| 1 | import UIKit |
| 2 | |
| 3 | // 🤖 TEMPORARY diagnostic (DEBUG only): a display link that records every |
| 4 | // dropped frame with what published/ran just before it, appended to |
| 5 | // Documents/hitches.log — pulled off the device with `devicectl device copy |
| 6 | // from` and read on the Mac. Delete once the scroll hitch is nailed. |
| 7 | #if DEBUG |
| 8 | final class HitchLogger { |
| 9 | static let shared = HitchLogger() |
| 10 | |
| 11 | private var link: CADisplayLink? |
| 12 | private var lastTimestamp: CFTimeInterval = 0 |
| 13 | private var recentNotes: [String] = [] |
| 14 | private var pending: [String] = [] |
| 15 | private lazy var file: URL = FileManager.default |
| 16 | .urls(for: .documentDirectory, in: .userDomainMask)[0] |
| 17 | .appendingPathComponent("hitches.log") |
| 18 | |
| 19 | func start() { |
| 20 | guard link == nil else { return } |
| 21 | try? FileManager.default.removeItem(at: file) |
| 22 | let l = CADisplayLink(target: self, selector: #selector(tick)) |
| 23 | l.add(to: .main, forMode: .common) |
| 24 | link = l |
| 25 | note("logger started") |
| 26 | } |
| 27 | |
| 28 | /// Breadcrumb: publishes, pins, gestures — whatever ran near a hitch. |
| 29 | func note(_ what: String) { |
| 30 | let stamp = String(format: "%.3f", CACurrentMediaTime()) |
| 31 | recentNotes.append("\(stamp) \(what)") |
| 32 | if recentNotes.count > 6 { recentNotes.removeFirst() } |
| 33 | } |
| 34 | |
| 35 | @objc private func tick(_ l: CADisplayLink) { |
| 36 | defer { lastTimestamp = l.timestamp } |
| 37 | guard lastTimestamp > 0 else { return } |
| 38 | let dt = l.timestamp - lastTimestamp |
| 39 | let expected = l.duration > 0 ? l.duration : 1.0 / 60.0 |
| 40 | guard dt > expected * 1.6 else { return } // a properly dropped frame |
| 41 | let ms = Int(dt * 1000) |
| 42 | pending.append("HITCH \(ms)ms at \(String(format: "%.3f", l.timestamp)) | recent: " |
| 43 | + recentNotes.joined(separator: " · ")) |
| 44 | flush() |
| 45 | } |
| 46 | |
| 47 | private func flush() { |
| 48 | guard !pending.isEmpty else { return } |
| 49 | let text = pending.joined(separator: "\n") + "\n" |
| 50 | pending.removeAll() |
| 51 | let file = self.file |
| 52 | // Off main — the logger's own synchronous writes were adding stalls |
| 53 | // to the very storms it measures. |
| 54 | writeQueue.async { |
| 55 | if let handle = try? FileHandle(forWritingTo: file) { |
| 56 | handle.seekToEndOfFile() |
| 57 | handle.write(Data(text.utf8)) |
| 58 | try? handle.close() |
| 59 | } else { |
| 60 | try? Data(text.utf8).write(to: file) |
| 61 | } |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | private let writeQueue = DispatchQueue(label: "hitch-log", qos: .utility) |
| 66 | } |
| 67 | #endif |
| 68 | |
amadan