refact(utils): Check current thread and dispatch only if needed

tests/app/utils/utils-tests.ts

@@ -18,7 +18,6 @@ export function test_releaseNativeObject_canBeCalledWithNativeObject() {
     }
 };
 
-
 export function test_executeOnMainThread_Works(done: Function) {
     utils.executeOnMainThread(() => {
         try {
@@ -30,6 +29,17 @@ export function test_executeOnMainThread_Works(done: Function) {
     });
 }
 
+export function test_dispatchToMainThread_Works(done: Function) {
+    utils.dispatchToMainThread(() => {
+        try {
+            TKUnit.assertTrue(utils.isMainThread());
+            done();
+        } catch (e) {
+            done(e);
+        }
+    });
+}
+
 export function test_mainThreadify_PassesArgs(done: Function) {
     const expectedN = 434;
     const expectedB = true;
@@ -49,7 +59,6 @@ export function test_mainThreadify_PassesArgs(done: Function) {
     f(expectedN, expectedB, expectedS);
 }
 
-
 function test_releaseNativeObject_canBeCalledWithNativeObject_iOS() {
     let deallocated = false;
     const obj = new ((<any>NSObject).extend({

tns-core-modules/utils/utils-common.ts

@@ -1,5 +1,5 @@
 import * as types from "./types";
-import { executeOnMainThread } from "./utils"
+import { dispatchToMainThread, isMainThread } from "./utils"
 
 export const RESOURCE_PREFIX = "res://";
 export const FILE_PREFIX = "file:///";
@@ -156,6 +156,14 @@ export function eliminateDuplicates(arr: Array<any>): Array<any> {
     return Array.from(new Set(arr));
 }
 
+export function executeOnMainThread(func: Function) {
+    if (isMainThread()) {
+        return func();
+    } else {
+        dispatchToMainThread(func);
+    }
+}
+
 export function mainThreadify(func: Function): (...args: any[]) => void {
     return function () {
         const argsToPass = arguments;

tns-core-modules/utils/utils.android.ts

@@ -373,7 +373,7 @@ Please ensure you have your manifest correctly configured with the FileProvider.
     }
 }
 
-export function executeOnMainThread(func: () => void) {
+export function dispatchToMainThread(func: () => void) {
     new android.os.Handler(android.os.Looper.getMainLooper())
         .post(new java.lang.Runnable({
             run: func

tns-core-modules/utils/utils.d.ts

@@ -273,6 +273,13 @@ export function releaseNativeObject(object: any /*java.lang.Object | NSObject*/)
  * Dispatches the passed function for execution on the main thread
  * @param func The function to execute on the main thread.
  */
+export function dispatchToMainThread(func: Function);
+
+/**
+ * Checks if the current thread is the main thread. Directly calls the passed function
+ * if it is, or dispatches it to the main thread otherwise.
+ * @param func The function to execute on the main thread.
+ */
 export function executeOnMainThread(func: Function);
 
 /**

tns-core-modules/utils/utils.ios.ts

@@ -159,7 +159,7 @@ export function openUrl(location: string): boolean {
     return false;
 }
 
-export function executeOnMainThread(func: () => void) {
+export function dispatchToMainThread(func: () => void) {
     NSOperationQueue.mainQueue.addOperationWithBlock(func);
 }