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Diffstat (limited to 'third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift')
-rw-r--r-- | third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift new file mode 100644 index 0000000000..695208861d --- /dev/null +++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift @@ -0,0 +1,62 @@ +private let UNIFFI_RUST_FUTURE_POLL_READY: Int8 = 0 +private let UNIFFI_RUST_FUTURE_POLL_MAYBE_READY: Int8 = 1 + +fileprivate func uniffiRustCallAsync<F, T>( + rustFutureFunc: () -> UnsafeMutableRawPointer, + pollFunc: (UnsafeMutableRawPointer, UnsafeMutableRawPointer) -> (), + completeFunc: (UnsafeMutableRawPointer, UnsafeMutablePointer<RustCallStatus>) -> F, + freeFunc: (UnsafeMutableRawPointer) -> (), + 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, ContinuationHolder($0).toOpaque()) + } + } 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(ptr: UnsafeMutableRawPointer, pollResult: Int8) { + ContinuationHolder.fromOpaque(ptr).resume(pollResult) +} + +// Wraps UnsafeContinuation in a class so that we can use reference counting when passing it across +// the FFI +fileprivate class ContinuationHolder { + let continuation: UnsafeContinuation<Int8, Never> + + init(_ continuation: UnsafeContinuation<Int8, Never>) { + self.continuation = continuation + } + + func resume(_ pollResult: Int8) { + self.continuation.resume(returning: pollResult) + } + + func toOpaque() -> UnsafeMutableRawPointer { + return Unmanaged<ContinuationHolder>.passRetained(self).toOpaque() + } + + static func fromOpaque(_ ptr: UnsafeRawPointer) -> ContinuationHolder { + return Unmanaged<ContinuationHolder>.fromOpaque(ptr).takeRetainedValue() + } +} + +fileprivate func uniffiInitContinuationCallback() { + {{ ci.ffi_rust_future_continuation_callback_set().name() }}(uniffiFutureContinuationCallback) +} |