Make React reloads and testing more reliable

Changed where we wait on the previous JS thread, which ultimately makes it more reliable and no longer leak memory on reloads.

Resolves #397

react-native/ios/RealmReact/RealmReact.mm

@@ -79,8 +79,6 @@ extern "C" JSGlobalContextRef RealmReactGetJSGlobalContextForExecutor(id executo
 
 @implementation RealmReact {
     NSMutableDictionary *_eventHandlers;
-    __weak NSThread *_currentJSThread;
-    __weak NSRunLoop *_currentJSRunLoop;
 
 #if DEBUG
     GCDWebServer *_webServer;
@@ -261,17 +259,6 @@ RCT_REMAP_METHOD(emit, emitEvent:(NSString *)eventName withObject:(id)object) {
     // shutdown rpc if in chrome debug mode
     [self shutdownRPC];
 #endif
-
-    // block until JS thread exits
-    NSRunLoop *runLoop = _currentJSRunLoop;
-    if (runLoop) {
-        CFRunLoopStop([runLoop getCFRunLoop]);
-        while (_currentJSThread && !_currentJSThread.finished) {
-            [NSThread sleepForTimeInterval:0.01];
-        }
-    }
-
-    realm::_impl::RealmCoordinator::clear_all_caches();
 }
 
 - (void)dealloc {
@@ -296,15 +283,24 @@ RCT_REMAP_METHOD(emit, emitEvent:(NSString *)eventName withObject:(id)object) {
     }
     else {
         __weak __typeof__(self) weakSelf = self;
+        __weak __typeof__(executor) weakExecutor = executor;
 
         [executor executeBlockOnJavaScriptQueue:^{
             __typeof__(self) self = weakSelf;
-            if (!self) {
+            __typeof__(executor) executor = weakExecutor;
+            if (!self || !executor) {
                 return;
             }
 
-            self->_currentJSThread = [NSThread currentThread];
+            // Make sure the previous JS thread is completely finished before continuing.
-            self->_currentJSRunLoop = [NSRunLoop currentRunLoop];
+            static __weak NSThread *s_currentJSThread;
+            while (s_currentJSThread && !s_currentJSThread.finished) {
+                [NSThread sleepForTimeInterval:0.1];
+            }
+            s_currentJSThread = [NSThread currentThread];
+
+            // Close all cached Realms from the previous JS thread.
+            realm::_impl::RealmCoordinator::clear_all_caches();
 
             JSGlobalContextRef ctx = RealmReactGetJSGlobalContextForExecutor(executor, true);
             RJSInitializeInContext(ctx);

tests/react-test-app/ios/ReactTests/RealmReactTests.m

@@ -78,23 +78,26 @@ extern NSMutableArray *RCTGetModuleClasses(void);
         return nil;
     }
 
-    RCTBridge *bridge = [RCTBridge currentBridge];
+    @autoreleasepool {
-    if (!bridge.valid) {
+        RCTBridge *bridge = [RCTBridge currentBridge];
-        [self waitForNotification:RCTJavaScriptDidLoadNotification];
+
-        bridge = [RCTBridge currentBridge];
+        if (!bridge.valid) {
+            [self waitForNotification:RCTJavaScriptDidLoadNotification];
+            bridge = [RCTBridge currentBridge];
+        }
+
+        if (bridge.executorClass != executorClass) {
+            bridge.executorClass = executorClass;
+
+            RCTBridge *parentBridge = [bridge valueForKey:@"parentBridge"];
+            [parentBridge invalidate];
+            [parentBridge setUp];
+
+            return [self currentBridge];
+        }
+
+        return bridge;
     }
-
-    if (bridge.executorClass != executorClass) {
-        bridge.executorClass = executorClass;
-
-        RCTBridge *parentBridge = [bridge valueForKey:@"parentBridge"];
-        [parentBridge invalidate];
-        [parentBridge setUp];
-
-        return [self currentBridge];
-    }
-
-    return bridge;
 }
 
 + (id<RCTJavaScriptExecutor>)currentExecutor {
@@ -102,37 +105,39 @@ extern NSMutableArray *RCTGetModuleClasses(void);
 }
 
 + (XCTestSuite *)defaultTestSuite {
-    XCTestSuite *suite = [super defaultTestSuite];
+    @autoreleasepool {
-    id<RCTJavaScriptExecutor> executor = [self currentExecutor];
+        XCTestSuite *suite = [super defaultTestSuite];
+        id<RCTJavaScriptExecutor> executor = [self currentExecutor];
+
+        // The executor may be nil if the executorClass was not found (i.e. release build).
+        if (!executor) {
+            return suite;
+        }
+
+        // FIXME: Remove this nonsense once the crashes go away when a test fails!
+        JSGlobalContextRef ctx = RealmReactGetJSGlobalContextForExecutor(executor, false);
+        if (ctx) {
+            JSGlobalContextSetIncludesNativeCallStackWhenReportingExceptions(ctx, false);
+        }
+
+        NSDictionary *testCaseNames = [self waitForEvent:@"realm-test-names"];
+        NSAssert(testCaseNames.count, @"No test names were provided by the JS");
+
+        NSString *nameSuffix = [self classNameSuffix];
+        if (nameSuffix.length) {
+            NSMutableDictionary *renamedTestCaseNames = [[NSMutableDictionary alloc] init];
+            for (NSString *name in testCaseNames) {
+                renamedTestCaseNames[[name stringByAppendingString:nameSuffix]] = testCaseNames[name];
+            }
+            testCaseNames = renamedTestCaseNames;
+        }
+
+        for (XCTestSuite *testSuite in [self testSuitesFromDictionary:testCaseNames]) {
+            [suite addTest:testSuite];
+        }
 
-    // The executor may be nil if the executorClass was not found (i.e. release build).
-    if (!executor) {
         return suite;
     }
-
-    // FIXME: Remove this nonsense once the crashes go away when a test fails!
-    JSGlobalContextRef ctx = RealmReactGetJSGlobalContextForExecutor(executor, false);
-    if (ctx) {
-        JSGlobalContextSetIncludesNativeCallStackWhenReportingExceptions(ctx, false);
-    }
-
-    NSDictionary *testCaseNames = [self waitForEvent:@"realm-test-names"];
-    NSAssert(testCaseNames.count, @"No test names were provided by the JS");
-
-    NSString *nameSuffix = [self classNameSuffix];
-    if (nameSuffix.length) {
-        NSMutableDictionary *renamedTestCaseNames = [[NSMutableDictionary alloc] init];
-        for (NSString *name in testCaseNames) {
-            renamedTestCaseNames[[name stringByAppendingString:nameSuffix]] = testCaseNames[name];
-        }
-        testCaseNames = renamedTestCaseNames;
-    }
-
-    for (XCTestSuite *testSuite in [self testSuitesFromDictionary:testCaseNames]) {
-        [suite addTest:testSuite];
-    }
-
-    return suite;
 }
 
 + (NSNotification *)waitForNotification:(NSString *)notificationName {