Made flipper plugins a little more robust

Summary: Added some assertions and string casts to make plugins a bit more robust

Reviewed By: passy

Differential Revision: D19427909

fbshipit-source-id: 46a3138805db865b538f745fae25ce1897e35736

react-native/react-native-flipper/android/src/main/java/com/facebook/flipper/reactnative/FlipperReactNativeJavaScriptPluginManager.java

@@ -72,10 +72,14 @@ public class FlipperReactNativeJavaScriptPluginManager {
   }
 
   public void send(String pluginId, String method, String data) {
+    FlipperReactNativeJavaScriptPlugin plugin = getPlugin(pluginId);
+    if (data == null) {
+      plugin.getConnection().send(method, (FlipperObject) null);
+      return;
+    }
     // Optimization: throwing raw strings around to the desktop would probably avoid some double
     // parsing...
     Object parsedData = parseJSON(data);
-    FlipperReactNativeJavaScriptPlugin plugin = getPlugin(pluginId);
     if (parsedData instanceof FlipperArray) {
       plugin.getConnection().send(method, (FlipperArray) parsedData);
     } else {
@@ -134,14 +138,17 @@ public class FlipperReactNativeJavaScriptPluginManager {
   }
 
   private static Object /* FlipperArray | FlipperObject */ parseJSON(String json) {
+    if (json == null) {
+      return null;
+    }
     // returns either a FlipperObject or Flipper array, pending the data
     try {
       JSONTokener tokener = new JSONTokener(json);
-      if (tokener.nextClean() == '[') {
+      char firstChar = tokener.nextClean();
       tokener.back();
+      if (firstChar == '[') {
         return new FlipperArray(new JSONArray(tokener));
       } else {
-        tokener.back();
         return new FlipperObject(new JSONObject(tokener));
       }
     } catch (JSONException e) {

react-native/react-native-flipper/android/src/main/java/com/facebook/flipper/reactnative/FlipperReactNativeJavaScriptReceiver.java

@@ -32,12 +32,14 @@ public class FlipperReactNativeJavaScriptReceiver implements FlipperReceiver {
 
   @Override
   public void onReceive(FlipperObject params, FlipperResponder responder) throws Exception {
-    String responderId = manager.createResponderId(responder);
     WritableMap eventData = Arguments.createMap();
     eventData.putString("plugin", plugin);
     eventData.putString("method", method);
     eventData.putString("params", params.toJsonString());
+    if (responder != null) {
+      String responderId = manager.createResponderId(responder);
       eventData.putString("responderId", responderId);
+    }
     module.sendJSEvent("react-native-flipper-receive-event", eventData);
   }
 }

react-native/react-native-flipper/index.js

@@ -17,6 +17,20 @@ export default Flipper;
 const listeners = {}; // plugin#method -> callback
 const plugins = {}; // plugin -> Plugin
 
+function assertSerializable(data) {
+  if (
+    data === undefined ||
+    Array.isArray(data) ||
+    (data && typeof data === 'object')
+  ) {
+    return true;
+  }
+  throw new Error(
+    'Flipper: Expected serializable (undefined, an array or an object). Got: ' +
+      data,
+  );
+}
+
 class Connection {
   connected;
   pluginId;
@@ -30,15 +44,20 @@ class Connection {
     if (!this.connected) {
       throw new Error('Cannot send data, not connected');
     }
+    assertSerializable(data);
     Flipper.send(this.pluginId, method, JSON.stringify(data));
   }
 
   reportErrorWithMetadata(reason, stackTrace) {
-    Flipper.reportErrorWithMetadata(this.pluginId, reason, stackTrace);
+    Flipper.reportErrorWithMetadata(
+      this.pluginId,
+      '' + reason,
+      '' + stackTrace,
+    );
   }
 
   reportError(error) {
-    Flipper.reportError(this.pluginId, error);
+    Flipper.reportError(this.pluginId, '' + error);
   }
 
   receive(method, listener) {
@@ -59,6 +78,7 @@ class Responder {
   }
 
   success(response) {
+    assertSerializable(response);
     Flipper.respondSuccess(
       this.responderId,
       response == null ? null : JSON.stringify(response),
@@ -66,15 +86,13 @@ class Responder {
   }
 
   error(response) {
+    assertSerializable(response);
     Flipper.respondError(this.responderId, JSON.stringify(response));
   }
 }
 
 function startEventListeners() {
   const emitter = new NativeEventEmitter(Flipper);
-  emitter.removeAllListeners('react-native-flipper-plugin-connect');
-  emitter.removeAllListeners('react-native-flipper-plugin-disconnect');
-  emitter.removeAllListeners('react-native-flipper-receive-event');
 
   emitter.addListener('react-native-flipper-plugin-connect', event => {
     const {plugin} = event;
@@ -98,7 +116,8 @@ function startEventListeners() {
     const {plugin, method, params, responderId} = event;
     const key = plugin + '#' + method;
     if (listeners[key]) {
-      const responder = new Responder(responderId);
+      const responder =
+        responderId != null ? new Responder(responderId) : undefined;
       listeners[key](JSON.parse(params), responder);
     }
   });