From c325b265e322f09c6020c8d509bd9e965dba1985 Mon Sep 17 00:00:00 2001
From: Tyge Løvset <tylo@norceresearch.no>
Date: Thu, 13 Jan 2022 17:48:39 +0100
Subject: Fixed threads_demo.c and made it "identical" to the c++ example.

---
 examples/threads_demo.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

(limited to 'examples')

diff --git a/examples/threads_demo.c b/examples/threads_demo.c
index a31c2662..667ffb5b 100644
--- a/examples/threads_demo.c
+++ b/examples/threads_demo.c
@@ -1,7 +1,6 @@
-// example based on https://en.cppreference.com/w/cpp/memory/shared_ptr
+// Example translated to C from https://en.cppreference.com/w/cpp/memory/shared_ptr
 
 #include <stdio.h>
-#include <unistd.h>
 #include <threads.h>
 #include <time.h>
 
@@ -10,7 +9,7 @@ struct Base
     int value;
 } typedef Base;
 
-#define i_type BaseRc
+#define i_type BaseArc
 #define i_val Base
 #define i_valdrop(x) printf("Drop Base: %d\n", (x)->value)
 #define i_opt c_no_cmp
@@ -18,42 +17,43 @@ struct Base
 
 mtx_t mtx;
 
-void* thr(BaseRc* lp)
+void* thr(BaseArc* p)
 {
-    sleep(1);
+    thrd_sleep(&(struct timespec){.tv_sec=1}, NULL); // sleep 1 sec
+    BaseArc lp = BaseArc_clone(*p);  // thread-safe, even though the
+                                     // shared use_count is incremented
+
     c_autoscope (mtx_lock(&mtx), mtx_unlock(&mtx))
     {
         printf("local pointer in a thread:\n"
-               "  p.get() = %p, p.use_count() = %ld\n", (void*)lp->get, *lp->use_count);
+               "  p.get() = %p, p.use_count() = %ld\n", (void*)lp.get, BaseArc_use_count(lp));
         /* safe to modify base here */
-        lp->get->value += 1;
+        lp.get->value += 1;
     }
     /* atomically decrease ref. */
-    BaseRc_drop(lp);
+    BaseArc_drop(&lp);
+    BaseArc_drop(p);
     return NULL;
 }
 
 int main()
 {
-    BaseRc p = BaseRc_from((Base){0});
+    BaseArc p = BaseArc_from((Base){0});
 
     mtx_init(&mtx, mtx_plain);
-    printf("Created a Base\n"
-           "  p.get() = %p, p.use_count() = %ld\n", (void*)p.get, *p.use_count);
-    enum {N = 3};
-    thrd_t t[N];
-    BaseRc c[N];
-    c_forrange (i, N) {
-        c[i] = BaseRc_clone(p);
-        thrd_create(&t[i], (thrd_start_t)thr, &c[i]);
-    }
-
-    printf("Shared ownership between %d threads and released\n"
+    printf("Created a shared Base\n"
+           "  p.get() = %p, p.use_count() = %ld\n", (void*)p.get, BaseArc_use_count(p));
+    thrd_t t1, t2, t3;
+    thrd_create(&t1, (thrd_start_t)thr, (BaseArc[]){BaseArc_clone(p)});
+    thrd_create(&t2, (thrd_start_t)thr, (BaseArc[]){BaseArc_clone(p)});
+    thrd_create(&t3, (thrd_start_t)thr, (BaseArc[]){BaseArc_clone(p)});
+
+    BaseArc_reset(&p);
+    printf("Shared ownership between 3 threads and released\n"
            "ownership from main:\n"
-           "  p.get() = %p, p.use_count() = %ld\n", N, (void*)p.get, *p.use_count);
-    BaseRc_reset(&p);
+           "  p.get() = %p, p.use_count() = %ld\n", (void*)p.get, BaseArc_use_count(p));
 
-    c_forrange (i, N) thrd_join(t[i], NULL);
+    thrd_join(t1, NULL); thrd_join(t3, NULL); thrd_join(t3, NULL);
     printf("All threads completed, the last one deleted Base\n");
 }
 
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