//
// QueueTestController.swift
// GCDDemo
//
// Created by shangkun on 2018/4/29.
// Copyright © 2018 J1. All rights reserved.
//
import UIKit
@objc class QueueTestController: UITableViewController {
// 除了主队列以外的所有异步执行都会新建线程, 并发执行。
// 在主队列下的任务不管是异步任务还是同步任务都不会开辟线程，任务只会在主线程顺序执行。
// serial将会执行完一个任务才会开始下一个，
// concurrent触发完一个就立即进入下一个，而不管它是否已完成。
lazy var scenes = [
[
"title":"主队列，同步 -> 1 死锁",
"action":"mainQueueSync"
],
[
"title":"主队列，异步 -> 132 没有开启新线程",
"action":"mainQueueAsync"
], [
"title":"串行队列，同步 -> 123 顺序执行，没有开启新线程",
"action":"serialQueueSync"
],
[
"title":"串行队列，异步 -> 132 并发执行，开启新线程",
"action":"serialQueueAsync"
], [
"title":"并行队列，同步 -> 123 顺序执行，没有开启新线程",
"action":"concurrentQueueSync"
],
[
"title":"并行队列，异步 -> 132 并发执行，开启新线程",
"action":"concurrentQueueAsync"
],
]
override func viewDidLoad() {
super.viewDidLoad()
title = "queue"
tableView.register(UITableViewCell.classForCoder(), forCellReuseIdentifier: "reuseIdentifier")
}
@objc func mainQueueSync() {
print("1 \(Thread.current)")
let queue = DispatchQueue.main
queue.sync {
print("2 \(Thread.current)")
}
print("3 \(Thread.current)")
/* 发生死锁，程序崩溃
主队列的同步线程，按照FIFO的原则（先入先出），2排在3后面会等3执行完，但因为同步线程，3又要等2执行完，相互等待成为死锁。
1 {number = 1, name = main}
*/
}
@objc func mainQueueAsync() {
print("1 \(Thread.current)")
let queue = DispatchQueue.main
queue.async {
for j in 0...10 {
print("2 j=\(j) \(Thread.current)")
}
}
print("3 \(Thread.current)")
/*
主线程顺序执行，异步实现最后执行，也在主线程中
没有开启新线程
1 {number = 1, name = main}
3 {number = 1, name = main}
2 j=0 {number = 1, name = main}
2 j=1 {number = 1, name = main}
2 j=2 {number = 1, name = main}
2 j=3 {number = 1, name = main}
2 j=4 {number = 1, name = main}
2 j=5 {number = 1, name = main}
2 j=6 {number = 1, name = main}
2 j=7 {number = 1, name = main}
2 j=8 {number = 1, name = main}
2 j=9 {number = 1, name = main}
2 j=10 {number = 1, name = main}
*/
}
@objc func serialQueueSync() {
print("1 \(Thread.current)")
let queue = DispatchQueue.init(label: "serialQueueSync")
queue.sync {
for i in 0...5 {
print("2 i=\(i) \(Thread.current)")
}
}
queue.sync {
for j in 0...5 {
print("2 j=\(j) \(Thread.current)")
}
}
print("3 \(Thread.current)")
/*
顺序执行，在主线程中
没有开启新线程
1 {number = 1, name = main}
2 i=0 {number = 1, name = main}
2 i=1 {number = 1, name = main}
2 i=2 {number = 1, name = main}
2 i=3 {number = 1, name = main}
2 i=4 {number = 1, name = main}
2 i=5 {number = 1, name = main}
2 j=0 {number = 1, name = main}
2 j=1 {number = 1, name = main}
2 j=2 {number = 1, name = main}
2 j=3 {number = 1, name = main}
2 j=4 {number = 1, name = main}
2 j=5 {number = 1, name = main}
3 {number = 1, name = main}
*/
}
@objc func serialQueueAsync() {
print("1 \(Thread.current)")
let queue = DispatchQueue.init(label: "serialQueueAsync")
queue.async {
for i in 0...5 {
print("2 i=\(i) \(Thread.current)")
}
}
queue.async {
for j in 0...5 {
print("2 j=\(j) \(Thread.current)")
}
}
print("3 \(Thread.current)")
/*
并发执行。 不在主线程
开启新线程
1 {number = 1, name = main}
3 {number = 1, name = main}
2 i=0 {number = 3, name = (null)}
2 i=1 {number = 3, name = (null)}
2 i=2 {number = 3, name = (null)}
2 i=3 {number = 3, name = (null)}
2 i=4 {number = 3, name = (null)}
2 i=5 {number = 3, name = (null)}
2 j=0 {number = 3, name = (null)}
2 j=1 {number = 3, name = (null)}
2 j=2 {number = 3, name = (null)}
2 j=3 {number = 3, name = (null)}
2 j=4 {number = 3, name = (null)}
2 j=5 {number = 3, name = (null)}
*/
}
@objc func concurrentQueueSync() {
print("1 \(Thread.current)")
let queue = DispatchQueue.init(label: "concurrentQueueSync", attributes: .concurrent)
queue.sync {
for i in 0...5 {
print("2 i=\(i) \(Thread.current)")
}
}
queue.sync {
for j in 0...5 {
print("2 j=\(j) \(Thread.current)")
}
}
print("3 \(Thread.current)")
/*
顺序执行，在主线程中
没有开启新线程
1 {number = 1, name = main}
2 i=0 {number = 1, name = main}
2 i=1 {number = 1, name = main}
2 i=2 {number = 1, name = main}
2 i=3 {number = 1, name = main}
2 i=4 {number = 1, name = main}
2 i=5 {number = 1, name = main}
2 j=0 {number = 1, name = main}
2 j=1 {number = 1, name = main}
2 j=2 {number = 1, name = main}
2 j=3 {number = 1, name = main}
2 j=4 {number = 1, name = main}
2 j=5 {number = 1, name = main}
3 {number = 1, name = main}
*/
}
@objc func concurrentQueueAsync() {
print("1 \(Thread.current)")
let queue = DispatchQueue.init(label: "concurrentQueueAsync")
queue.async {
for i in 0...5 {
print("2 i=\(i) \(Thread.current)")
}
}
queue.async {
for j in 0...5 {
print("2 j=\(j) \(Thread.current)")
}
}
print("3 \(Thread.current)")
/*
并发执行。 不在主线程
开启新线程
1 {number = 1, name = main}
3 {number = 1, name = main}
2 i=0 {number = 6, name = (null)}
2 i=1 {number = 6, name = (null)}
2 i=2 {number = 6, name = (null)}
2 i=3 {number = 6, name = (null)}
2 i=4 {number = 6, name = (null)}
2 i=5 {number = 6, name = (null)}
2 j=0 {number = 6, name = (null)}
2 j=1 {number = 6, name = (null)}
2 j=2 {number = 6, name = (null)}
2 j=3 {number = 6, name = (null)}
2 j=4 {number = 6, name = (null)}
2 j=5 {number = 6, name = (null)}
*/
}
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return scenes.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath)
cell.textLabel?.text = scenes[indexPath.item]["title"]
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
if let function = scenes[indexPath.item]["action"] {
let selector = Selector(function)
if self.responds(to: selector) {
perform(selector)
}
}
}
}
