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feat: Finalizer for MLKitScanDecoder #2937

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merged 2 commits into from
Sep 7, 2022
Merged

feat: Finalizer for MLKitScanDecoder #2937

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6c453b5
MLKitScanDecoder uses a Finalizer to ensure the Isolate is always dis…
g123k Sep 6, 2022
9c1b363
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g123k Sep 6, 2022
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19 changes: 19 additions & 0 deletions packages/smooth_app/lib/pages/scan/mkit_scan_helper.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,12 @@ class MLKitScanDecoder {
scanMode: scanMode,
);

/// Ensures the dispose() method is called if this class is GC'ed.
static final Finalizer<_MLKitScanDecoderMainIsolate> _finalizer =
Finalizer<_MLKitScanDecoderMainIsolate>(
(_MLKitScanDecoderMainIsolate isolate) => isolate.dispose(),
);

final DevModeScanMode scanMode;
final _MLKitScanDecoderMainIsolate _mainIsolate;

Expand All @@ -40,11 +46,18 @@ class MLKitScanDecoder {
// OK -> continue
}

/// The next call with recreate the isolate if necessary.
/// Re-attaching it to the finalizer is mandatory.
if (_mainIsolate.isDisposed) {
_finalizer.attach(this, _mainIsolate, detach: this);
}

return _mainIsolate.decode(image);
}

Future<void> dispose() async {
_mainIsolate.dispose();
_finalizer.detach(this);
Logs.d(tag: 'MLKitScanDecoder', 'Disposed');
}
}
Expand Down Expand Up @@ -150,6 +163,12 @@ class _MLKitScanDecoderMainIsolate {
_isolate?.kill(priority: Isolate.immediate);
_isolate = null;
}

bool get isDisposed =>
_isIsolateInitialized == false &&
_completer == null &&
_sendPort == null &&
_isolate == null;
}

// ignore: avoid_classes_with_only_static_members
Expand Down