Adding support to cancel a headless task

Libraries/ReactNative/AppRegistry.js

@@ -21,6 +21,9 @@ const renderApplication = require('renderApplication');
 
 type Task = (taskData: any) => Promise<void>;
 type TaskProvider = () => Task;
+type TaskCanceller = () => void;
+type TaskCancelProvider = () => TaskCanceller;
+
 export type ComponentProvider = () => React$ComponentType<any>;
 export type ComponentProviderInstrumentationHook = (
  component: ComponentProvider,
@@ -47,7 +50,8 @@ export type WrapperComponentProvider = any => React$ComponentType<*>;
 const runnables: Runnables = {};
 let runCount = 1;
 const sections: Runnables = {};
-const tasks: Map<string, TaskProvider> = new Map();
+const taskProviders: Map<string, TaskProvider> = new Map();
+const taskCancelProviders: Map<string, TaskCancelProvider> = new Map();
 let componentProviderInstrumentationHook: ComponentProviderInstrumentationHook = (
  component: ComponentProvider,
 ) => component();
@@ -209,13 +213,23 @@ const AppRegistry = {
  *
  * See http://facebook.github.io/react-native/docs/appregistry.html#registerheadlesstask
  */
- registerHeadlessTask(taskKey: string, task: TaskProvider): void {
- if (tasks.has(taskKey)) {
+ registerHeadlessTask(taskKey: string, taskProvider: TaskProvider): void {
+ this.registerCancellableHeadlessTask(taskKey, taskProvider, () => () => { /* Cancel is no-op */ });
+ },
+
+ /**
+ * Register a cancellable headless task. A headless task is a bit of code that runs without a UI.
+ *
+ * See http://facebook.github.io/react-native/docs/appregistry.html#registercancellableheadlesstask
+ */
+ registerCancellableHeadlessTask(taskKey: string, taskProvider: TaskProvider, taskCancelProvider: TaskCancelProvider): void {
+ if (taskProviders.has(taskKey)) {
  console.warn(
- `registerHeadlessTask called multiple times for same key '${taskKey}'`,
+ `registerHeadlessTask or registerCancellableHeadlessTask called multiple times for same key '${taskKey}'`,
  );
  }
- tasks.set(taskKey, task);
+ taskProviders.set(taskKey, taskProvider);
+ taskCancelProviders.set(taskKey, taskCancelProvider);
  },
 
  /**
@@ -224,7 +238,7 @@ const AppRegistry = {
  * See http://facebook.github.io/react-native/docs/appregistry.html#startheadlesstask
  */
  startHeadlessTask(taskId: number, taskKey: string, data: any): void {
- const taskProvider = tasks.get(taskKey);
+ const taskProvider = taskProviders.get(taskKey);
  if (!taskProvider) {
  throw new Error(`No task registered for key ${taskKey}`);
  }
@@ -237,6 +251,19 @@ const AppRegistry = {
  NativeModules.HeadlessJsTaskSupport.notifyTaskFinished(taskId);
  });
  },
+
+ /**
+ * Only called from native code. Cancels a headless task.
+ *
+ * See http://facebook.github.io/react-native/docs/appregistry.html#cancelheadlesstask
+ */
+ cancelHeadlessTask(taskId: number, taskKey: string): void {
+ const taskCancelProvider = taskCancelProviders.get(taskKey);
+ if (!taskCancelProvider) {
+ throw new Error(`No task canceller registered for key '${taskKey}'`);
+ }
+ taskCancelProvider()();
+ }
 };
 
 BatchedBridge.registerCallableModule('AppRegistry', AppRegistry);