Caching remote config to disk

Sources/EmbraceConfigInternal/EmbraceConfigurable/RemoteConfig.swift

@@ -9,6 +9,8 @@ import EmbraceConfiguration
 /// Remote config uses the Embrace Config Service to request config values
 public class RemoteConfig {
 
+    let logger: InternalLogger
+
     // config requests
     @ThreadSafe var payload: RemoteConfigPayload
     let fetcher: RemoteConfigFetcher
@@ -19,6 +21,8 @@ public class RemoteConfig {
 
     @ThreadSafe private(set) var updating = false
 
+    let cacheURL: URL?
+
     public convenience init(
         options: RemoteConfig.Options,
         payload: RemoteConfigPayload = RemoteConfigPayload(),
@@ -38,6 +42,42 @@ public class RemoteConfig {
         self.payload = payload
         self.fetcher = fetcher
         self.deviceIdHexValue = options.deviceId.intValue(digitCount: Self.deviceIdUsedDigits)
+        self.logger = logger
+
+        if let url = options.cacheLocation {
+            try? FileManager.default.createDirectory(at: url, withIntermediateDirectories: true)
+            self.cacheURL = options.cacheLocation?.appendingPathComponent("cache")
+            loadFromCache()
+        } else {
+            self.cacheURL = nil
+        }
+    }
+
+    func loadFromCache() {
+        guard let url = cacheURL,
+              FileManager.default.fileExists(atPath: url.path) else {
+            return
+        }
+
+        do {
+            let data = try Data(contentsOf: url)
+            payload = try JSONDecoder().decode(RemoteConfigPayload.self, from: data)
+        } catch {
+            logger.error("Error loading cached remote config!")
+        }
+    }
+
+    func saveToCache(_ data: Data?) {
+        guard let url = cacheURL,
+              let data = data else {
+            return
+        }
+
+        do {
+            try data.write(to: url, options: .atomic)
+        } catch {
+            logger.warning("Error saving remote config cache!")
+        }
     }
 }
 
@@ -67,7 +107,7 @@ extension RemoteConfig: EmbraceConfigurable {
         }
 
         updating = true
-        fetcher.fetch { [weak self] newPayload in
+        fetcher.fetch { [weak self] newPayload, data in
             defer { self?.updating = false }
             guard let strongSelf = self else {
                 completion(false, nil)
@@ -82,6 +122,8 @@ extension RemoteConfig: EmbraceConfigurable {
             let didUpdate = strongSelf.payload != newPayload
             strongSelf.payload = newPayload
 
+            strongSelf.saveToCache(data)
+
             completion(didUpdate, nil)
         }
     }

Sources/EmbraceConfigInternal/EmbraceConfigurable/RemoteConfig/RemoteConfig+Options.swift

@@ -17,6 +17,8 @@ public extension RemoteConfig {
         let appVersion: String
         let userAgent: String
 
+        let cacheLocation: URL?
+
         let urlSessionConfiguration: URLSessionConfiguration
 
         public init(
@@ -28,6 +30,7 @@ public extension RemoteConfig {
             sdkVersion: String,
             appVersion: String,
             userAgent: String,
+            cacheLocation: URL?,
             urlSessionConfiguration: URLSessionConfiguration = URLSessionConfiguration.default
         ) {
             self.apiBaseUrl = apiBaseUrl
@@ -38,6 +41,7 @@ public extension RemoteConfig {
             self.sdkVersion = sdkVersion
             self.appVersion = appVersion
             self.userAgent = userAgent
+            self.cacheLocation = cacheLocation
             self.urlSessionConfiguration = urlSessionConfiguration
         }
     }

Sources/EmbraceConfigInternal/EmbraceConfigurable/RemoteConfig/RemoteConfigFetcher.swift

@@ -27,9 +27,9 @@ class RemoteConfigFetcher {
         )
     }
 
-    func fetch(completion: @escaping (RemoteConfigPayload?) -> Void) {
+    func fetch(completion: @escaping (RemoteConfigPayload?, Data?) -> Void) {
         guard let request = newRequest() else {
-            completion(nil)
+            completion(nil, nil)
             return
         }
 
@@ -38,19 +38,19 @@ class RemoteConfigFetcher {
 
             guard let data = data, error == nil else {
                 self?.logger.error("Error fetching remote config:\n\(String(describing: error?.localizedDescription))")
-                completion(nil)
+                completion(nil, nil)
                 return
             }
 
             guard let httpResponse = response as? HTTPURLResponse else {
                 self?.logger.error("Error fetching remote config - Invalid response:\n\(String(describing: response?.description))")
-                completion(nil)
+                completion(nil, nil)
                 return
             }
 
             guard httpResponse.statusCode >= 200 && httpResponse.statusCode < 300 else {
                 self?.logger.error("Error fetching remote config - Invalid response:\n\(httpResponse.description))")
-                completion(nil)
+                completion(nil, nil)
                 return
             }
 
@@ -59,11 +59,11 @@ class RemoteConfigFetcher {
                 let payload = try JSONDecoder().decode(RemoteConfigPayload.self, from: data)
 
                 self?.logger.info("Successfully fetched remote config")
-                completion(payload)
+                completion(payload, data)
             } catch {
                 self?.logger.error("Error decoding remote config:\n\(error.localizedDescription)")
                 // if a decoding issue happens, instead of returning `nil`, we provide a default `RemoteConfigPayload`
-                completion(RemoteConfigPayload())
+                completion(RemoteConfigPayload(), nil)
             }
         }
 

Sources/EmbraceCore/FileSystem/EmbraceFileSystem.swift

@@ -11,6 +11,7 @@ public struct EmbraceFileSystem {
     static let uploadsDirectoryName = "uploads"
     static let crashesDirectoryName = "crashes"
     static let captureDirectoryName = "capture"
+    static let configDirectoryName = "config"
 
     static let defaultPartitionId = "default"
 
@@ -53,8 +54,7 @@ public struct EmbraceFileSystem {
     /// ```
     /// - Parameters:
     ///    - name: The name of the subdirectory
-    ///    - partitionIdentifier: The main partition identifier to use
-    ///     identifier to use
+    ///    - partitionId: The main partition identifier to use
     ///    - appGroupId: The app group identifier if using an app group container.
     static func directoryURL(name: String, partitionId: String, appGroupId: String? = nil) -> URL? {
         guard let baseURL = systemDirectory(appGroupId: appGroupId) else {
@@ -104,4 +104,16 @@ public struct EmbraceFileSystem {
             appGroupId: appGroupId
         )
     }
+
+    /// Returns the subdirectory for config cache
+    /// ```
+    /// io.embrace.data/<version>/<partition-id>/config
+    /// ```
+    static func configDirectoryURL(partitionIdentifier: String, appGroupId: String? = nil) -> URL? {
+        return directoryURL(
+            name: configDirectoryName,
+            partitionId: partitionIdentifier,
+            appGroupId: appGroupId
+        )
+    }
 }

Sources/EmbraceCore/Internal/Embrace+Config.swift

@@ -47,7 +47,8 @@ extension Embrace {
             osVersion: EMBDevice.appVersion ?? "",
             sdkVersion: EmbraceMeta.sdkVersion,
             appVersion: EMBDevice.operatingSystemVersion,
-            userAgent: EmbraceMeta.userAgent
+            userAgent: EmbraceMeta.userAgent,
+            cacheLocation: EmbraceFileSystem.configDirectoryURL(partitionIdentifier: appId, appGroupId: options.appGroupId)
         )
 
         return RemoteConfig(

Tests/EmbraceConfigInternalTests/EmbraceConfigurable/RemoteConfig/RemoteConfigFetcherTests.swift

@@ -40,6 +40,7 @@ class RemoteConfigFetcherTests: XCTestCase {
             sdkVersion: sdkVersion,
             appVersion: appVersion,
             userAgent: userAgent,
+            cacheLocation: nil,
             urlSessionConfiguration: Self.urlSessionConfig
         )
     }
@@ -145,7 +146,7 @@ class RemoteConfigFetcherTests: XCTestCase {
         let fetcher = RemoteConfigFetcher(options: options, logger: logger)
 
         let expectation = expectation(description: "URL request")
-        fetcher.fetch { payload in
+        fetcher.fetch { payload, data in
             XCTAssertNotNil(payload)
             expectation.fulfill()
         }
@@ -163,7 +164,7 @@ class RemoteConfigFetcherTests: XCTestCase {
         let fetcher = RemoteConfigFetcher(options: options, logger: logger)
 
         let expectation = expectation(description: "URL request")
-        fetcher.fetch { payload in
+        fetcher.fetch { payload, data in
             XCTAssertNil(payload)
             expectation.fulfill()
         }

Tests/EmbraceConfigInternalTests/EmbraceConfigurable/RemoteConfigTests.swift

@@ -21,33 +21,10 @@ final class RemoteConfigTests: XCTestCase {
         sdkVersion: TestConstants.sdkVersion,
         appVersion: TestConstants.appVersion,
         userAgent: TestConstants.userAgent,
+        cacheLocation: nil,
         urlSessionConfiguration: URLSessionConfiguration.default
     )
 
-    func mockSuccessfulResponse() throws {
-        var url = try XCTUnwrap(URL(string: "\(options.apiBaseUrl)/v2/config"))
-
-        if #available(iOS 16.0, watchOS 9.0, *) {
-            url.append(queryItems: [
-                .init(name: "appId", value: options.appId),
-                .init(name: "osVersion", value: options.osVersion),
-                .init(name: "appVersion", value: options.appVersion),
-                .init(name: "deviceId", value: options.deviceId.hex),
-                .init(name: "sdkVersion", value: options.sdkVersion)
-            ])
-        } else {
-            XCTFail("This will fail on versions prior to iOS 16.0")
-        }
-
-        let path = Bundle.module.path(
-            forResource: "remote_config",
-            ofType: "json",
-            inDirectory: "Fixtures"
-        )!
-        let data = try Data(contentsOf: URL(fileURLWithPath: path))
-        EmbraceHTTPMock.mock(url: url, response: .withData(data, statusCode: 200))
-    }
-
     // MARK: Tests
 
     func test_isEnabled_returnsCorrectValues() {