add original source

source/listing_7.3.cpp

@@ -0,0 +1,31 @@
+#include <atomic>
+#include <memory>
+
+template<typename T>
+class lock_free_stack
+{
+private:
+    struct node
+    {
+        std::shared_ptr<T> data;
+        node* next;
+        node(T const& data_):
+            data(std::make_shared<T>(data_))
+        {}
+    };
+    std::atomic<node*> head;
+public:
+    void push(T const& data)
+    {
+        node* const new_node=new node(data);
+        new_node->next=head.load();
+        while(!head.compare_exchange_weak(new_node->next,new_node));
+    }
+    std::shared_ptr<T> pop()
+    {
+        node* old_head=head.load();
+        while(old_head &&
+              !head.compare_exchange_weak(old_head,old_head->next));
+        return old_head ? old_head->data : std::shared_ptr<T>();
+    }
+};