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private let UNIFFI_RUST_FUTURE_POLL_READY: Int8 = 0
private let UNIFFI_RUST_FUTURE_POLL_MAYBE_READY: Int8 = 1
fileprivate let uniffiContinuationHandleMap = UniffiHandleMap<UnsafeContinuation<Int8, Never>>()
fileprivate func uniffiRustCallAsync<F, T>(
rustFutureFunc: () -> UInt64,
pollFunc: (UInt64, @escaping UniffiRustFutureContinuationCallback, UInt64) -> (),
completeFunc: (UInt64, UnsafeMutablePointer<RustCallStatus>) -> F,
freeFunc: (UInt64) -> (),
liftFunc: (F) throws -> T,
errorHandler: ((RustBuffer) throws -> Error)?
) async throws -> T {
// Make sure to call uniffiEnsureInitialized() since future creation doesn't have a
// RustCallStatus param, so doesn't use makeRustCall()
uniffiEnsureInitialized()
let rustFuture = rustFutureFunc()
defer {
freeFunc(rustFuture)
}
var pollResult: Int8;
repeat {
pollResult = await withUnsafeContinuation {
pollFunc(
rustFuture,
uniffiFutureContinuationCallback,
uniffiContinuationHandleMap.insert(obj: $0)
)
}
} while pollResult != UNIFFI_RUST_FUTURE_POLL_READY
return try liftFunc(makeRustCall(
{ completeFunc(rustFuture, $0) },
errorHandler: errorHandler
))
}
// Callback handlers for an async calls. These are invoked by Rust when the future is ready. They
// lift the return value or error and resume the suspended function.
fileprivate func uniffiFutureContinuationCallback(handle: UInt64, pollResult: Int8) {
if let continuation = try? uniffiContinuationHandleMap.remove(handle: handle) {
continuation.resume(returning: pollResult)
} else {
print("uniffiFutureContinuationCallback invalid handle")
}
}
{%- if ci.has_async_callback_interface_definition() %}
private func uniffiTraitInterfaceCallAsync<T>(
makeCall: @escaping () async throws -> T,
handleSuccess: @escaping (T) -> (),
handleError: @escaping (Int8, RustBuffer) -> ()
) -> UniffiForeignFuture {
let task = Task {
do {
handleSuccess(try await makeCall())
} catch {
handleError(CALL_UNEXPECTED_ERROR, {{ Type::String.borrow()|lower_fn }}(String(describing: error)))
}
}
let handle = UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.insert(obj: task)
return UniffiForeignFuture(handle: handle, free: uniffiForeignFutureFree)
}
private func uniffiTraitInterfaceCallAsyncWithError<T, E>(
makeCall: @escaping () async throws -> T,
handleSuccess: @escaping (T) -> (),
handleError: @escaping (Int8, RustBuffer) -> (),
lowerError: @escaping (E) -> RustBuffer
) -> UniffiForeignFuture {
let task = Task {
do {
handleSuccess(try await makeCall())
} catch let error as E {
handleError(CALL_ERROR, lowerError(error))
} catch {
handleError(CALL_UNEXPECTED_ERROR, {{ Type::String.borrow()|lower_fn }}(String(describing: error)))
}
}
let handle = UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.insert(obj: task)
return UniffiForeignFuture(handle: handle, free: uniffiForeignFutureFree)
}
// Borrow the callback handle map implementation to store foreign future handles
// TODO: consolidate the handle-map code (https://github.com/mozilla/uniffi-rs/pull/1823)
fileprivate var UNIFFI_FOREIGN_FUTURE_HANDLE_MAP = UniffiHandleMap<UniffiForeignFutureTask>()
// Protocol for tasks that handle foreign futures.
//
// Defining a protocol allows all tasks to be stored in the same handle map. This can't be done
// with the task object itself, since has generic parameters.
protocol UniffiForeignFutureTask {
func cancel()
}
extension Task: UniffiForeignFutureTask {}
private func uniffiForeignFutureFree(handle: UInt64) {
do {
let task = try UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.remove(handle: handle)
// Set the cancellation flag on the task. If it's still running, the code can check the
// cancellation flag or call `Task.checkCancellation()`. If the task has completed, this is
// a no-op.
task.cancel()
} catch {
print("uniffiForeignFutureFree: handle missing from handlemap")
}
}
// For testing
public func uniffiForeignFutureHandleCount{{ ci.namespace()|class_name }}() -> Int {
UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.count
}
{%- endif %}
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