59 lines
2.2 KiB
Dart
59 lines
2.2 KiB
Dart
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// lib/editor/persistence/sidecar_flush_observer.dart
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//
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// Phase 6 / §F.3 of the file-based storage plan (docs/plans/2026-06-24-file-
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// based-storage.md): app-lifecycle flush hardening.
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//
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// The per-file SidecarRepository debounces writes by 800 ms. That window is the
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// data-loss gap on a Windows tablet: if the OS suspends or closes the app
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// before the timer fires, the last strokes never reach disk. This observer
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// listens for the app leaving the foreground and DRAINS every open repo's
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// pending write before the process can be frozen, so "never lose the last
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// strokes on app close" holds even when the editor's own dispose() doesn't run.
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//
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// Registered once in BadNoteApp; it delegates to
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// [SidecarRepositoryRegistry.flushAll], which awaits every repo's flush().
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import 'package:flutter/widgets.dart';
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import 'sidecar_repository.dart';
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/// A [WidgetsBindingObserver] that flushes all open sidecar repositories when
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/// the app leaves the foreground (`inactive`/`paused`/`detached`/`hidden`).
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class SidecarFlushObserver with WidgetsBindingObserver {
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/// Whether the observer is currently registered with the binding.
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bool get isAttached => _attached;
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bool _attached = false;
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/// Register with [WidgetsBinding.instance] so lifecycle changes are observed.
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void attach() {
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if (_attached) return;
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WidgetsBinding.instance.addObserver(this);
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_attached = true;
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}
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/// Stop observing lifecycle changes.
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void detach() {
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if (!_attached) return;
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WidgetsBinding.instance.removeObserver(this);
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_attached = false;
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}
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@override
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void didChangeAppLifecycleState(AppLifecycleState state) {
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switch (state) {
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// Any transition out of the foreground is a potential suspend/kill point:
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// drain pending sidecar writes now (the editors' own dispose() may never
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// run when the OS freezes the process).
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case AppLifecycleState.inactive:
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case AppLifecycleState.hidden:
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case AppLifecycleState.paused:
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case AppLifecycleState.detached:
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// Fire-and-forget at the framework boundary, but each write is atomic
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// and awaited inside flushAll, so a half-written sidecar is impossible.
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SidecarRepositoryRegistry.flushAll();
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case AppLifecycleState.resumed:
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break;
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}
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}
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}
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