Fix issue with saving e-tags for xcstrings file.

Make e-tag storage atomic. Read file content before adding new e-tag. Add serial queue for writing operations.

Author: serhii-londar

Sources/CrowdinSDK/CrowdinFileSystem/File.swift

@@ -84,6 +84,10 @@ class ReadWriteFile<T: ReadWriteProtocol>: File {
         guard let file = self.file else { return }
         file.write(to: self.path)
     }
+    
+    func read() {
+        self.file = T.read(from: self.path)
+    }
 }
 
 #if os(iOS) || os(tvOS) || os(watchOS)

Sources/CrowdinSDK/CrowdinSDK/Localization/Provider/LocalizationProvider.swift

@@ -15,7 +15,7 @@ protocol LocalizationProviderProtocol {
     var localStorage: LocalLocalizationStorageProtocol { get }
     var remoteStorage: RemoteLocalizationStorageProtocol { get }
 
-    var localization: String { get  set }
+    var localization: String { get set }
     var localizations: [String] { get }
 
     func refreshLocalization()

Sources/CrowdinSDK/Providers/Crowdin/LocalizationDownloader/CrowdinLocalizationDownloader.swift

@@ -88,8 +88,7 @@ class CrowdinLocalizationDownloader: CrowdinDownloaderProtocol {
 
         xcstrings.forEach { filePath in
             let download = CrowdinXcstringsDownloadOperation(filePath: filePath,
-                                                             localization: localization,
-                                                             language: manifestManager.xcstringsLanguage,
+                                                             localization: manifestManager.xcstringsLanguage,
                                                              timestamp: timestamp,
                                                              contentDeliveryAPI: contentDeliveryAPI)
             download.completion = { [weak self] (strings, plurals, error) in

Sources/CrowdinSDK/Providers/Crowdin/LocalizationDownloader/ETagStorage/FileEtagStorage.swift

@@ -9,49 +9,65 @@ import Foundation
 
 final class FileEtagStorage: AnyEtagStorage {
     private static let fileName = "Etags.json"
+    private let queue = DispatchQueue(label: "com.crowdin.FileEtagStorage")
     let localization: String
-    let dictionaryFile: DictionaryFile
-
-    var etags: [String: [String: String]] {
-        get {
-            (dictionaryFile.file as? [String: [String: String]]) ?? [String: [String: String]]()
-        }
-        set {
-            dictionaryFile.file = newValue
-            try? dictionaryFile.save()
-        }
+    private var dictionaryFile: DictionaryFile
+    
+    private func getEtags() -> [String: [String: String]] {
+        dictionaryFile.read()
+        return (dictionaryFile.file as? [String: [String: String]]) ?? [:]
     }
-
+    
     init(localization: String) {
         self.localization = localization
-        dictionaryFile = DictionaryFile(path: CrowdinFolder.shared.path + "/" + FileEtagStorage.fileName)
+        let path = CrowdinFolder.shared.path + "/" + FileEtagStorage.fileName
+        self.dictionaryFile = DictionaryFile(path: path)
         if !dictionaryFile.isCreated {
             dictionaryFile.create()
         }
     }
-
+    
     func save(etag: String?, for file: String) {
-        var localizationEtags = etags[localization] ?? [:]
-        localizationEtags[file] = etag
-        etags[localization] = localizationEtags
+        queue.sync {
+            var currentEtags = getEtags()
+            var localizationEtags = currentEtags[localization] ?? [:]
+            localizationEtags[file] = etag
+            currentEtags[localization] = localizationEtags
+            dictionaryFile.file = currentEtags
+            try? self.dictionaryFile.save()
+        }
     }
-
+    
     func etag(for file: String) -> String? {
-        etags[localization]?[file]
+        queue.sync {
+            let currentEtags = getEtags()
+            return currentEtags[localization]?[file]
+        }
     }
-
+    
     func clear() {
-        etags[localization] = nil
+        queue.sync {
+            var currentEtags = getEtags()
+            currentEtags[localization] = nil
+            dictionaryFile.file = currentEtags
+            try? self.dictionaryFile.save()
+        }
     }
-
+    
     func clear(for file: String) {
-        var localizationEtags = etags[localization] ?? [:]
-        localizationEtags[file] = nil
-        etags[localization] = localizationEtags
+        queue.sync {
+            var currentEtags = getEtags()
+            var localizationEtags = currentEtags[localization] ?? [:]
+            localizationEtags[file] = nil
+            currentEtags[localization] = localizationEtags
+            dictionaryFile.file = currentEtags
+            try? self.dictionaryFile.save()
+        }
     }
-
+    
     /// Remove file
     static func clear() {
-        try? DictionaryFile(path: CrowdinFolder.shared.path + "/" + FileEtagStorage.fileName).remove()
+        let path = CrowdinFolder.shared.path + "/" + FileEtagStorage.fileName
+        try? DictionaryFile(path: path).remove()
     }
 }

Sources/CrowdinSDK/Providers/Crowdin/LocalizationDownloader/Operations/CrowdinXcstringsDownloadOperation.swift

@@ -174,18 +174,18 @@ class CrowdinXcstringsDownloadOperation: CrowdinDownloadOperation {
     var completion: CrowdinDownloadOperationCompletion? = nil
     let localization: String
 
-    init(filePath: String, localization: String, language: String, timestamp: TimeInterval?, contentDeliveryAPI: CrowdinContentDeliveryAPI, completion: CrowdinDownloadOperationCompletion?) {
+    init(filePath: String, localization: String, timestamp: TimeInterval?, contentDeliveryAPI: CrowdinContentDeliveryAPI, completion: CrowdinDownloadOperationCompletion?) {
         self.localization = localization
         self.timestamp = timestamp
-        self.eTagStorage = FileEtagStorage(localization: language)
+        self.eTagStorage = FileEtagStorage(localization: localization)
         super.init(filePath: filePath, contentDeliveryAPI: contentDeliveryAPI)
         self.completion = completion
     }
 
-    required init(filePath: String, localization: String, language: String, timestamp: TimeInterval?, contentDeliveryAPI: CrowdinContentDeliveryAPI) {
+    required init(filePath: String, localization: String, timestamp: TimeInterval?, contentDeliveryAPI: CrowdinContentDeliveryAPI) {
         self.localization = localization
         self.timestamp = timestamp
-        self.eTagStorage = FileEtagStorage(localization: language)
+        self.eTagStorage = FileEtagStorage(localization: localization)
         super.init(filePath: filePath, contentDeliveryAPI: contentDeliveryAPI)
     }