Aufgabe 3

aufgabe04/aufgabe3.c

+// dining philosophers with unshared chopsticks
+#include <stdio.h> 
+#include <stdlib.h>
+#include <pthread.h> 
+#include <semaphore.h> 
+#include <unistd.h> 
+
+#define NUM_THREADS     5
+sem_t chopsticks[NUM_THREADS]; 
+
+void* Philosopher (void *threadid) 
+{
+  long tid;
+  tid = (long)threadid;
+
+  for (int i= 0; i < 10; i++) {
+    // thinking
+    sleep (0.5);
+
+    //wait 
+    
+    sem_wait(&chopsticks[tid]); 
+    sem_wait(&chopsticks[(tid+1) % NUM_THREADS]); 
+    
+    printf("%ld Dining..\n", tid); 
+    sleep(0.5); 
+    printf("%ld Finished..\n", tid); 
+    
+    sem_post(&chopsticks[tid]); 
+    sem_post(&chopsticks[(tid+1) % NUM_THREADS]); 
+  }
+} 
+
+
+int main (void) 
+{ 
+  pthread_t threads[NUM_THREADS];
+  int rc;
+  long t;
+
+  for(int i=0;i<NUM_THREADS;i++){
+    sem_init(&chopsticks[i],0,1);
+  }
+
+  for(t=0; t < NUM_THREADS; t++) {
+     printf ("In main: creating thread %ld\n", t);
+     rc = pthread_create (&threads[t], NULL, Philosopher, (void *)t);
+     if (rc) {
+        printf ("ERROR; return code from pthread_create () is %d\n", rc);
+        exit (-1);
+     }
+  }
+
+  for(t=0; t < NUM_THREADS; t++) {
+     pthread_join (threads[t], NULL);
+  }
+
+  for(int i=0;i<NUM_THREADS;i++){
+    sem_destroy(&chopsticks[i]);
+  }
+
+  return 0; 
+} 
+