Enable runOnBackgroundThread for spawn() on Windows

Author: iCharlesHu

Sources/Subprocess/Configuration.swift

@@ -660,7 +660,11 @@ internal struct IODescriptor: ~Copyable {
     #endif
 
     internal var closeWhenDone: Bool
+    #if canImport(WinSDK)
+    internal nonisolated(unsafe) let descriptor: Descriptor
+    #else
     internal let descriptor: Descriptor
+    #endif
 
     internal init(
         _ descriptor: Descriptor,

Sources/Subprocess/IO/AsyncIO+Windows.swift

@@ -60,9 +60,11 @@ final class AsyncIO: @unchecked Sendable {
     internal init() {
         var maybeSetupError: SubprocessError? = nil
         // Create the the completion port
-        guard let ioCompletionPort = CreateIoCompletionPort(
-            INVALID_HANDLE_VALUE, nil, 0, 0
-        ), ioCompletionPort != INVALID_HANDLE_VALUE else {
+        guard
+            let ioCompletionPort = CreateIoCompletionPort(
+                INVALID_HANDLE_VALUE, nil, 0, 0
+            ), ioCompletionPort != INVALID_HANDLE_VALUE
+        else {
             let error = SubprocessError(
                 code: .init(.asyncIOFailed("CreateIoCompletionPort failed")),
                 underlyingError: .init(rawValue: GetLastError())
@@ -86,50 +88,12 @@ final class AsyncIO: @unchecked Sendable {
                     }
                 }
 
-                // Monitor loop
-                while true {
-                    var bytesTransferred: DWORD = 0
-                    var targetFileDescriptor: UInt64 = 0
-                    var overlapped: LPOVERLAPPED? = nil
                 // Monitor loop
                 while true {
                     var bytesTransferred: DWORD = 0
                     var targetFileDescriptor: UInt64 = 0
                     var overlapped: LPOVERLAPPED? = nil
 
-                    let monitorResult = GetQueuedCompletionStatus(
-                        context.ioCompletionPort,
-                        &bytesTransferred,
-                        &targetFileDescriptor,
-                        &overlapped,
-                        INFINITE
-                    )
-                    if !monitorResult {
-                        let lastError = GetLastError()
-                        if lastError == ERROR_BROKEN_PIPE {
-                            // We finished reading the handle. Signal EOF by
-                            // finishing the stream.
-                            // NOTE: here we deliberately leave now unused continuation
-                            // in the store. Windows does not offer an API to remove a
-                            // HANDLE from an IOCP port, therefore we leave the registration
-                            // to signify the HANDLE has already been resisted.
-                            let continuation = _registration.withLock { store -> SignalStream.Continuation? in
-                                if let continuation = store[targetFileDescriptor] {
-                                    return continuation
-                                }
-                                return nil
-                            }
-                            continuation?.finish()
-                            continue
-                        } else {
-                            let error = SubprocessError(
-                                code: .init(.asyncIOFailed("GetQueuedCompletionStatus failed")),
-                                underlyingError: .init(rawValue: lastError)
-                            )
-                            reportError(error)
-                            break
-                        }
-                    }
                     let monitorResult = GetQueuedCompletionStatus(
                         context.ioCompletionPort,
                         &bytesTransferred,

Sources/Subprocess/Platforms/Subprocess+Unix.swift

@@ -674,51 +674,6 @@ extension PlatformOptions: CustomStringConvertible, CustomDebugStringConvertible
         return self.description(withIndent: 0)
     }
 }
-
-// Special keys used in Error's user dictionary
-extension String {
-    static let debugDescriptionErrorKey = "DebugDescription"
-}
-
-internal func pthread_create(_ body: @Sendable @escaping () -> ()) throws(SubprocessError.UnderlyingError) -> pthread_t {
-    final class Context {
-        let body: @Sendable () -> ()
-        init(body: @Sendable @escaping () -> Void) {
-            self.body = body
-        }
-    }
-    #if canImport(Glibc) || canImport(Musl)
-    func proc(_ context: UnsafeMutableRawPointer?) -> UnsafeMutableRawPointer? {
-        (Unmanaged<AnyObject>.fromOpaque(context!).takeRetainedValue() as! Context).body()
-        return nil
-    }
-    #elseif canImport(Bionic)
-    func proc(_ context: UnsafeMutableRawPointer) -> UnsafeMutableRawPointer {
-        (Unmanaged<AnyObject>.fromOpaque(context).takeRetainedValue() as! Context).body()
-        return context
-    }
-    #endif
-    #if (os(Linux) && canImport(Glibc)) || canImport(Bionic)
-    var thread = pthread_t()
-    #else
-    var thread: pthread_t?
-    #endif
-    let rc = pthread_create(
-        &thread,
-        nil,
-        proc,
-        Unmanaged.passRetained(Context(body: body)).toOpaque()
-    )
-    if rc != 0 {
-        throw SubprocessError.UnderlyingError(rawValue: rc)
-    }
-    #if (os(Linux) && canImport(Glibc)) || canImport(Bionic)
-    return thread
-    #else
-    return thread!
-    #endif
-}
-
 #endif // !canImport(Darwin)
 
 extension ProcessIdentifier {