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 "enum_class.h"
  26 #include "log.h"
  27 #include "blocking_bounded_queue_adapter.h"
  28 #include "blocking_priority_queue.h"
  29
  30
  31 #include <tbb/atomic.h>
  32 #include <tbb/concurrent_priority_queue.h>
  33
  34 #include <boost/thread.hpp>
  35 #include <boost/optional.hpp>
  36 #include <boost/assign/list_of.hpp>
  37
  38 #include <functional>
  39
  40 namespace caspar {
  41
  42 struct task_priority_def
  43 {
  44         enum type
  45         {
  46                 lowest_priority = 0,
  47                 lower_priority,
  48                 low_priority,
  49                 normal_priority,
  50                 high_priority,
  51                 higher_priority
  52         };
  53 };
  54 typedef enum_class<task_priority_def> task_priority;
  55
  56 class executor sealed
  57 {
  58         executor(const executor&);
  59         executor& operator=(const executor&);
  60
  61         typedef blocking_priority_queue<std::function<void()>, task_priority>   function_queue_t;
  62
  63         const std::wstring                                                                                      name_;
  64         tbb::atomic<bool>                                                                                       is_running_;
  65         boost::thread                                                                                           thread_;
  66         function_queue_t                                                                                        execution_queue_;
  67
  68 public:
  69         executor(const std::wstring& name)
  70                 : name_(name)
  71                 , execution_queue_(512, boost::assign::list_of
  72                                 (task_priority::lowest_priority)
  73                                 (task_priority::lower_priority)
  74                                 (task_priority::low_priority)
  75                                 (task_priority::normal_priority)
  76                                 (task_priority::high_priority)
  77                                 (task_priority::higher_priority))
  78         {
  79                 is_running_ = true;
  80                 thread_ = boost::thread([this]{run();});
  81         }
  82
  83         ~executor()
  84         {
  85                 try
  86                 {
  87                         internal_begin_invoke([=]
  88                         {
  89                                 is_running_ = false;
  90                         }).wait();
  91                 }
  92                 catch(...)
  93                 {
  94                         CASPAR_LOG_CURRENT_EXCEPTION();
  95                 }
  96
  97                 thread_.join();
  98         }
  99
 100         template<typename Func>
 101         auto begin_invoke(Func&& func, task_priority priority = task_priority::normal_priority) -> boost::unique_future<decltype(func())> // noexcept
 102         {
 103                 if(!is_running_)
 104                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("executor not running.") << source_info(name_));
 105
 106                 return internal_begin_invoke(std::forward<Func>(func), priority);
 107         }
 108
 109         template<typename Func>
 110         auto invoke(Func&& func, task_priority prioriy = task_priority::normal_priority) -> decltype(func()) // noexcept
 111         {
 112                 if(is_current())  // Avoids potential deadlock.
 113                         return func();
 114
 115                 return begin_invoke(std::forward<Func>(func), prioriy).get();
 116         }
 117
 118         void yield(task_priority minimum_priority)
 119         {
 120                 if(!is_current())
 121                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("Executor can only yield inside of thread context.")  << source_info(name_));
 122
 123                 std::function<void ()> func;
 124
 125                 while (execution_queue_.try_pop(func, minimum_priority))
 126                         func();
 127         }
 128
 129         void set_capacity(function_queue_t::size_type capacity)
 130         {
 131                 execution_queue_.set_capacity(capacity);
 132         }
 133
 134         function_queue_t::size_type capacity() const
 135         {
 136                 return execution_queue_.capacity();
 137         }
 138
 139         void clear()
 140         {
 141                 std::function<void ()> func;
 142                 while(execution_queue_.try_pop(func));
 143         }
 144
 145         void stop()
 146         {
 147                 invoke([this]
 148                 {
 149                         is_running_ = false;
 150                 });
 151         }
 152
 153         void wait()
 154         {
 155                 invoke([]{}, task_priority::lowest_priority);
 156         }
 157
 158         function_queue_t::size_type size() const
 159         {
 160                 return execution_queue_.size();
 161         }
 162
 163         bool is_running() const
 164         {
 165                 return is_running_;
 166         }
 167
 168         bool is_current() const
 169         {
 170                 return boost::this_thread::get_id() == thread_.get_id();
 171         }
 172
 173 private:
 174
 175         std::wstring print() const
 176         {
 177                 return L"executor[" + name_ + L"]";
 178         }
 179
 180         template<typename Func>
 181         auto internal_begin_invoke(
 182                 Func&& func,
 183                 task_priority priority = task_priority::normal_priority) -> boost::unique_future<decltype(func())> // noexcept
 184         {
 185                 typedef typename std::remove_reference<Func>::type      function_type;
 186                 typedef decltype(func())                                                        result_type;
 187                 typedef boost::packaged_task<result_type>                       task_type;
 188
 189                 std::unique_ptr<task_type> task;
 190
 191                 // Use pointers since the boost thread library doesn't fully support move semantics.
 192
 193                 auto raw_func2 = new function_type(std::forward<Func>(func));
 194                 try
 195                 {
 196                         task.reset(new task_type([raw_func2]() -> result_type
 197                         {
 198                                 std::unique_ptr<function_type> func2(raw_func2);
 199                                 return (*func2)();
 200                         }));
 201                 }
 202                 catch(...)
 203                 {
 204                         delete raw_func2;
 205                         throw;
 206                 }
 207
 208                 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.
 209                 {
 210                         try
 211                         {
 212                                 if(is_current())  // Avoids potential deadlock.
 213                                         my_task();
 214                         }
 215                         catch(boost::task_already_started&){}
 216                 }));
 217
 218                 auto future = task->get_future();
 219
 220                 auto raw_task = task.release();
 221                 auto function = [raw_task]
 222                 {
 223                         std::unique_ptr<task_type> task(raw_task);
 224                         try
 225                         {
 226                                 (*task)();
 227                         }
 228                         catch(boost::task_already_started&){}
 229                 };
 230
 231                 if (!execution_queue_.try_push(priority, function))
 232                 {
 233                         CASPAR_LOG(debug) << print() << L" Overflow. Blocking caller.";
 234                         execution_queue_.push(priority, function);
 235                 }
 236
 237                 return std::move(future);
 238         }
 239
 240         void run() // noexcept
 241         {
 242                 win32_exception::install_handler();
 243                 while(is_running_)
 244                 {
 245                         try
 246                         {
 247                                 std::function<void ()> func;
 248                                 execution_queue_.pop(func);
 249                                 func();
 250                         }
 251                         catch(...)
 252                         {
 253                                 CASPAR_LOG_CURRENT_EXCEPTION();
 254                         }
 255                 }
 256         }
 257 };
 258
 259 }