fix(DataStore): Clear API should delete local store (#1685)

lawmicha · web-flow · commit 2b528494959a · 2022-03-16T13:24:57.000-04:00
* fix(DataStore): clear should be successful if engine is not running

* fix(DataStore): Clear API should delete local store
diff --git a/AmplifyPlugins/DataStore/AWSDataStoreCategoryPlugin/AWSDataStorePlugin+DataStoreBaseBehavior.swift b/AmplifyPlugins/DataStore/AWSDataStoreCategoryPlugin/AWSDataStorePlugin+DataStoreBaseBehavior.swift
@@ -21,7 +21,7 @@ extension AWSDataStorePlugin: DataStoreBaseBehavior {
                                where condition: QueryPredicate? = nil,
                                completion: @escaping DataStoreCallback<M>) {
         log.verbose("Saving: \(model) with condition: \(String(describing: condition))")
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
 
         // TODO: Refactor this into a proper request/result where the result includes metadata like the derived
         // mutation type
@@ -63,7 +63,7 @@ extension AWSDataStorePlugin: DataStoreBaseBehavior {
     public func query<M: Model>(_ modelType: M.Type,
                                 byId id: String,
                                 completion: DataStoreCallback<M?>) {
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
         let predicate: QueryPredicate = field("id") == id
         query(modelType, where: predicate, paginate: .firstResult) {
             switch $0 {
@@ -99,7 +99,7 @@ extension AWSDataStorePlugin: DataStoreBaseBehavior {
                                 sort sortInput: [QuerySortDescriptor]? = nil,
                                 paginate paginationInput: QueryPaginationInput? = nil,
                                 completion: DataStoreCallback<[M]>) {
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
         storageEngine.query(modelType,
                             modelSchema: modelSchema,
                             predicate: predicate,
@@ -120,7 +120,7 @@ extension AWSDataStorePlugin: DataStoreBaseBehavior {
                                  withId id: String,
                                  where predicate: QueryPredicate? = nil,
                                  completion: @escaping DataStoreCallback<Void>) {
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
         storageEngine.delete(modelType, modelSchema: modelSchema, withId: id, predicate: predicate) { result in
             self.onDeleteCompletion(result: result, modelSchema: modelSchema, completion: completion)
         }
@@ -136,7 +136,7 @@ extension AWSDataStorePlugin: DataStoreBaseBehavior {
                                  modelSchema: ModelSchema,
                                  where predicate: QueryPredicate? = nil,
                                  completion: @escaping DataStoreCallback<Void>) {
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
         storageEngine.delete(type(of: model),
                              modelSchema: modelSchema,
                              withId: model.id,
@@ -155,7 +155,7 @@ extension AWSDataStorePlugin: DataStoreBaseBehavior {
                                  modelSchema: ModelSchema,
                                  where predicate: QueryPredicate,
                                  completion: @escaping DataStoreCallback<Void>) {
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
         let onCompletion: DataStoreCallback<[M]> = { result in
             switch result {
             case .success(let models):
@@ -174,52 +174,57 @@ extension AWSDataStorePlugin: DataStoreBaseBehavior {
     }
 
     public func start(completion: @escaping DataStoreCallback<Void>) {
-        reinitStorageEngineIfNeeded { result in
+        initStorageEngineAndStartSync { result in
             completion(result)
         }
     }
 
     public func stop(completion: @escaping DataStoreCallback<Void>) {
-        storageEngineInitSemaphore.wait()
-        operationQueue.operations.forEach { operation in
-            if let operation = operation as? DataStoreObserveQueryOperation {
-                operation.resetState()
+        storageEngineInitQueue.sync {
+            operationQueue.operations.forEach { operation in
+                if let operation = operation as? DataStoreObserveQueryOperation {
+                    operation.resetState()
+                }
+            }
+            dispatchedModelSyncedEvents.forEach { _, dispatchedModelSynced in
+                dispatchedModelSynced.set(false)
+            }
+            if storageEngine == nil {
+
+                completion(.successfulVoid)
+                return
+            }
+
+            storageEngine.stopSync { result in
+                self.storageEngine = nil
+                completion(result)
             }
-        }
-        dispatchedModelSyncedEvents.forEach { _, dispatchedModelSynced in
-            dispatchedModelSynced.set(false)
-        }
-        if storageEngine == nil {
-            storageEngineInitSemaphore.signal()
-            completion(.successfulVoid)
-            return
-        }
-        storageEngineInitSemaphore.signal()
-        storageEngine.stopSync { result in
-            self.storageEngine = nil
-            completion(result)
         }
     }
 
     public func clear(completion: @escaping DataStoreCallback<Void>) {
-        storageEngineInitSemaphore.wait()
-        operationQueue.operations.forEach { operation in
-            if let operation = operation as? DataStoreObserveQueryOperation {
-                operation.resetState()
-            }
-        }
-        dispatchedModelSyncedEvents.forEach { _, dispatchedModelSynced in
-            dispatchedModelSynced.set(false)
-        }
-        if storageEngine == nil {
-            storageEngineInitSemaphore.signal()
-            completion(.successfulVoid)
+        if case let .failure(error) = initStorageEngine() {
+            completion(.failure(causedBy: error))
             return
         }
-        storageEngineInitSemaphore.signal()
-        storageEngine.clear { result in
-            self.storageEngine = nil
-            completion(result)
+
+        storageEngineInitQueue.sync {
+            operationQueue.operations.forEach { operation in
+                if let operation = operation as? DataStoreObserveQueryOperation {
+                    operation.resetState()
+                }
+            }
+            dispatchedModelSyncedEvents.forEach { _, dispatchedModelSynced in
+                dispatchedModelSynced.set(false)
+            }
+            if storageEngine == nil {
+                completion(.successfulVoid)
+                return
+            }
+            storageEngine.clear { result in
+                self.storageEngine = nil
+                completion(result)
+            }
         }
     }
 
diff --git a/AmplifyPlugins/DataStore/AWSDataStoreCategoryPlugin/AWSDataStorePlugin+DataStoreSubscribeBehavior.swift b/AmplifyPlugins/DataStore/AWSDataStoreCategoryPlugin/AWSDataStorePlugin+DataStoreSubscribeBehavior.swift
@@ -12,7 +12,7 @@ extension AWSDataStorePlugin: DataStoreSubscribeBehavior {
 
     @available(iOS 13.0, *)
     public var publisher: AnyPublisher<MutationEvent, DataStoreError> {
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
         // Force-unwrapping: The optional 'dataStorePublisher' is expected
         // to exist for deployment targets >=iOS13.0
         return dataStorePublisher!.publisher
@@ -45,7 +45,7 @@ extension AWSDataStorePlugin: DataStoreSubscribeBehavior {
                                        where predicate: QueryPredicate? = nil,
                                        sort sortInput: [QuerySortDescriptor]? = nil)
     -> AnyPublisher<DataStoreQuerySnapshot<M>, DataStoreError> {
-        reinitStorageEngineIfNeeded()
+        initStorageEngineAndStartSync()
 
         guard let dataStorePublisher = dataStorePublisher else {
             return Fail(error: DataStoreError.unknown(
diff --git a/AmplifyPlugins/DataStore/AWSDataStoreCategoryPlugin/AWSDataStorePlugin.swift b/AmplifyPlugins/DataStore/AWSDataStoreCategoryPlugin/AWSDataStorePlugin.swift
@@ -39,7 +39,7 @@ final public class AWSDataStorePlugin: DataStoreCategoryPlugin {
     let validAuthPluginKey: String
 
     var storageEngine: StorageEngineBehavior!
-    var storageEngineInitSemaphore: DispatchSemaphore
+    var storageEngineInitQueue = DispatchQueue(label: "AWSDataStorePlugin.storageEngineInitQueue")
     var storageEngineBehaviorFactory: StorageEngineBehaviorFactory
 
     var iStorageEngineSink: Any?
@@ -73,7 +73,6 @@ final public class AWSDataStorePlugin: DataStoreCategoryPlugin {
             self.dataStorePublisher = nil
         }
         self.dispatchedModelSyncedEvents = [:]
-        self.storageEngineInitSemaphore = DispatchSemaphore(value: 1)
     }
 
     /// Internal initializer for testing
@@ -94,7 +93,6 @@ final public class AWSDataStorePlugin: DataStoreCategoryPlugin {
         self.dispatchedModelSyncedEvents = [:]
         self.validAPIPluginKey = validAPIPluginKey
         self.validAuthPluginKey = validAuthPluginKey
-        self.storageEngineInitSemaphore = DispatchSemaphore(value: 1)
     }
 
     /// By the time this method gets called, DataStore will already have invoked
@@ -109,23 +107,44 @@ final public class AWSDataStorePlugin: DataStoreCategoryPlugin {
         ModelListDecoderRegistry.registerDecoder(DataStoreListDecoder.self)
     }
 
-    func reinitStorageEngineIfNeeded(completion: @escaping DataStoreCallback<Void> = {_ in}) {
-        storageEngineInitSemaphore.wait()
+    /// Initializes the underlying storage engine
+    /// - Returns: success if the engine is successfully initialized or
+    ///            a failure with a DataStoreError
+    func initStorageEngine() -> DataStoreResult<Void> {
+        storageEngineInitQueue.sync {
+            if storageEngine != nil {
+                return .successfulVoid
+            }
+            var result: DataStoreResult<Void>
+            do {
+                if #available(iOS 13.0, *) {
+                    if self.dataStorePublisher == nil {
+                        self.dataStorePublisher = DataStorePublisher()
+                    }
+                }
+                try resolveStorageEngine(dataStoreConfiguration: dataStoreConfiguration)
+                try storageEngine.setUp(modelSchemas: ModelRegistry.modelSchemas)
+                try storageEngine.applyModelMigrations(modelSchemas: ModelRegistry.modelSchemas)
+                result = .successfulVoid
+            } catch {
+                result = .failure(causedBy: error)
+                log.error(error: error)
+            }
+            return result
+        }
+    }
+
+    /// Initializes the underlying storage engine and starts the syncing process
+    /// - Parameter completion: completion handler called with a success if the sync process started
+    ///                         or with a DataStoreError in case of failure
+    func initStorageEngineAndStartSync(completion: @escaping DataStoreCallback<Void> = { _ in }) {
         if storageEngine != nil {
-            storageEngineInitSemaphore.signal()
             completion(.successfulVoid)
             return
         }
-        do {
-            if #available(iOS 13.0, *) {
-                if self.dataStorePublisher == nil {
-                    self.dataStorePublisher = DataStorePublisher()
-                }
-            }
-            try resolveStorageEngine(dataStoreConfiguration: dataStoreConfiguration)
-            try storageEngine.setUp(modelSchemas: ModelRegistry.modelSchemas)
-            try storageEngine.applyModelMigrations(modelSchemas: ModelRegistry.modelSchemas)
-            storageEngineInitSemaphore.signal()
+
+        switch initStorageEngine() {
+        case .success:
             storageEngine.startSync { result in
 
                 self.operationQueue.operations.forEach { operation in
@@ -135,10 +154,8 @@ final public class AWSDataStorePlugin: DataStoreCategoryPlugin {
                 }
                 completion(result)
             }
-        } catch {
-            storageEngineInitSemaphore.signal()
+        case .failure(let error):
             completion(.failure(causedBy: error))
-            log.error(error: error)
         }
     }
 
diff --git a/AmplifyPlugins/DataStore/AWSDataStoreCategoryPluginTests/Core/AWSAPICategoryPluginTests.swift b/AmplifyPlugins/DataStore/AWSDataStoreCategoryPluginTests/Core/AWSAPICategoryPluginTests.swift
@@ -460,4 +460,33 @@ class AWSAPICategoryPluginTests: XCTestCase {
             XCTFail("DataStore configuration should not fail with nil configuration. \(error)")
         }
     }
+
+    /// - Given: Datastore plugin is NOT initialized
+    /// - When:
+    ///     - plugin.clear() is called
+    /// - Then: StorageEngine.clear is called
+    func testClearStorageWhenEngineIsNotStarted() {
+        let storageEngine = MockStorageEngineBehavior()
+        let pluginClearExpectation = expectation(description: "DataStore plugin .clear should called")
+        let storageClearExpectation = expectation(description: "StorageEngine .clear should be called")
+        storageEngine.responders[.clear] = ClearResponder { _ in
+            storageClearExpectation.fulfill()
+        }
+        let storageEngineBehaviorFactory: StorageEngineBehaviorFactory = {_, _, _, _, _, _  throws in
+            return storageEngine
+        }
+        let dataStorePublisher = DataStorePublisher()
+        let plugin = AWSDataStorePlugin(modelRegistration: TestModelRegistration(),
+                                        storageEngineBehaviorFactory: storageEngineBehaviorFactory,
+                                        dataStorePublisher: dataStorePublisher,
+                                        validAPIPluginKey: "MockAPICategoryPlugin",
+                                        validAuthPluginKey: "MockAuthCategoryPlugin")
+
+        plugin.clear {
+            if case .success = $0 {
+                pluginClearExpectation.fulfill()
+            }
+        }
+        waitForExpectations(timeout: 1.0)
+    }
 }
