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         enum stop_policy\r
  22         {\r
  23                 wait,\r
  24                 no_wait\r
  25         };\r
  26         \r
  27         explicit executor(const std::function<void()>& f = nullptr)\r
  28         {\r
  29                 is_running_ = false;\r
  30                 f_ = f != nullptr ? f : [this]{run();};\r
  31         }\r
  32 \r
  33         ~executor()\r
  34         {\r
  35                 stop();\r
  36         }\r
  37 \r
  38         void start() // noexcept\r
  39         {\r
  40                 if(is_running_.fetch_and_store(true))\r
  41                         return;\r
  42                 thread_ = boost::thread(f_);\r
  43         }\r
  44                         \r
  45         void stop(stop_policy policy = wait) // noexcept\r
  46         {\r
  47                 is_running_ = false;    \r
  48                 execution_queue_.push([]{});\r
  49                 if(policy == wait && boost::this_thread::get_id() != thread_.get_id())\r
  50                         thread_.join();\r
  51         }\r
  52 \r
  53         void clear()\r
  54         {\r
  55                 std::function<void()> func;\r
  56                 while(execution_queue_.try_pop(func)){}\r
  57         }\r
  58                         \r
  59         template<typename Func>\r
  60         auto begin_invoke(Func&& func) -> boost::unique_future<decltype(func())> // noexcept\r
  61         {       \r
  62                 typedef boost::packaged_task<decltype(func())> task_type;\r
  63                                 \r
  64                 auto task = task_type(std::forward<Func>(func));\r
  65                 auto future = task.get_future();\r
  66                 \r
  67                 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
  68                 {\r
  69                         try\r
  70                         {\r
  71                                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
  72                                         my_task();\r
  73                         }\r
  74                         catch(boost::task_already_started&){}\r
  75                 }));\r
  76                                 \r
  77                 struct task_adaptor_t\r
  78                 {\r
  79                         task_adaptor_t(const task_adaptor_t& other) : task(std::move(other.task)){}\r
  80                         task_adaptor_t(task_type&& task) : task(std::move(task)){}\r
  81                         void operator()() const { task(); }\r
  82                         mutable task_type task;\r
  83                 } task_adaptor(std::move(task));\r
  84 \r
  85                 execution_queue_.try_push([=]\r
  86                 {\r
  87                         try{task_adaptor();}\r
  88                         catch(boost::task_already_started&){}\r
  89                         catch(...){CASPAR_LOG_CURRENT_EXCEPTION();}\r
  90                 });\r
  91 \r
  92                 return std::move(future);               \r
  93         }\r
  94         \r
  95         template<typename Func>\r
  96         auto invoke(Func&& func) -> decltype(func())\r
  97         {\r
  98                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
  99                         return func();\r
 100                 \r
 101                 return begin_invoke(std::forward<Func>(func)).get();\r
 102         }\r
 103 \r
 104         tbb::concurrent_bounded_queue<std::function<void()>>::size_type size() const { return execution_queue_.size();  }\r
 105         bool empty() const              { return execution_queue_.empty();      }\r
 106         bool is_running() const { return is_running_;                           }       \r
 107                 \r
 108 private:\r
 109         \r
 110         void execute() // noexcept\r
 111         {\r
 112                 std::function<void()> func;\r
 113                 execution_queue_.pop(func);     \r
 114                 func();\r
 115         }\r
 116 \r
 117         void run() // noexcept\r
 118         {\r
 119                 win32_exception::install_handler();\r
 120                 while(is_running_)\r
 121                         execute();\r
 122         }\r
 123         \r
 124         std::function<void()> f_;\r
 125         boost::thread thread_;\r
 126         tbb::atomic<bool> is_running_;\r
 127         tbb::concurrent_bounded_queue<std::function<void()>> execution_queue_;\r
 128 };\r
 129 \r
 130 }