feat: Implement AsyncEventLoop and MultiThreadedEventLoopGroup

[scottmarchant]

Summary

Implements AsyncEventLoop and MultiThreadedEventLoopGroup atop AsyncEventLoopExecutor for non-Posix runtimes.

Details

• 023e473 feat: Implement AsynceEventLoop and MultiThreadedEventLoopGroup using Swift Concurrency and the AsyncEventLoopExecutor. Forms a key foundation for several vapor repositories to use NIO without using NIOPosix. This enables a large amount of wasm compilation for packages that currently consume NIOPosix.

Usage Examples

• Schedule work on a manual-time async event loop and advance time deterministically:

let loop = AsyncEventLoop()
let scheduled = loop.scheduleTask(in: .seconds(1)) { "done" }
// Wait more than one second…
let value = try await scheduled.futureResult.get()  // "done"

• Run tasks on a MultiThreadedEventLoopGroup:

let group = MultiThreadedEventLoopGroup(numberOfThreads: 2)
let loop = group.next()
let future: EventLoopFuture<String> = loop.submit { "hello" }
let value = try await future.get() // "hello"
try await group.shutdownGracefully()

Testing Performed

Tests coverage provided in tests ported from NIOPosix: #6, #7, #10.

The changes have also been tested in real-world application by running GraphManager and QuantumProjectManager in the browser to migrate database schemas, connect with our server, and pull data from a real user account.

PR Dependencies

#11

Overview of all changes

All planned changes can be viewed together in #2