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         virtual ~executor()\r
  34         {\r
  35                 stop();\r
  36         }\r
  37 \r
  38         void set_capacity(size_t capacity)\r
  39         {\r
  40                 execution_queue_.set_capacity(capacity);\r
  41         }\r
  42 \r
  43         void start() // noexcept\r
  44         {\r
  45                 if(is_running_.fetch_and_store(true))\r
  46                         return;\r
  47                 thread_ = boost::thread(f_);\r
  48         }\r
  49                         \r
  50         void stop(stop_policy policy = wait) // noexcept\r
  51         {\r
  52                 is_running_ = false;    \r
  53                 execution_queue_.push([]{});\r
  54                 if(policy == wait && boost::this_thread::get_id() != thread_.get_id())\r
  55                         thread_.join();\r
  56         }\r
  57 \r
  58         void clear()\r
  59         {\r
  60                 std::function<void()> func;\r
  61                 while(execution_queue_.try_pop(func)){}\r
  62         }\r
  63                         \r
  64         template<typename Func>\r
  65         auto begin_invoke(Func&& func) -> boost::unique_future<decltype(func())> // noexcept\r
  66         {       \r
  67                 typedef boost::packaged_task<decltype(func())> task_type;\r
  68                                 \r
  69                 auto task = task_type(std::forward<Func>(func));\r
  70                 auto future = task.get_future();\r
  71                 \r
  72                 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
  73                 {\r
  74                         try\r
  75                         {\r
  76                                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
  77                                         my_task();\r
  78                         }\r
  79                         catch(boost::task_already_started&){}\r
  80                 }));\r
  81                                 \r
  82                 struct task_adaptor_t\r
  83                 {\r
  84                         task_adaptor_t(const task_adaptor_t& other) : task(std::move(other.task)){}\r
  85                         task_adaptor_t(task_type&& task) : task(std::move(task)){}\r
  86                         void operator()() const { task(); }\r
  87                         mutable task_type task;\r
  88                 } task_adaptor(std::move(task));\r
  89 \r
  90                 execution_queue_.push([=]\r
  91                 {\r
  92                         try{task_adaptor();}\r
  93                         catch(boost::task_already_started&){}\r
  94                         catch(...){CASPAR_LOG_CURRENT_EXCEPTION();}\r
  95                 });\r
  96 \r
  97                 return std::move(future);               \r
  98         }\r
  99         \r
 100         template<typename Func>\r
 101         auto invoke(Func&& func) -> decltype(func())\r
 102         {\r
 103                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
 104                         return func();\r
 105                 \r
 106                 return begin_invoke(std::forward<Func>(func)).get();\r
 107         }\r
 108 \r
 109         tbb::concurrent_bounded_queue<std::function<void()>>::size_type size() const { return execution_queue_.size();  }\r
 110         bool empty() const              { return execution_queue_.empty();      }\r
 111         bool is_running() const { return is_running_;                           }       \r
 112                 \r
 113 private:\r
 114         \r
 115         void execute() // noexcept\r
 116         {\r
 117                 std::function<void()> func;\r
 118                 execution_queue_.pop(func);     \r
 119                 func();\r
 120         }\r
 121 \r
 122         void run() // noexcept\r
 123         {\r
 124                 win32_exception::install_handler();\r
 125                 while(is_running_)\r
 126                         execute();\r
 127         }\r
 128         \r
 129         std::function<void()> f_;\r
 130         boost::thread thread_;\r
 131         tbb::atomic<bool> is_running_;\r
 132         tbb::concurrent_bounded_queue<std::function<void()>> execution_queue_;\r
 133 };\r
 134 \r
 135 }