Fix release()-ing of items from the callback pool (#476)

* Fix release()-ing of items from the callback pool

These were being removed according to the wrong key.

* Fix race condition looking up key

* Add more synchronization

Author: slycoder

RNSound/RNSound.m

@@ -67,10 +67,10 @@ -(NSString *) getDirectory:(int)directory {
 
 -(void) audioPlayerDidFinishPlaying:(AVAudioPlayer*)player
                        successfully:(BOOL)flag {
-  NSNumber* key = [self keyForPlayer:player];
-  if (key == nil) return;
+  @synchronized(self) {
+    NSNumber* key = [self keyForPlayer:player];
+    if (key == nil) return;
 
-  @synchronized(key) {
     [self setOnPlay:NO forPlayerKey:key];
     RCTResponseSenderBlock callback = [self callbackForKey:key];
     if (callback) {
@@ -199,12 +199,14 @@ -(NSDictionary *)constantsToExport {
   }
 
   if (player) {
-    player.delegate = self;
-    player.enableRate = YES;
-    [player prepareToPlay];
-    [[self playerPool] setObject:player forKey:key];
-    callback(@[[NSNull null], @{@"duration": @(player.duration),
-                                @"numberOfChannels": @(player.numberOfChannels)}]);
+    @synchronized(self) {
+      player.delegate = self;
+      player.enableRate = YES;
+      [player prepareToPlay];
+      [[self playerPool] setObject:player forKey:key];
+      callback(@[[NSNull null], @{@"duration": @(player.duration),
+                                  @"numberOfChannels": @(player.numberOfChannels)}]);
+    }
   } else {
     callback(@[RCTJSErrorFromNSError(error)]);
   }
@@ -240,13 +242,15 @@ -(NSDictionary *)constantsToExport {
 }
 
 RCT_EXPORT_METHOD(release:(nonnull NSNumber*)key) {
-  AVAudioPlayer* player = [self playerForKey:key];
-  if (player) {
-    [player stop];
-    [[self callbackPool] removeObjectForKey:player];
-    [[self playerPool] removeObjectForKey:key];
-    NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
-    [notificationCenter removeObserver:self];
+  @synchronized(self) {
+    AVAudioPlayer* player = [self playerForKey:key];
+    if (player) {
+      [player stop];
+      [[self callbackPool] removeObjectForKey:key];
+      [[self playerPool] removeObjectForKey:key];
+      NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
+      [notificationCenter removeObserver:self];
+    }
   }
 }