iOS 13.3 downloader porcessActions递归调用到Stack内存crash

[wentaozone]

环境：Xcode 11.3.1 iPhone XR 13.3

在cell中切换播放视频: 切换视频方式为 销毁avplayer，销毁avplayerLayer，再重新创建.
原因： https://www.cnblogs.com/sundaysgarden/articles/9080511.html

主要代码：
`
private func prepareToPlay(_ item:AVPlayerItem? = nil){

    if let item = item {
        self.player = AVPlayer(playerItem: item)
    }else{
        self.player = AVPlayer()
    }
    playerLayer = AVPlayerLayer(player: self.player)
    playerLayer?.frame = self.bounds
    self.playerView.layer.insertSublayer(playerLayer!, at: 0)
    self.player!.actionAtItemEnd = .none
    
    self.player!.addObserver(self, forKeyPath: "status", options: .new, context: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(didPlayToEndTime(_:)), name: Foundation.Notification.Name.AVPlayerItemDidPlayToEndTime, object: nil)
    self.timeObServer = self.player!.addPeriodicTimeObserver(forInterval: CMTime(value: 1, timescale: 30), queue: .main) {[unowned self] (time) in
        
        self.currentTime = time
        
        guard let currentItem = self.player?.currentItem else {return}
        let curretnTime = Float(self.currentTime.value) / Float(self.currentTime.timescale)
        let totalTime = Float(CMTimeGetSeconds(currentItem.duration))
        let progress = (curretnTime/totalTime)/self.progressSlider.maximumValue
        if !self.progressSlider.isTracking{
            self.progressSlider.setValue(progress, animated: true)
        }

        if totalTime > 0{
            let date = Date(timeIntervalSince1970: TimeInterval(curretnTime))
            let format = curretnTime > 3600 ? "hh:mm:ss" : "mm:ss"
            let xxx = date.toString(format: format, timezone:TimeZone(abbreviation: "UTC")!)
            let date1 = Date(timeIntervalSince1970: TimeInterval(totalTime))
            let format1 = totalTime > 3600 ? "hh:mm:ss" : "mm:ss"
            let xxx1 = date1.toString(format: format1, timezone:TimeZone(abbreviation: "UTC")!)
            
            self.timeLabel.text = "\(xxx) / \(xxx1)"
        }
    }
}
private func stop(){
    if let indexPath =  self.userInfo as? IndexPath{
        print("视频操作: 停止 \(indexPath) \(String(describing: url))")
    }
    self.playState = .Init
    guard let player = self.player else {return}
    if player.timeControlStatus != .paused{
        player.removeObserver(self, forKeyPath: "status")
        player.removeTimeObserver(self.timeObServer as Any)
        player.pause()
        resourceManager.cancelLoaders()
        NotificationCenter.default.removeObserver(self, name: Foundation.Notification.Name.AVPlayerItemDidPlayToEndTime, object: nil)
    }
    if player.currentItem != nil{
        player.replaceCurrentItem(with: nil)
    }
    self.player = nil
    if let avlayer = self.playerLayer {
        avlayer.removeFromSuperlayer()
        self.playerLayer = nil
    }
    
    
    self.playBtn.isSelected = false
    self.playBtn.setImage(UIImage(named: "vp_button_play"), for: .normal)
    self.coverImageView.isHidden = false
    self.show()
}

`

原因在于获取cacheActions数量太多导致process递归调用层次太深。猜想这里可以把多个连续块合并为一个块，而大大减小生成的cacheActions数量。 或者直接限制一个Request获取的 actions数量不要超过1000.

[panmingyang2009]

可能在这个 PR 里被修复了：#85