/*
 * ewd123a.go
 *
 * A program to represent the first mutex strategy, as described in EWD123.
 *
 * Copyright (c) 2019-2019 HS Emden/Leer
 * All Rights Reserved.
 *
 * version 1.00 - 21 Oct 2019 - GJV - initial version
 *
 * author: Gert Veltink, gert.veltink@hs-emden-leer.de (GJV)
 */

package ewd123a

import (
	"../controller"
	"log"
)

// global synchronization variable
var turn = 1

// Start starts the execution of EWD123a.
func Start() {
	go process1()
	go process2()
}

// process1 simulates the behaviour of the first process
func process1() {
L1:
	//wait till turn = 2 (program can run)
	if turn == 2 {
		//log.Printf("Process 1 waiting\n")
		goto L1
	}

	controller.EnterCriticalSection(1)
	controller.InsideCriticalSection(1, 50)
	controller.LeaveCriticalSection(1)

	turn = 2
	//Process 2 can run now (and will in some cases)

	controller.OutsideCriticalSection(1, 100)

	if controller.ProcessCrashed(0.01) {
		log.Printf("Process 1 crashed\n")
		return
	}

	goto L1
}

// process2 simulates the behaviour of the second process
func process2() {
L2:
	if turn == 1 {
		//log.Printf("Process 2 waiting\n")
		goto L2
	}

	controller.EnterCriticalSection(2)
	controller.InsideCriticalSection(2, 50)
	controller.LeaveCriticalSection(2)

	turn = 1
	//Process can run now (and will in some cases)

	controller.OutsideCriticalSection(2, 100)

	if controller.ProcessCrashed(0.01) {
		log.Printf("Process 2 crashed\n")
		return
	}

	goto L2
}