add original source

source/listing_5.2.cpp

@@ -0,0 +1,22 @@
+#include <vector>
+#include <atomic>
+#include <iostream>
+#include <chrono>
+#include <thread>
+
+std::vector<int> data;
+std::atomic_bool data_ready(false);
+
+void reader_thread()
+{
+    while(!data_ready.load())
+    {
+        std::this_thread::sleep_for(std::chrono::milliseconds(1));
+    }
+    std::cout<<"The answer="<<data[0]<<"\n";
+}
+void writer_thread()
+{
+    data.push_back(42);
+    data_ready=true;
+}