Enhanced Fast Deployment doesn't work with Application subclasses

[brendanzagaeski]

While checking the accuracy of what I had written for the Xamarin.Android 9.2 preview release notes related to Enhanced Fast Deployment, I realized I should check the exact old test case from Xamarin Bugzilla Bug 55050. It turns out the test case fails with a different error with the new version of Enhanced Fast Deployment. The error on an Android 8.0 emulator is very similar to the one seen by a user in Developer Community 435111 (probably only different because I'm using a newer preview version), but the error is different on an Android 7.1 emulator and on an Android 9.0 device, so I am filing a new issue to record all 3 versions of the error message.

Steps to Reproduce

1. Download the test case.

2. Build and install the app with enhanced fast deployment enabled:

    msbuild -t:Install -p:DefineConstants=INCLUDE_APP

3. Run the app.

Expected Behavior

The app launches successfully and displays the "HELLO WORLD, CLICK ME!" button. (This is how the test case behaves when Enhanced Fast Deployment is disabled.)

Actual Behavior

The app exits unexpectedly during initialization.

Excerpt from the adb logcat output on Android 9.0 (API level 28) arm64-v8a Google Pixel 3 device

AndroidRuntime: Shutting down VM
--------- beginning of crash
AndroidRuntime: FATAL EXCEPTION: main
AndroidRuntime: Process: scratch.bxc55050, PID: 7870
AndroidRuntime: java.lang.IllegalAccessError: Illegal class access: 'mono.android.Runtime' attempting to access 'mono.android.GCUserPeer' (declaration of 'mono.android.Runtime' appears in /data/app/scratch.bxc55050--x-XSYlRTtX_PyHDVMsL9A==/base.apk)
AndroidRuntime:        at mono.android.Runtime.<clinit>(Runtime.java:8)
AndroidRuntime:        at mono.android.Runtime.init(Native Method)
AndroidRuntime:        at mono.MonoPackageManager.LoadApplication(MonoPackageManager.java:51)
AndroidRuntime:        at mono.MonoRuntimeProvider.attachInfo(MonoRuntimeProvider.java:42)
AndroidRuntime:        at android.app.ActivityThread.installProvider(ActivityThread.java:6402)
AndroidRuntime:        at android.app.ActivityThread.installContentProviders(ActivityThread.java:5949)
AndroidRuntime:        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5864)
AndroidRuntime:        at android.app.ActivityThread.access$1100(ActivityThread.java:200)
AndroidRuntime:        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1651)
AndroidRuntime:        at android.os.Handler.dispatchMessage(Handler.java:106)
AndroidRuntime:        at android.os.Looper.loop(Looper.java:193)
AndroidRuntime:        at android.app.ActivityThread.main(ActivityThread.java:6680)
AndroidRuntime:        at java.lang.reflect.Method.invoke(Native Method)
AndroidRuntime:        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
AndroidRuntime:        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
ActivityManager:   Force finishing activity scratch.bxc55050/md58bfd9258c6beb71a97a5dd7a0600aa01.MainActivity

Excerpt from the adb logcat output on Android 8.0 (API level 26) x86 emulator

AndroidRuntime: Shutting down VM
--------- beginning of crash
AndroidRuntime: FATAL EXCEPTION: main
AndroidRuntime: Process: scratch.bxc55050, PID: 6136
AndroidRuntime: java.lang.UnsatisfiedLinkError: No implementation found for void mono.android.Runtime.init(java.lang.String, java.lang.String[], java.lang.String, java.lang.String[], java.lang.ClassLoader, java.lang.String[], java.lang.String[], java.lang.String, int, java.lang.String[]) (tried Java_mono_android_Runtime_init and Java_mono_android_Runtime_init__Ljava_lang_String_2_3Ljava_lang_String_2Ljava_lang_String_2_3Ljava_lang_String_2Ljava_lang_ClassLoader_2_3Ljava_lang_String_2_3Ljava_lang_String_2Ljava_lang_String_2I_3Ljava_lang_String_2)
AndroidRuntime:        at mono.android.Runtime.init(Native Method)
AndroidRuntime:        at mono.MonoPackageManager.LoadApplication(MonoPackageManager.java:51)
AndroidRuntime:        at mono.MonoRuntimeProvider.attachInfo(MonoRuntimeProvider.java:42)
AndroidRuntime:        at android.app.ActivityThread.installProvider(ActivityThread.java:6239)
AndroidRuntime:        at android.app.ActivityThread.installContentProviders(ActivityThread.java:5805)
AndroidRuntime:        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5722)
AndroidRuntime:        at android.app.ActivityThread.-wrap1(Unknown Source:0)
AndroidRuntime:        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1656)
AndroidRuntime:        at android.os.Handler.dispatchMessage(Handler.java:106)
AndroidRuntime:        at android.os.Looper.loop(Looper.java:164)
AndroidRuntime:        at android.app.ActivityThread.main(ActivityThread.java:6494)
AndroidRuntime:        at java.lang.reflect.Method.invoke(Native Method)
AndroidRuntime:        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
AndroidRuntime:        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
ActivityManager:   Force finishing activity scratch.bxc55050/md58bfd9258c6beb71a97a5dd7a0600aa01.MainActivity

Excerpt from the adb logcat output on Android 7.1 (API level 25) x86 emulator

AndroidRuntime: Shutting down VM
--------- beginning of crash
AndroidRuntime: FATAL EXCEPTION: main
AndroidRuntime: Process: scratch.bxc55050, PID: 31891
AndroidRuntime: java.lang.IllegalAccessError: Illegal class access: 'mono.MonoPackageManager' attempting to access 'mono.MonoPackageManager_Resources' (declaration of 'mono.MonoPackageManager' appears in /data/app/scratch.bxc55050-1/base.apk)
AndroidRuntime:        at mono.MonoPackageManager.LoadApplication(MonoPackageManager.java:54)
AndroidRuntime:        at mono.MonoRuntimeProvider.attachInfo(MonoRuntimeProvider.java:42)
AndroidRuntime:        at android.app.ActivityThread.installProvider(ActivityThread.java:5853)
AndroidRuntime:        at android.app.ActivityThread.installContentProviders(ActivityThread.java:5445)
AndroidRuntime:        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5384)
AndroidRuntime:        at android.app.ActivityThread.-wrap2(ActivityThread.java)
AndroidRuntime:        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1545)
AndroidRuntime:        at android.os.Handler.dispatchMessage(Handler.java:102)
AndroidRuntime:        at android.os.Looper.loop(Looper.java:154)
AndroidRuntime:        at android.app.ActivityThread.main(ActivityThread.java:6119)
AndroidRuntime:        at java.lang.reflect.Method.invoke(Native Method)
AndroidRuntime:        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
AndroidRuntime:        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
ActivityManager:   Force finishing activity scratch.bxc55050/md58bfd9258c6beb71a97a5dd7a0600aa01.MainActivity

Version Information

Visual Studio 2019 Int Preview
Xamarin.Android SDK 9.1.103.12 (HEAD/7e1c4688)

VS bug #790706

[dellis1972]

Looks like this is "mostly" working. The only combination that still doesn't seem to work is

useSharedRuntime=true
embedAssemblies=false
fastDevType=Assemblies;Dexes

which is a bit weird.

07-29 19:08:09.958  4002  4002 E AndroidRuntime: FATAL EXCEPTION: main
07-29 19:08:09.958  4002  4002 E AndroidRuntime: Process: UnnamedProject.UnnamedProject, PID: 4002
07-29 19:08:09.958  4002  4002 E AndroidRuntime: java.lang.RuntimeException: Unable to instantiate application md52d9cf6333b8e95e8683a477bc589eda5.MyApplication: java.lang.ClassNotFoundException: Didn't find class "md52d9cf6333b8e95e8683a477bc589eda5.MyApplication" on path: DexPathList[[zip file "/data/app/UnnamedProject.UnnamedProject-xRamv17Vp3Mi_sS--jN9tw==/base.apk"],nativeLibraryDirectories=[/data/app/UnnamedProject.UnnamedProject-xRamv17Vp3Mi_sS--jN9tw==/lib/x86, /data/app/UnnamedProject.UnnamedProject-xRamv17Vp3Mi_sS--jN9tw==/base.apk!/lib/x86, /system/lib]]
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.LoadedApk.makeApplication(LoadedApk.java:1069)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5842)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.ActivityThread.access$1100(ActivityThread.java:199)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1650)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.os.Handler.dispatchMessage(Handler.java:106)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.os.Looper.loop(Looper.java:193)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.ActivityThread.main(ActivityThread.java:6669)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at java.lang.reflect.Method.invoke(Native Method)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: Caused by: java.lang.ClassNotFoundException: Didn't find class "md52d9cf6333b8e95e8683a477bc589eda5.MyApplication" on path: DexPathList[[zip file "/data/app/UnnamedProject.UnnamedProject-xRamv17Vp3Mi_sS--jN9tw==/base.apk"],nativeLibraryDirectories=[/data/app/UnnamedProject.UnnamedProject-xRamv17Vp3Mi_sS--jN9tw==/lib/x86, /data/app/UnnamedProject.UnnamedProject-xRamv17Vp3Mi_sS--jN9tw==/base.apk!/lib/x86, /system/lib]]
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:134)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.AppComponentFactory.instantiateApplication(AppComponentFactory.java:50)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.Instrumentation.newApplication(Instrumentation.java:1120)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	at android.app.LoadedApk.makeApplication(LoadedApk.java:1061)
07-29 19:08:09.958  4002  4002 E AndroidRuntime: 	... 9 more
07-29 19:08:09.960  1813  3739 W ActivityManager:   Force finishing activity UnnamedProject.UnnamedProject/md52d9cf6333b8e95e8683a477bc589eda5.MainActivity

[dellis1972]

I managed to figure out why the combination above does not work.
The problem is this, when we are using enhanced fast deployment we deploy a small subset of our java runtime. This contains the ContentProviders that get the application running. This works for normal applications because they use the Application class directly. This is provided by the android runtime.

In the case of a custom application, we need the java side of the C# class in order to create the object. The problem here is the java code is NOT in the app, but in the .__override__ directory which we use for fast deployment. Seeing as it is the Application which is responsible for creating the ContentProviders and its the ContentProviders which tell Java where to find the classes.dex files in the .__override__ directory this was never going to work.

What we need to do is somehow include the Application subclass and all its dependencies in the apk. We also need to make sure they are excluded from any .dex file which is fast deployed. This is because the android runtime errors if it finds duplicate classes.

This is going to take some time to figure out and I suspect it will require changes to the GenerateJavaStubs Task and it's dependencies.

[dellis1972]

Unit test added #3408

[dellis1972]

Still unsure how to fix the last case of a Custom App and FastDev.
Any ideas @jonathanpeppers @pjcollins ? This comment #2730 (comment) pretty much summarises what is going on.

[jonathanpeppers]

Maybe we need to figure out how they deploy java code changes with Apply Changes and go about it a different way?

The parts of Apply Changes we would need here might be small. We have the benefit of restarting the app, while they are doing a "java hot reload".