cache sync calls

Author: geof90

CodePush.js

@@ -170,16 +170,28 @@ function setUpTestDependencies(testSdk, providedTestConfig, testNativeBridge) {
   if (testNativeBridge) NativeCodePush = testNativeBridge;
 }
 
+// This function allows sync operations to be chained on to each other so that they do not
+// interleave in the event that sync() is called multiple times.
+const sync = (() => {
+  let syncPromiseChain = Promise.resolve();
+  return (options = {}, syncStatusChangeCallback, downloadProgressCallback) => {
+    syncPromiseChain = syncPromiseChain
+      .catch(() => {})
+      .then(() => syncOperation(options, syncStatusChangeCallback, downloadProgressCallback));
+    return syncPromiseChain;
+  };
+})();
+
 /*
- * The sync method provides a simple, one-line experience for
+ * The syncOperation method provides a simple, one-line experience for
  * incorporating the check, download and application of an update.
  * 
  * It simply composes the existing API methods together and adds additional
  * support for respecting mandatory updates, ignoring previously failed
  * releases, and displaying a standard confirmation UI to the end-user
  * when an update is available.
  */
-async function sync(options = {}, syncStatusChangeCallback, downloadProgressCallback) {  
+async function syncOperation(options = {}, syncStatusChangeCallback, downloadProgressCallback) {  
   const syncOptions = {
 
     deploymentKey: null,

CodePushPackage.m

@@ -449,7 +449,7 @@ + (void)copyEntriesInFolder:(NSString *)sourceFolder
 }
 
 + (void)installPackage:(NSDictionary *)updatePackage
-               error:(NSError **)error
+                 error:(NSError **)error
 {
     NSString *packageHash = updatePackage[@"packageHash"];
     NSMutableDictionary *info = [self getCurrentPackageInfo:error];

Examples/CodePushDemoApp/crossplatformdemo.js

@@ -92,16 +92,22 @@ let CodePushDemoApp = React.createClass({
   render() {
     let syncView, syncButton, progressView;
 
+      syncButton = ( 
+        <Button style={{color: 'green'}} onPress={this.sync}>
+          Start Sync!
+        </Button>
+      );
+      
     if (this.state.syncMessage) {
       syncView = (
         <Text style={styles.messages}>{this.state.syncMessage}</Text>
       );
     } else {
-      syncButton = ( 
+      /*syncButton = ( 
         <Button style={{color: 'green'}} onPress={this.sync}>
           Start Sync!
         </Button>
-      );
+      );*/
     }
 
     if (this.state.progress) {