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I'll give this a closer look actually tomorrow |
| printer.print( | ||
| """ | ||
| let environment$ = try! JavaVirtualMachine.shared().environment() | ||
| environment$.interface.PushLocalFrame(environment$, \(paramCount * 2 + 4)) |
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we should be checking the result of the push, we may be OOMing the JVM here, and we'd pop the wrong frame because we didn't push one (!)
jint PushLocalFrame(JNIEnv *env, jint capacity);
Creates a new local reference frame, in which at least a given number of local references can be created. Returns 0 on success, a negative number and a pending OutOfMemoryError on failure.
if pushed != JNI_OK
and need to guard the pop the same...
We may suggest doing a withFrame pattern tbh: swiftlang/swift-java-jni-core#11
| // and call it. | ||
| // Size the frame to 1 ref per argument; no result ref needed for void calls. | ||
| let jniMethod = environment.interface.CallVoidMethodA! | ||
| environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each args) + 1)) |
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Again we need to check the result type, so I think we need a with... pattern here - proposing one here swiftlang/swift-java-jni-core#11
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We were hitting "JNI ERROR (app bug): local reference table overflow (max=512)".
In order to improve this, I've added some
DeleteLocalRefsand explicitPush/Popof local frames to SwiftJava where I saw fit.These changes made our app stopping crashing with that error.
This also modifies the "implement Swift protocols in Java" generated wrappers, such that all calls are wrapped in a local frame to ensure that resources are cleaned up, as this might not be called from a JVM thread and be auto-cleaned.