add original source

source/listing_5.12.cpp

@@ -0,0 +1,33 @@
+#include <atomic>
+#include <thread>
+#include <assert.h>
+
+std::atomic<bool> x,y;
+std::atomic<int> z;
+
+void write_x_then_y()
+{
+    x.store(true,std::memory_order_relaxed);
+    std::atomic_thread_fence(std::memory_order_release);
+    y.store(true,std::memory_order_relaxed);
+}
+
+void read_y_then_x()
+{
+    while(!y.load(std::memory_order_relaxed));
+    std::atomic_thread_fence(std::memory_order_acquire);
+    if(x.load(std::memory_order_relaxed))
+        ++z;
+}
+
+int main()
+{
+    x=false;
+    y=false;
+    z=0;
+    std::thread a(write_x_then_y);
+    std::thread b(read_y_then_x);
+    a.join();
+    b.join();
+    assert(z.load()!=0);
+}