Swift 4.0 Multiprocessing

main.swift

//
//  main.swift
//  Multithreading
//
//  Created by menangen on 16/01/2019.
//  Copyright © 2019 menangen. All rights reserved.
//

import Foundation

var udpArray: [String] = ["Packet1", "Packet2", "Packet3"]

var thread1Buffer: [String] = []

let operationLoopQueue = OperationQueue()
let udpQueue = OperationQueue()

let bufferSemaphore  = DispatchSemaphore(value: 1)
let runLoopSemaphore = DispatchSemaphore(value: 0)

let runLoopBlock = BlockOperation {
        
    print("Enter Block A")
    var el: String
    
    while true {
        runLoopSemaphore.wait()
        
        bufferSemaphore.wait()
        el = thread1Buffer.popLast() ?? "NULL"
        bufferSemaphore.signal()
        print("\t Processing |\(el)|", Thread.current)
        
        sleep(3)
        
        bufferSemaphore.wait()
        if (thread1Buffer.count == 0) { break }
        bufferSemaphore.signal()
    }
}


    
udpQueue.addOperation({
    for el in udpArray {
        sleep(1)
        
        bufferSemaphore.wait()
        
        thread1Buffer.append(el); print("Sending \(el) to Thread", Thread.current)
        
        runLoopSemaphore.signal()
        bufferSemaphore.signal()
    }
})


operationLoopQueue.addOperations([runLoopBlock], waitUntilFinished: true)

print("thread1Buffer on END: ", thread1Buffer)