Add Async Await support to NIOTSListenerBootstrap childChannelInitializer

[hishnash]

Expected behavior

When using NIOTSListenerBootstrap I would expect to be able to provide an async block since the common methods one would call within this have await-able versions. eg channel.pipeline.addHandler.

SwiftNIO version/commit hash

swift-nio==2.33.0
swift-swift-nio-transport-services==1.11.3

Swift & OS version (output of swift --version && uname -a)

swift-driver version: 1.26.9 Apple Swift version 5.5.1 (swiftlang-1300.0.31.4 clang-1300.0.29.6)
Target: x86_64-apple-macosx12.0
Darwin Matthauss-MacBook-Pro-2.local 21.2.0 Darwin Kernel Version 21.2.0: Wed Oct 20 00:23:27 PDT 2021; root:xnu-8019.60.40.0.1~26/RELEASE_X86_64 x86_64

P.S maybe there is an easy way to create an async task connected to the event loop that returns a EventLoopFuture<Void> but I cant find such a method on the channel.eventloop (more of an issue for SwiftNIO repo through)

[Lukasa]

Yeah, this is something we want to do, but thus far haven't got around to it. In the meantime, you can use this:

extension NIOTSListenerBootstrap {
    public func serverChannelInitializer(_ initializer: @escaping @Sendable (Channel) async throws -> Void) -> Self {
        return self.serverChannelInitializer { channel in
            let promise = channel.eventLoop.makePromise(of: Void.self)
            promise.completeWithTask {
                await initializer(channel)
            }
            return promise.futureResult
        }
    }

    public func childChannelInitializer(_ initializer: @escaping @Sendable (Channel) async throws -> Void) -> Self {
        return self.childChannelInitializer { channel in
            let promise = channel.eventLoop.makePromise(of: Void.self)
            promise.completeWithTask {
                await initializer(channel)
            }
            return promise.futureResult
        }
    }
}