//
// RuntimeBasement__weekViewController.swift
// iOS底层
//
// Created by yanqunchao on 2019/5/21.
// Copyright © 2019 yanqunchao. All rights reserved.
//
import UIKit
let WEAK_INLINE_COUNT = 4
class RuntimeBasement__weekViewController: UIViewController {
class WeakEntryT:NSObject {
var referent:NSObject? // 被弱引用的对象
var inline_referrers: [UnsafeMutablePointer<NSObject>?] = [UnsafeMutablePointer<NSObject>?](repeating: nil, count: WEAK_INLINE_COUNT)
init(newReferent:NSObject,newReferrer:UnsafeMutablePointer<NSObject>) {
print("【创建】新的弱引用入口")
self.referent = newReferent
inline_referrers[0] = newReferrer
inline_referrers[0]?.pointee = newReferent
for i in 1..<WEAK_INLINE_COUNT{
inline_referrers[i] = nil;
}
}
}
class RefcountMap:NSObject {
}
class WeakTableT:NSObject {
var weakEntries:[WeakEntryT?] = [WeakEntryT?](repeating: nil, count: 4)
var mask:Int?
}
class SideTable {
var recnts:RefcountMap?
var weak_table: WeakTableT?
init() {
self.weak_table = WeakTableT()
}
class func lockTwo(oldTable:SideTable,newTable:SideTable){}
class func unlockTwo(oldTable:SideTable,newTable:SideTable){}
};
class objc_object:NSObject {
};
//存储所有弱引用的散列表
lazy var SideTables : [SideTable] = {
var sideTables:[SideTable] = []
for i in 0..<64{
sideTables.append(SideTable())
}
return sideTables
}() //初始化64个元素大小的SideTables数组
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = .white
let obj1 = NSObject()
let obj2 = NSObject()
weak var weakObj1:NSObject? = obj1
weak var weakObj2:NSObject? = obj2
_ = storeWeak(location: &weakObj1!, newObj: obj1)
_ = storeWeak(location: &weakObj2!, newObj: obj1)
_ = storeWeak(location: &weakObj1!, newObj: obj2)
let sideTable = side_table_for_referent(referent: obj1)
weak_clear_no_lock(weakTable: sideTable!.weak_table!, referent: obj1)
let sideTable2 = side_table_for_referent(referent: obj2)
weak_clear_no_lock(weakTable: sideTable2!.weak_table!, referent: obj2)
}
func printLocation(location:UnsafeMutablePointer<Any>) {
print("\(location)")
}
func storeWeak(location:UnsafeMutablePointer<NSObject>, newObj:NSObject) -> NSObject?
{
let sideTable = side_table_for_referent(referent: newObj)
// // 加锁操作，防止多线程中竞争冲突
// SideTable.lockTwo(oldTable: oldTable!, newTable: newTable!)
if isOld(location: location) {
print("【注销】旧的弱引用指针指向的对象")
weak_unregister_no_lock(weakTable: sideTable!.weak_table!, oldObj: newObj, location: location)
}
print("【注册】新的弱引用指针指向的对象")
weak_register_no_lock(weakTable: sideTable!.weak_table!, newObj: newObj, location: location)
return newObj
}
func isOld(location:UnsafeMutablePointer<NSObject>)->Bool {
var isOld = false
for sideTable in self.SideTables {
for entry in sideTable.weak_table!.weakEntries {
if entry != nil {
isOld = referrerIsExsit(entry: entry!, newReferrer: location)
if isOld == true {
print("【存在】弱引用地址")
return true
}
}
}
}
print("【不存在】弱引用地址")
return false
}
func side_table_for_referent(referent:NSObject) -> SideTable?{
let mask = SideTables.count - 1
let begin = weakEntryHash(key: referent, mask: mask)!
print("\r\n\r\n\r\n【筛选】到位置在第\(begin)的SideTable")
return SideTables[begin]
}
//移除旧的弱引用
func weak_unregister_no_lock(weakTable:WeakTableT,oldObj:NSObject,location:UnsafeMutablePointer<NSObject>){
let entry = weak_entry_for_referent(weakTable: weakTable, referent: oldObj)
if (entry != nil) {
remove_referrer(entry: entry!, old_referrer: location)
}
}
//添加新的弱引用
func weak_register_no_lock(weakTable:WeakTableT,newObj:NSObject,location:UnsafeMutablePointer<NSObject>){
var entry = weak_entry_for_referent(weakTable: weakTable, referent: newObj)
let new_referrer = location
if (entry != nil) { // 如果能找到weak_entry,则将referrer插入到weak_entry中
append_referrer(entry: entry!, newReferrer: new_referrer);
}
else { // 如果找不到，就新建一个，并插入到weaktalbe的weakEntries数组里面
entry = WeakEntryT(newReferent: newObj, newReferrer: new_referrer)
weak_entry_insert(weak_table: weakTable, new_entry: entry!)
}
}
func weak_clear_no_lock(weakTable:WeakTableT,referent:NSObject?)
{
let entry = weak_entry_for_referent(weakTable: weakTable, referent: referent!)
if (entry == nil) {
// XXX shouldn't happen, but does with mismatched CF/objc
print("XXX no entry for clear deallocating\( referent!)")
return
}
for referrer in entry!.inline_referrers {
if referrer?.pointee == referent {
//弱引用地址指向的对象的置为空
// referrer?.pointee = nil
print("弱引用地址指向的对象的置为空")
}
}
weak_entry_remove(weak_table: weakTable, entry: entry!)
}
func weak_entry_remove(weak_table:WeakTableT, entry:WeakEntryT) {
//清空弱引用入口
for (i,entry1) in weak_table.weakEntries.enumerated() {
if entry1 == entry {
weak_table.weakEntries[i] = nil
return
}
}
}
func weak_entry_insert(weak_table:WeakTableT,new_entry:WeakEntryT) {
var weak_entries = weak_table.weakEntries
let mask = weak_entries.count - 1
let begin = weakEntryHash(key: new_entry.referent!, mask: mask)
var i = begin
repeat {
let weakEntry = weak_entries[i!]
if weakEntry?.referent == nil{
print("【填充】新的入口到弱引用表中")
weak_entries[i!] = new_entry
weak_table.weakEntries = weak_entries
return
}
i = weakEntryNext(i: i!, mask: mask)
}while(i != begin)
}
func weak_entry_for_referent(weakTable:WeakTableT,referent:NSObject) -> WeakEntryT?{
let weakEntries = weakTable.weakEntries
let mask = weakEntries.count - 1
let begin = weakEntryHash(key: referent, mask: mask)
var i = begin
var runCount = 0
repeat {
let weakEntry = weakEntries[i!]
if weakEntry?.referent == referent {
print("【找到】对应的弱引用入口")
return weakEntry
}
if runCount == mask + 1 { //跑一圈没找到
print("【没找到】对应的弱引用入口")
return nil
}
i = weakEntryNext(i: i!, mask: mask)
runCount += 1
}while(i != begin)
print("【没找到】对应的弱引用入口")
return nil
}
func weakEntryNext(i:Int,mask:Int) ->Int? {
var index = i
if index != 0 {
index = index - 1
return index
}else {
return mask
}
}
func weakEntryHash(key:NSObject,mask:Int) ->Int? {
let keyAddr = Unmanaged.passUnretained(key as AnyObject).toOpaque()
let keyAddrStr = "\(keyAddr)"
let lastKeyStr = keyAddrStr.suffix(keyAddrStr.count - 2)
let keyInt = ConvertUtil.hexTodec(number: String(lastKeyStr))
return keyInt & mask
}
//添加弱引用
func append_referrer(entry:WeakEntryT,newReferrer:UnsafeMutablePointer<NSObject>){
print("【添加】弱引用地址")
for (i, referrer) in entry.inline_referrers.enumerated() {
if referrer == nil {
entry.inline_referrers[i] = newReferrer
entry.inline_referrers[i]?.pointee = entry.referent!
return
}
}
}
func remove_referrer(entry:WeakEntryT,old_referrer:UnsafeMutablePointer<NSObject>){
print("【删除】弱引用地址")
for (i, referrer) in entry.inline_referrers.enumerated() {
if referrer == old_referrer {
entry.inline_referrers[i] = nil
return
}
}
}
//inline_referrers是否存在referrr
func referrerIsExsit(entry:WeakEntryT,newReferrer:UnsafeMutablePointer<NSObject>) -> Bool{
for (i, referrer) in entry.inline_referrers.enumerated() {
if referrer == newReferrer{
//元素置为空
entry.inline_referrers[i] = nil
return true
}
}
return false
}
}
iOS原理之Runtime-__weak的实现原理
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