Add Sendable annotations to new async APIs

Sources/NIOHTTP2/HTTP2ChannelHandler+InlineStreamMultiplexer.swift

@@ -229,15 +229,22 @@ extension NIOHTTP2Handler {
     /// You can open a stream by calling ``openStream(_:)``. Locally-initiated stream channel objects are initialized upon creation using the supplied `initializer` which returns a type
     /// `Output`. This type may be `HTTP2Frame` or changed to any other type.
     @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
-    public struct AsyncStreamMultiplexer<InboundStreamOutput> {
-        private let inlineStreamMultiplexer: InlineStreamMultiplexer
+    public struct AsyncStreamMultiplexer<InboundStreamOutput: Sendable>: Sendable {
+        private let inlineStreamMultiplexer: NIOLoopBound<InlineStreamMultiplexer>
+        private let eventLoop: any EventLoop
         public let inbound: NIOHTTP2AsyncSequence<InboundStreamOutput>
 
         // Cannot be created by users.
-        internal init(_ inlineStreamMultiplexer: InlineStreamMultiplexer, continuation: any AnyContinuation, inboundStreamChannels: NIOHTTP2AsyncSequence<InboundStreamOutput>) {
-            self.inlineStreamMultiplexer = inlineStreamMultiplexer
-            self.inlineStreamMultiplexer.setChannelContinuation(continuation)
+        internal init(
+            _ inlineStreamMultiplexer: InlineStreamMultiplexer,
+            continuation: any AnyContinuation,
+            inboundStreamChannels: NIOHTTP2AsyncSequence<InboundStreamOutput>,
+            eventLoop: any EventLoop
+        ) {
+            self.inlineStreamMultiplexer = NIOLoopBound(inlineStreamMultiplexer, eventLoop: eventLoop)
+            inlineStreamMultiplexer.setChannelContinuation(continuation)
             self.inbound = inboundStreamChannels
+            self.eventLoop = eventLoop
         }
 
 
@@ -246,7 +253,9 @@ extension NIOHTTP2Handler {
         ///   initializing the stream's `Channel`.
         /// - Returns: The result of the `initializer`.
         public func openStream<Output: Sendable>(_ initializer: @escaping NIOChannelInitializerWithOutput<Output>) async throws -> Output {
-            return try await self.inlineStreamMultiplexer.createStreamChannel(initializer).get()
+            return try await self.eventLoop.submit {
+                self.inlineStreamMultiplexer.value.createStreamChannel(initializer)
+            }.flatMap { $0 }.get()
         }
     }
 }

Sources/NIOHTTP2/HTTP2ChannelHandler.swift

@@ -1187,7 +1187,12 @@ extension NIOHTTP2Handler {
 
         switch self.inboundStreamMultiplexer {
         case let .some(.inline(multiplexer)):
-            return AsyncStreamMultiplexer(multiplexer, continuation: continuation, inboundStreamChannels: inboundStreamChannels)
+            return AsyncStreamMultiplexer(
+                multiplexer,
+                continuation: continuation,
+                inboundStreamChannels: inboundStreamChannels,
+                eventLoop: self.eventLoop!
+            )
         case .some(.legacy), .none:
             throw NIOHTTP2Errors.missingMultiplexer()
         }

Sources/NIOHTTP2/HTTP2PipelineHelpers.swift

@@ -605,7 +605,7 @@ extension ChannelPipeline.SynchronousOperations {
 }
 
 /// `NIONegotiatedHTTPVersion` is a generic negotiation result holder for HTTP/1.1 and HTTP/2
-public enum NIONegotiatedHTTPVersion<HTTP1Output: Sendable, HTTP2Output: Sendable> {
+public enum NIONegotiatedHTTPVersion<HTTP1Output: Sendable, HTTP2Output: Sendable>: Sendable {
     /// Protocol negotiation resulted in the connection using HTTP/1.1.
     case http1_1(HTTP1Output)
     /// Protocol negotiation resulted in the connection using HTTP/2.