Delete stale Firestore instances after FIRApp is deleted. (#809)

Author: ryanwilson

Firestore/Example/Tests/API/FIRFirestoreTests.mm

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2018 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 <FirebaseCore/FIRAppInternal.h>
+#import <FirebaseCore/FIROptionsInternal.h>
+#import <FirebaseFirestore/FIRFirestore.h>
+
+#import <XCTest/XCTest.h>
+
+@interface FIRFirestoreTests : XCTestCase
+@end
+
+@implementation FIRFirestoreTests
+
+- (void)testDeleteApp {
+  // Create a FIRApp for testing.
+  NSString *appName = @"custom_app_name";
+  FIROptions *options =
+      [[FIROptions alloc] initWithGoogleAppID:@"1:123:ios:123ab" GCMSenderID:@"gcm_sender_id"];
+  options.projectID = @"project_id";
+  [FIRApp configureWithName:appName options:options];
+
+  // Ensure the app is set appropriately.
+  FIRApp *app = [FIRApp appNamed:appName];
+  FIRFirestore *firestore = [FIRFirestore firestoreForApp:app];
+  XCTAssertEqualObjects(firestore.app, app);
+
+  // Ensure that firestoreForApp returns the same instance.
+  XCTAssertEqualObjects(firestore, [FIRFirestore firestoreForApp:app]);
+
+  XCTestExpectation *defaultAppDeletedExpectation =
+      [self expectationWithDescription:
+                @"Deleting the default app should invalidate the default "
+                @"Firestore instance."];
+  [app deleteApp:^(BOOL success) {
+    // Recreate the FIRApp with the same name, fetch a new Firestore instance and make sure it's
+    // different than the other one.
+    [FIRApp configureWithName:appName options:options];
+    FIRApp *newApp = [FIRApp appNamed:appName];
+    FIRFirestore *newInstance = [FIRFirestore firestoreForApp:newApp];
+    XCTAssertNotEqualObjects(newInstance, firestore);
+
+    [defaultAppDeletedExpectation fulfill];
+  }];
+
+  [self waitForExpectations:@[ defaultAppDeletedExpectation ] timeout:2];
+}
+
+@end

Firestore/Source/API/FIRFirestore.mm

@@ -16,7 +16,7 @@
 
 #import "FIRFirestore.h"
 
-#import <FirebaseCore/FIRApp.h>
+#import <FirebaseCore/FIRAppInternal.h>
 #import <FirebaseCore/FIRLogger.h>
 #import <FirebaseCore/FIROptions.h>
 
@@ -80,6 +80,36 @@ @implementation FIRFirestore {
   return instances;
 }
 
++ (void)initialize {
+  NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
+  [center addObserverForName:kFIRAppDeleteNotification
+                      object:nil
+                       queue:nil
+                  usingBlock:^(NSNotification *_Nonnull note) {
+                    NSString *appName = note.userInfo[kFIRAppNameKey];
+                    if (appName == nil) return;
+
+                    NSMutableDictionary *instances = [self instances];
+                    @synchronized(instances) {
+                      // Since the key for instances isn't just the app name, iterate over all the
+                      // keys to get the one(s) we have to delete. There could be multiple in case
+                      // the user calls firestoreForApp:database:.
+                      NSMutableArray *keysToDelete = [[NSMutableArray alloc] init];
+                      NSString *keyPrefix = [NSString stringWithFormat:@"%@|", appName];
+                      for (NSString *key in instances.allKeys) {
+                        if ([key hasPrefix:keyPrefix]) {
+                          [keysToDelete addObject:key];
+                        }
+                      }
+
+                      // Loop through the keys found and delete them from the stored instances.
+                      for (NSString *key in keysToDelete) {
+                        [instances removeObjectForKey:key];
+                      }
+                    }
+                  }];
+}
+
 + (instancetype)firestore {
   FIRApp *app = [FIRApp defaultApp];
   if (!app) {
@@ -109,6 +139,9 @@ + (instancetype)firestoreForApp:(FIRApp *)app database:(NSString *)database {
          "database",
         util::WrapNSStringNoCopy(DatabaseId::kDefaultDatabaseId));
   }
+
+  // Note: If the key format changes, please change the code that detects FIRApps being deleted
+  // contained in +initialize. It checks for the app's name followed by a | character.
   NSString *key = [NSString stringWithFormat:@"%@|%@", app.name, database];
 
   NSMutableDictionary<NSString *, FIRFirestore *> *instances = self.instances;