Summary:
## The Problem
1. `CatalystInstanceImpl` indirectly holds on to the `jsi::Runtime`. When you destroy `CatalystInstanceImpl`, you destroy the `jsi::Runtime`. As a part of reloading React Native, we destroy and re-create `CatalystInstanceImpl`, which destroys and re-creates the `jsi::Runtime`.
2. When JS passes in a callback to a TurboModule method, we take that callback (a `jsi::Function`) and wrap it in a Java `Callback` (implemented by `JCxxCallbackImpl`). This Java `Callback`, when executed, schedules the `jsi::Function` to be invoked on a Java thread at a later point in time. **Note:** The Java NativeModule can hold on to the Java `Callback` (and, by transitivity, the `jsi::Function`) for potentially forever.
3. It is a requirement of `jsi::Runtime` that all objects associated with the Runtime (ex: `jsi::Function`) must be destroyed before the Runtime itself is destroyed. See: https://fburl.com/m3mqk6wt
### jsi.h
```
/// .................................................... In addition, to
/// make shutdown safe, destruction of objects associated with the Runtime
/// must be destroyed before the Runtime is destroyed, or from the
/// destructor of a managed HostObject or HostFunction. Informally, this
/// means that the main source of unsafe behavior is to hold a jsi object
/// in a non-Runtime-managed object, and not clean it up before the Runtime
/// is shut down. If your lifecycle is such that avoiding this is hard,
/// you will probably need to do use your own locks.
class Runtime {
public:
virtual ~Runtime();
```
Therefore, when you delete `CatalystInstanceImpl`, you could end up with a situation where the `jsi::Runtime` is destroyed before all `jsi::Function`s are destroyed. In dev, this leads the program to crash when you reload the app after having used a TurboModule method that uses callbacks.
## The Solution
If the only reference to a `HostObject` or a `HostFunction` is in the JS Heap, then the `HostObject` and `HostFunction` destructors can destroy JSI objects. The TurboModule cache is the only thing, aside from the JS Heap, that holds a reference to all C++ TurboModules. But that cache (and the entire native side of `TurboModuleManager`) is destroyed when we call `mHybridData.resetNative()` in `TurboModuleManager.onCatalystInstanceDestroy()` in D16552730. (I verified this by commenting out `mHybridData.resetNative()` and placing a breakpoint in the destructor of `JavaTurboModule`). So, when we're cleaning up `TurboModuleManager`, the only reference to a Java TurboModule is the JS Heap. Therefore, it's safe and correct for us to destroy all `jsi::Function`s created by the Java TurboModule in `~JavaTurboModule`. So, in this diff, I keep a set of all `CallbackWrappers`, and explicitly call `destroy()` on them in the `JavaTurboModule` destructor. Note that since `~JavaTurboModule` accesses `callbackWrappers_`, it must be executed on the JS Thread, since `createJavaCallbackFromJSIFunction` also accesses `callbackWrappers_` on the JS Thread.
For additional safety, I also eagerly destroyed the `jsi::Function` after it's been invoked once. I'm not yet sure if we only want JS callbacks to only ever be invoked once. So, I've created a Task to document this work: T48128233.
Reviewed By: mdvacca
Differential Revision: D16623340
fbshipit-source-id: 3a4c3efc70b9b3c8d329f19fdf4b4423c489695b
Summary: When you create a TurboModule from the JS side, we instantiate its Java class and simply make this `javaobject` a `jni::global_ref` in C++. But the reason why we need to make this a global ref is because `JavaTurboModule` needs it to be a global reference for method calls. Making this a `jni::global_ref` from the perspective to TurboModuleManager doesn't really make any sense. So, this diff refactors that bit of code.
Differential Revision: D16622133
fbshipit-source-id: 6a5c20bb405b945c06378a3423d5e7eb38ef244c
Summary:
## The Problem
1. `CatalystInstanceImpl` indirectly holds on to the `jsi::Runtime`. When you destroy `CatalystInstanceImpl`, you destroy the `jsi::Runtime`. As a part of reloading React Native, we destroy and re-create `CatalystInstanceImpl`, which destroys and re-creates the `jsi::Runtime`.
2. When JS passes in a callback to a TurboModule method, we take that callback (a `jsi::Function`) and wrap it in a Java `Callback` (implemented by `JCxxCallbackImpl`). This Java `Callback`, when executed, schedules the `jsi::Function` to be invoked on a Java thread at a later point in time. **Note:** The Java NativeModule can hold on to the Java `Callback` (and, by transitivity, the `jsi::Function`) for potentially forever.
3. It is a requirement of `jsi::Runtime` that all objects associated with the Runtime (ex: `jsi::Function`) must be destroyed before the Runtime itself is destroyed. See: https://fburl.com/m3mqk6wt
### jsi.h
```
/// .................................................... In addition, to
/// make shutdown safe, destruction of objects associated with the Runtime
/// must be destroyed before the Runtime is destroyed, or from the
/// destructor of a managed HostObject or HostFunction. Informally, this
/// means that the main source of unsafe behavior is to hold a jsi object
/// in a non-Runtime-managed object, and not clean it up before the Runtime
/// is shut down. If your lifecycle is such that avoiding this is hard,
/// you will probably need to do use your own locks.
class Runtime {
public:
virtual ~Runtime();
```
Therefore, when you delete `CatalystInstanceImpl`, you could end up with a situation where the `jsi::Runtime` is destroyed before all `jsi::Function`s are destroyed. In dev, this leads the program to crash when you reload the app after having used a TurboModule method that uses callbacks.
## The Solution
If the only reference to a `HostObject` or a `HostFunction` is in the JS Heap, then the `HostObject` and `HostFunction` destructors can destroy JSI objects. The TurboModule cache is the only thing, aside from the JS Heap, that holds a reference to all C++ TurboModules. But that cache (and the entire native side of `TurboModuleManager`) is destroyed when we call `mHybridData.resetNative()` in `TurboModuleManager.onCatalystInstanceDestroy()` in D16552730. (I verified this by commenting out `mHybridData.resetNative()` and placing a breakpoint in the destructor of `JavaTurboModule`). So, when we're cleaning up `TurboModuleManager`, the only reference to a Java TurboModule is the JS Heap. Therefore, it's safe and correct for us to destroy all `jsi::Function`s created by the Java TurboModule in `~JavaTurboModule`. So, in this diff, I keep a set of all `CallbackWrappers`, and explicitly call `destroy()` on them in the `JavaTurboModule` destructor. Note that since `~JavaTurboModule` accesses `callbackWrappers_`, it must be executed on the JS Thread, since `createJavaCallbackFromJSIFunction` also accesses `callbackWrappers_` on the JS Thread.
For additional safety, I also eagerly destroyed the `jsi::Function` after it's been invoked once. I'm not yet sure if we only want JS callbacks to only ever be invoked once. So, I've created a Task to document this work: T48128233.
Reviewed By: mhorowitz
Differential Revision: D16589168
fbshipit-source-id: a1c0786999c22bef55d416beb0fc40261447a807
Summary: When you create a TurboModule from the JS side, we instantiate its Java class and simply make this `javaobject` a `jni::global_ref` in C++. But the reason why we need to make this a global ref is because `JavaTurboModule` needs it to be a global reference for method calls. Making this a `jni::global_ref` from the perspective to TurboModuleManager doesn't really make any sense. So, this diff refactors that bit of code.
Reviewed By: mdvacca
Differential Revision: D16555673
fbshipit-source-id: 2778fc5a372c41847e8296c2e22bb9a8826fcc52
Summary:
When you call a TurboModule method with JS arguments, we necessarily convert these JS args to Java objects/primitives before passing them to the Java implementation of the method. The problem is that we let the type of the JS arg dictate the type of the Java object/primitive to convert said arg to. This means that if a JS developer passes in an `number` to a function that expects an `Array`, we'll convert the number to a `double` and try to call the Java method with that `double`, when it actually expects a `ReadableArray`. This will trigger a JNI error, and crash the program. Ideally, we should be able to catch these type mismatches early on.
In this diff, on every TurboModule method call, I parse the method signature to determine the Java type of each JS argument. Then, for any argument, if the JS arg and the Java arg types aren't compatible, I raise an exception, which gets displayed as a RedBox in development. This diff also implements support for `?number` and `?boolean` argument and return types in TurboModules.
Reviewed By: mdvacca
Differential Revision: D16214814
fbshipit-source-id: 4399bb88c5344cff50aa8fe8d54eb2000990a852
Summary: Looks like FBJNI exports a C Macro that does exactly what `throwIfJNIReportsPendingException` does. Therefore, I'm replacing `throwIfJNIReportsPendingException` with calls to `FACEBOOK_JNI_THROW_PENDING_EXCEPTION()`.
Reviewed By: mdvacca
Differential Revision: D15174820
fbshipit-source-id: 9dfb519352cbd5f37527675323cbabad05e31d4a
Summary:
`jclass` in `JNI` is just a regular local reference. Therefore, it's unsafe to keep a static reference to it. Link: http://journals.ecs.soton.ac.uk/java/tutorial/native1.1/implementing/refs.html.
This bug made it so that when you clicked on `getConstants` twice in the TurboModule playground, the app would crash.
Reviewed By: mdvacca
Differential Revision: D15174821
fbshipit-source-id: 13b2b8726473acc9b07306558044d26bed0db92d
Summary: Previously, we'd override the `TurboModule::get` method inside the `JavaTurboModule` class to return a special `jsi::Function` in the case that the property being accessed was "getConstants". We really don't need to do this because we can simply special-case the invocation of the `getConstants` method inside the `JavaTurboModule::invokeJavaMethod` method.
Reviewed By: mdvacca
Differential Revision: D15174822
fbshipit-source-id: 0ee705be841757d3870c908da911c3872b977a9f
Summary: `jClassName_` is unnecessary because you can use `JNIEnv::GetObjectClass` to get the TurboModule's Java class.
Reviewed By: fkgozali
Differential Revision: D14937480
fbshipit-source-id: 2c1c9be53217331152270dbac3d13f372a2ed818
Summary:
If you call into a Java method (from C++ using JNI) that raises an exception, the JNI call won't actually raise a C++ error. Instead, the `JNIEnv` will record the pending Java exception and the C++ will continue executing as normal. This is bad because the next time you call into JNI, the app will actually crash, unless you explicitly cleared the exception using `JNIEnv::ExceptionClear()` before the JNI call.
With respect to TurboModules, we need to make sure that RedBoxes show up whenever a native methods raise an exception. We also don't want the app to crash when a JNI method call fails because of a raised exception. Therefore, in this diff, I raise a C++ exception if `JNIEnv::ExceptionCheck()` is true.
Reviewed By: mdvacca
Differential Revision: D14738540
fbshipit-source-id: 4c3063aa93ae7aef025bd2dab6b45059bb8fb409
Summary:
If the return type of a TurboModule method is `Promise`, the infra should create a `com.facebook.react.bridge.Promise` object and pass it as the final argument of the TurboModule Java method call. The Java TurboModule method can then do some work asynchronously and either resolve or reject the promise at some point in time.
**Note:** I stacked a diff for error handling on top of this one.
Reviewed By: mdvacca
Differential Revision: D13653156
fbshipit-source-id: 4c30c3223ad8f47c6ba7f1236527aaced01c8ae8
Summary:
This commit moves all the turbo module files for Android to Github.
Note that gradle build is not yet enabled.
Sample Turbo Modules will be added in a later commit.
Other missing features
- Support for `CxxModule`
- Remove usage of folly::dynamic for arguments and result conversion
- Support for Promise return types.
Reviewed By: mdvacca
Differential Revision: D13647438
fbshipit-source-id: 5f1188556d6c64bfa2b2fd2146ac72b0fb456891
Ramanpreet Nara
Eric Williamson
Kevin Gozali
Ram N