Implement Dart executor for async functions in Jason (#200, #182)

jason/flutter/lib/jason.dart

@@ -5,6 +5,7 @@ import 'dart:io';
 
 import 'media_manager.dart';
 import 'room_handle.dart';
+import 'util/executor.dart';
 import 'util/move_semantic.dart';
 import 'util/nullable_pointer.dart';
 import 'util/callback.dart' as callback;
@@ -27,6 +28,12 @@ typedef _free_Dart = void Function(Pointer);
 
 final DynamicLibrary dl = _dl_load();
 
+/// [Executor] that drives Rust futures.
+///
+/// Instantiated in the [_dl_load()] function, and must not be touched ever
+/// after that.
+var executor;
+
 final _new = dl.lookupFunction<_new_C, _new_Dart>('Jason__new');
 
 final _media_manager = dl.lookupFunction<_mediaManager_C, _mediaManager_Dart>(
@@ -64,6 +71,8 @@ DynamicLibrary _dl_load() {
   callback.registerFunctions(dl);
   completer.registerFunctions(dl);
 
+  executor = Executor(dl);
+
   return dl;
 }
 

jason/flutter/lib/reconnect_handle.dart

@@ -48,19 +48,19 @@ class ReconnectHandle {
   /// Tries to reconnect a `Room` in a loop with a growing backoff delay.
   ///
   /// The first attempt to reconnect is guaranteed to happen not earlier than
-  /// `starting_delay_ms`.
+  /// [starting_delay_ms].
   ///
   /// Also, it guarantees that delay between reconnection attempts won't be
-  /// greater than `max_delay_ms`.
+  /// greater than [max_delay_ms].
   ///
   /// After each reconnection attempt, delay between reconnections will be
-  /// multiplied by the given `multiplier` until it reaches `max_delay_ms`.
+  /// multiplied by the given [multiplier] until it reaches [max_delay_ms].
   ///
   /// If the `Room` is already reconnecting then new reconnection attempt won't
   /// be performed. Instead, it will wait for the first reconnection attempt
   /// result and use it here.
   ///
-  /// If `multiplier` is negative number then `multiplier` will be considered as
+  /// If [multiplier] is negative number then [multiplier] will be considered as
   /// `0.0`.
   Future<void> reconnectWithBackoff(
       int startingDelayMs, double multiplier, int maxDelay) async {

jason/flutter/lib/room_handle.dart

@@ -143,7 +143,7 @@ class RoomHandle {
   RoomHandle(this.ptr);
 
   /// Connects to a media server and joins the `Room` with the provided
-  /// authorization `token`.
+  /// authorization [token].
   ///
   /// Authorization token has a fixed format:
   /// `{{ Host URL }}/{{ Room ID }}/{{ Member ID }}?token={{ Auth Token }}`
@@ -157,23 +157,23 @@ class RoomHandle {
     }
   }
 
-  /// Updates this `Room`'s `MediaStreamSettings`. This affects all the
-  /// `PeerConnection`s in this `Room`. If `MediaStreamSettings` are configured
+  /// Updates this `Room`'s [MediaStreamSettings]. This affects all the
+  /// `PeerConnection`s in this `Room`. If [MediaStreamSettings] are configured
   /// for some `Room`, then this `Room` can only send media tracks that
-  /// correspond to these settings. `MediaStreamSettings` update will change
+  /// correspond to these settings. [MediaStreamSettings] update will change
   /// media tracks in all sending peers, so that might cause a new
   /// [getUserMedia()][1] request to happen.
   ///
   /// Media obtaining/injection errors are additionally fired to
-  /// `on_failed_local_media` callback.
+  /// [RoomHandle.onFailedLocalMedia()] callback.
   ///
-  /// If `stop_first` set to `true` then affected local `Tracks` will be
-  /// dropped before new `MediaStreamSettings` are applied. This is usually
+  /// If [stop_first] set to `true` then affected local [LocalMediaTrack]s will
+  /// be dropped before new [MediaStreamSettings] are applied. This is usually
   /// required when changing video source device due to hardware limitations,
   /// e.g. having an active track sourced from device `A` may hinder
   /// [getUserMedia()][1] requests to device `B`.
   ///
-  /// `rollback_on_fail` option configures `MediaStreamSettings` update request
+  /// [rollback_on_fail] option configures [MediaStreamSettings] update request
   /// to automatically rollback to previous settings if new settings cannot be
   /// applied.
   ///