Don't die when flipper isn't initialized and a plugin is used

Summary: This diff makes sure that the app doesn't die, or dies in a meaningful way if things are misconfigured.

Reviewed By: passy

Differential Revision: D19468273

fbshipit-source-id: 2471c263391906113446af57d795d1199eb1730e

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

@@ -7,6 +7,7 @@
 
 package com.facebook.flipper.reactnative;
 
+import com.facebook.react.bridge.Callback;
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.react.bridge.ReactMethod;
@@ -40,8 +41,9 @@ public class FlipperModule extends ReactContextBaseJavaModule {
   }
 
   @ReactMethod
-  public void registerPlugin(final String pluginId, final Boolean inBackground) {
-    this.manager.registerPlugin(this, pluginId, inBackground);
+  public void registerPlugin(
+      final String pluginId, final Boolean inBackground, final Callback statusCallback) {
+    this.manager.registerPlugin(this, pluginId, inBackground, statusCallback);
   }
 
   @ReactMethod

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

@@ -12,6 +12,7 @@ import com.facebook.flipper.core.FlipperArray;
 import com.facebook.flipper.core.FlipperClient;
 import com.facebook.flipper.core.FlipperObject;
 import com.facebook.flipper.core.FlipperResponder;
+import com.facebook.react.bridge.Callback;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicLong;
@@ -51,7 +52,15 @@ public class FlipperReactNativeJavaScriptPluginManager {
   }
 
   public void registerPlugin(
-      FlipperModule module, final String pluginId, final Boolean inBackground) {
+      FlipperModule module,
+      final String pluginId,
+      final Boolean inBackground,
+      final Callback statusCallback) {
+    if (this.flipperClient == null) {
+      // Flipper is not available in this build
+      statusCallback.invoke("noflipper");
+      return;
+    }
     FlipperReactNativeJavaScriptPlugin existing = getPlugin(pluginId);
     if (existing != null) {
       // Make sure events are emitted on the right application context
@@ -60,6 +69,7 @@ public class FlipperReactNativeJavaScriptPluginManager {
       if (existing.isConnected()) {
         existing.fireOnConnect();
       }
+      statusCallback.invoke("ok");
       return;
     }
     // we always create a new plugin class on the fly,
@@ -69,6 +79,7 @@ public class FlipperReactNativeJavaScriptPluginManager {
           // inner class with no new members
         };
     this.flipperClient.addPlugin(plugin);
+    statusCallback.invoke("ok");
   }
 
   public void send(String pluginId, String method, String data) {

react-native/react-native-flipper/index.d.ts

@@ -64,6 +64,7 @@ declare module 'Flipper' {
   export function registerPlugin(
     pluginId: string,
     runInBackground: boolean,
+    statusCallback: (status: 'noflipper' | 'ok') => void,
   ): void;
   export function send(pluginId: string, method: string, data: string): void;
   export function reportErrorWithMetadata(

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

@@ -125,6 +125,10 @@ function startEventListeners() {
 
 // $FlowFixMe
 export function addPlugin(plugin) {
+  if (!Flipper) {
+    printNoFlipperWarning();
+    return;
+  }
   if (!plugin || typeof plugin !== 'object') {
     throw new Error('Expected plugin, got ' + plugin);
   }
@@ -141,7 +145,22 @@ export function addPlugin(plugin) {
   plugin._connection = new Connection(id);
   plugins[id] = plugin;
 
-  Flipper.registerPlugin(id, runInBackground);
+  Flipper.registerPlugin(id, runInBackground, status => {
+    if (status === 'noflipper') {
+      printNoFlipperWarning();
+    }
+  });
 }
 
-startEventListeners();
+function printNoFlipperWarning() {
+  // $FlowFixMe
+  if (typeof __DEV__ !== 'undefined' && __DEV__) {
+    console.warn(
+      'The native module for Flipper seems unavailable. Make sure `initializeFlipper(this, getReactNativeHost().getReactInstanceManager()` is called in MainApplication.java:onCreate, and that `react-native-flipper` is installed as yarn dependency',
+    );
+  }
+}
+
+if (Flipper) {
+  startEventListeners();
+}