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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <pthread.h>
  4. #include <semaphore.h>
  5. #include <unistd.h>
  6.  
  7.  
  8. //global variables 
  9. int c1,c2; //counters for imp1, imp2
  10. pthread_mutex_t m1, m2;
  11. sem_t corridor; 
  12.  
  13. //implementation thread attendant
  14. void* attendant(void* arg){
  15.     sleep(2); //rest 2 seconds
  16.     if (c1==0 && c2==0){
  17.         printf("I'm starting to clean up\n");
  18.         sem_wait(&corridor);
  19.         sleep(2);
  20.         sem_post(&corridor);
  21.         printf ("I finished cleaning n");
  22.         }else{
  23.            printf ("I can't clean, the corridor is busy\n");
  24.         }
  25.     return NULL;
  26. }
  27.  
  28.  
  29. //thread employee type 1
  30. void* emp1(void *arg){
  31.     printf("I'm the number %d\n", c1);
  32.     pthread_mutex_lock(&m1); //beginning critical section
  33.     c1++;                    //it increases to signal the presence of a thread of the same type that wants to enter the corridor
  34.     if (c1 == 1){            //the thread is the only one in the corridor. Can pass
  35.         printf ("I am the first of my group n");
  36.         sem_wait(&corridor);  //takes possession of the corridor
  37.     }
  38.     pthread_mutex_unlock(&m1); //allows other threads of the same type to pass in the corridor since it was the first in his group. End of critical section
  39.  
  40.     // invents "passage" function
  41.  
  42.     pthread_mutex_lock(&m1);  //beginning of the critical section. Once crossed the corridor, the variable c1 is modified. A mutex is used to avoid inconsistency
  43.     c1--;
  44.     if(c1 == 0){
  45.         printf ("I am the last of my group n");
  46.         sem_post(&corridor);
  47.     } //if c1 == 0, it is the last thread imp1 and releases the corridor
  48.     pthread_mutex_unlock(&m1); //end critical section
  49.     return NULL;
  50. }
  51.  
  52.  
  53. //thread employee type 2 
  54. void* emp2(void *arg){
  55.     printf("I'm the number %d\n", c1);
  56.     pthread_mutex_lock(&m2); //beginning critical section
  57.     c2++;                    //it increases to signal the presence of a thread of the same type that wants to enter the corridor
  58.     if (c2 == 1){            // the thread is the only one in the corridor. Can pass
  59.         printf ("I am the first of my group n");
  60.         sem_wait(&corridor);  //takes possession of the corridor
  61.     }
  62.     pthread_mutex_unlock(&m2); //allows other threads of the same type to pass in the corridor since it was the first in his group. End of critical sectionritica
  63.  
  64.     // invents "passage" function
  65.  
  66.     pthread_mutex_lock(&m2);  //beginning of the critical section. Once crossed the corridor, the variable c1 is modified. A mutex is used to avoid inconsistency
  67.     c2--;
  68.     if(c2 == 0){
  69.         printf ("I am the last of my group n");
  70.         sem_post(&corridor);
  71.     }//if c1 == 0, it is the last thread imp1 and releases the corridor
  72.     pthread_mutex_unlock(&m2); //end critical section
  73.     return NULL;
  74. }
  75.  
  76.  
  77. int main(int argc, char const *argv[]) {
  78.     //pthread_t emp1, emp2, attendant;
  79.     pthread_t idt;
  80.     int r; //var random to create thread emp1 or emp2
  81.     int i; //index 
  82.  
  83.     //variable initialization
  84.     c1 = c2 = 0;
  85.     pthread_mutex_init(&m1, NULL); 
  86.     pthread_mutex_init(&m2, NULL);
  87.     sem_init(&corridor,0,1); 
  88.  
  89.     pthread_create(&idt,NULL,attendant,NULL); 
  90.     while(i<40){
  91.         r = rand()%2;
  92.         if(r==0){
  93.             printf("Employee creation 1\n");
  94.             pthread_create(&idt,NULL,emp1,NULL);
  95.         }else{
  96.             printf("Employee creation 1\n");
  97.             pthread_create(&idt,NULL,emp2,NULL);
  98.         }
  99.         i++;
  100.     }
  101.     return 0;
  102. }
Success #stdin #stdout 0s 42256KB
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Standard input is empty
stdout
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Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
Employee creation 1
https://ideone.com/3CIb4J
language:
C99 (gcc 8.3)
created:
6 years ago
visibility:
secret

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