feat(thread_pool): add run_future method

Author: huangrt01

thread/ThreadPool.cc

@@ -47,11 +47,14 @@ void ThreadPool::start(int numThreads)
 
 void ThreadPool::stop()
 {
+  printf("starting to stop the pool.\n");
   running_ = false;
   cond_.notifyAll();
   for_each(threads_.begin(),
            threads_.end(),
            boost::bind(&muduo::Thread::join, _1));
+  threads_.clear();
+  printf("stop the pool successfully.\n");
 }
 
 void ThreadPool::run(const Task& task)

thread/ThreadPool.h

@@ -17,6 +17,7 @@
 #include <boost/ptr_container/ptr_vector.hpp>
 
 #include <deque>
+#include <future>
 
 namespace muduo
 {
@@ -34,6 +35,23 @@ class ThreadPool : boost::noncopyable
 
   void run(const Task& f);
 
+  template<typename Func, typename... Args>
+  inline auto run_future(Func&& func, Args&&... args) -> std::future<typename std::result_of<Func(Args...)>::type>
+  {
+      if (threads_.empty()) {
+        func(args...);
+      }
+      using ret_type = typename std::result_of<Func(Args...)>::type;
+      auto task = std::make_shared<std::packaged_task<ret_type()>>(std::bind(std::forward<Func>(func), std::forward<Args>(args)...));
+      auto ret = task->get_future();
+      do {
+          MutexLockGuard lock(mutex_);
+          queue_.push_back([task]() { (*task)(); });
+          cond_.notify();
+      } while (0);
+      return std::move(ret);
+  }
+
  private:
   void runInThread();
   Task take();

thread/test/ThreadPool_test.cc

@@ -17,8 +17,9 @@ void printString(const std::string& str)
 int main()
 {
   muduo::ThreadPool pool("MainThreadPool");
-  pool.start(5);
 
+
+  pool.start(5);
   pool.run(print);
   pool.run(print);
   for (int i = 0; i < 100; ++i)
@@ -32,5 +33,22 @@ int main()
   pool.run(boost::bind(&muduo::CountDownLatch::countDown, &latch));
   latch.wait();
   pool.stop();
+
+  printf("Testing run_future\n");
+  pool.start(5);
+  pool.run(print);
+  pool.run(print);
+  std::vector<std::future<void>> futures;
+  for (int i = 0; i < 100; ++i)
+  {
+    char buf[32];
+    snprintf(buf, sizeof buf, "task %d", i);
+    futures.emplace_back(std::move(pool.run_future(boost::bind(printString, std::string(buf))))); 
+  }
+  for (auto& future : futures)
+  {
+    future.get();
+  }
+  pool.stop();
 }