Fix concurrency bug in the test framework that caused Firestore's transaction_extra_test.cc to hang (#426)

Author: dconeybe

firestore/integration_test_internal/src/transaction_extra_test.cc

@@ -30,8 +30,6 @@ using TransactionExtraTest = FirestoreIntegrationTest;
 
 TEST_F(TransactionExtraTest,
        TestRetriesWhenDocumentThatWasReadWithoutBeingWrittenChanges) {
-  SKIP_TEST_ON_IOS;  // TODO(b/183294303): Fix this test on iOS.
-
   DocumentReference doc1 = TestFirestore()->Collection("counter").Document();
   DocumentReference doc2 = TestFirestore()->Collection("counter").Document();
   WriteDocument(doc1, MapFieldValue{{"count", FieldValue::Integer(15)}});
@@ -71,8 +69,6 @@ TEST_F(TransactionExtraTest,
 }
 
 TEST_F(TransactionExtraTest, TestReadingADocTwiceWithDifferentVersions) {
-  SKIP_TEST_ON_IOS;  // TODO(b/183294303): Fix this test on iOS.
-
   int counter = 0;
   DocumentReference doc = TestFirestore()->Collection("counters").Document();
   WriteDocument(doc, MapFieldValue{{"count", FieldValue::Double(15.0)}});

testing/sample_framework/src/ios/ios_app_framework.mm

@@ -47,10 +47,19 @@ @interface FTAViewController : UIViewController
 // Test Loop on iOS doesn't provide the app under test a path to save logs to, so set it here.
 #define GAMELOOP_DEFAULT_LOG_FILE "Results1.json"
 
-static int g_exit_status = 0;
-static bool g_shutdown = false;
-static NSCondition *g_shutdown_complete;
-static NSCondition *g_shutdown_signal;
+enum class RunningState {
+  kRunning,
+  kShuttingDown,
+  kShutDown
+};
+
+// Note: g_running_state and g_exit_status must only be accessed while holding the lock from
+// g_running_state_condition; also, any changes to these values should be followed up with a
+// call to [g_running_state_condition broadcast].
+static NSCondition *g_running_state_condition;
+static RunningState g_running_state = RunningState::kRunning;
+static int g_exit_status = -1;
+
 static UITextView *g_text_view;
 static UIView *g_parent_view;
 static FTAViewController *g_view_controller;
@@ -70,9 +79,14 @@ - (void)viewDidLoad {
     char *argv[1];
     argv[0] = new char[strlen(TESTAPP_NAME) + 1];
     strcpy(argv[0], TESTAPP_NAME);  // NOLINT
-    [g_shutdown_signal lock];
-    g_exit_status = common_main(1, argv);
-    [g_shutdown_complete signal];
+    int common_main_result = common_main(1, argv);
+
+    [g_running_state_condition lock];
+    g_exit_status = common_main_result;
+    g_running_state = RunningState::kShutDown;
+    [g_running_state_condition broadcast];
+    [g_running_state_condition unlock];
+
     delete[] argv[0];
     argv[0] = nullptr;
     [NSThread sleepForTimeInterval:kGameLoopSecondsToPauseBeforeQuitting];
@@ -87,9 +101,17 @@ - (void)viewDidLoad {
 namespace app_framework {
 
 bool ProcessEvents(int msec) {
-  [g_shutdown_signal
-      waitUntilDate:[NSDate dateWithTimeIntervalSinceNow:static_cast<float>(msec) / 1000.0f]];
-  return g_shutdown;
+  NSDate* endDate = [NSDate dateWithTimeIntervalSinceNow:static_cast<float>(msec) / 1000.0f];
+  [g_running_state_condition lock];
+
+  if (g_running_state == RunningState::kRunning) {
+    [g_running_state_condition waitUntilDate:endDate];
+  }
+
+  RunningState running_status = g_running_state;
+  [g_running_state_condition unlock];
+
+  return running_status != RunningState::kRunning;
 }
 
 std::string PathForResource() {
@@ -297,8 +319,13 @@ int main(int argc, char* argv[]) {
   close(filedes[0]);
   close(filedes[1]);
 
+  int exit_status = -1;
+  [g_running_state_condition lock];
+  exit_status = g_exit_status;
+  [g_running_state_condition unlock];
+
   NSLog(@"Application Exit");
-  return g_exit_status;
+  return exit_status;
 }
 
 @implementation AppDelegate
@@ -317,9 +344,7 @@ - (BOOL)application:(UIApplication *)app
 
 - (BOOL)application:(UIApplication*)application
     didFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
-  g_shutdown_complete = [[NSCondition alloc] init];
-  g_shutdown_signal = [[NSCondition alloc] init];
-  [g_shutdown_complete lock];
+  g_running_state_condition = [[NSCondition alloc] init];
 
   self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
   g_view_controller = [[FTAViewController alloc] init];
@@ -339,8 +364,17 @@ - (BOOL)application:(UIApplication*)application
 }
 
 - (void)applicationWillTerminate:(UIApplication *)application {
-  g_shutdown = true;
-  [g_shutdown_signal signal];
-  [g_shutdown_complete wait];
+  [g_running_state_condition lock];
+
+  if (g_running_state == RunningState::kRunning) {
+    g_running_state = RunningState::kShuttingDown;
+    [g_running_state_condition broadcast];
+  }
+
+  while (g_running_state != RunningState::kShutDown) {
+    [g_running_state_condition wait];
+  }
+
+  [g_running_state_condition unlock];
 }
 @end