c thread pool future swift

cthreadpoolfuture.swift

// attempted to replace GCD but it turns out GCD was not in fact broken so uh Linux
import Foundation
import CThreadPool

var pool: threadpool?

public class Future {
    private var semaphore: DispatchSemaphore
    private var store: Any?
    private var executor: () -> Any

    init(executor: @escaping () -> Any) {
        self.semaphore = DispatchSemaphore(value: 0)
        self.executor = executor

        if pool == nil {
            pool = thpool_init(CInt(
                ProcessInfo.processInfo.environment["FAULT_THREADS"] ?? ""
            ) ?? 64)
        }

        let _ = thpool_add_work(pool!, {
            pointer in
            let this = Unmanaged<Future>.fromOpaque(pointer!).takeUnretainedValue()
            this.store = this.executor()
            this.semaphore.signal()
        }, Unmanaged.passUnretained(self).toOpaque())
    }

    public var value: Any {
        self.semaphore.wait()
        let value = store!
        return value
    }
}