同时访问 0x1c0a7f0f8，但修改需要 Xcode 9 beta 4 上的独占访问错误 [英] Simultaneous accesses to 0x1c0a7f0f8, but modification requires exclusive access error on Xcode 9 beta 4
问题描述
我的项目同时使用了 Objective-C 和 Swift 代码.当用户登录时，它会调用一组用于用户首选项的 api，我有一个 DataCoordinator.swift 类来调度 API 操作，我从 UserDetailViewController.m 类进行调用以加载用户首选项.在我使用 Xcode 9 beta 4 将代码迁移到 Swift 4 之前，它可以正常工作.现在，当我登录时，它会在我的 DataCoordinator 类中给我这个错误而崩溃.下面是我的 DataCoordinator 和 Viewcontroller 类的示例.
my project uses both Objective-C and Swift code. When a user logs in, it calls a set of apis for user preference, I have a DataCoordinator.swift class which schedules the API operation and I make this calls from UserDetailViewController.m class to load user preferences. This use to work fine before I migrated my code to Swift 4 using Xcode 9 beta 4. Now when I login it crashes by giving me this error in my DataCoordinator class. Below is a sample of my DataCoordinator and Viewcontroller class.
DataCoordinator.swift
import UIKit
@objcMembers
class DataCoordinator: NSObject {
//MARK:- Private
fileprivate var user = myDataStore.sharedInstance().user
fileprivate var preferenceFetchOperations = [FetchOperation]()
fileprivate func scheduleFetchOperation(_ operation:FetchOperation, inFetchOperations operations:inout [FetchOperation]) {
guard operations.index(of: operation) == nil else { return }
operations.append(operation)
}
fileprivate func completeFetchOperation(_ fetchOperation:FetchOperation, withError error:Error?, andCompletionHandler handler:@escaping FetchCompletionHandler) {
func removeOperation(_ operation:FetchOperation, fromOperations operations:inout [FetchOperation]) {
if operations.count > 0 {
operations.remove(at: operations.index(of: fetchOperation)!)
handler(error)
}
}
if preferenceFetchOperations.contains(fetchOperation) {
removeOperation(fetchOperation, fromOperations: &preferenceFetchOperations)
}
}
fileprivate func schedulePreferencesFetchOperation(_ serviceName:String, fetch:@escaping FetchOperationBlock){
let operation = FetchOperation(name: serviceName, fetch: fetch);
scheduleFetchOperation(operation, inFetchOperations: &preferenceFetchOperations)
}
fileprivate func runOperationsIn(_ fetchOperations:inout [FetchOperation]) {
for var operation in fetchOperations {
guard operation.isActivated == false else { continue }
operation.isActivated = true
operation.execute()
}
}
//MARK:- Non-Private
typealias FetchCompletionHandler = (_ error:Error?)->Void
var numberOfPreferencesFetchCalls:Int {
get { return preferenceFetchOperations.count }
}
// MARK: -
func fetchPreferences(_ completionHandler:@escaping FetchCompletionHandler) -> Void {
defer {
runOperationsIn(&preferenceFetchOperations)
}
schedulePreferencesFetchOperation("com.fetchPreferences.type1") {[unowned self] (operation:FetchOperation) in
WebServiceManager.getType1Detail(for: user) {[unowned self] (error) in
self.completeFetchOperation(operation, withError: error, andCompletionHandler: completionHandler)
}
}
schedulePreferencesFetchOperation("com.fetchPreferences.type2") {[unowned self] (operation:FetchOperation) in
WebServiceManager.getType2Detail(for: user) {[unowned self] (error) in
self.completeFetchOperation(operation, withError: error, andCompletionHandler: completionHandler)
}
}
schedulePreferencesFetchOperation("com.fetchPreferences.type3") {[unowned self] (operation:FetchOperation) in
WebServiceManager.getType3Detail(for: user) {[unowned self] (error) in
self.completeFetchOperation(operation, withError: error, andCompletionHandler: completionHandler)
}
}
schedulePreferencesFetchOperation("com.fetchPreferences.type4") {[unowned self] (operation:FetchOperation) in
WebServiceManager.getType4Detail(for: user) {[unowned self] (error) in
self.completeFetchOperation(operation, withError: error, andCompletionHandler: completionHandler)
}
}
}
}
// MARK:- Fetch Operation Struct
private typealias FetchOperationBlock = (_ operation:FetchOperation)->Void
private struct FetchOperation:Hashable {
fileprivate var runToken = 0
fileprivate let fetchBlock:FetchOperationBlock
let name:String!
var isActivated:Bool {
get {
return runToken == 0 ? false : true
}
mutating set {
if runToken == 0 && newValue == true {
runToken = 1
}
}
}
fileprivate var hashValue: Int {
get {
return name.hashValue
}
}
func execute() -> Void {
fetchBlock(self)
}
init (name:String, fetch:@escaping FetchOperationBlock) {
self.name = name
self.fetchBlock = fetch
}
}
private func ==(lhs: FetchOperation, rhs: FetchOperation) -> Bool {
return lhs.hashValue == rhs.hashValue
}
//这就是我在viewcontrollers viewDidLoad方法中的调用方式
//This is how I call it in my viewcontrollers viewDidLoad method
__weak UserDetailViewController *weakSelf = self;
[self.dataCoordinator fetchPreferences:^(NSError * _Nullable error) {
if (error == nil) {
[weakSelf didFetchPrefrences];
}
else {
// handle error
}
}];
//completion response
- (void)didFetchPrefrences {
//when api calls complete load data
if (self.dataCoordinator.numberOfPreferencesFetchCalls == 0) {
//Load details
}
}
我不知道该怎么做，我在 https:/看到了一个错误报告/bugs.swift.org/browse/SR-5119 但它似乎已在 Xcode 9 beta 3 中修复.感谢任何帮助
I'm not sure how to proceed on this, I saw a bug report at https://bugs.swift.org/browse/SR-5119 but it seems to be fixed in Xcode 9 beta 3. Any help is appreciated
推荐答案
我认为这个错误"可能是 Swift 4 的功能"，特别是他们称之为对内存的独占访问"的东西.
I think this 'bug' may be a Swift 4 'feature', specifically something they call 'Exclusive access to Memory'.
观看此 WWDC 视频.在 50 分钟左右，长发演讲者解释了它.
Check out this WWDC video. Around the 50 minute mark, the long-haired speaker explains it.
https://developer.apple.com/videos/play/wwdc2017/402/?time=233
如果您愿意忽略它，可以尝试在您的方案设置中关闭线程清理器.然而，调试器试图告诉你一个微妙的线程问题，所以它可能更好地利用你的时间来试图找出为什么你在读取数组的同时写入了一些东西.
You could try turning the thread sanitizer off in your scheme settings if you're happy to ignore it. However, the debugger is trying to tell you about a subtle threading issue so it's probably a better use of your time to try to figure out why you've got something writing to your array at the same time it's being read from.
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