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 "os/general_protection_fault.h"
  25 #include "except.h"
  26 #include "log.h"
  27 #include "blocking_bounded_queue_adapter.h"
  28 #include "blocking_priority_queue.h"
  29 #include "future.h"
  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
  37 #include <functional>
  38 #include <future>
  39
  40 namespace caspar {
  41
  42 enum class task_priority
  43 {
  44         lowest_priority = 0,
  45         lower_priority,
  46         low_priority,
  47         normal_priority,
  48         high_priority,
  49         higher_priority
  50 };
  51
  52 class executor final
  53 {
  54         executor(const executor&);
  55         executor& operator=(const executor&);
  56
  57         typedef blocking_priority_queue<std::function<void()>, task_priority>   function_queue_t;
  58
  59         const std::wstring                                                                                      name_;
  60         tbb::atomic<bool>                                                                                       is_running_;
  61         boost::thread                                                                                           thread_;
  62         function_queue_t                                                                                        execution_queue_;
  63
  64 public:
  65         executor(const std::wstring& name)
  66                 : name_(name)
  67                 , execution_queue_(512, std::vector<task_priority> {
  68                         task_priority::lowest_priority,
  69                         task_priority::lower_priority,
  70                         task_priority::low_priority,
  71                         task_priority::normal_priority,
  72                         task_priority::high_priority,
  73                         task_priority::higher_priority
  74                 })
  75         {
  76                 is_running_ = true;
  77                 thread_ = boost::thread([this]{run();});
  78         }
  79
  80         ~executor()
  81         {
  82                 CASPAR_LOG(trace) << L"Shutting down " << name_;
  83
  84                 try
  85                 {
  86                         if (is_running_)
  87                                 internal_begin_invoke([=]
  88                                 {
  89                                         is_running_ = false;
  90                                 }).wait();
  91                 }
  92                 catch(...)
  93                 {
  94                         CASPAR_LOG_CURRENT_EXCEPTION();
  95                 }
  96
  97                 join();
  98         }
  99
 100         void join()
 101         {
 102                 thread_.join();
 103         }
 104
 105         template<typename Func>
 106         auto begin_invoke(Func&& func, task_priority priority = task_priority::normal_priority) -> std::future<decltype(func())> // noexcept
 107         {
 108                 if(!is_running_)
 109                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("executor not running.") << source_info(name_));
 110
 111                 return internal_begin_invoke(std::forward<Func>(func), priority);
 112         }
 113
 114         template<typename Func>
 115         auto invoke(Func&& func, task_priority prioriy = task_priority::normal_priority) -> decltype(func()) // noexcept
 116         {
 117                 if(is_current())  // Avoids potential deadlock.
 118                         return func();
 119
 120                 return begin_invoke(std::forward<Func>(func), prioriy).get();
 121         }
 122
 123         void yield(task_priority minimum_priority)
 124         {
 125                 if(!is_current())
 126                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("Executor can only yield inside of thread context.")  << source_info(name_));
 127
 128                 std::function<void ()> func;
 129
 130                 while (execution_queue_.try_pop(func, minimum_priority))
 131                         func();
 132         }
 133
 134         void set_capacity(function_queue_t::size_type capacity)
 135         {
 136                 execution_queue_.set_capacity(capacity);
 137         }
 138
 139         function_queue_t::size_type capacity() const
 140         {
 141                 return execution_queue_.capacity();
 142         }
 143
 144         bool is_full() const
 145         {
 146                 return execution_queue_.space_available() == 0;
 147         }
 148
 149         void clear()
 150         {
 151                 std::function<void ()> func;
 152                 while(execution_queue_.try_pop(func));
 153         }
 154
 155         void stop()
 156         {
 157                 invoke([this]
 158                 {
 159                         is_running_ = false;
 160                 });
 161         }
 162
 163         void wait()
 164         {
 165                 invoke([]{}, task_priority::lowest_priority);
 166         }
 167
 168         function_queue_t::size_type size() const
 169         {
 170                 return execution_queue_.size();
 171         }
 172
 173         bool is_running() const
 174         {
 175                 return is_running_;
 176         }
 177
 178         bool is_current() const
 179         {
 180                 return boost::this_thread::get_id() == thread_.get_id();
 181         }
 182
 183         std::wstring name() const
 184         {
 185                 return name_;
 186         }
 187
 188 private:
 189
 190         std::wstring print() const
 191         {
 192                 return L"executor[" + name_ + L"]";
 193         }
 194
 195         template<typename Func>
 196         auto internal_begin_invoke(
 197                 Func&& func,
 198                 task_priority priority = task_priority::normal_priority) -> std::future<decltype(func())> // noexcept
 199         {
 200                 typedef typename std::remove_reference<Func>::type      function_type;
 201                 typedef decltype(func())                                                        result_type;
 202                 typedef std::packaged_task<result_type()>                       task_type;
 203
 204                 std::shared_ptr<task_type> task;
 205
 206                 // Use pointers since the boost thread library doesn't fully support move semantics.
 207
 208                 auto raw_func2 = new function_type(std::forward<Func>(func));
 209                 try
 210                 {
 211                         task.reset(new task_type([raw_func2]() -> result_type
 212                         {
 213                                 std::unique_ptr<function_type> func2(raw_func2);
 214                                 return (*func2)();
 215                         }));
 216                 }
 217                 catch(...)
 218                 {
 219                         delete raw_func2;
 220                         throw;
 221                 }
 222
 223                 auto future = task->get_future().share();
 224                 auto function = [task]
 225                 {
 226                         try
 227                         {
 228                                 (*task)();
 229                         }
 230                         catch(std::future_error&){}
 231                 };
 232
 233                 if (!execution_queue_.try_push(priority, function))
 234                 {
 235                         CASPAR_LOG(debug) << print() << L" Overflow. Blocking caller.";
 236                         execution_queue_.push(priority, function);
 237                 }
 238
 239                 return std::async(std::launch::deferred, [=]() mutable -> result_type
 240                 {
 241                         if (!is_ready(future) && is_current()) // Avoids potential deadlock.
 242                         {
 243                                 function();
 244                         }
 245
 246                         return future.get();
 247                 });
 248         }
 249
 250         void run() // noexcept
 251         {
 252                 ensure_gpf_handler_installed_for_thread(u8(name_).c_str());
 253                 while(is_running_)
 254                 {
 255                         try
 256                         {
 257                                 std::function<void ()> func;
 258                                 execution_queue_.pop(func);
 259                                 func();
 260                         }
 261                         catch(...)
 262                         {
 263                                 CASPAR_LOG_CURRENT_EXCEPTION();
 264                         }
 265                 }
 266         }
 267 };
 268
 269 }