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{{#no_platforms}}
// You have generated a new plugin project without specifying the `--platforms`
// flag. An FFI plugin project that supports no platforms is generated.
// To add platforms, run `flutter create -t plugin_ffi --platforms <platforms> .`
// in this directory. You can also find a detailed instruction on how to
// add platforms in the `pubspec.yaml` at
// https://flutter.dev/docs/development/packages-and-plugins/developing-packages#plugin-platforms.
{{/no_platforms}}
import 'dart:async';
import 'dart:ffi';
import 'dart:io';
import 'dart:isolate';
import '{{projectName}}_bindings_generated.dart';
/// A very short-lived native function.
///
/// For very short-lived functions, it is fine to call them on the main isolate.
/// They will block the Dart execution while running the native function, so
/// only do this for native functions which are guaranteed to be short-lived.
int sum(int a, int b) => _bindings.sum(a, b);
/// A longer lived native function, which occupies the thread calling it.
///
/// Do not call these kind of native functions in the main isolate. They will
/// block Dart execution. This will cause dropped frames in Flutter applications.
/// Instead, call these native functions on a separate isolate.
///
/// Modify this to suit your own use case. Example use cases:
///
/// 1. Reuse a single isolate for various different kinds of requests.
/// 2. Use multiple helper isolates for parallel execution.
Future<int> sumAsync(int a, int b) async {
final SendPort helperIsolateSendPort = await _helperIsolateSendPort;
final int requestId = _nextSumRequestId++;
final _SumRequest request = _SumRequest(requestId, a, b);
final Completer<int> completer = Completer<int>();
_sumRequests[requestId] = completer;
helperIsolateSendPort.send(request);
return completer.future;
}
const String _libName = '{{projectName}}';
/// The dynamic library in which the symbols for [{{pluginDartClass}}Bindings] can be found.
final DynamicLibrary _dylib = () {
if (Platform.isMacOS || Platform.isIOS) {
return DynamicLibrary.open('$_libName.framework/$_libName');
}
if (Platform.isAndroid || Platform.isLinux) {
return DynamicLibrary.open('lib$_libName.so');
}
if (Platform.isWindows) {
return DynamicLibrary.open('$_libName.dll');
}
throw UnsupportedError('Unknown platform: ${Platform.operatingSystem}');
}();
/// The bindings to the native functions in [_dylib].
final {{pluginDartClass}}Bindings _bindings = {{pluginDartClass}}Bindings(_dylib);
/// A request to compute `sum`.
///
/// Typically sent from one isolate to another.
class _SumRequest {
final int id;
final int a;
final int b;
const _SumRequest(this.id, this.a, this.b);
}
/// A response with the result of `sum`.
///
/// Typically sent from one isolate to another.
class _SumResponse {
final int id;
final int result;
const _SumResponse(this.id, this.result);
}
/// Counter to identify [_SumRequest]s and [_SumResponse]s.
int _nextSumRequestId = 0;
/// Mapping from [_SumRequest] `id`s to the completers corresponding to the correct future of the pending request.
final Map<int, Completer<int>> _sumRequests = <int, Completer<int>>{};
/// The SendPort belonging to the helper isolate.
Future<SendPort> _helperIsolateSendPort = () async {
// The helper isolate is going to send us back a SendPort, which we want to
// wait for.
final Completer<SendPort> completer = Completer<SendPort>();
// Receive port on the main isolate to receive messages from the helper.
// We receive two types of messages:
// 1. A port to send messages on.
// 2. Responses to requests we sent.
final ReceivePort receivePort = ReceivePort()
..listen((dynamic data) {
if (data is SendPort) {
// The helper isolate sent us the port on which we can sent it requests.
completer.complete(data);
return;
}
if (data is _SumResponse) {
// The helper isolate sent us a response to a request we sent.
final Completer<int> completer = _sumRequests[data.id]!;
_sumRequests.remove(data.id);
completer.complete(data.result);
return;
}
throw UnsupportedError('Unsupported message type: ${data.runtimeType}');
});
// Start the helper isolate.
await Isolate.spawn((SendPort sendPort) async {
final ReceivePort helperReceivePort = ReceivePort()
..listen((dynamic data) {
// On the helper isolate listen to requests and respond to them.
if (data is _SumRequest) {
final int result = _bindings.sum_long_running(data.a, data.b);
final _SumResponse response = _SumResponse(data.id, result);
sendPort.send(response);
return;
}
throw UnsupportedError('Unsupported message type: ${data.runtimeType}');
});
// Send the the port to the main isolate on which we can receive requests.
sendPort.send(helperReceivePort.sendPort);
}, receivePort.sendPort);
// Wait until the helper isolate has sent us back the SendPort on which we
// can start sending requests.
return completer.future;
}();