Another update from ingydotnet^djgoku

Task/Checkpoint-synchronization/C++/checkpoint-synchronization.cpp

@@ -0,0 +1,51 @@
+#include <iostream>
+#include <chrono>
+#include <atomic>
+#include <mutex>
+#include <random>
+#include <thread>
+
+std::mutex cout_lock;
+
+class Latch
+{
+    std::atomic<int> semafor;
+  public:
+    Latch(int limit) : semafor(limit) {}
+
+    void wait()
+    {
+        semafor.fetch_sub(1);
+        while(semafor.load() > 0)
+            std::this_thread::yield();
+    }
+};
+
+struct Worker
+{
+    static void do_work(int how_long, Latch& barrier, std::string name)
+    {
+        std::this_thread::sleep_for(std::chrono::milliseconds(how_long));
+        {   std::lock_guard<std::mutex> lock(cout_lock);
+            std::cout << "Worker " << name << " finished work\n";   }
+        barrier.wait();
+        {   std::lock_guard<std::mutex> lock(cout_lock);
+            std::cout << "Worker " << name << " finished assembly\n";   }
+    }
+};
+
+int main()
+{
+    Latch latch(5);
+    std::mt19937 rng(std::random_device{}());
+    std::uniform_int_distribution<> dist(300, 3000);
+    std::thread threads[] {
+        std::thread(&Worker::do_work, dist(rng), std::ref(latch), "John"),
+        std::thread{&Worker::do_work, dist(rng), std::ref(latch), "Henry"},
+        std::thread{&Worker::do_work, dist(rng), std::ref(latch), "Smith"},
+        std::thread{&Worker::do_work, dist(rng), std::ref(latch), "Jane"},
+        std::thread{&Worker::do_work, dist(rng), std::ref(latch), "Mary"},
+    };
+    for(auto& t: threads) t.join();
+    std::cout << "Assembly is finished";
+}