git.sesse.net Git - casparcg/blob - common/concurrency/executor.h

   1 #pragma once\r
   2 \r
   3 #include "../exception/win32_exception.h"\r
   4 #include "../log/log.h"\r
   5 \r
   6 #include <tbb/atomic.h>\r
   7 #include <tbb/concurrent_queue.h>\r
   8 \r
   9 #include <boost/thread.hpp>\r
  10 #include <boost/noncopyable.hpp>\r
  11 \r
  12 #include <functional>\r
  13 #include <array>\r
  14 \r
  15 namespace caspar {\r
  16 \r
  17 class executor : boost::noncopyable\r
  18 {\r
  19 public:\r
  20         \r
  21         explicit executor(const std::function<void()>& f = nullptr)\r
  22         {\r
  23                 is_running_ = false;\r
  24                 f_ = f != nullptr ? f : [this]{run();};\r
  25         }\r
  26 \r
  27         ~executor()\r
  28         {\r
  29                 stop();\r
  30         }\r
  31 \r
  32         void start() // noexcept\r
  33         {\r
  34                 if(is_running_.fetch_and_store(true))\r
  35                         return;\r
  36                 thread_ = boost::thread(f_);\r
  37         }\r
  38                 \r
  39         void stop(bool wait = true) // noexcept\r
  40         {\r
  41                 is_running_ = false;    \r
  42                 execution_queue_.push([]{});\r
  43                 if(wait && boost::this_thread::get_id() != thread_.get_id())\r
  44                         thread_.join();\r
  45         }\r
  46                         \r
  47         template<typename Func>\r
  48         auto begin_invoke(Func&& func) -> boost::unique_future<decltype(func())> // noexcept\r
  49         {       \r
  50                 typedef boost::packaged_task<decltype(func())> task_type;\r
  51                                 \r
  52                 auto task = task_type(std::forward<Func>(func));\r
  53                 auto future = task.get_future();\r
  54                 \r
  55                 task.set_wait_callback(std::function<void(task_type&)>([=](task_type& my_task) // The std::function wrapper is required in order to add ::result_type to functor class.\r
  56                 {\r
  57                         try\r
  58                         {\r
  59                                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
  60                                         my_task();\r
  61                         }\r
  62                         catch(boost::task_already_started&){}\r
  63                 }));\r
  64                                 \r
  65                 struct task_adaptor_t\r
  66                 {\r
  67                         task_adaptor_t(const task_adaptor_t& other) : task(std::move(other.task)){}\r
  68                         task_adaptor_t(task_type&& task) : task(std::move(task)){}\r
  69                         void operator()() const { task(); }\r
  70                         mutable task_type task;\r
  71                 } task_adaptor(std::move(task));\r
  72 \r
  73                 execution_queue_.try_push([=]\r
  74                 {\r
  75                         try{task_adaptor();}\r
  76                         catch(boost::task_already_started&){}\r
  77                         catch(...){CASPAR_LOG_CURRENT_EXCEPTION();}\r
  78                 });\r
  79 \r
  80                 return std::move(future);               \r
  81         }\r
  82         \r
  83         template<typename Func>\r
  84         auto invoke(Func&& func) -> decltype(func())\r
  85         {\r
  86                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
  87                         return func();\r
  88                 \r
  89                 return begin_invoke(std::forward<Func>(func)).get();\r
  90         }\r
  91 \r
  92         tbb::concurrent_bounded_queue<std::function<void()>>::size_type size() const { return execution_queue_.size();  }\r
  93         bool empty() const              { return execution_queue_.empty();      }\r
  94         bool is_running() const { return is_running_;                           }       \r
  95                 \r
  96 private:\r
  97         \r
  98         void execute() // noexcept\r
  99         {\r
 100                 std::function<void()> func;\r
 101                 execution_queue_.pop(func);     \r
 102                 func();\r
 103         }\r
 104 \r
 105         void run() // noexcept\r
 106         {\r
 107                 win32_exception::install_handler();\r
 108                 while(is_running_)\r
 109                         execute();\r
 110         }\r
 111         \r
 112         std::function<void()> f_;\r
 113         boost::thread thread_;\r
 114         tbb::atomic<bool> is_running_;\r
 115         tbb::concurrent_bounded_queue<std::function<void()>> execution_queue_;\r
 116 };\r
 117 \r
 118 }