Fin de T2, et début t3.

ex3/T3.md

+# Task 3
+
+The problem is that each thread is unlocking a mutex it didn't unlock.
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ex3/dining.c

+#include <pthread.h>
+#include <stdio.h>
 #include "dp.h"
 
 int left_neighbor(int number)
@@ -23,7 +25,7 @@ void test(int i)
     {
         state[i] = EATING;
 
-        pthread_cond_signal(cond_vars + i);
+        // TODO unblock threads from condition variable
     }
 }
 
@@ -38,7 +40,7 @@ void pickup_forks(int number)
     {
         sleep(1);
 
-        pthread_cond_wait(cond_vars + number, &mutex_lock);
+        // TODO wait on condition variable and mutex
     }
 
     pthread_mutex_unlock(&mutex_lock);

ex3/main.c

+/*
+    Note on the task 2:
+    The code given didn't work because of a design flaw, so we replaced dining.c and philosopher.c by a single dp.c file.
+    We also moved some functions and variables from one file to another, and modified the Makefile according to these changes.
+*/
+
 #include "dp.h"
 
 extern pthread_t tid[NUMBER];

ex3/philosopher.c

+#include <pthread.h>
+#include <stdio.h>
+#include <time.h>
 #include "dp.h"
 
 // structure of a dining philosopher alternating between thinking and eating

ex3/t3.c

+#include <pthread.h>
+
+pthread_mutex_t first_mutex;
+pthread_mutex_t second_mutex;
+
+// thread one runs in this function
+void *do_work_one(void *param)
+{
+    int done = 0;
+    while (!done)
+    {
+        pthread_mutex_lock(&first_mutex);
+        if (pthread_mutex_trylock(&second_mutex) == 0)
+        {
+            // do some work
+            pthread_mutex_unlock(&second_mutex);
+            done = 1;
+        }
+        pthread_mutex_unlock(&first_mutex);
+    }
+    pthread_exit(0);
+}
+
+// thread two runs in this function
+void *do_work_two(void *param)
+{
+    int done = 0;
+    while (!done)
+    {
+        pthread_mutex_lock(&second_mutex);
+        if (pthread_mutex_trylock(&first_mutex) == 0)
+        {
+            // do some work
+            pthread_mutex_unlock(&first_mutex);
+            done = 1;
+        }
+        pthread_mutex_unlock(&second_mutex);
+    }
+    pthread_exit(0);
+}
+
+int main() {
+    pthread_mutex_init(&first_mutex, NULL);
+    pthread_mutex_init(&second_mutex, NULL);
+
+    pthread_t tid1, tid2;
+
+    pthread_create(&tid1, NULL, do_work_one, NULL);
+    pthread_create(&tid2, NULL, do_work_two, NULL);
+
+    pthread_join(tid1, NULL);
+    pthread_join(tid2, NULL);
+
+    return 0;
+}
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