Add TD 8 & 9

TD/TD8/exercise1a.c

@@ -0,0 +1,84 @@
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define N 20
+#define PROD 5
+#define CONS 5
+#define PROD_MAX 500
+
+int shared_buffer[N];
+
+void* producteur(void* args) {
+    int j, product = 0;
+    int count = 0;
+    while (1) {
+        int i = -1;
+        while (++i < N) {
+            if (shared_buffer[i] == -1) {
+                break;
+            }
+        }
+        if (i >= N) {
+            sleep(0.05);
+            continue;
+        }
+        product = (rand()%500+product)%20000;
+        j = (i+j)%20000;
+        shared_buffer[i] = product;
+        count++;
+        if (!(count % 5000))
+            printf("produit: %d %d\n", j, product);
+        sleep(0.05);
+    }
+    return NULL;
+}
+
+void* consommateur(void* args) {
+    int j, product = 0;
+    int count = 0;
+    while (1) {
+        int i = -1;
+        while (++i < N) {
+            if (shared_buffer[i] != -1) {
+                break;
+            }
+        }
+        if (i >= N) {
+            sleep(0.05);
+            continue;
+        }
+        product = (shared_buffer[i]+product)%20000;
+        j = (i+j)%20000;
+        shared_buffer[i] = -1;
+        count++;
+        if (!(count %5000))
+            printf("résultat: %d %d %d\n", j, product);
+        sleep(0.05);
+    }
+    return NULL;
+}
+
+
+
+int main() {
+    for (int i=0; i < N; i++) {
+        shared_buffer[i] = -1;
+    }
+    
+    pthread_t tid[PROD+CONS];
+    for (int i=0; i < PROD; i++) {
+        pthread_create(&(tid[i]), NULL, &producteur, NULL);
+    }
+
+    for (int i=0; i < CONS; i++) {
+        pthread_create(&(tid[i+PROD]), NULL, &consommateur, NULL);
+    }
+
+    for (int i=0; i < PROD+CONS; i++) {
+        pthread_join(tid[i], NULL);
+    }
+
+    return 0;
+}

TD/TD8/exercise1b.c

@@ -0,0 +1,120 @@
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <semaphore.h>
+
+#define N 10
+#define PROD 5
+#define CONS 3
+#define PROD_MAX 500
+#define DELAY 1
+
+#define RED     "\033[31m"
+#define RESET   "\033[0m"
+
+
+sem_t sem_prod;
+sem_t sem_cons;
+sem_t sem_renderer;
+
+int shared_buffer[N];
+pthread_mutex_t lock;
+
+void* producteur(void* args) {
+    while (1) {
+        sem_wait(&sem_prod);
+        pthread_mutex_lock(&lock);
+            int i = -1;
+            while (++i < N) {
+                if (shared_buffer[i] == -1) {
+                    shared_buffer[i] = rand()%PROD_MAX;
+                    sem_post(&sem_cons);
+                    sem_post(&sem_renderer);
+                    //printf("placed@%d !\n", i);
+                    break;
+                }
+            }
+            if (i >= N) {
+                fprintf(stderr, "Can't place my product !\n");
+                exit(1);
+            }
+        pthread_mutex_unlock(&lock);
+        sleep(DELAY);
+    }
+    return NULL;
+}
+
+void* consommateur(void* args) {
+    while (1) {
+        sem_wait(&sem_cons);
+        pthread_mutex_lock(&lock);
+            int i = -1;
+            while (++i < N) {
+                if (shared_buffer[i] != -1) {
+                    shared_buffer[i] = -1;
+                    //printf("got@%d !\n", i);
+                    sem_post(&sem_prod);
+                    sem_post(&sem_renderer);
+                    break;
+                }
+            }
+            if (i >= N) {
+                fprintf(stderr, "Can't get a product !\n");
+                exit(1);
+            }
+        pthread_mutex_unlock(&lock);
+        sleep(DELAY);
+    }
+    return NULL;
+}
+
+void* renderer(void* args) {
+    while (1) {
+        sem_wait(&sem_renderer);
+        pthread_mutex_lock(&lock);
+        printf("\r");
+        for (int i=0; i < N; i++) {
+            if (shared_buffer[i] == -1) {
+                printf(RED "%3d " RESET, shared_buffer[i]);
+            } else {
+                printf("%3d ", shared_buffer[i]);
+            }
+        }
+        pthread_mutex_unlock(&lock);
+    }
+}
+
+
+
+int main() {
+    for (int i=0; i < N; i++) {
+        shared_buffer[i] = -1;
+    }
+
+    pthread_mutex_init(&lock, NULL);
+    
+    pthread_t tid[PROD+CONS+1];
+    sem_init(&sem_prod, 0, N);
+    sem_init(&sem_cons, 0, 0);
+    sem_init(&sem_renderer, 0, 1);
+    for (int i=0; i < PROD; i++) {
+        pthread_create(&(tid[i]), NULL, &producteur, NULL);
+    }
+
+    for (int i=0; i < CONS; i++) {
+        pthread_create(&(tid[i+PROD]), NULL, &consommateur, NULL);
+    }
+
+    // Additional renderer thread to display the state of the market
+    pthread_create(&(tid[CONS+PROD]), NULL, &renderer, NULL);
+
+
+    for (int i=0; i < PROD+CONS+1; i++) {
+        pthread_join(tid[i], NULL);
+    }
+    sem_destroy(&sem_cons);
+    sem_destroy(&sem_prod);
+
+    return 0;
+}

TD/TD8/exercise2.c

@@ -0,0 +1,146 @@
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+/*
+Ordre des pipes:
+AB 0
+AC 1
+AD 2
+BI 3
+CE 4
+CF 5
+DH 6
+EG 7
+FG 8
+GI 9
+HI 10
+IA 11
+*/
+
+int main() {
+    int* fds[12];
+
+    for (int i=0; i < 12; i++) {
+        fds[i] = malloc(sizeof(int)*2);
+        pipe(fds[i]);
+    }
+
+    int i=0;
+    for (; i < 9; i++) {
+        if (fork()) { break; } // Generate 9 processes
+        if (i == 8) { return 0; }
+    }
+
+    int input[3] = {-1, -1, -1};
+    int output[3] = {-1, -1, -1};
+
+    char id = 'A'+i;
+    switch (id) {
+        case 'A': {// A
+            input[0] = 11;
+            output[0] = 0;
+            output[1] = 1;
+            output[2] = 2;
+        } break;
+        case 'B': {// B
+            input[0] = 0;
+            output[0] = 3;
+        } break;
+        case 'C': {// C
+            input[0] = 1;
+            output[0] = 4;
+            output[1] = 5;
+        } break;
+        case 'D': {// D
+            input[0] = 2;
+            output[0] = 6;
+        } break;
+        case 'E': {// E
+            input[0] = 4;
+            output[0] = 7;
+        } break;
+        case 'F': {// F
+            input[0] = 5;
+            output[0] = 8;
+        } break;
+        case 'G': {// G
+            input[0] = 7;
+            input[1] = 8;
+            output[0] = 9;
+        } break;
+        case 'H': {// H
+            input[0] = 6;
+            output[0] = 10;
+        } break;
+        case 'I': {// I
+            input[0] = 3;
+            input[1] = 9;
+            input[2] = 10;
+            output[0] = 11;
+        } break;
+        default:
+            return -1;
+    }
+
+    FILE* in_stream[3];
+    FILE* out_stream[3];
+
+    for (int j=0; j < 3; j++) {
+        if (input[j] != -1) {
+            in_stream[j] = fdopen(fds[input[j]][0], "r");
+        }
+        if (output[j] != -1) {
+            out_stream[j] = fdopen(fds[output[j]][1], "w");
+        }
+    }
+
+
+    printf("%c: got %d %d %d > %d %d %d\n", id, input[0], input[1], input[2], output[0], output[1], output[2]);
+    sleep(1);
+
+    if (id == 'I') {
+        int c;
+        while (1) { // Get things from stdin
+            c = getchar();
+            for (int j=0; j < 3; j++) {
+                if (output[j] != -1) {
+                    fputc(c, out_stream[j]);
+                }
+            }
+        }
+        return 0;
+    }
+    while (1) {
+        printf("%c listening...\n", id);
+
+        int c, d;
+        d = -1;
+        for (int j=0; j < 3; j++) {
+            if (input[j] != -1) {
+                c = fgetc(in_stream[j]);
+                if (d != -1 && c != d) {
+                    fprintf(stderr, "%c got two different chars: %c vs %c\n", id, c, d);
+                }
+                d = c;
+            }
+        }
+        printf("%c received %c\n", id, c);
+        for (int j=0; j < 3; j++) {
+            if (output[j] != -1) {
+                printf("%c transmits %c to %d\n", id, c, output[j]);
+                fputc(c, out_stream[j]);
+            }
+        }
+    }
+
+    for (int j=0; j < 3; j++) {
+        if (input[j] != -1) {
+            fclose(in_stream[j]);
+        }
+        if (output[j] != -1) {
+            fclose(out_stream[j]);
+        }
+    }
+}

TD/TD8/index.md

@@ -0,0 +1,12 @@
+# TD 8: Threads and synchronisation
+
+## Reasoning operating systems: questions
+
+1. Différent mécanismes pour différentes utilisations:
+   - mutex locks pour gérer l'accès à une ressource
+   - sémaphores pour gérer l'accès à une quantité de variables
+   - variables de condition
+   - spin lock: comme sémaphore mais avec du temps processus
+2. Cela indique quelles fourchettes sont utilisées,
+   chaque philosophe n'utilisant que 2 fourchettes ou aucune à la fois
+3. Deadlock possible

TD/TD9/exercice1.c

@@ -0,0 +1,69 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <limits.h>
+#include <stdbool.h>
+
+#define N 50
+//#define SHOW_DETAILS
+
+pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+
+void* access_res(void* args) {
+  int id = *(int*)args;
+  *(int*)args = 0;
+
+  for (int i=0; i < INT_MAX; i++) {
+    pthread_mutex_lock(&lock);
+    *(int*)args += 1;
+    pthread_mutex_unlock(&lock);
+  }
+  *(int*)args = -1;
+
+  return NULL;
+}
+
+int main() {
+  pthread_t tid[N];
+  int args[N]; // Reuse it for the number of accesses
+
+  for (int i=0; i < N; i++) {
+    args[i] = i;
+    pthread_create(&(tid[i]), NULL, &access_res, (void*)&(args[i]));
+  }
+
+  bool is_end = false;
+  while (!is_end) {
+    #ifdef SHOW_DETAILS
+      printf("Accesses:\n");
+    #endif
+    int max, min, avg;
+    max = avg = 0;
+    min = INT_MAX;
+    for (int i=0; i < N; i++) {
+      #ifdef SHOW_DETAILS
+        printf("%d ", args[i]);
+      #endif
+      if (args[i] == -1)
+        is_end = true;
+
+      if (args[i] > max)
+        max = args[i];
+  
+      if (args[i] < min)
+        min = args[i];
+
+      avg += args[i]/N;
+    }
+    #ifdef SHOW_DETAILS
+      printf("\n");
+    #endif
+    printf("min max avg : %d %d %d\n", min, max, avg);
+    sleep(1);
+  }
+
+  for (int i=0; i < N; i++) {
+    pthread_join(tid[i], NULL);
+  }
+}

TD/TD9/exercice2.c

@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+pthread_mutex_t mutex1 = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t mutex2 = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t mutex3 = PTHREAD_MUTEX_INITIALIZER;
+
+
+void* process_fun(void* arg) {
+  int id = *(int*)arg;
+  bool success = false;
+  pthread_mutex_t* mutexs[3];
+  if (id == 0) { // Gives deadlock sometimes
+    mutexs[0] = &mutex1;
+    mutexs[1] = &mutex2;
+    mutexs[2] = &mutex3;
+  } else if (id == 1) {
+    mutexs[0] = &mutex2;
+    mutexs[1] = &mutex1;
+    mutexs[2] = &mutex3;
+  } else if (id == 2) {
+    mutexs[0] = &mutex1;
+    mutexs[1] = &mutex2;
+    mutexs[2] = &mutex3;
+  }
+
+  while (!success) {
+    bool csucc = true;
+    for (int i=0; i < 3; i++) {
+      if (pthread_mutex_trylock(mutexs[i]) != 0) {
+        for (int j=0; j < i; j++) {
+          pthread_mutex_unlock(mutexs[i]);
+        }
+        csucc = false;
+        break;
+      }
+    }
+    success = csucc;
+  }
+  printf("I have access\n");
+  pthread_mutex_unlock(mutexs[0]);
+  pthread_mutex_unlock(mutexs[1]);
+  pthread_mutex_unlock(mutexs[2]);
+
+  return NULL;
+}
+
+int main() {
+  pthread_t tid[3];
+  int args[3];
+
+  for (int i=0; i < 3; i++) {
+    args[i] = i;
+    pthread_create(&(tid[i]), NULL, &process_fun, &(args[i]));
+  }
+
+  for (int i=0; i < 3; i++) {
+    pthread_join(tid[i], NULL);
+  }
+}

TD/TD9/index.md

@@ -0,0 +1,8 @@
+# Deadlocks
+
+## Reasoning operating systems
+
+1. Les processus 1 et 4 sont en deadlock.
+2. On n'a pas le graphe des tâches qui vont arriver en avance. Donc c'est plus compliqué dans un monde réel
+3. 1/6 : same order is deadlock free
+