all problems documented

EWD123/ewd123.go

@@ -32,7 +32,7 @@ func main() {
 
 	log.Printf("*** Start\n")
 
-	var variant = "dekker"
+	var variant = "a"
 	if len(os.Args[1:]) > 0 { // do we have arguments?
 		variant = os.Args[1]
 	}

EWD123/ewd123a/ewd123a.go

@@ -25,11 +25,18 @@ var turn = 1
 func Start() {
 	go process1()
 	go process2()
+	/**
+
+
+	Prozesse wechseln sich immer nur ab.
+	Ablauf ist 1,2,1,2,1,2,1,2,1,2
+	*/
 }
 
 // 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
@@ -40,6 +47,7 @@ L1:
 	controller.LeaveCriticalSection(1)
 
 	turn = 2
+	//Process 2 can run now (and will in some cases)
 
 	controller.OutsideCriticalSection(1, 100)
 
@@ -64,6 +72,7 @@ L2:
 	controller.LeaveCriticalSection(2)
 
 	turn = 1
+	//Process can run now (and will in some cases)
 
 	controller.OutsideCriticalSection(2, 100)
 

EWD123/ewd123b/ewd123b.go

@@ -16,6 +16,7 @@ package ewd123b
 import (
 	"../controller"
 	"log"
+	"time"
 )
 
 // global synchronization variables
@@ -25,14 +26,21 @@ var c1, c2 = 1, 1
 func Start() {
 	go process1()
 	go process2()
+	/**
+
+	 */
 }
 
 // process1 simulates the behaviour of the first process
 func process1() {
 L1:
+	//wait till c2 = 0 (other process no longer inside critical section)
 	if c2 == 0 {
 		goto L1
 	}
+	//if the other process inspects c1 at this moment both will enter the critical section
+	//we can force this behaviour if we wait for a moment
+	time.Sleep(100 * time.Millisecond)
 
 	c1 = 0
 

EWD123/ewd123c/ewd123c.go

@@ -15,7 +15,7 @@ package ewd123c
 
 import (
 	"../controller"
-	"log"
+	"time"
 )
 
 // global synchronization variables
@@ -32,6 +32,9 @@ func process1() {
 A1:
 	c1 = 0
 L1:
+	//if process 2 inspects c1 at this moment, both processes will wait for each other to set cX.
+	//we can force this behavior if we wait for a moment
+	time.Sleep(100 * time.Millisecond)
 	if c2 == 0 {
 		goto L1
 	}
@@ -43,10 +46,12 @@ L1:
 	c1 = 1
 	controller.OutsideCriticalSection(1, 100)
 
+	/*
 		if controller.ProcessCrashed(0.1) {
 			log.Println("Process 1 crashed")
 			return
 		}
+	*/
 
 	goto A1
 
@@ -68,10 +73,12 @@ L2:
 	c2 = 1
 	controller.OutsideCriticalSection(2, 100)
 
+	/*
 		if controller.ProcessCrashed(0.1) {
 			log.Println("Process 2 crashed")
 			return
 		}
+	*/
 
 	goto A2
 }

EWD123/ewd123d/ewd123d.go

@@ -15,7 +15,6 @@ package ewd123d
 
 import (
 	"../controller"
-	"log"
 )
 
 // global synchronization variables
@@ -32,6 +31,8 @@ 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
 	}
@@ -44,10 +45,10 @@ L1:
 
 	controller.OutsideCriticalSection(1, 100)
 
-	if controller.ProcessCrashed(0.1) {
+	/*if controller.ProcessCrashed(0.1) {
 		log.Println("Process 1 crashed")
 		return
-	}
+	}*/
 
 	goto L1
 }
@@ -69,10 +70,10 @@ L2:
 
 	controller.OutsideCriticalSection(2, 100)
 
-	if controller.ProcessCrashed(0.1) {
+	/*if controller.ProcessCrashed(0.1) {
 		log.Println("Process 2 crashed")
 		return
-	}
+	}*/
 
 	goto L2
 }

EWD123/ewd123dekker/ewd123dekker.go

@@ -34,6 +34,7 @@ A1:
 	c1 = 0
 L1:
 	if c2 == 0 {
+		//if both processes are stuck here, the turn variable will decide which process runs first
 		if turn == 1 {
 			goto L1
 		}