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// Async return type handlers
internal const val UNIFFI_RUST_FUTURE_POLL_READY = 0.toByte()
internal const val UNIFFI_RUST_FUTURE_POLL_WAKE = 1.toByte()
internal val uniffiContinuationHandleMap = UniffiHandleMap<CancellableContinuation<Byte>>()
// FFI type for Rust future continuations
internal object uniffiRustFutureContinuationCallbackImpl: UniffiRustFutureContinuationCallback {
override fun callback(data: Long, pollResult: Byte) {
uniffiContinuationHandleMap.remove(data).resume(pollResult)
}
}
internal suspend fun<T, F, E: kotlin.Exception> uniffiRustCallAsync(
rustFuture: Long,
pollFunc: (Long, UniffiRustFutureContinuationCallback, Long) -> Unit,
completeFunc: (Long, UniffiRustCallStatus) -> F,
freeFunc: (Long) -> Unit,
liftFunc: (F) -> T,
errorHandler: UniffiRustCallStatusErrorHandler<E>
): T {
try {
do {
val pollResult = suspendCancellableCoroutine<Byte> { continuation ->
pollFunc(
rustFuture,
uniffiRustFutureContinuationCallbackImpl,
uniffiContinuationHandleMap.insert(continuation)
)
}
} while (pollResult != UNIFFI_RUST_FUTURE_POLL_READY);
return liftFunc(
uniffiRustCallWithError(errorHandler, { status -> completeFunc(rustFuture, status) })
)
} finally {
freeFunc(rustFuture)
}
}
{%- if ci.has_async_callback_interface_definition() %}
internal inline fun<T> uniffiTraitInterfaceCallAsync(
crossinline makeCall: suspend () -> T,
crossinline handleSuccess: (T) -> Unit,
crossinline handleError: (UniffiRustCallStatus.ByValue) -> Unit,
uniffiOutDroppedCallback: UniffiForeignFutureDroppedCallbackStruct,
) {
// Using `GlobalScope` is labeled as a "delicate API" and generally discouraged in Kotlin programs, since it breaks structured concurrency.
// However, our parent task is a Rust future, so we're going to need to break structure concurrency in any case.
//
// Uniffi does its best to support structured concurrency across the FFI.
// If the Rust future is dropped, `uniffiForeignFutureDroppedCallbackImpl` is called, which will cancel the Kotlin coroutine if it's still running.
@OptIn(DelicateCoroutinesApi::class)
val job = GlobalScope.launch coroutineBlock@ {
// Note: it's important we call either `handleSuccess` or `handleError` exactly once. Each
// call consumes an Arc reference, which means there should be no possibility of a double
// call. The following code is structured so that will will never call both `handleSuccess`
// and `handleError`, even in the face of weird exceptions.
//
// In extreme circumstances we may not call either, for example if we fail to make the JNA
// call to `handleSuccess`. This means we will leak the Arc reference, which is better than
// double-freeing it.
val callResult = try {
makeCall()
} catch(e: kotlin.Exception) {
handleError(
UniffiRustCallStatus.create(
UNIFFI_CALL_UNEXPECTED_ERROR,
{{ Type::String.borrow()|lower_fn }}(e.toString()),
)
)
return@coroutineBlock
}
handleSuccess(callResult)
}
val handle = uniffiForeignFutureHandleMap.insert(job)
uniffiOutDroppedCallback.uniffiSetValue(UniffiForeignFutureDroppedCallbackStruct(handle, uniffiForeignFutureDroppedCallbackImpl))
}
internal inline fun<T, reified E: Throwable> uniffiTraitInterfaceCallAsyncWithError(
crossinline makeCall: suspend () -> T,
crossinline handleSuccess: (T) -> Unit,
crossinline handleError: (UniffiRustCallStatus.ByValue) -> Unit,
crossinline lowerError: (E) -> RustBuffer.ByValue,
uniffiOutDroppedCallback: UniffiForeignFutureDroppedCallbackStruct,
) {
// See uniffiTraitInterfaceCallAsync for details on `DelicateCoroutinesApi`
@OptIn(DelicateCoroutinesApi::class)
val job = GlobalScope.launch coroutineBlock@ {
// See the note in uniffiTraitInterfaceCallAsync for details on `handleSuccess` and
// `handleError`.
val callResult = try {
makeCall()
} catch(e: kotlin.Exception) {
if (e is E) {
handleError(
UniffiRustCallStatus.create(
UNIFFI_CALL_ERROR,
lowerError(e),
)
)
} else {
handleError(
UniffiRustCallStatus.create(
UNIFFI_CALL_UNEXPECTED_ERROR,
{{ Type::String.borrow()|lower_fn }}(e.toString()),
)
)
}
return@coroutineBlock
}
handleSuccess(callResult)
}
val handle = uniffiForeignFutureHandleMap.insert(job)
uniffiOutDroppedCallback.uniffiSetValue(UniffiForeignFutureDroppedCallbackStruct(handle, uniffiForeignFutureDroppedCallbackImpl))
}
internal val uniffiForeignFutureHandleMap = UniffiHandleMap<Job>()
internal object uniffiForeignFutureDroppedCallbackImpl: UniffiForeignFutureDroppedCallback {
override fun callback(handle: Long) {
val job = uniffiForeignFutureHandleMap.remove(handle)
if (!job.isCompleted) {
job.cancel()
}
}
}
// For testing
public fun uniffiForeignFutureHandleCount() = uniffiForeignFutureHandleMap.size
{%- endif %}