Excerpt of code called from deadlocking test

LockingExcerpt.m

- (void)lockWithCompletionBlock:(dispatch_block_t)completionBlock {
  @synchronized(_lockSempahore) {
    if (!self.locked) {
      self.locked = YES;
      
      [[NSOperationQueue mainQueue] addOperationWithBlock:completionBlock];
      return;
    }
    [self.blocksWaitingOnLockAcquisition addObject:completionBlock];
  }
}