new file: ex41_01.cpp

ch41/ex41_01.cpp

@@ -0,0 +1,59 @@
+//!
+//! @author Yue Wang
+//! @date   13 11 2014
+//!
+//! @ex 41.01
+//!     (a) share data between two threads.
+//!     (b) use mutex to avoid data race.
+//!
+//  to compile (on linux)   :
+//      g++ -std=c++11 -Wall ex41_01.cpp  -pthread
+//!
+
+#include <iostream>
+#include <thread>
+#include <mutex>
+#include <chrono>
+#include <memory>
+#include <vector>
+#include <string>
+
+using SharedData = std::shared_ptr<std::vector<std::string>>;
+
+void task1(SharedData data, std::mutex* mutex)
+{
+    std::this_thread::sleep_for(std::chrono::milliseconds{5});
+
+    std::unique_lock<std::mutex> lock{*mutex};
+    for(const auto& elem : *data)
+        std::cout << "\nfrom task 1 " << elem << " ";
+}
+
+void task2(SharedData data, std::mutex* mutex)
+{
+    std::unique_lock<std::mutex> lock{*mutex};
+    data->push_back("pezy--added by task2");
+}
+
+int main()
+{
+    //! data for sharing
+    auto data = std::make_shared<std::vector<std::string> >();
+    *data = {"alan","moophy","yue wang"};
+
+    //! two threads
+    static std::mutex mutex;
+    std::thread t1(task1,data,&mutex), t2(task2,data,&mutex);
+
+    t1.join();
+    t2.join();
+    std::cout << "\n\ndone\n";
+}
+//! output :
+
+//from task 1 alan
+//from task 1 moophy
+//from task 1 yue wang
+//from task 1 pezy--added by task2
+
+//done