Add pthread example

meson.build

@@ -36,4 +36,5 @@ subdir('array')
 subdir('hashtable')
 subdir('list')
 subdir('openmp')
+subdir('pthread')
 subdir('winter')

pthread/meson.build

+executable('thread-incr', 'thread-incr.c',
+           dependencies: thread_dep,
+           link_with: lib_utils,
+           include_directories: incdir)

pthread/thread-incr.c

+#include <stdio.h>
+#include <stdlib.h>
+
+#include <pthread.h>
+
+#include <utils.h>
+
+typedef struct
+{
+    pthread_t thread;
+    int id;
+    int loops;
+} ThreadData;
+
+static volatile int glob = 0;
+static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
+
+static void
+err_exit (const char *func)
+{
+    fprintf (stderr, "Error: %s\n", func);
+}
+
+static void *
+thread_func (void *arg)
+{
+    ThreadData *data = (ThreadData *) arg;
+
+    for (int j = 0; j < data->loops; j++)
+    {
+        if (pthread_mutex_lock (&mtx))
+            err_exit ("pthread_mutex_lock");
+
+        printf ("Thread #%d: glob = %d\n", data->id, glob);
+
+        int loc = glob;
+        loc++;
+        glob = loc;
+
+        if (pthread_mutex_unlock (&mtx))
+            err_exit ("pthread_mutex_unlock");
+    }
+
+    return NULL;
+}
+
+int
+main (int argc, char **argv)
+{
+    int *loops = get_ints (argc, argv, 1, "Number of loops");
+
+    ThreadData *t1 = malloc (sizeof (ThreadData));
+    t1->id = 1;
+    t1->loops = *loops;
+    if (pthread_create (&t1->thread, NULL, thread_func, t1))
+        err_exit ("pthread_create");
+
+    ThreadData *t2 = malloc (sizeof (ThreadData));
+    t2->id = 2;
+    t2->loops = *loops;
+    if (pthread_create (&t2->thread, NULL, thread_func, t2))
+        err_exit ("pthread_create");
+
+    if (pthread_join (t1->thread, NULL))
+        err_exit ("pthread_join");
+    if (pthread_join (t2->thread, NULL))
+        err_exit ("pthread_join");
+
+    printf ("End: glob = %d\n", glob);
+    
+    free (t1);
+    free (t2);
+
+    return 0;
+}