perfDir, "enable")); err == nil {
prof = perf.New(true, perfDir, "logic_frames.csv")
editor.PerfRecord = func(rec editor.ProbeRecord) {
prof.Record(perf.Ctx{
Page: rec.Page,
ScrollDP: rec.ScrollDP,
MaxScrollDP: rec.MaxScrollDP,
TotalLines: rec.TotalLines,
VisStart: rec.VisStart,
VisEnd: rec.VisEnd,
})
}
logic.EnableDebugCmdPoll(perfDir)
perfOn = true
log.Printf("PERF: enabled (dir=%s)", perfDir)
}
// The search bar's widget.Editor is owned by the MAIN goroutine: Gio
// mutates it during draw, and the logic goroutine must never touch it
// (architecture.md §1). Its text is forwarded to the logic goroutine via
@ -76,6 +104,9 @@ func run(w *app.Window) error {
for {
switch e := w.Event().(type) {
case app.DestroyEvent:
if prof != nil {
prof.Stop()
}
logic.Shutdown()
return e.Err
case app.ConfigEvent:
@ -85,6 +116,18 @@ func run(w *app.Window) error {
PixelHeight: e.Config.Size.Y,
}
case app.FrameEvent:
if perfOn {
presentN++
if presentStart.IsZero() {
presentStart = time.Now()
}
if time.Since(presentStart) >= 2*time.Second {
dt := time.Since(presentStart).Seconds()
log.Printf("PERF-PRESENT frames=%d fps=%.1f", presentN, float64(presentN)/dt)
presentN = 0
presentStart = time.Time{}
}
}
gtx := app.NewContext(&ops, e)
newScale := gtx.Metric.PxPerDp
// Read ONLY the frame-receiver-stored snapshot; the main goroutine

View File

@ -9,6 +9,18 @@ line-by-line code — so they stay true as the implementation evolves.
| [`architecture.md`](./architecture.md) | How it works: single-owner concurrency model, channel topology, Frame handoff contract, ownership rules, editor/browser/render internals. |
| [`development_plan.md`](./development_plan.md) | The active plan: completed phases, remaining work, and the on-device observation loop. |
## Package inventory
| Package | Role |
|---------|------|
| `internal/editor` | Chunked buffer, line index, virtualized viewport, IME ops, autosave, logic goroutine, state, Frame |
| `internal/browser` | Directory browsing, search, sort, pagination, browser state machine |
| `internal/ui` | Element tree, frame layout, renderer (op-based), IME wiring, gestures |
| `internal/perf` | Default-off performance profiler (per-logic-frame cadence + scroll state → CSV) |
| `internal/io/pool` | Worker pool (8 workers, 2 priority lanes) + file/dir tasks |
| `internal/test/e2e` | Harness driving the real `Logic` + `Inspect` |
| `cmd/pad` | `main.go` (entry), `impl_android.go` (base path) |
## Documentation policy
1. **Docs describe invariants and contracts, not code lines.** If a document

View File

@ -304,3 +304,32 @@ Only the visible byte range is shaped and drawn each frame:
(`development_plan.md` Phase 4).
- Dead task types (`ReadChunk`, `SaveState`, `SaveUndo`, …) and unused element
types are candidates for removal in the same round.
## 11. Performance profiler (default-off, `internal/perf`)
Pad ships a built-in profiler that is **off by default** and costs nothing when
off. It is the in-app frame-timing tool (see `development_plan.md` §9: `gfxinfo`
cannot measure this app because it renders into a `SurfaceView`).
- **Enable** by creating the marker file
`/storage/emulated/0/PadPerf/enable` before launch. `main.go` then creates a
`perf.Profiler` that writes `logic_frames.csv` (one row per logic frame: seq,
ms-since-start, frame delta, page, scroll Dp, max-scroll Dp, total lines,
visible byte range) and logs a rolling ~1 s `PERF` summary. `DestroyEvent`
stops it (final flush + `PERF stopped` summary with p50/p90/p99/max).
- **Hook**: `internal/editor.PerfRecord` is a package-level func, set by
`main.go` only when enabled. `Logic.emitFrame` calls it on the owner
goroutine with a `ProbeRecord` **before** sending the frame. When disabled it
is `nil` and the per-frame cost is a single nil check.
- **Debug scroll jumps** (for testing, off by default): with the profiler on,
`main.go` also polls `/storage/emulated/0/PadPerf/cmd` (a one-shot file
consumed on read). `top`, `bottom`, `frac <0..1>`, and `dp <int>` jump the
editor's `ScrollOffset` (clamped to `[0, MaxScroll]`) and emit a frame. This
lets a test drive large-offset scrolls deterministically without pixel taps.
- The profiler is owned by the goroutine that creates it and is single-goroutine
(no locks). It does **not** `Sync()` the CSV per flush (only per row batch) to
avoid periodic fsync hitches in the logic path.
- **Measured** (emulator, 10 MB file, 2026-08): logic-frame cadence is flat
across scroll offsets 0.02→1.0 (no large-offset degradation); the visible byte
range stays ≤ ~4.3 KB (0.04% of the file); PSS plateaus ~250 MB (bounded
high-water mark, no leak). See `development_plan.md` Phase 6.

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@ -1,7 +1,7 @@
# Development Plan: reach a lean, usable Android text editor
Status: v4, 2026-08-16 (Phases 03 complete; doc reorganization done). Written
against the **live** repo `/home/gmp/pad`. v1 (the widget-rebuild plan) is
Status: v5, 2026-08-16 (Phases 03 + doc reorg + Phase 6 scroll-perf/clamping
verification complete). Written against the **live** repo `/home/gmp/pad`. v1 (the widget-rebuild plan) is
superseded — see §12 for why. Doc reorganization (2026-08-16): the over-detailed
docs (`*_implementation_plan.md`, `touch.md`, `element_model.md`,
`layout_rendering.md`, `virtual_scroll_render_optimization.md`,
@ -11,7 +11,10 @@ adds the doc policy + build/install recipe. See `doc/README.md`.
Phases 03 done: single-owner no-lock architecture, Android IME wiring, on-device
IME validation (passing), viewport-on-open fix, chunked-buffer drift fix, the
whole-file shaper memory-leak fix, a measured 50 MB size limit, and the IME
rapid-commit desync fix (snippet/selection dedup). Remaining: real-device
rapid-commit desync fix (snippet/selection dedup). Phase 6 (2026-08-16) added a
default-off in-app performance profiler and verified: scroll does not degrade at
large offsets (10 MB file), scroll clamping is exact across 2→130,955-line
files, and memory plateaus ~250 MB (no leak). Remaining: real-device
swipe/autocorrect sign-off (the emulator's AOSP/Gboard keyboard is a proxy).
## 1. Decision summary (updated)
@ -239,7 +242,43 @@ but are not needed for a usable v1.
- ✓ Build/install recipe (2026-08-16: in `doc/README.md`; machine-local script
`/tmp/build_pad.sh`).
- ☐ In-repo device test checklist (the adb tap/swipe/IME sequences used in
Phases 23 are in this plan's phase notes but not a standalone checklist).
Phases 23 and Phase 6 are in this plan's phase notes but not a standalone
checklist).
### Phase 6 — scroll performance & clamping verification — DONE (2026-08-16)
Goal: (a) confirm scroll does not degrade at large offsets in a large file,
(b) confirm scroll clamping is correct across file sizes. Enabled the default-off
in-app profiler (architecture.md §11) and drove deterministic `frac` scroll
jumps + real swipes on the emulator.
**Scroll performance at large offsets (10 MB file, 130,955 lines):** swept
`frac` 0.02→1.0 with swipes. Logic-frame cadence is **flat across all offsets**
(p50 ~3844 ms, p90 ~5175 ms, no trend up at 0.9/0.98/1.0) — **no large-offset
degradation**. The visible byte range stays **≤ 4,274 B (0.04% of the file)** at
every offset, confirming the shaper never lays out the whole file. `ScreenRecord`
and `gfxinfo` were ruled out as metrics (downsampled / View-layer-only, since Pad
renders into a `SurfaceView`); the in-app profiler is the instrument.
**Scroll clamping (6 sizes, 2→130,955 lines):** for each, `top` and `bottom`
commands set the offset to exactly 0 and to exactly `maxScroll`; **no frame ever
exceeded `maxScroll` or went negative**. Sub-viewport files (`tiny_1line` 2 lines,
`small_10` 11 lines) correctly have `maxScroll = 0` and cannot scroll; larger
files' `maxScroll` scales correctly with content. No blank viewport at any size
(content verified on-screen).
**Memory (bonus):** PSS **plateaus ~250 MB** for the 10 MB file under sustained
scroll (bounded high-water mark from the shaper glyph cache + Go heap; grows
~13 MB over the first ~30 scrolls then flat) — **no leak**, well under the 2.5 GB
OOM line. The profiler's own overhead is negligible (same plateau with it off).
**Test-harness gotcha:** the 390×844 Dp window is **letterboxed** on the
1080×2400 screen (~28 px left / ~133 px top offset), so on-screen tap
coordinates are offset from the naive 1:1 Dp→px map. The editor back-arrow hits
at ~`(86, 264)` px, not the glyph's apparent 1:1 position. Browser file rows
(newest-first) start ~y=520 px, ~134 px apart. Verify every open via the exact
logcat line `Logic: OpenFileChan /storage/emulated/0/Notes/<file>`, not a loose
`OpenFileChan` match.
## 6. File-size decision (re-framed)

View File

@ -119,15 +119,19 @@ Full details, channel topology, and ownership rules: [`architecture.md`](./archi
owner-dispatches-a-task pattern.
6. **Logic work stays < 16 ms.** Anything that can block or scan more than the
viewport goes to the worker pool.
7. **Scroll offset is always clamped to `[0, maxScroll]`,** where
`maxScroll = contentHeight viewportHeight` floored at 0. A file whose
content fits the viewport has `maxScroll = 0` and cannot scroll. Verified
on-device across 2→130,955 lines (`development_plan.md` Phase 6).
## 6. Performance expectations (validated on-device)
| Operation | Target | Measured (10 MB file, Android 35 emulator) |
|---|---|---|
| Open file | instant feel | ~120 ms (stat + read + line index) |
| Scroll | 60 fps | flat ~240 MB RSS, no growth, no OOM |
| Scroll | 60 fps | logic-frame cadence flat across offsets 0.02→1.0 — **no large-offset degradation**; present fps is emulator-limited (~1427 on the software-rendered emulator, not a Pad quality metric) |
| Type | responsive | single IME path; rapid commits land cleanly |
| Memory | bounded | ~150 MB PSS / ~230 MB RSS at 10 MB file, flat |
| Memory | bounded | PSS plateaus ~250 MB at a 10 MB file (bounded high-water mark, no growth under sustained scroll; no OOM) |
## 7. Deferred / not implemented (explicit non-goals for v1)

View File

@ -2,6 +2,10 @@ package editor
import (
"log"
"os"
"path/filepath"
"strconv"
"strings"
"sync"
"time"
@ -51,23 +55,25 @@ type ResultEvent struct {
// the channels below. The only exception is Inspect, a test-only request
// channel whose fn still executes on the owner.
type Logic struct {
state *State
browserManager *browser.BrowserManager
configChan chan ConfigUpdate
frameChan chan Frame // frames carry the view-state snapshot
inputChan chan []ui.InputEvent
layoutChan chan ui.GlyphLayout
resultChan chan ResultEvent
searchQueryChan chan string
openFileChan chan string
retryChan chan string // auto-save retries
autosaveChan chan struct{} // auto-save debounce ticks (timer -> owner)
inspectChan chan *inspectReq
workerPool *pool.WorkerPool
mockFS pool.FileSystem
done chan struct{}
exitWg sync.WaitGroup
saveTimer *time.Timer // auto-save debounce timer; non-nil while pending
state *State
browserManager *browser.BrowserManager
configChan chan ConfigUpdate
frameChan chan Frame // frames carry the view-state snapshot
inputChan chan []ui.InputEvent
layoutChan chan ui.GlyphLayout
resultChan chan ResultEvent
searchQueryChan chan string
openFileChan chan string
retryChan chan string // auto-save retries
autosaveChan chan struct{} // auto-save debounce ticks (timer -> owner)
inspectChan chan *inspectReq
workerPool *pool.WorkerPool
mockFS pool.FileSystem
done chan struct{}
exitWg sync.WaitGroup
saveTimer *time.Timer // auto-save debounce timer; non-nil while pending
lastEmit time.Time // time of the last frame emission (profiler cadence)
debugCmdC chan string // one-shot debug commands from the cmd-file poller; nil = disabled
}
// NewLogic creates a new Logic instance, accepting an optional mockFS.
@ -127,8 +133,6 @@ func (l *Logic) FrameChan() <-chan Frame {
return l.frameChan
}
// InputChan returns the input channel for the logic goroutine.
func (l *Logic) InputChan() chan<- []ui.InputEvent {
return l.inputChan
@ -169,7 +173,7 @@ func (l *Logic) Run() {
case update := <-l.configChan:
log.Printf("Logic: ConfigEvent")
update.apply(l.state)
l.frameChan <- l.frameOf(l.state.layout(l.browserManager))
l.emitFrame()
case layout := <-l.layoutChan:
// Store the full GlyphLayout on editor state.
// Derive LastLineY from it for scroll clamping.
@ -181,14 +185,14 @@ func (l *Logic) Run() {
}
if derivedLastLineY != l.state.LastLineY {
l.state.LastLineY = derivedLastLineY
l.frameChan <- l.frameOf(l.state.layout(l.browserManager))
l.emitFrame()
}
case events := <-l.inputChan:
log.Printf("Logic: InputEvents")
for _, evt := range events {
evt.Handler(evt.Data)
}
l.frameChan <- l.frameOf(l.state.layout(l.browserManager))
l.emitFrame()
case query := <-l.searchQueryChan:
log.Printf("Logic: SearchQuery")
if query != l.state.Browser.Query {
@ -197,7 +201,7 @@ func (l *Logic) Run() {
browser.HandleSearch(&l.state.Browser, query)
}
}
l.frameChan <- l.frameOf(l.state.layout(l.browserManager))
l.emitFrame()
case path := <-l.openFileChan:
log.Printf("Logic: OpenFileChan %s", path)
// Create chunked buffer for virtual scrolling
@ -241,11 +245,138 @@ func (l *Logic) Run() {
case res := <-l.workerPool.ResultChan():
l.handleWorkerResult(res)
case <-l.resultChan:
l.frameChan <- l.frameOf(l.state.layout(l.browserManager))
l.emitFrame()
case cmd := <-l.debugCmdC:
l.applyDebugCmd(cmd)
}
}
}
// emitFrame computes the current frame, records a profiler probe (if enabled),
// and hands it to the main goroutine. Centralizing emission here ensures the
// in-app profiler (PerfRecord) sees every frame exactly once, on the owner
// goroutine. Must be called on the logic goroutine.
func (l *Logic) emitFrame() {
elems := l.state.layout(l.browserManager)
now := time.Now()
if PerfRecord != nil {
var delta time.Duration
if !l.lastEmit.IsZero() {
delta = now.Sub(l.lastEmit)
}
l.lastEmit = now
s := l.state
rec := ProbeRecord{T: now, DeltaMs: float64(delta.Nanoseconds()) / 1e6, Page: pageName(s.page)}
if s.page == EditorPage {
rec.ScrollDP = float32(s.ScrollOffset)
rec.MaxScrollDP = float32(s.MaxScroll)
rec.VisStart = s.VisibleStart
rec.VisEnd = s.VisibleEnd
if cb := s.Editor.ChunkedBuffer; cb != nil {
if li := cb.LineIndex; li != nil {
rec.TotalLines = li.LineCount()
}
}
} else {
rec.ScrollDP = float32(s.Browser.ScrollOffset)
}
PerfRecord(rec)
}
l.frameChan <- l.frameOf(elems)
}
// EnableDebugCmdPoll starts a background poller (debug-only) that watches
// <dir>/cmd for a one-shot scroll command and forwards it to the owner for
// application. Used to jump the editor to specific scroll offsets for
// performance/clamping validation. The poller does the (blocking) file read
// off the owner and sends the command via debugCmdC; the owner applies it.
func (l *Logic) EnableDebugCmdPoll(dir string) {
l.debugCmdC = make(chan string, 1)
l.exitWg.Add(1)
go func() {
defer l.exitWg.Done()
t := time.NewTicker(120 * time.Millisecond)
defer t.Stop()
cmdPath := filepath.Join(dir, "cmd")
for {
select {
case <-l.done:
return
case <-t.C:
b, err := os.ReadFile(cmdPath)
if err != nil {
continue
}
cmd := strings.TrimSpace(string(b))
if cmd == "" {
continue
}
// Consume the command so it is applied exactly once.
_ = os.WriteFile(cmdPath, nil, 0o644)
select {
case l.debugCmdC <- cmd:
case <-l.done:
return
}
}
}
}()
}
// applyDebugCmd applies a one-shot debug scroll command from the cmd-file
// poller. Commands: "top", "bottom", "frac <0..1>", "dp <int>". Must be
// called on the logic goroutine.
func (l *Logic) applyDebugCmd(cmd string) {
s := l.state
if s.page != EditorPage {
log.Printf("DebugCmd: %q ignored (not on editor page)", cmd)
return
}
fields := strings.Fields(cmd)
if len(fields) == 0 {
return
}
var target ui.Dp
switch fields[0] {
case "top":
target = 0
case "bottom":
target = s.MaxScroll
case "frac":
if len(fields) < 2 {
return
}
f, err := strconv.ParseFloat(fields[1], 64)
if err != nil || f < 0 || f > 1 {
log.Printf("DebugCmd: bad frac %q", fields[1])
return
}
target = ui.Dp(float64(f) * float64(s.MaxScroll))
case "dp":
if len(fields) < 2 {
return
}
n, err := strconv.Atoi(fields[1])
if err != nil {
log.Printf("DebugCmd: bad dp %q", fields[1])
return
}
target = ui.Dp(n)
default:
log.Printf("DebugCmd: unknown %q", cmd)
return
}
if target < 0 {
target = 0
}
if target > s.MaxScroll {
target = s.MaxScroll
}
s.ScrollOffset = target
log.Printf("DebugCmd: %q -> scroll=%d maxScroll=%d", cmd, int(s.ScrollOffset), int(s.MaxScroll))
l.emitFrame()
}
// fullContentBytes reconstructs the full file content from the chunked
// buffer (or the deprecated full Buffer). Returns ok=false on error.
// Must be called on the logic goroutine.
@ -330,7 +461,7 @@ func (l *Logic) handleWorkerResult(res pool.Result) {
l.state.Editor.TooLarge = true
l.state.Editor.TooLargeSize = stat.Size
log.Printf("Logic: %s is %d bytes, exceeds the %d-byte edit limit", stat.Path, stat.Size, MaxEditableFileSize)
l.frameChan <- l.frameOf(l.state.layout(l.browserManager))
l.emitFrame()
return
}
if l.state.Editor.ChunkedBuffer != nil {
@ -375,7 +506,7 @@ func (l *Logic) handleWorkerResult(res pool.Result) {
})
}
}
l.frameChan <- l.frameOf(l.state.layout(l.browserManager))
l.emitFrame()
}
// applyBuildIndexResult applies a completed BuildIndexTask result to browser state.
@ -405,7 +536,7 @@ func (l *Logic) PruneMaps() {
return
}
// Simply clear the maps for now. A true LRU would require
// Simply clear the maps for now. A true LRU would require
// tracking access times.
l.state.Editor.fileVersion = make(map[string]int)
l.state.Editor.lastWriteVersion = make(map[string]int)

View File

@ -0,0 +1,30 @@
package editor
import "time"
// ProbeRecord captures per-frame context for the in-app profiler (see
// internal/perf). It is filled on the logic goroutine and handed to the
// PerfRecord hook once per frame emission. Debug-only: PerfRecord is nil
// unless the app enables profiling (cmd/pad), so the per-frame cost is a
// single nil check.
type ProbeRecord struct {
T time.Time
DeltaMs float64 // ms since the previous frame emission
Page string // "editor" | "browser"
ScrollDP float32 // editor scroll offset (Dp); browser scroll when on browser
MaxScrollDP float32 // editor max scroll (Dp)
TotalLines int
VisStart int // visible byte range start
VisEnd int // visible byte range end (exclusive)
}
// PerfRecord is an optional per-frame probe hook, set by the app when in-app
// profiling is enabled. It is called on the logic goroutine, once per frame.
var PerfRecord func(ProbeRecord)
func pageName(p Page) string {
if p == EditorPage {
return "editor"
}
return "browser"
}

View File

@ -133,15 +133,20 @@ func (e *EditorState) IncrementRetryAttempts(filename string) int {
// State holds all application state owned by the logic goroutine.
type State struct {
PixelWidth int // raw pixel width from Gio ConfigEvent
PixelHeight int // raw pixel height from Gio ConfigEvent
scale float32
page Page // current page (Browser or Editor)
WordWrap bool
ScrollOffset ui.Dp // vertical scroll position in Dp
ByteOffset int // Byte offset of the first visible line
LastLineY ui.Dp // last line baseline offset from text origin, from renderer
MaxScroll ui.Dp // max scroll offset (content height - viewport height)
PixelWidth int // raw pixel width from Gio ConfigEvent
PixelHeight int // raw pixel height from Gio ConfigEvent
scale float32
page Page // current page (Browser or Editor)
WordWrap bool
ScrollOffset ui.Dp // vertical scroll position in Dp
ByteOffset int // Byte offset of the first visible line
LastLineY ui.Dp // last line baseline offset from text origin, from renderer
MaxScroll ui.Dp // max scroll offset (content height - viewport height)
// VisibleStart/VisibleEnd are the byte range the last editor layout shaped
// for the viewport. Set by EditorLayout each frame; read by the profiler
// probe to confirm the shaped range stays viewport-bounded (not the file).
VisibleStart int
VisibleEnd int
FocusedElementID string // ID of the currently focused element
Elems []ui.Element
lastEvictionTime time.Time // Throttles chunk eviction
@ -929,13 +934,17 @@ func EditorLayout(screenWidth, screenHeight ui.Dp, wordWrap bool) []ui.Element {
// Content() will load chunks immediately needed by the viewport.
cb.Prefetch(scrollChunk, 1)
} else {
fmt.Printf("LAYOUT: fallback, no cb\n")
// Fallback: no chunked buffer, use full buffer (small files)
visibleContent = TheState.Editor.Buffer
visibleCursorPos = TheState.Editor.CursorPosition
visibleScrollOffset = TheState.ScrollOffset
}
// Record the shaped visible range for the profiler probe (confirms the
// virtual-scroll window stays viewport-bounded, not the whole file).
TheState.VisibleStart = start
TheState.VisibleEnd = end
// Record the visible window for IME: the snippet is this window, so an
// EditEvent.Range (relative to the window) is offset by IMEWindowStartByte
// to address the buffer. start is 0 for small (string) files, so the

210
internal/perf/perf.go Normal file
View File

@ -0,0 +1,210 @@
// Package perf provides a lightweight, dependency-free in-app frame profiler.
//
// It is owned by a single goroutine (the logic goroutine) and records
// per-frame timing plus a small context (scroll offset, max scroll, total
// lines, visible byte range) so scroll performance and clamping can be
// analysed offline. It is an instrumentation facility: the app enables it at
// runtime (see cmd/pad) and the per-frame cost is a slice append plus
// occasional log/flush. With the record hook nil (the default), it is unused.
package perf
import (
"fmt"
"log"
"math"
"os"
"path/filepath"
"sort"
"time"
)
// Ctx is the per-frame context recorded alongside timing.
type Ctx struct {
Page string // "editor" | "browser"
ScrollDP float32 // scroll offset (Dp)
MaxScrollDP float32 // max scroll (Dp)
TotalLines int
VisStart int // visible byte range start
VisEnd int // visible byte range end (exclusive)
}
// Row is one recorded frame, the unit of CSV output.
type Row struct {
Seq int
Tms float64 // ms since profiling started
DeltaMs float64 // ms since previous frame emission
Page string
ScrollDP float32
MaxScrollDP float32
TotalLines int
VisStart int
VisEnd int
}
// Profiler records logic-frame cadence plus context. All methods must be
// called from the owning goroutine only (no locks).
type Profiler struct {
enabled bool
outPath string
start time.Time
last time.Time
lastLog time.Time
lastFlush time.Time
buf []Row
seq int
file *os.File
}
// New creates a profiler. If enabled and outDir is non-empty, it creates the
// output directory and file (named outDir/name). A failed file disables CSV
// output but keeps the logcat summaries.
func New(enabled bool, outDir, name string) *Profiler {
p := &Profiler{enabled: enabled}
if !enabled {
return p
}
p.start = time.Now()
p.lastLog = time.Now()
p.lastFlush = time.Now()
if outDir != "" {
if err := os.MkdirAll(outDir, 0o755); err == nil {
p.outPath = filepath.Join(outDir, name)
if f, err := os.Create(p.outPath); err == nil {
p.file = f
} else {
log.Printf("PERF: cannot create %s: %v", p.outPath, err)
}
} else {
log.Printf("PERF: cannot create dir %s: %v", outDir, err)
}
}
return p
}
// Record is called once per frame emission, on the owner goroutine. It is the
// only hot-path cost: a slice append, with a logcat summary ~1/s and a disk
// flush ~2/s (the flush is a single small write, never per-frame).
func (p *Profiler) Record(ctx Ctx) {
if !p.enabled {
return
}
now := time.Now()
if p.start.IsZero() {
p.start = now
p.lastLog = now
p.lastFlush = now
}
var delta time.Duration
if !p.last.IsZero() {
delta = now.Sub(p.last)
}
p.last = now
p.seq++
p.buf = append(p.buf, Row{
Seq: p.seq,
Tms: float64(now.Sub(p.start).Nanoseconds()) / 1e6,
DeltaMs: float64(delta.Nanoseconds()) / 1e6,
Page: ctx.Page,
ScrollDP: ctx.ScrollDP,
MaxScrollDP: ctx.MaxScrollDP,
TotalLines: ctx.TotalLines,
VisStart: ctx.VisStart,
VisEnd: ctx.VisEnd,
})
if now.Sub(p.lastLog) >= time.Second {
p.logSummary()
p.lastLog = now
}
if now.Sub(p.lastFlush) >= 2*time.Second {
p.flush()
p.lastFlush = now
}
}
// logSummary prints a rolling percentile summary of the frames buffered since
// the last flush to logcat.
func (p *Profiler) logSummary() {
n := len(p.buf)
if n == 0 {
return
}
ds := make([]float64, n)
for i, r := range p.buf {
ds[i] = r.DeltaMs
}
p50, p90, p99, mx := percentiles(ds)
over16, over33 := 0, 0
for _, d := range ds {
if d > 16.7 {
over16++
}
if d > 33.4 {
over33++
}
}
log.Printf("PERF frames=%d p50=%.1f p90=%.1f p99=%.1f max=%.1f ms over16.7=%.0f%% over33.4=%.0f%%",
n, p50, p90, p99, mx, pct(over16, n), pct(over33, n))
}
// flush appends the buffered rows to the CSV file and clears the buffer.
func (p *Profiler) flush() {
if len(p.buf) > 0 && p.file != nil {
for _, r := range p.buf {
fmt.Fprintf(p.file, "%d,%.3f,%.3f,%s,%.1f,%.1f,%d,%d,%d\n",
r.Seq, r.Tms, r.DeltaMs, r.Page, r.ScrollDP, r.MaxScrollDP, r.TotalLines, r.VisStart, r.VisEnd)
}
}
p.buf = p.buf[:0]
}
// Stop flushes remaining rows and closes the file. Call once on shutdown.
func (p *Profiler) Stop() {
if !p.enabled {
return
}
p.flush()
if p.file != nil {
p.file.Close()
p.file = nil
}
log.Printf("PERF stopped: %d frames, out=%s", p.seq, p.outPath)
}
// percentiles returns p50/p90/p99/max of ds in ms.
func percentiles(ds []float64) (p50, p90, p99, mx float64) {
if len(ds) == 0 {
return
}
s := make([]float64, len(ds))
copy(s, ds)
sort.Float64s(s)
p50 = s[pctlIdx(len(s), 0.50)]
p90 = s[pctlIdx(len(s), 0.90)]
p99 = s[pctlIdx(len(s), 0.99)]
if p99 < p90 {
p99 = p90
}
mx = s[len(s)-1]
return
}
// pctlIdx returns the nearest-rank index for fraction f (in [0,1]) of n
// samples: the smallest i such that i/n >= f, clamped to [0, n-1].
func pctlIdx(n int, f float64) int {
i := int(math.Ceil(float64(n)*f)) - 1
if i < 0 {
i = 0
}
if i >= n {
i = n - 1
}
return i
}
func pct(part, whole int) float64 {
if whole == 0 {
return 0
}
return 100 * float64(part) / float64(whole)
}

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@ -0,0 +1,74 @@
package perf
import (
"os"
"path/filepath"
"strings"
"testing"
"time"
)
func TestPercentiles(t *testing.T) {
ds := []float64{10, 20, 30, 40, 50, 60, 70, 80, 90, 100}
p50, p90, p99, mx := percentiles(ds)
if p50 != 50 {
t.Errorf("p50 = %v, want 50", p50)
}
if p90 != 90 {
t.Errorf("p90 = %v, want 90", p90)
}
if p99 != 100 {
t.Errorf("p99 = %v, want 100", p99)
}
if mx != 100 {
t.Errorf("max = %v, want 100", mx)
}
// Empty input is a no-op.
if _, _, _, m := percentiles(nil); m != 0 {
t.Errorf("empty max = %v, want 0", m)
}
}
func TestDisabledIsNoOp(t *testing.T) {
p := New(false, t.TempDir(), "x.csv")
p.Record(Ctx{Page: "editor"})
if p.enabled {
t.Fatalf("disabled profiler reported enabled")
}
if p.seq != 0 || len(p.buf) != 0 {
t.Errorf("disabled profiler recorded: seq=%d buf=%d", p.seq, len(p.buf))
}
}
func TestRecordFlushAndStop(t *testing.T) {
dir := t.TempDir()
p := New(true, dir, "logic_frames.csv")
if p == nil || p.file == nil {
t.Fatalf("expected an open output file, got %+v", p)
}
for i := 0; i < 5; i++ {
p.Record(Ctx{Page: "editor", ScrollDP: float32(i * 10), MaxScrollDP: 1000, TotalLines: 42, VisStart: i, VisEnd: i + 100})
}
// Force a flush regardless of the 2s timer.
p.lastFlush = time.Time{}
p.Record(Ctx{Page: "editor", ScrollDP: 50})
p.Stop()
out := filepath.Join(dir, "logic_frames.csv")
b, err := os.ReadFile(out)
if err != nil {
t.Fatalf("read csv: %v", err)
}
lines := strings.Split(strings.TrimSpace(string(b)), "\n")
if len(lines) != 6 {
t.Fatalf("want 6 CSV rows, got %d:\n%s", len(lines), b)
}
// First row is seq 1, editor page.
if !strings.HasPrefix(lines[0], "1,") || !strings.Contains(lines[0], "editor") {
t.Errorf("unexpected first row: %s", lines[0])
}
// Last row should have TotalLines 42 (from the 5th record) and the 6th (Stop flush).
if !strings.Contains(lines[4], "42") {
t.Errorf("row 5 missing TotalLines=42: %s", lines[4])
}
}