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         virtual ~executor()\r
  28         {\r
  29                 wait();\r
  30                 stop();\r
  31                 if(boost::this_thread::get_id() != thread_.get_id())\r
  32                         thread_.join();\r
  33         }\r
  34 \r
  35         void set_capacity(size_t capacity)\r
  36         {\r
  37                 execution_queue_.set_capacity(capacity);\r
  38         }\r
  39 \r
  40         void start() // noexcept\r
  41         {\r
  42                 if(is_running_.fetch_and_store(true))\r
  43                         return;\r
  44                 thread_ = boost::thread(f_);\r
  45                 try\r
  46                 {\r
  47                         execution_queue_.clear();\r
  48                 }\r
  49                 catch(boost::broken_promise&){}\r
  50         }\r
  51                         \r
  52         void stop() // noexcept\r
  53         {\r
  54                 is_running_ = false;    \r
  55                 execution_queue_.push([]{});\r
  56         }\r
  57 \r
  58         void wait()\r
  59         {\r
  60                 invoke([]{});\r
  61         }\r
  62 \r
  63         void clear()\r
  64         {\r
  65                 std::function<void()> func;\r
  66                 while(execution_queue_.try_pop(func)){}\r
  67         }\r
  68                         \r
  69         template<typename Func>\r
  70         auto begin_invoke(Func&& func) -> boost::unique_future<decltype(func())> // noexcept\r
  71         {       \r
  72                 typedef boost::packaged_task<decltype(func())> task_type;\r
  73                                 \r
  74                 auto task = task_type(std::forward<Func>(func));\r
  75                 auto future = task.get_future();\r
  76                 \r
  77                 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
  78                 {\r
  79                         try\r
  80                         {\r
  81                                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
  82                                         my_task();\r
  83                         }\r
  84                         catch(boost::task_already_started&){}\r
  85                 }));\r
  86                                 \r
  87                 struct task_adaptor_t\r
  88                 {\r
  89                         task_adaptor_t(const task_adaptor_t& other) : task(std::move(other.task)){}\r
  90                         task_adaptor_t(task_type&& task) : task(std::move(task)){}\r
  91                         void operator()() const { task(); }\r
  92                         mutable task_type task;\r
  93                 } task_adaptor(std::move(task));\r
  94 \r
  95                 execution_queue_.push([=]\r
  96                 {\r
  97                         try{task_adaptor();}\r
  98                         catch(boost::task_already_started&){}\r
  99                         catch(...){CASPAR_LOG_CURRENT_EXCEPTION();}\r
 100                 });\r
 101 \r
 102                 return std::move(future);               \r
 103         }\r
 104         \r
 105         template<typename Func>\r
 106         auto invoke(Func&& func) -> decltype(func())\r
 107         {\r
 108                 if(boost::this_thread::get_id() == thread_.get_id())  // Avoids potential deadlock.\r
 109                         return func();\r
 110                 \r
 111                 return begin_invoke(std::forward<Func>(func)).get();\r
 112         }\r
 113 \r
 114         tbb::concurrent_bounded_queue<std::function<void()>>::size_type size() const { return execution_queue_.size();  }\r
 115         bool empty() const              { return execution_queue_.empty();      }\r
 116         bool is_running() const { return is_running_;                           }       \r
 117                 \r
 118 private:\r
 119         \r
 120         void execute() // noexcept\r
 121         {\r
 122                 std::function<void()> func;\r
 123                 execution_queue_.pop(func);     \r
 124                 func();\r
 125         }\r
 126 \r
 127         void run() // noexcept\r
 128         {\r
 129                 win32_exception::install_handler();\r
 130                 while(is_running_)\r
 131                         execute();\r
 132         }\r
 133         \r
 134         std::function<void()> f_;\r
 135         boost::thread thread_;\r
 136         tbb::atomic<bool> is_running_;\r
 137         tbb::concurrent_bounded_queue<std::function<void()>> execution_queue_;\r
 138 };\r
 139 \r
 140 }