The source code for din_philo.c is shown below:
1 /* 2 * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All Rights Reserved. 3 * @(#)din_philo.c 1.4 (Oracle) 10/03/26 4 */ 5 6 #include <pthread.h> 7 #include <stdio.h> 8 #include <unistd.h> 9 #include <stdlib.h> 10 #include <errno.h> 11 #include <assert.h> 12 13 #define PHILOS 5 14 #define DELAY 5000 15 #define FOOD 100 16 17 void *philosopher (void *id); 18 void grab_chopstick (int, 19 int, 20 char *); 21 void down_chopsticks (int, 22 int); 23 int food_on_table (); 24 25 pthread_mutex_t chopstick[PHILOS]; 26 pthread_t philo[PHILOS]; 27 pthread_mutex_t food_lock; 28 int sleep_seconds = 0; 29 30 31 int 32 main (int argn, 33 char **argv) 34 { 35 int i; 36 37 if (argn == 2) 38 sleep_seconds = atoi (argv[1]); 39 40 pthread_mutex_init (&food_lock, NULL); 41 for (i = 0; i < PHILOS; i++) 42 pthread_mutex_init (&chopstick[i], NULL); 43 for (i = 0; i < PHILOS; i++) 44 pthread_create (&philo[i], NULL, philosopher, (void *)i); 45 for (i = 0; i < PHILOS; i++) 46 pthread_join (philo[i], NULL); 47 return 0; 48 } 49 50 void * 51 philosopher (void *num) 52 { 53 int id; 54 int i, left_chopstick, right_chopstick, f; 55 56 id = (int)num; 57 printf ("Philosopher %d is done thinking and now ready to eat.\n", id); 58 right_chopstick = id; 59 left_chopstick = id + 1; 60 61 /* Wrap around the chopsticks. */ 62 if (left_chopstick == PHILOS) 63 left_chopstick = 0; 64 65 while (f = food_on_table ()) { 66 67 /* Thanks to philosophers #1 who would like to take a nap 68 * before picking up the chopsticks, the other philosophers 69 * may be able to eat their dishes and not deadlock. 70 */ 71 if (id == 1) 72 sleep (sleep_seconds); 73 74 grab_chopstick (id, right_chopstick, "right "); 75 grab_chopstick (id, left_chopstick, "left"); 76 77 printf ("Philosopher %d: eating.\n", id); 78 usleep (DELAY * (FOOD - f + 1)); 79 down_chopsticks (left_chopstick, right_chopstick); 80 } 81 82 printf ("Philosopher %d is done eating.\n", id); 83 return (NULL); 84 } 85 86 int 87 food_on_table () 88 { 89 static int food = FOOD; 90 int myfood; 91 92 pthread_mutex_lock (&food_lock); 93 if (food > 0) { 94 food--; 95 } 96 myfood = food; 97 pthread_mutex_unlock (&food_lock); 98 return myfood; 99 } 100 101 void 102 grab_chopstick (int phil, 103 int c, 104 char *hand) 105 { 106 pthread_mutex_lock (&chopstick[c]); 107 printf ("Philosopher %d: got %s chopstick %d\n", phil, hand, c); 108 } 109 110 void 111 down_chopsticks (int c1, 112 int c2) 113 { 114 pthread_mutex_unlock (&chopstick[c1]); 115 pthread_mutex_unlock (&chopstick[c2]); 116 }