/*
 * ewd123d.go
 *
 * A program to represent the fourth 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 ewd123d

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

// global synchronization variables
var c1, c2 = 1, 1

// Start starts the execution of EWD123d.
func Start() {
	go process1()
	go process2()
}

// process1 simulates the behaviour of the first process
func process1() {
L1:
	c1 = 0
	if c2 == 0 {
		//when both processes are at this stage, they will wait for each other to clear this area
		//for this to happen the processes need to be executed at exactly the same time.
		c1 = 1
		goto L1
	}

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

	c1 = 1

	controller.OutsideCriticalSection(1, 100)

	if controller.ProcessCrashed(0.1) {
		log.Println("Process 1 crashed")
		return
	}

	goto L1
}

// process2 simulates the behaviour of the second process
func process2() {
L2:
	c2 = 0
	if c1 == 0 {
		c2 = 1
		goto L2
	}

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

	c2 = 1

	controller.OutsideCriticalSection(2, 100)

	if controller.ProcessCrashed(0.1) {
		log.Println("Process 2 crashed")
		return
	}

	goto L2
}