I'm calling "Isolate->IdleNotification(100)" within an isolate scope (via "v8::Isolate::Scope ..."), and at some point when "V8::GetCurrentPlatform()->CallOnBackgroundThread(...)" is called within V8, "V8::GetCurrentPlatform()" returns NULL, and the whole thing dies a fatal death. Any ideas why the current platform might be null? Or rather, what should be done to make sure it isn't? Everything else seems to be working just fine.
Addition details: I'm using Visual Studio 2013, and compiled the source, the resulting libraries of which I use with the V8.Net wrapper (on codeplex). I run the following code before triggering the idle notification call:
v8::Locker __lockScope(engine->Isolate());
v8::Isolate::Scope __isolateScope(engine->Isolate());
v8::HandleScope __handleScope(Isolate::GetCurrent());
I tried different combinations, and it seems only v8::Locker __lockScope is required, but the platform is still null;
v8::Platform* V8::GetCurrentPlatform() {
DCHECK(platform_); // <-- 'platform_' is NULL
return platform_;
}
Got this working shortly after, but forgot to post the answer. Here it is: Google changed stuff (surprise! :/), and now you have to initialize a platform first. I did this and it all works again:
v8::V8::InitializePlatform(v8::platform::CreateDefaultPlatform());
// Sets the v8::Platform to use. This should be invoked before V8 is initialized.
v8::V8::InitializeICU();
// Initialize the ICU library bundled with V8. (if using the bundled ICU)
v8::V8::Initialize();
// Initialize V8.
Related
I've been tasked with maintaining a Xamarin native project using MvvmCross 5.6.2. Not knowing exactly how to approach this, I've decided to update to one major version at a time (6 first, then 7 and 8). I'm not sure why I specifically have chosen 6.4.2, but it was maybe because this was the latest version of the majority of the plugins I was using on Nuget.
So far, the update has been a success and I have been able to fix all build errors. However, when running the application, I've been getting a null reference exception which I can't fully trace.
Based on the limited application output, I've been able to determine that the problem lies somewhere in my Android's setup.cs class (I think). I've been following Nick's .NET Travels advice on MvvmCross debugging. From viewing the MvvmCross 6.4.2. source and pasting in the following code in my own overrides:
public virtual void LoadPlugins(IMvxPluginManager pluginManager)
{
Type pluginAttribute = typeof(MvxPluginAttribute);
IEnumerable<Assembly> pluginAssemblies = GetPluginAssemblies();
foreach (Assembly item in pluginAssemblies)
{
IEnumerable<Type> enumerable = item.ExceptionSafeGetTypes();
foreach (Type item2 in enumerable)
{
if (TypeContainsPluginAttribute(item2))
{
pluginManager.EnsurePluginLoaded(item2);
}
}
}
bool TypeContainsPluginAttribute(Type type)
{
object[] customAttributes = type.GetCustomAttributes(pluginAttribute, inherit: false);
return ((customAttributes != null && customAttributes.Length != 0) ? 1 : 0) > (false ? 1 : 0);
}
}
public virtual IEnumerable<Assembly> GetPluginAssemblies()
{
string mvvmCrossAssemblyName = typeof(MvxPluginAttribute).Assembly.GetName().Name;
Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();
var test = from asmb in assemblies.AsParallel()
where AssemblyReferencesMvvmCross(asmb, mvvmCrossAssemblyName)
select asmb;
return test;
}
I'm able to see that GetPluginAssemblies doesn't return any enumerable, and the LoadPlugins method then produces the NullReferenceException. But I can't see what this NullReference actually is.
I followed the upgrading from 5 to 6 guide https://www.mvvmcross.com/documentation/upgrading/upgrade-to-mvvmcross-60.
I looked at the MvvmCross 6 and 6.4.0 release pages:
https://www.mvvmcross.com/mvvmcross-6.0.0-release/
https://www.mvvmcross.com/mvvmcross-6.4.0-release/
And I followed Benjamin Mayrargue's guide: https://medium.com/#bigoudi/upgrading-from-mvvmcross-5-to-mvvmcross-6-7ded83ecb69d
But I have been unable to load my plugins (previously they were bootstraps, but most of the guides say these can be discarded now and that loading plugins is easier).
I also attempted the answer suggested in this question How to use an mvvmcross plugin such as the file plugin.
But to no avail.
So I am asking if anyone knows a good guide or how to use plugins in MvvmCross 6.4.2.
Thank you.
Plugins are just a way to register things in the IoC Container. This is done by MvvmCross during startup using the LoadPlugins method in your Setup file.
Most of the time it should just work. However, there are some caveats.
If the Linker has gone ahead and linked away some of the plugins code, you will have a bad time. What you can do about that is to hint the mono linker to not strip the code away.
Add a LinkerPleaseInclude class and add a Include method in it that looks something like:
new MvvmCross.Plugin.Color.Platforms.Ios.Plugin().Load();
You can do that for every plugin you may want to use.
If LoadPlugins doesn't find the entry Assembly, sometimes it also does not register the plugins. You can override LoadPlugins in your Setup class and just call EnsurePluginLoaded:
public override void LoadPlugins(IMvxPluginManager pluginManager)
{
base.LoadPlugins(pluginManager);
pluginManager.EnsurePluginLoaded<MvvmCross.Plugin.Color.Platforms.Ios.Plugin>();
}
I want to thank Cheesebaron for his plugin support. I think I've fixed my issue and as it turned out, I don't think there is a plugin issue after all (yet).
Thanks to Toolmakersteve also. His suggestion for using a try catch in the OnCreate of my overridden MvxSplashScreenAppCompatActivity surfaced an issue with setting a theme for this activity. In actuality, this class was initially a MvxSplashScreenActivity.
Reverting this line, I then started getting NullReferenceExceptions on specific lines, all relating to IoC and lazy construction of singletons. The class Mvx seemed to be throwing up this error. On a sort of hunch from previous experience with my updating, I removed the MvvmCross.Platform using statement and checked what suggestions Mvx had available to it. It suggested MvvmCross and MvvmCross.Platform, so I tried the former instead. Sure enough, this moved my execution further, throwing up more Null Reference Exceptions. I also encountered one instance of failing to resolve IMvxResourceLoader from MvvmCross.Platform.Platform. Switching that to MvvmCross.Base did the trick.
This was only a chance fix through a bit of guess work. #CheeseBaron, should I add this as a note to this bit of documentation https://www.mvvmcross.com/documentation/upgrading/upgrade-to-mvvmcross-60? As mentioned, I'm as far as 6.4.2 now, so I'm not certain this is the right place for it.
I've got a few bugs with embedded resources to fix now, but if I encounter any more that are relevant to my question, I'll list them here.
I've got a sample uirouter/angular-hybrid app, successfully built with #ngtools/webpack AngularCompiler plugin and running. I've updated the main.aot.ts boot function to use bootstrapModuleFactory and can get the injector from the platformRef available in the promise success handler. But injector.get(UIRouter) fails with "Cannot read property 'config' of null."
platformBrowser().bootstrapModuleFactory(AppModuleNgFactory).then((platformRef) => {
const urlService: UrlService = platformRef.injector.get(UIRouter).urlService;
function startUIRouter() {
urlService.listen();
urlService.sync();
}
platformRef.injector.get<NgZone>(NgZone).run(startUIRouter);
});
I confirmed that the injector.get(NgZone) will succeed and injector.get(UIRouter) will fail. I tried moving the call to injector.get(UIRouter) inside the NgZone run func without success.
I also tried moving the upgrade.bootstrap call into the promise success function above to ensure it had booted first, without fixing the problem.
A simple angularjs component is rendering fine, so the boot process seems to be succeeding, except for not being able to call the listen() and sync() functions on the UIRouter.urlService.
I also confirmed the development config and non-aot production config, for this same sample app, do not have this problem and seem to be working fine.
Using versions:
uirouter/angular-hybrid v6.0.2
angular packages at v7.1.4, but also failed with 6.0.0 (which is the angular version in the package.json in the docs for uirouter/angular-hybrid v6.0.2)
Thanks for any ideas.
The problem was that the config object I was passing to UIRouterUpgradeModule.forRoot was being imported from a file that was using a default export of the object, and the object had a reference to a config function that was not being exported. This combination hid the problem during the build, and resulted in the symptom at runtime of not having the UIRouter object available to the injector.
Replacing the default export with a named export triggered the AOT compiler to complain about the non-exported function reference. Additionally exporting the function then allowed a successful build, a happy injector, and a successful runtime boot.
I am building an iOS app with Xamarin and MvvmCross the required the use of Bluetooth LE. I am trying to use this plugin:
https://github.com/aritchie/bluetoothle
Here is my code:
var server = CrossBleAdapter.Current.CreateGattServer();
await server.Start(new AdvertisementData()); // throws exception
It throws an exception when trying to start the server:
{System.ArgumentException: Invalid State - Unknown at
Plugin.BluetoothLE.Server.GattServer.Start
(Plugin.BluetoothLE.Server.AdvertisementData adData) [0x0005f] in
<4281c4bd57f24525b20baae1afdf610b>:0
Apparently this plugin is easy to use so I must be missing something obvious?
That Exception indicates that the hardware is in invalid or initializing state and can be seen here: https://github.com/aritchie/bluetoothle/blob/master/Plugin.BluetoothLE.Apple.Shared/Server/GattServer.cs#L74
if (this.manager.State != CBPeripheralManagerState.PoweredOn)
throw new ArgumentException("Invalid State - " + this.manager.State);
I believe this is a bug in the code as it does not wait for the delegate to signal that the State has changed.
I found a solution. Instead of placing the code in my Core project, I placed it inside the iOS project itself, in a ViewDidAppear function, and placed a global variable in my UIViewController class:
private IGattServer server = CrossBleAdapter.Current.CreateGattServer();
I think you need to access the adapter with the appropriate thread, or at the appropriate time (after other initialization), hence why it was crashing before. I couldn't find an appropriate place to put this in my Core project, so I'm not sure if I have to put this code in each platform. Anyhow here's a solution for anyone else with this problem.
Is there any way to remove a record from Launch Services database which was added using LSRegisterURL?
I have several apps that can open the same URL and I want to manage which one of them should open it. Unfortunately now I face a problem that at some point LSRegisterURL stop working. E.g. it works until some point, then, I guess, Launch Services database (or cache) gets overflown and subsequent calls to LSRegisterURL don't have any effect.
So my idea is to clean up Launch Services database by removing old records, but I can't find any related function.
I came across a private API in LaunchServices today that appears to do the trick. It seems to work on Mac OS X 10.7 thru 10.11. I've barely tested it yet, so YMMV:
extern void _LSUnregisterURL(CFURLRef url) __attribute__((weak_import));
- (void) unregisterAppAtURL:(NSURL *)appURL
{
if( _LSUnregisterURL != NULL )
{
CFURLRef urlRef = (__bridge CFURLRef)appURL;
if( urlRef )
{
_LSUnregisterURL( urlRef );
}
}
}
There are several other private API's similar to this (which you can find by using nm). Keep in mind that if you go private, you can't submit to the App Store. Hope that helps someone.
As it comes from the further tests OS X frees the Launch Services database itself. The exact algorithm is not clear, but rebooting Mac in most cases helps to remove the records to the missed applications and/or make the app specified by the most recent call to LSRegisterURL to become the default one.
I've created a plugin and registered it using hte registration tool. I've also added a step that is supposed to handle a message of creation of an instance. Sadly, the intended behavior doesn't occur.
My guess is that something inside the plugin crashes but I have no idea on how to debug it. Setting up breakpoints is not going to work agains on-line version, I understand, so I'm not even trying.
For legal and technical reasons, I won't be able to lift over the solution to an on-premise installation, neither. Is guessing my only option?
For server-side (plugins) I'm using ITracingService. For client-side I log everything to console. The downside with the first is that you actually need to crash the execution to get to see anything. The downside with the latter is that plugins sometimes get executed without GUI being invoked at all.
When it comes to heavier projects, I simply set up a WCF web service that I call from the plugin and write to that. That way, on one screen, I'm executing the plugin while on the other, I'm getting a nice log file (or just put the sent information to on the screen).
You could, for instance, start with a very basic update of a field on the instance of your entity that's being created. When you have that working, you can always fall back to the last working version. If you don't even get that to work, it mean, probably, that you're setting up the plugin registration incorrectly.
A very efficient way would be to lift over the solution to an on-premise version where you have full control but I see in your question that it's not en option.
In case you could lift the solution to an on-premise version, here's a link on how to debug plugins.
Don't forget that you also have access to the ITracingService.
You can get a reference to it in your Execute method and then write to it every so often in your code to log variables or courses of action that you are attempting or have succeeded with. You can also use it to surface more valuable information when an exception occurs.
It's basically like writing to a console. Then, if anything causes the plug-in to crash at runtime then you can see everything that you've traced when you click Download Log File on the error shown to the user.
Beware though - unless your plug-in actually throws an exception (deliberate or otherwise) then you have no access to whatever was traced.
Example:
public void Execute(IServiceProvider serviceProvider)
{
// Obtain the execution context from the service provider.
IPluginExecutionContext context =
(IPluginExecutionContext)serviceProvider.GetService(
typeof(IPluginExecutionContext));
// Get a reference to the tracing service.
ITracingService tracingService =
(ITracingService)serviceProvider.GetService(typeof(ITracingService));
try
{
tracingService.Trace("Getting entity from InputParameters...");
// may fail for some messages, since "Target" is not present
var myEntity = (Entity)context.InputParameters["Target"];
tracingService.Trace("Got entity OK");
// some other logic here...
}
catch (FaultException<OrganizationServiceFault> ex)
{
_trace.Trace(ex.ToString());
while (ex.InnerException != null)
{
ex = (FaultException<OrganizationServiceFault>)ex.InnerException;
_trace.Trace(ex.ToString());
}
throw new InvalidPluginExecutionException(
string.Format("An error occurred in your plugin: {0}", ex));
}
catch (Exception ex)
{
_trace.Trace(ex.ToString());
while (ex.InnerException != null)
{
ex = ex.InnerException;
_trace.Trace(ex.ToString());
}
throw;
}
}