Strict concurrency for NIOTransportServices and tests

Package.swift

@@ -15,13 +15,31 @@
 
 import PackageDescription
 
+let strictConcurrencyDevelopment = false
+
+let strictConcurrencySettings: [SwiftSetting] = {
+    var initialSettings: [SwiftSetting] = []
+    initialSettings.append(contentsOf: [
+        .enableUpcomingFeature("StrictConcurrency"),
+        .enableUpcomingFeature("InferSendableFromCaptures"),
+    ])
+
+    if strictConcurrencyDevelopment {
+        // -warnings-as-errors here is a workaround so that IDE-based development can
+        // get tripped up on -require-explicit-sendable.
+        initialSettings.append(.unsafeFlags(["-require-explicit-sendable", "-warnings-as-errors"]))
+    }
+
+    return initialSettings
+}()
+
 let package = Package(
     name: "swift-nio-transport-services",
     products: [
         .library(name: "NIOTransportServices", targets: ["NIOTransportServices"])
     ],
     dependencies: [
-        .package(url: "https://github.com/apple/swift-nio.git", from: "2.62.0"),
+        .package(url: "https://github.com/apple/swift-nio.git", from: "2.81.0"),
         .package(url: "https://github.com/apple/swift-atomics.git", from: "1.0.2"),
     ],
     targets: [
@@ -33,7 +51,8 @@ let package = Package(
                 .product(name: "NIOFoundationCompat", package: "swift-nio"),
                 .product(name: "NIOTLS", package: "swift-nio"),
                 .product(name: "Atomics", package: "swift-atomics"),
-            ]
+            ],
+            swiftSettings: strictConcurrencySettings
         ),
         .executableTarget(
             name: "NIOTSHTTPClient",
@@ -58,7 +77,8 @@ let package = Package(
                 .product(name: "NIOCore", package: "swift-nio"),
                 .product(name: "NIOEmbedded", package: "swift-nio"),
                 .product(name: "Atomics", package: "swift-atomics"),
-            ]
+            ],
+            swiftSettings: strictConcurrencySettings
         ),
     ]
 )

Sources/NIOTransportServices/AcceptHandler.swift

@@ -20,11 +20,11 @@ internal class AcceptHandler<ChildChannel: Channel>: ChannelInboundHandler {
     typealias InboundIn = ChildChannel
     typealias InboundOut = ChildChannel
 
-    private let childChannelInitializer: ((Channel) -> EventLoopFuture<Void>)?
+    private let childChannelInitializer: (@Sendable (Channel) -> EventLoopFuture<Void>)?
     private let childChannelOptions: ChannelOptions.Storage
 
     init(
-        childChannelInitializer: ((Channel) -> EventLoopFuture<Void>)?,
+        childChannelInitializer: (@Sendable (Channel) -> EventLoopFuture<Void>)?,
         childChannelOptions: ChannelOptions.Storage
     ) {
         self.childChannelInitializer = childChannelInitializer
@@ -35,11 +35,12 @@ internal class AcceptHandler<ChildChannel: Channel>: ChannelInboundHandler {
         let newChannel = self.unwrapInboundIn(data)
         let childLoop = newChannel.eventLoop
         let ctxEventLoop = context.eventLoop
-        let childInitializer = self.childChannelInitializer ?? { _ in childLoop.makeSucceededFuture(()) }
+        let childInitializer = self.childChannelInitializer ?? { @Sendable _ in childLoop.makeSucceededFuture(()) }
+        let childChannelOptions = self.childChannelOptions
 
-        @inline(__always)
+        @Sendable @inline(__always)
         func setupChildChannel() -> EventLoopFuture<Void> {
-            self.childChannelOptions.applyAllChannelOptions(to: newChannel).flatMap { () -> EventLoopFuture<Void> in
+            childChannelOptions.applyAllChannelOptions(to: newChannel).flatMap { () -> EventLoopFuture<Void> in
                 childLoop.assertInEventLoop()
                 return childInitializer(newChannel)
             }
@@ -48,8 +49,8 @@ internal class AcceptHandler<ChildChannel: Channel>: ChannelInboundHandler {
         @inline(__always)
         func fireThroughPipeline(_ future: EventLoopFuture<Void>) {
             ctxEventLoop.assertInEventLoop()
-            future.flatMap { (_) -> EventLoopFuture<Void> in
-                ctxEventLoop.assertInEventLoop()
+            assert(ctxEventLoop === context.eventLoop)
+            future.assumeIsolated().flatMap { (_) -> EventLoopFuture<Void> in
                 guard context.channel.isActive else {
                     return newChannel.close().flatMapThrowing {
                         throw ChannelError.ioOnClosedChannel
@@ -75,4 +76,7 @@ internal class AcceptHandler<ChildChannel: Channel>: ChannelInboundHandler {
         }
     }
 }
+
+@available(*, unavailable)
+extension AcceptHandler: Sendable {}
 #endif

Sources/NIOTransportServices/Datagram/NIOTSDatagramBootstrap.swift

@@ -41,7 +41,7 @@ import Network
 @available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *)
 public final class NIOTSDatagramBootstrap {
     private let group: EventLoopGroup
-    private var channelInitializer: ((Channel) -> EventLoopFuture<Void>)?
+    private var channelInitializer: (@Sendable (Channel) -> EventLoopFuture<Void>)?
     private var connectTimeout: TimeAmount = TimeAmount.seconds(10)
     private var channelOptions = ChannelOptions.Storage()
     private var qos: DispatchQoS?
@@ -79,7 +79,8 @@ public final class NIOTSDatagramBootstrap {
     ///
     /// - parameters:
     ///     - handler: A closure that initializes the provided `Channel`.
-    public func channelInitializer(_ handler: @escaping (Channel) -> EventLoopFuture<Void>) -> Self {
+    @preconcurrency
+    public func channelInitializer(_ handler: @Sendable @escaping (Channel) -> EventLoopFuture<Void>) -> Self {
         self.channelInitializer = handler
         return self
     }
@@ -180,17 +181,18 @@ public final class NIOTSDatagramBootstrap {
         }
     }
 
-    private func connect0(_ binder: @escaping (Channel, EventLoopPromise<Void>) -> Void) -> EventLoopFuture<Channel> {
+    private func connect0(
+        _ binder: @Sendable @escaping (Channel, EventLoopPromise<Void>) -> Void
+    ) -> EventLoopFuture<Channel> {
         let conn: Channel = NIOTSDatagramChannel(
             eventLoop: self.group.next() as! NIOTSEventLoop,
             qos: self.qos,
             udpOptions: self.udpOptions,
             tlsOptions: self.tlsOptions
         )
-        let initializer = self.channelInitializer ?? { _ in conn.eventLoop.makeSucceededFuture(()) }
-        let channelOptions = self.channelOptions
+        let initializer = self.channelInitializer ?? { @Sendable _ in conn.eventLoop.makeSucceededFuture(()) }
 
-        return conn.eventLoop.submit {
+        return conn.eventLoop.submit { [channelOptions, connectTimeout] in
             channelOptions.applyAllChannelOptions(to: conn).flatMap {
                 initializer(conn)
             }.flatMap {
@@ -199,8 +201,8 @@ public final class NIOTSDatagramBootstrap {
             }.flatMap {
                 let connectPromise: EventLoopPromise<Void> = conn.eventLoop.makePromise()
                 binder(conn, connectPromise)
-                let cancelTask = conn.eventLoop.scheduleTask(in: self.connectTimeout) {
-                    connectPromise.fail(ChannelError.connectTimeout(self.connectTimeout))
+                let cancelTask = conn.eventLoop.scheduleTask(in: connectTimeout) {
+                    connectPromise.fail(ChannelError.connectTimeout(connectTimeout))
                     conn.close(promise: nil)
                 }
 
@@ -215,4 +217,7 @@ public final class NIOTSDatagramBootstrap {
         }.flatMap { $0 }
     }
 }
+
+@available(*, unavailable)
+extension NIOTSDatagramBootstrap: Sendable {}
 #endif

Sources/NIOTransportServices/Datagram/NIOTSDatagramChannel.swift

@@ -243,4 +243,7 @@ extension NIOTSDatagramChannel {
         SynchronousOptions(channel: self)
     }
 }
+
+@available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *)
+extension NIOTSDatagramChannel: @unchecked Sendable {}
 #endif

Sources/NIOTransportServices/Datagram/NIOTSDatagramListener.swift

@@ -57,8 +57,8 @@ import Network
 public final class NIOTSDatagramListenerBootstrap {
     private let group: EventLoopGroup
     private let childGroup: EventLoopGroup
-    private var serverChannelInit: ((Channel) -> EventLoopFuture<Void>)?
-    private var childChannelInit: ((Channel) -> EventLoopFuture<Void>)?
+    private var serverChannelInit: (@Sendable (Channel) -> EventLoopFuture<Void>)?
+    private var childChannelInit: (@Sendable (Channel) -> EventLoopFuture<Void>)?
     private var serverChannelOptions = ChannelOptions.Storage()
     private var childChannelOptions = ChannelOptions.Storage()
     private var serverQoS: DispatchQoS?
@@ -154,7 +154,9 @@ public final class NIOTSDatagramListenerBootstrap {
     ///
     /// - parameters:
     ///     - initializer: A closure that initializes the provided `Channel`.
-    public func serverChannelInitializer(_ initializer: @escaping (Channel) -> EventLoopFuture<Void>) -> Self {
+    @preconcurrency
+    public func serverChannelInitializer(_ initializer: @Sendable @escaping (Channel) -> EventLoopFuture<Void>) -> Self
+    {
         self.serverChannelInit = initializer
         return self
     }
@@ -167,7 +169,8 @@ public final class NIOTSDatagramListenerBootstrap {
     ///
     /// - parameters:
     ///     - initializer: A closure that initializes the provided `Channel`.
-    public func childChannelInitializer(_ initializer: @escaping (Channel) -> EventLoopFuture<Void>) -> Self {
+    @preconcurrency
+    public func childChannelInitializer(_ initializer: @Sendable @escaping (Channel) -> EventLoopFuture<Void>) -> Self {
         self.childChannelInit = initializer
         return self
     }
@@ -305,10 +308,13 @@ public final class NIOTSDatagramListenerBootstrap {
     private func bind0(
         existingNWListener: NWListener? = nil,
         shouldRegister: Bool,
-        _ binder: @escaping (NIOTSDatagramListenerChannel, EventLoopPromise<Void>) -> Void
+        _ binder: @Sendable @escaping (NIOTSDatagramListenerChannel, EventLoopPromise<Void>) -> Void
     ) -> EventLoopFuture<Channel> {
         let eventLoop = self.group.next() as! NIOTSEventLoop
-        let serverChannelInit = self.serverChannelInit ?? { _ in eventLoop.makeSucceededFuture(()) }
+        let serverChannelInit =
+            self.serverChannelInit ?? {
+                @Sendable _ in eventLoop.makeSucceededFuture(())
+            }
         let childChannelInit = self.childChannelInit
         let serverChannelOptions = self.serverChannelOptions
         let childChannelOptions = self.childChannelOptions
@@ -339,17 +345,19 @@ public final class NIOTSDatagramListenerBootstrap {
             )
         }
 
-        return eventLoop.submit {
+        return eventLoop.submit { [bindTimeout] in
             serverChannelOptions.applyAllChannelOptions(to: serverChannel).flatMap {
                 serverChannelInit(serverChannel)
             }.flatMap {
                 eventLoop.assertInEventLoop()
-                return serverChannel.pipeline.addHandler(
-                    AcceptHandler<NIOTSDatagramChannel>(
-                        childChannelInitializer: childChannelInit,
-                        childChannelOptions: childChannelOptions
+                return eventLoop.makeCompletedFuture {
+                    try serverChannel.pipeline.syncOperations.addHandler(
+                        AcceptHandler<NIOTSDatagramChannel>(
+                            childChannelInitializer: childChannelInit,
+                            childChannelOptions: childChannelOptions
+                        )
                     )
-                )
+                }
             }.flatMap {
                 if shouldRegister {
                     return serverChannel.register()
@@ -360,7 +368,7 @@ public final class NIOTSDatagramListenerBootstrap {
                 let bindPromise = eventLoop.makePromise(of: Void.self)
                 binder(serverChannel, bindPromise)
 
-                if let bindTimeout = self.bindTimeout {
+                if let bindTimeout = bindTimeout {
                     let cancelTask = eventLoop.scheduleTask(in: bindTimeout) {
                         bindPromise.fail(NIOTSErrors.BindTimeout(timeout: bindTimeout))
                         serverChannel.close(promise: nil)
@@ -382,4 +390,7 @@ public final class NIOTSDatagramListenerBootstrap {
         }
     }
 }
+
+@available(*, unavailable)
+extension NIOTSDatagramListenerBootstrap: Sendable {}
 #endif

Sources/NIOTransportServices/Datagram/NIOTSDatagramListenerChannel.swift

@@ -135,7 +135,7 @@ internal final class NIOTSDatagramListenerChannel: StateManagedListenerChannel<N
             tlsOptions: self.childTLSOptions
         )
 
-        self.pipeline.fireChannelRead(NIOAny(newChannel))
+        self.pipeline.fireChannelRead(newChannel)
         self.pipeline.fireChannelReadComplete()
     }
 

Sources/NIOTransportServices/NIOTSChannelOptions.swift

@@ -13,11 +13,11 @@
 //===----------------------------------------------------------------------===//
 #if canImport(Network)
 import NIOCore
-@preconcurrency import Network
+import Network
 
 /// Options that can be set explicitly and only on bootstraps provided by `NIOTransportServices`.
 @available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *)
-public struct NIOTSChannelOptions {
+public struct NIOTSChannelOptions: Sendable {
     /// See: ``Types/NIOTSWaitForActivityOption``.
     public static let waitForActivity = NIOTSChannelOptions.Types.NIOTSWaitForActivityOption()
 
@@ -32,7 +32,7 @@ public struct NIOTSChannelOptions {
 
     /// See: ``Types/NIOTSMetadataOption``
     public static let metadata = {
-        (definition: NWProtocolDefinition) -> NIOTSChannelOptions.Types.NIOTSMetadataOption in
+        @Sendable (definition: NWProtocolDefinition) -> NIOTSChannelOptions.Types.NIOTSMetadataOption in
         .init(definition: definition)
     }
 
@@ -66,7 +66,7 @@ public struct NIOTSChannelOptions {
 @available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *)
 extension NIOTSChannelOptions {
     /// A namespace for ``NIOTSChannelOptions`` datastructures.
-    public enum Types {
+    public enum Types: Sendable {
         /// ``NIOTSWaitForActivityOption`` controls whether the `Channel` should wait for connection changes
         /// during the connection process if the connection attempt fails. If Network.framework believes that
         /// a connection may succeed in future, it may transition into the `.waiting` state. By default, this option