Goroutines.swift

//
//  Goroutines.swift
//  TestGoer
//
//  Created by Doug Marcey on 6/11/14.
//  Copyright (c) 2014 Doug Marcey. All rights reserved.
//

import Foundation

let NoWorkQueued = 0
let WorkQueued = 1

let SpaceAvailable = 0
let LimitReached = 1

class Channel<T> {
    
    var items = T[]()
    let queueLock = NSConditionLock(condition: NoWorkQueued)
    let limitLock = NSConditionLock(condition: SpaceAvailable)
    let limit: Int
    
    
    init(limit:Int = 1) {
        self.limit = limit
    }
    
    func append(item:T, timeout:Int = 3) {
        if limitLock.lockWhenCondition(SpaceAvailable, beforeDate: NSDate(timeIntervalSinceNow: NSTimeInterval(timeout))) {
            queueLock.lock()
            items.append(item)
            limitLock.unlockWithCondition(items.count == self.limit ? LimitReached : SpaceAvailable)
            queueLock.unlockWithCondition(WorkQueued)
        }
    }
    
    func shift(timeout:Int = 3) -> T? {
        var item:T? = nil
        if queueLock.lockWhenCondition(WorkQueued, beforeDate: NSDate(timeIntervalSinceNow: NSTimeInterval(timeout))) {
            limitLock.lock()
            item = items.removeAtIndex(0)
            limitLock.unlockWithCondition(items.count == self.limit ? LimitReached : SpaceAvailable)
            queueLock.unlockWithCondition((items.count > 0 ? WorkQueued : NoWorkQueued))
        }
        return item
    }
}

operator infix <- {associativity right}
@infix func <-<T>(c:Channel<T>, item:T) -> Channel<T> {
    c.append(item)
    return c
}


operator prefix <- {}
@prefix func <-<T>(c: Channel<T>) -> T? {
    return c.shift()
}


func go(routine :() -> ()) {
    dispatch_async(dispatch_get_global_queue(0, 0)) {
        routine()
        go(routine)
    }
}

func go(routine :() -> Any) {
    dispatch_async(dispatch_get_global_queue(0, 0)) {
        routine()
        go(routine)
    }
}

main.swift

import Foundation

let c = Channel<String>()
let c2 = Channel<Int>()
var cc = 0

go {
    if let i = <-c {
        println(i)
        c2 <- ++cc
    }
}

go {
    if let i = <-c2 {
        println("Message " + String(i))
    }
}

for i in 1..20 {
    c <- "Hello " + String(i)
}

sleep(5)

func worker(done:Channel<Bool>) -> () -> () {
    return {
        println("Working...")
        sleep(1)
        println("Done")
        done <- true
    }
}

let done = Channel<Bool>()
go(worker(done))
<-done