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

   1 /*
   2 * Copyright (c) 2011 Sveriges Television AB <info@casparcg.com>
   3 *
   4 * This file is part of CasparCG (www.casparcg.com).
   5 *
   6 * CasparCG is free software: you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation, either version 3 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * CasparCG is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with CasparCG. If not, see <http://www.gnu.org/licenses/>.
  18 *
  19 * Author: Robert Nagy, ronag89@gmail.com
  20 */
  21
  22 #pragma once
  23
  24 #include "except.h"
  25 #include "log.h"
  26 #include "blocking_bounded_queue_adapter.h"
  27 #include "blocking_priority_queue.h"
  28 #include "future.h"
  29
  30 #include <tbb/atomic.h>
  31 #include <tbb/concurrent_priority_queue.h>
  32
  33 #include <boost/thread.hpp>
  34 #include <boost/optional.hpp>
  35
  36 #include <functional>
  37 #include <future>
  38
  39 namespace caspar {
  40
  41 enum class task_priority
  42 {
  43         lowest_priority = 0,
  44         lower_priority,
  45         low_priority,
  46         normal_priority,
  47         high_priority,
  48         higher_priority
  49 };
  50
  51 class executor final
  52 {
  53         executor(const executor&);
  54         executor& operator=(const executor&);
  55
  56         typedef blocking_priority_queue<std::function<void()>, task_priority>   function_queue_t;
  57
  58         const std::wstring                                                                                      name_;
  59         tbb::atomic<bool>                                                                                       is_running_;
  60         boost::thread                                                                                           thread_;
  61         function_queue_t                                                                                        execution_queue_;
  62
  63 public:
  64         executor(const std::wstring& name)
  65                 : name_(name)
  66                 , execution_queue_(512, std::vector<task_priority> {
  67                         task_priority::lowest_priority,
  68                         task_priority::lower_priority,
  69                         task_priority::low_priority,
  70                         task_priority::normal_priority,
  71                         task_priority::high_priority,
  72                         task_priority::higher_priority
  73                 })
  74         {
  75                 is_running_ = true;
  76                 thread_ = boost::thread([this]{run();});
  77         }
  78
  79         ~executor()
  80         {
  81                 try
  82                 {
  83                         internal_begin_invoke([=]
  84                         {
  85                                 is_running_ = false;
  86                         }).wait();
  87                 }
  88                 catch(...)
  89                 {
  90                         CASPAR_LOG_CURRENT_EXCEPTION();
  91                 }
  92
  93                 thread_.join();
  94         }
  95
  96         template<typename Func>
  97         auto begin_invoke(Func&& func, task_priority priority = task_priority::normal_priority) -> std::future<decltype(func())> // noexcept
  98         {
  99                 if(!is_running_)
 100                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("executor not running.") << source_info(name_));
 101
 102                 return internal_begin_invoke(std::forward<Func>(func), priority);
 103         }
 104
 105         template<typename Func>
 106         auto invoke(Func&& func, task_priority prioriy = task_priority::normal_priority) -> decltype(func()) // noexcept
 107         {
 108                 if(is_current())  // Avoids potential deadlock.
 109                         return func();
 110
 111                 return begin_invoke(std::forward<Func>(func), prioriy).get();
 112         }
 113
 114         void yield(task_priority minimum_priority)
 115         {
 116                 if(!is_current())
 117                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("Executor can only yield inside of thread context.")  << source_info(name_));
 118
 119                 std::function<void ()> func;
 120
 121                 while (execution_queue_.try_pop(func, minimum_priority))
 122                         func();
 123         }
 124
 125         void set_capacity(function_queue_t::size_type capacity)
 126         {
 127                 execution_queue_.set_capacity(capacity);
 128         }
 129
 130         function_queue_t::size_type capacity() const
 131         {
 132                 return execution_queue_.capacity();
 133         }
 134
 135         bool is_full() const
 136         {
 137                 return execution_queue_.space_available() == 0;
 138         }
 139
 140         void clear()
 141         {
 142                 std::function<void ()> func;
 143                 while(execution_queue_.try_pop(func));
 144         }
 145
 146         void stop()
 147         {
 148                 invoke([this]
 149                 {
 150                         is_running_ = false;
 151                 });
 152         }
 153
 154         void wait()
 155         {
 156                 invoke([]{}, task_priority::lowest_priority);
 157         }
 158
 159         function_queue_t::size_type size() const
 160         {
 161                 return execution_queue_.size();
 162         }
 163
 164         bool is_running() const
 165         {
 166                 return is_running_;
 167         }
 168
 169         bool is_current() const
 170         {
 171                 return boost::this_thread::get_id() == thread_.get_id();
 172         }
 173
 174 private:
 175
 176         std::wstring print() const
 177         {
 178                 return L"executor[" + name_ + L"]";
 179         }
 180
 181         template<typename Func>
 182         auto internal_begin_invoke(
 183                 Func&& func,
 184                 task_priority priority = task_priority::normal_priority) -> std::future<decltype(func())> // noexcept
 185         {
 186                 typedef typename std::remove_reference<Func>::type      function_type;
 187                 typedef decltype(func())                                                        result_type;
 188                 typedef std::packaged_task<result_type()>                       task_type;
 189
 190                 std::shared_ptr<task_type> task;
 191
 192                 // Use pointers since the boost thread library doesn't fully support move semantics.
 193
 194                 auto raw_func2 = new function_type(std::forward<Func>(func));
 195                 try
 196                 {
 197                         task.reset(new task_type([raw_func2]() -> result_type
 198                         {
 199                                 std::unique_ptr<function_type> func2(raw_func2);
 200                                 return (*func2)();
 201                         }));
 202                 }
 203                 catch(...)
 204                 {
 205                         delete raw_func2;
 206                         throw;
 207                 }
 208
 209                 auto future = task->get_future().share();
 210                 auto function = [task]
 211                 {
 212                         try
 213                         {
 214                                 (*task)();
 215                         }
 216                         catch(std::future_error&){}
 217                 };
 218
 219                 if (!execution_queue_.try_push(priority, function))
 220                 {
 221                         CASPAR_LOG(debug) << print() << L" Overflow. Blocking caller.";
 222                         execution_queue_.push(priority, function);
 223                 }
 224
 225                 return std::async(std::launch::deferred, [=]() mutable -> result_type
 226                 {
 227                         if (!is_ready(future) && is_current()) // Avoids potential deadlock.
 228                         {
 229                                 function();
 230                         }
 231
 232                         return future.get();
 233                 });
 234         }
 235
 236         void run() // noexcept
 237         {
 238                 win32_exception::install_handler();
 239                 while(is_running_)
 240                 {
 241                         try
 242                         {
 243                                 std::function<void ()> func;
 244                                 execution_queue_.pop(func);
 245                                 func();
 246                         }
 247                         catch(...)
 248                         {
 249                                 CASPAR_LOG_CURRENT_EXCEPTION();
 250                         }
 251                 }
 252         }
 253 };
 254
 255 }