[Discussion] Hot reload API design

[Dr-TSNG]

Hot reload (reloading modules without restarting target app / system) will be a new feature in API 102. Please give your suggestions about the interfaces.

Preview (may change later):

// XposedModuleInterface.java
interface PrepareHotReloadParam {
    @Nullable Bundle getData();
    void saveInstances(@Nullable Bundle in);
}
// Called in old modules
default bool onPrepareHotReload(@NonNull PrepareHotReloadParam param) {
    return isSuccess;
}
// Called in updated modules
default void onHotReloaded(@Nullable Bundle savedInstances) {
}

// IXposedService.aidl
HookedProcess getRunningTargets();

// HookedProcess.aidl
bool requestHotReload(in Bundle data);

Updated module will be loaded with a new ClassLoader, and the old module should manually stop all threads created when onHotReloadRequested is called.

Issues under discussion:

• Should the framework always invalidate old hooks before a new version is loaded into the target process or just pass hook handles to the new modules?
• How to handle native libraries, should the framework provide XposedInterface.(un)loadLibrary or simply doesn't support this senario?
• Should the process be atomic - the framework pauses all threads / all hooked methods before hot reload completed?

[HChenX]

想请问个问题：如果有些方法只在应用启动时被初始化一次，而 Hook 依赖这个方法的产物，再进行热更新后旧获取产物还能继续使用吗？

[Dr-TSNG]

想请问个问题：如果有些方法只在应用启动时被初始化一次，而 Hook 依赖这个方法的产物，再进行热更新后旧获取产物还能继续使用吗？

参考 activity 销毁重建，需要自己使用 Bundle 序列化。直接传递对象是不行的，因为 classloader 不一样了。

[Dr-TSNG]

@Dr-TSNG 为什么用 Bundle 而不是 Object

喜欢 java.lang.ClassCastException 吗😁

[HChenX]

参考 activity 销毁重建，需要自己使用 Bundle 序列化。直接传递对象是不行的，因为 classloader 不一样了。

有些数据是不支持序列化传递的，但是是刚需数据怎么办（）

[HChenX]

@Dr-TSNG 为什么用 Bundle 而不是 Object

需要用 Bundle 序列化传递，不然 classloader 不一样会崩。

[vvb2060]

有些数据是不支持序列化传递的，但是是刚需数据怎么办（）

说明你的设计有问题

[vvb2060]

想请问个问题：如果有些方法只在应用启动时被初始化一次，而 Hook 依赖这个方法的产物，再进行热更新后旧获取产物还能继续使用吗？

可以，这个对象来自app的classloader，它是稳定的，只有模块的cl会变

[HChenX]

可以，这个对象来自app的classloader，它是稳定的，只有模块的cl会变

懂了

[hxreborn]

Hey, thanks for the work on libxposed and for opening this discussion. The API 101 redesign was great to work with, and excited to see hot reload coming in 102

I migrated a few of my modules to API 101 and had a thought on this:

Should the framework always invalidate old hooks before a new version is loaded into the target process, or just pass hook handles to the new modules?

The preview API with onHotReloaded(Bundle) looks like the right direction to me. I never store HookHandles in any of my modules, I register hooks in onPackageReady and forget about them. Re-registering fresh in onHotReloaded with state passed through the Bundle would be the simpler path. I know modules that use .unhook() for temporary hooks have different needs here, but for the fire-and-forget pattern, passing handles around feels like extra state management I’d rather avoid