Implement app-lifecycle groundwork (#2800)

* Create the lifecycle class

* Add running in background properties and implement archive paths for the stateful classes.

* Move -stopTimer into the upload coordinator

* Add test for encoding and decoding the storage singleton.

* Add a test transport target.

* Style

* Temporarily commenting out sending lifecycle events.

* More style.

* Demonstrate that I know what year I made this file

Author: mikehaney24

GoogleDataTransport/GoogleDataTransport/Classes/GDTLifecycle.m

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2019 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import "GDTLifecycle.h"
+
+#import <GoogleDataTransport/GDTEvent.h>
+
+#import "GDTRegistrar_Private.h"
+#import "GDTStorage_Private.h"
+#import "GDTTransformer_Private.h"
+#import "GDTUploadCoordinator_Private.h"
+
+@implementation GDTLifecycle
+
++ (void)load {
+  [self sharedInstance];
+}
+
+/** Creates/returns the singleton instance of this class.
+ *
+ * @return The singleton instance of this class.
+ */
++ (instancetype)sharedInstance {
+  static GDTLifecycle *sharedInstance;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    sharedInstance = [[GDTLifecycle alloc] init];
+  });
+  return sharedInstance;
+}
+
+- (instancetype)init {
+  self = [super init];
+  if (self) {
+    NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
+    [notificationCenter addObserver:self
+                           selector:@selector(applicationDidEnterBackground:)
+                               name:UIApplicationDidEnterBackgroundNotification
+                             object:nil];
+    [notificationCenter addObserver:self
+                           selector:@selector(applicationWillEnterForeground:)
+                               name:UIApplicationWillEnterForegroundNotification
+                             object:nil];
+
+    NSString *name = UIApplicationWillTerminateNotification;
+    [notificationCenter addObserver:self
+                           selector:@selector(applicationWillTerminate:)
+                               name:name
+                             object:nil];
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
+- (void)applicationDidEnterBackground:(NSNotification *)notification {
+  //  UIApplication *application = [UIApplication sharedApplication];
+  //  [[GDTTransformer sharedInstance] appWillBackground:application];
+  //  [[GDTStorage sharedInstance] appWillBackground:application];
+  //  [[GDTUploadCoordinator sharedInstance] appWillBackground:application];
+  //  [[GDTRegistrar sharedInstance] appWillBackground:application];
+}
+
+- (void)applicationWillEnterForeground:(NSNotification *)notification {
+  //  UIApplication *application = [UIApplication sharedApplication];
+  //  [[GDTTransformer sharedInstance] appWillForeground:application];
+  //  [[GDTStorage sharedInstance] appWillForeground:application];
+  //  [[GDTUploadCoordinator sharedInstance] appWillForeground:application];
+  //  [[GDTRegistrar sharedInstance] appWillForeground:application];
+}
+
+- (void)applicationWillTerminate:(NSNotification *)notification {
+  //  UIApplication *application = [UIApplication sharedApplication];
+  //  [[GDTTransformer sharedInstance] appWillTerminate:application];
+  //  [[GDTStorage sharedInstance] appWillTerminate:application];
+  //  [[GDTUploadCoordinator sharedInstance] appWillTerminate:application];
+  //  [[GDTRegistrar sharedInstance] appWillTerminate:application];
+}
+
+@end

GoogleDataTransport/GoogleDataTransport/Classes/GDTStorage.m

@@ -43,6 +43,15 @@
 
 @implementation GDTStorage
 
++ (NSString *)archivePath {
+  static NSString *archivePath;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    archivePath = [GDTStoragePath() stringByAppendingPathComponent:@"GDTStorageArchive"];
+  });
+  return archivePath;
+}
+
 + (instancetype)sharedInstance {
   static GDTStorage *sharedStorage;
   static dispatch_once_t onceToken;

GoogleDataTransport/GoogleDataTransport/Classes/GDTUploadCoordinator.m

@@ -36,6 +36,18 @@ + (instancetype)sharedInstance {
   return sharedUploader;
 }
 
++ (NSString *)archivePath {
+  static NSString *archivePath;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    NSString *cachePath =
+        NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];
+    NSString *storagePath = [NSString stringWithFormat:@"%@/google-sdks-events", cachePath];
+    archivePath = [storagePath stringByAppendingPathComponent:@"GDTUploadCoordinator"];
+  });
+  return archivePath;
+}
+
 - (instancetype)init {
   self = [super init];
   if (self) {
@@ -149,6 +161,13 @@ - (void)startTimer {
   });
 }
 
+/** Stops the currently running timer. */
+- (void)stopTimer {
+  if (_timer) {
+    dispatch_source_cancel(_timer);
+  }
+}
+
 /** Checks the next upload time for each target and makes a determination on whether to upload
  * events for that target or not. If so, queries the prioritizers
  */

GoogleDataTransport/GoogleDataTransport/Classes/Private/GDTStorage_Private.h

@@ -35,6 +35,17 @@ NS_ASSUME_NONNULL_BEGIN
 /** The upload coordinator instance to use. */
 @property(nonatomic) GDTUploadCoordinator *uploader;
 
+/** If YES, every call to -storeLog results in background task and serializes the singleton to disk.
+ */
+@property(nonatomic, readonly) BOOL runningInBackground;
+
+/** Returns the path to the keyed archive of the singleton. This is where the singleton is saved
+ * to disk during certain app lifecycle events.
+ *
+ * @return File path to serialized singleton.
+ */
++ (NSString *)archivePath;
+
 @end
 
 NS_ASSUME_NONNULL_END

GoogleDataTransport/GoogleDataTransport/Classes/Private/GDTTransformer_Private.h

@@ -28,6 +28,9 @@ NS_ASSUME_NONNULL_BEGIN
 /** The storage instance used to store events. Should only be used to inject a testing fake. */
 @property(nonatomic) GDTStorage *storageInstance;
 
+/** If YES, every call to -transformEvent will result in a background task. */
+@property(nonatomic, readonly) BOOL runningInBackground;
+
 @end
 
 NS_ASSUME_NONNULL_END

GoogleDataTransport/GoogleDataTransport/Classes/Private/GDTUploadCoordinator_Private.h

@@ -58,9 +58,22 @@ NS_ASSUME_NONNULL_BEGIN
 /** The registrar object the coordinator will use. Generally used for testing. */
 @property(nonatomic) GDTRegistrar *registrar;
 
+/** If YES, completion and other operations will result in serializing the singleton to disk. */
+@property(nonatomic, readonly) BOOL runningInBackground;
+
+/** Returns the path to the keyed archive of the singleton. This is where the singleton is saved
+ * to disk during certain app lifecycle events.
+ *
+ * @return File path to serialized singleton.
+ */
++ (NSString *)archivePath;
+
 /** Starts the upload timer. */
 - (void)startTimer;
 
+/** Stops the upload timer from running. */
+- (void)stopTimer;
+
 @end
 
 NS_ASSUME_NONNULL_END

GoogleDataTransport/GoogleDataTransport/Classes/Public/GDTLifecycle.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2019 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import <Foundation/Foundation.h>
+#import <UIKit/UIKit.h>
+
+@class GDTEvent;
+
+NS_ASSUME_NONNULL_BEGIN
+
+/** A protocol defining the lifecycle events objects in the library must respond to immediately. */
+@protocol GDTLifecycleProtocol <NSObject>
+
+@required
+
+/** Indicates an imminent app termination in the rare occurrence when -applicationWillTerminate: has
+ * been called.
+ *
+ * @param app The UIApplication instance.
+ */
+- (void)appWillTerminate:(UIApplication *)app;
+
+/** Indicates that the app is moving to background and eventual suspension.
+ *
+ * @param app The UIApplication instance.
+ */
+- (void)appWillBackground:(UIApplication *)app;
+
+/** Indicates that the app is resuming operation.
+ *
+ * @param app The UIApplication instance.
+ */
+- (void)appWillForeground:(UIApplication *)app;
+
+@end
+
+/** This class manages the library's response to app lifecycle events.
+ *
+ * When backgrounding, the library doesn't stop processing events, it's just that several background
+ * tasks will end up being created for every event that's sent, and the stateful objects of the
+ * library (GDTStorage and GDTUploadCoordinator singletons) will deserialize themselves from and to
+ * disk before and after every operation, respectively.
+ */
+@interface GDTLifecycle : NSObject <UIApplicationDelegate>
+
+@end
+
+NS_ASSUME_NONNULL_END

GoogleDataTransport/GoogleDataTransport/Classes/Public/GDTTargets.h

@@ -21,6 +21,9 @@
  */
 typedef NS_ENUM(NSInteger, GDTTarget) {
 
+  /** A target only used in testing. */
+  kGDTTargetTest = 999,
+
   /** The CCT target. */
   kGDTTargetCCT = 1000,
 };

GoogleDataTransport/Tests/Common/Categories/GDTUploadCoordinator+Testing.h

@@ -15,6 +15,7 @@
  */
 
 #import "GDTUploadCoordinator.h"
+#import "GDTUploadCoordinator_Private.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -23,9 +24,6 @@ NS_ASSUME_NONNULL_BEGIN
 /** Resets the properties of the singleton, but does not reallocate a new singleton. */
 - (void)reset;
 
-/** Stops the upload timer from running. */
-- (void)stopTimer;
-
 /** The time interval, in nanoseconds, that the time should be called on. */
 @property(nonatomic, readwrite) uint64_t timerInterval;
 

GoogleDataTransport/Tests/Common/Categories/GDTUploadCoordinator+Testing.m

@@ -32,10 +32,6 @@ - (void)reset {
   self.registrar = [GDTRegistrar sharedInstance];
 }
 
-- (void)stopTimer {
-  dispatch_source_cancel(self.timer);
-}
-
 - (void)setTimerInterval:(uint64_t)timerInterval {
   [self setValue:@(timerInterval) forKey:@"_timerInterval"];
   dispatch_source_set_timer(self.timer, DISPATCH_TIME_NOW, timerInterval, self.timerLeeway);

GoogleDataTransport/Tests/Unit/GDTStorageTest.m

@@ -264,7 +264,25 @@ - (void)testNSSecureCoding {
     XCTAssertNil([[GDTStorage sharedInstance].storedEvents lastObject]);
   });
 
-  // TODO(mikehaney24): Ensure that the object created by alloc is discarded?
+  GDTStorage *unarchivedStorage = [NSKeyedUnarchiver unarchiveObjectWithData:storageData];
+  XCTAssertNotNil([unarchivedStorage.storedEvents lastObject]);
+}
+
+/** Tests encoding and decoding the storage singleton when calling -sharedInstance. */
+- (void)testNSSecureCodingWithSharedInstance {
+  GDTEvent *event = [[GDTEvent alloc] initWithMappingID:@"404" target:target];
+  event.dataObjectTransportBytes = [@"testString" dataUsingEncoding:NSUTF8StringEncoding];
+  XCTAssertNoThrow([[GDTStorage sharedInstance] storeEvent:event]);
+  event = nil;
+  NSData *storageData = [NSKeyedArchiver archivedDataWithRootObject:[GDTStorage sharedInstance]];
+  dispatch_sync([GDTStorage sharedInstance].storageQueue, ^{
+    XCTAssertNotNil([[GDTStorage sharedInstance].storedEvents lastObject]);
+  });
+  [[GDTStorage sharedInstance] removeEvents:[GDTStorage sharedInstance].storedEvents.set];
+  dispatch_sync([GDTStorage sharedInstance].storageQueue, ^{
+    XCTAssertNil([[GDTStorage sharedInstance].storedEvents lastObject]);
+  });
+
   GDTStorage *unarchivedStorage = [NSKeyedUnarchiver unarchiveObjectWithData:storageData];
   XCTAssertNotNil([unarchivedStorage.storedEvents lastObject]);
 }