ETagManager/HTTPClient: sending new X-RC-Last-Refresh-Time head…

…er (#2373) Fixes SDK-3024 and SDK-3026. --------- Co-authored-by: Andy Boedo <andresboedo@gmail.com>
RevenueCat · Apr 14, 2023 · 8b4c2eb · 8b4c2eb
1 parent eeb0ced
commit 8b4c2eb
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Showing 5 changed files with 186 additions and 124 deletions.
diff --git a/Sources/Networking/HTTPClient/ETagManager.swift b/Sources/Networking/HTTPClient/ETagManager.swift
@@ -17,6 +17,7 @@ import Foundation
 class ETagManager {
 
     static let eTagRequestHeaderName = HTTPClient.RequestHeader.eTag.rawValue
+    static let eTagValidationTimeRequestHeaderName = HTTPClient.RequestHeader.eTagValidationTime.rawValue
     static let eTagResponseHeaderName = HTTPClient.ResponseHeader.eTag.rawValue
 
     private let userDefaults: SynchronizedUserDefaults
@@ -43,7 +44,7 @@ class ETagManager {
         withSignatureVerification: Bool,
         refreshETag: Bool = false
     ) -> [String: String] {
-        func eTag() -> String? {
+        func eTag() -> (tag: String, date: String)? {
             if refreshETag { return nil }
             guard let storedETagAndResponse = self.storedETagAndResponse(for: urlRequest) else { return nil }
 
@@ -53,10 +54,20 @@ class ETagManager {
                 storedETagAndResponse.verificationResult == .verified
             )
 
-            return shouldUseETag ? storedETagAndResponse.eTag : nil
+            if shouldUseETag {
+                return (tag: storedETagAndResponse.eTag,
+                        date: storedETagAndResponse.validationTime.millisecondsSince1970.description)
+            } else {
+                return nil
+            }
         }
 
-        return [HTTPClient.RequestHeader.eTag.rawValue: eTag() ?? ""]
+        let (etag, date) = eTag() ?? ("", "")
+
+        return [
+            HTTPClient.RequestHeader.eTag.rawValue: etag,
+            HTTPClient.RequestHeader.eTagValidationTime.rawValue: date
+        ]
     }
 
     func httpResultFromCacheOrBackend(with response: HTTPResponse<Data?>,
@@ -70,8 +81,11 @@ class ETagManager {
         }
 
         if self.shouldUseCachedVersion(responseCode: statusCode) {
-            if let storedResponse = self.storedHTTPResponse(for: request, withRequestDate: response.requestDate) {
-                return storedResponse
+            if let storedResponse = self.storedETagAndResponse(for: request) {
+                let newResponse = storedResponse.withUpdatedValidationTime()
+
+                self.storeIfPossible(newResponse, for: request)
+                return newResponse.asResponse(withRequestDate: response.requestDate)
             }
             if retried {
                 Logger.warn(
@@ -108,7 +122,7 @@ private extension ETagManager {
 
     func storedETagAndResponse(for request: URLRequest) -> Response? {
         return self.userDefaults.read {
-            if let cacheKey = eTagDefaultCacheKey(for: request),
+            if let cacheKey = self.eTagDefaultCacheKey(for: request),
                let value = $0.object(forKey: cacheKey),
                let data = value as? Data {
                 return try? JSONDecoder.default.decode(Response.self, jsonData: data)
@@ -126,18 +140,24 @@ private extension ETagManager {
                                              response: HTTPResponse<Data?>,
                                              eTag: String) {
         if let data = response.body,
-           response.shouldStore(ignoreVerificationErrors: self.shouldIgnoreVerificationErrors),
-           let cacheKey = self.eTagDefaultCacheKey(for: request) {
-            let eTagAndResponse = Response(
-                eTag: eTag,
-                statusCode: response.statusCode,
-                data: data,
-                verificationResult: response.verificationResult
+           response.shouldStore(ignoreVerificationErrors: self.shouldIgnoreVerificationErrors) {
+            self.storeIfPossible(
+                Response(
+                    eTag: eTag,
+                    statusCode: response.statusCode,
+                    data: data,
+                    verificationResult: response.verificationResult
+                ),
+                for: request
             )
-            if let dataToStore = eTagAndResponse.asData() {
-                self.userDefaults.write {
-                    $0.set(dataToStore, forKey: cacheKey)
-                }
+        }
+    }
+
+    func storeIfPossible(_ response: Response, for request: URLRequest) {
+        if let cacheKey = self.eTagDefaultCacheKey(for: request),
+           let dataToStore = response.asData() {
+            self.userDefaults.write {
+                $0.set(dataToStore, forKey: cacheKey)
             }
         }
     }
@@ -173,18 +193,23 @@ extension ETagManager {
         var eTag: String
         var statusCode: HTTPStatusCode
         var data: Data
+        /// Used by the backend for advanced load shedding techniques.
+        @DefaultDecodable.Now
+        var validationTime: Date
         @DefaultValue<VerificationResult>
         var verificationResult: VerificationResult
 
         init(
             eTag: String,
             statusCode: HTTPStatusCode,
             data: Data,
+            validationTime: Date = Date(),
             verificationResult: VerificationResult
         ) {
             self.eTag = eTag
             self.statusCode = statusCode
             self.data = data
+            self.validationTime = validationTime
             self.verificationResult = verificationResult
         }
 
@@ -210,6 +235,13 @@ extension ETagManager.Response {
         )
     }
 
+    fileprivate func withUpdatedValidationTime() -> Self {
+        var copy = self
+        copy.validationTime = Date()
+
+        return copy
+    }
+
 }
 
 // MARK: -

diff --git a/Sources/Networking/HTTPClient/HTTPClient.swift b/Sources/Networking/HTTPClient/HTTPClient.swift
@@ -101,6 +101,7 @@ extension HTTPClient {
         case location = "Location"
         case nonce = "X-Nonce"
         case eTag = "X-RevenueCat-ETag"
+        case eTagValidationTime = "X-RC-Last-Refresh-Time"
 
     }
 

diff --git a/Tests/UnitTests/Mocks/MockETagManager.swift b/Tests/UnitTests/Mocks/MockETagManager.swift
@@ -29,8 +29,11 @@ class MockETagManager: ETagManager {
     var invokedETagHeaderParametersList: [ETagHeaderRequest] = []
     var stubbedETagHeaderResult: [String: String]! = [:]
 
-    func stubResponseEtag(_ tag: String) {
-        self.stubbedETagHeaderResult[ETagManager.eTagResponseHeaderName] = tag
+    func stubResponseEtag(_ tag: String, validationTime: Date = Date()) {
+        self.stubbedETagHeaderResult = [
+            ETagManager.eTagRequestHeaderName: tag,
+            ETagManager.eTagValidationTimeRequestHeaderName: validationTime.millisecondsSince1970.description
+        ]
     }
 
     override func eTagHeader(