//
//  DispatchQueue+Extension.swift
//  SwiftBilibili
//
//  Created by 罗文 on 2021/1/15.
//  Copyright © 2021年 罗文. All rights reserved.
//

import Foundation

extension DispatchQueue {
    
    static var `default`: DispatchQueue { return DispatchQueue.global(qos: .`default`) }
    static var userInteractive: DispatchQueue { return DispatchQueue.global(qos: .userInteractive) }
    static var userInitiated: DispatchQueue { return DispatchQueue.global(qos: .userInitiated) }
    static var utility: DispatchQueue { return DispatchQueue.global(qos: .utility) }
    static var background: DispatchQueue { return DispatchQueue.global(qos: .background) }
    
    
    class func delay(time:Double,action:@escaping ()->()) {
        
        let when = DispatchTime.now() + time
        
        DispatchQueue.main.asyncAfter(deadline: when) {
            action()
        }
    }
    
    private static var _onceTracker = [String]()
    class func once(_ token: String, block:()->Void) {
        objc_sync_enter(self)
        defer { objc_sync_exit(self) }
        
        if _onceTracker.contains(token) {
            return
        }
        _onceTracker.append(token)
        block()
    }
    

    
}