Revision 2:8bab2e3d3005, committed 2015-09-28

Comitter:

lucastai

Date:

Mon Sep 28 15:38:35 2015 +0000

Parent:

1:21958cb07fb4

Commit message:

3rd;

Changed in this revision

--- a/main.cpp	Sat Sep 26 21:48:56 2015 +0000
+++ b/main.cpp	Mon Sep 28 15:38:35 2015 +0000
@@ -1,4 +1,3 @@
-#include "mbed.h"
 #include "TextLCD.h"
 #include "Mutex.h"
 #include "rtos.h"
@@ -13,22 +12,28 @@
 
 // Eating routine
 void eat(const int* phil) {
-    // All chopsticks (0-4) are behind an individual mutex, and must be aquired from lowest to highest
-    // Each philosopher picks up the chopsticks to his left (index - 1) and right (index % 5), or waits for one
-    chopsticks[(int)phil - 1].lock();
-    chopsticks[(int)phil % 5].lock();
+    // All chopsticks (0-4) are behind an individual mutex
+    // Each philosopher picks up the even chopstick of the left right pair first, ie. they alternate between which
+    // they pick up first based on their ID
+    
+    if((int)phil % 2 == 0){    
+        chopsticks[(int)phil % 5].lock();
+        chopsticks[(int)phil - 1].lock();
+    }else{
+        chopsticks[(int)phil - 1].lock();
+        chopsticks[(int)phil % 5].lock();
+    }
+           
+    // we locate the part of the LCD, put the char to signifiy the philosopher eating
+    lcd.locate((int)phil,0);
+    lcd.putc((int)phil + 48);
     
     //The eating period is between 1000 and 2000 ms
     int eatPeriod = rand()%1000 + 1000;
-    
-    // we locate the part of the LCD 
-    lcd.locate((int)phil,0);
-    lcd.putc((int)phil + 48);
-    
     // The thread waits while the philosopher is eating
     Thread::wait(eatPeriod);
     
-    //After eating, the philosopher puts down the chopsticks 
+    //After eating, the philosopher puts down the chopsticks and clears himself from the LCD
     lcd.locate((int)phil,0);
     lcd.printf(" ");
     chopsticks[(int)phil - 1].unlock();
@@ -40,12 +45,11 @@
     while (true) {
         //Decide a time between 5-10 seconds between eating requests
         int waitPeriod = rand()%5000 + 5000;
+        // wait until time elapses to eat again
+        Thread::wait(waitPeriod);
         
         //Performing the eating routine
         eat((const int*)args); 
-        
-        // wait until time elapses to eat again
-        Thread::wait(waitPeriod);
     }
 }