Adding audio_pool class to play audio really, really fast

lib/audio_pool.dart

@@ -0,0 +1,68 @@
+import 'dart:async';
+
+import 'package:audioplayers/audio_cache.dart';
+import 'package:audioplayers/audioplayers.dart';
+import 'package:synchronized/synchronized.dart';
+
+typedef void Stoppable();
+
+class AudioPool {
+
+  AudioCache cache;
+  Map<String, AudioPlayer> currentPlayers = {};
+  List<AudioPlayer> availablePlayers = [];
+
+  String sound;
+  bool repeating;
+  int minPlayers, maxPlayers;
+
+  Lock _lock = new Lock();
+
+  AudioPool(this.sound, { this.repeating = false, this.maxPlayers = 1, this.minPlayers = 1, String prefix = 'audio/sfx/' }) {
+    cache = new AudioCache(prefix: prefix);
+  }
+
+  void init() async {
+    for (int i = 0; i < minPlayers; i++) {
+      availablePlayers.add(await _createNewAudioPlayer());
+    }
+  }
+
+  Future<Stoppable> start({ double volume = 1.0 }) async {
+    return _lock.synchronized(() async {
+      if (availablePlayers.isEmpty) {
+        availablePlayers.add(await _createNewAudioPlayer());
+      }
+      AudioPlayer player = availablePlayers.removeAt(0);
+      currentPlayers[player.playerId] = player;
+      await player.setVolume(volume);
+      await player.resume();
+      Stoppable stop = () {
+        _lock.synchronized(() async {
+          AudioPlayer p = currentPlayers.remove(player.playerId);
+          p.completionHandler = null;
+          await p.stop();
+          if (availablePlayers.length >= maxPlayers) {
+            await p.release();
+          } else {
+            availablePlayers.add(p);
+          }
+        });
+      };
+      if (repeating) {
+        player.completionHandler = player.resume;
+      } else {
+        player.completionHandler = stop;
+      }
+      return stop;
+    });
+  }
+
+  Future<AudioPlayer> _createNewAudioPlayer() async {
+    AudioPlayer player = new AudioPlayer();
+    String url = (await cache.load(sound)).path;
+    await player.setUrl(url);
+    await player.setReleaseMode(ReleaseMode.STOP);
+    return player;
+  }
+}

pubspec.yaml

@@ -14,6 +14,7 @@ dependencies:
   ordered_set: ^1.1.1
   path_provider: ^0.4.1
   box2d_flame: ^0.4.2
+  synchronized: ^1.5.1+1
 
 dev_dependencies:
   test: ^1.3.0