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                 try
  83                 {
  84                         internal_begin_invoke([=]
  85                         {
  86                                 is_running_ = false;
  87                         }).wait();
  88                 }
  89                 catch(...)
  90                 {
  91                         CASPAR_LOG_CURRENT_EXCEPTION();
  92                 }
  93
  94                 join();
  95         }
  96
  97         void join()
  98         {
  99                 thread_.join();
 100         }
 101
 102         template<typename Func>
 103         auto begin_invoke(Func&& func, task_priority priority = task_priority::normal_priority) -> std::future<decltype(func())> // noexcept
 104         {
 105                 if(!is_running_)
 106                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("executor not running.") << source_info(name_));
 107
 108                 return internal_begin_invoke(std::forward<Func>(func), priority);
 109         }
 110
 111         template<typename Func>
 112         auto invoke(Func&& func, task_priority prioriy = task_priority::normal_priority) -> decltype(func()) // noexcept
 113         {
 114                 if(is_current())  // Avoids potential deadlock.
 115                         return func();
 116
 117                 return begin_invoke(std::forward<Func>(func), prioriy).get();
 118         }
 119
 120         void yield(task_priority minimum_priority)
 121         {
 122                 if(!is_current())
 123                         CASPAR_THROW_EXCEPTION(invalid_operation() << msg_info("Executor can only yield inside of thread context.")  << source_info(name_));
 124
 125                 std::function<void ()> func;
 126
 127                 while (execution_queue_.try_pop(func, minimum_priority))
 128                         func();
 129         }
 130
 131         void set_capacity(function_queue_t::size_type capacity)
 132         {
 133                 execution_queue_.set_capacity(capacity);
 134         }
 135
 136         function_queue_t::size_type capacity() const
 137         {
 138                 return execution_queue_.capacity();
 139         }
 140
 141         bool is_full() const
 142         {
 143                 return execution_queue_.space_available() == 0;
 144         }
 145
 146         void clear()
 147         {
 148                 std::function<void ()> func;
 149                 while(execution_queue_.try_pop(func));
 150         }
 151
 152         void stop()
 153         {
 154                 invoke([this]
 155                 {
 156                         is_running_ = false;
 157                 });
 158         }
 159
 160         void wait()
 161         {
 162                 invoke([]{}, task_priority::lowest_priority);
 163         }
 164
 165         function_queue_t::size_type size() const
 166         {
 167                 return execution_queue_.size();
 168         }
 169
 170         bool is_running() const
 171         {
 172                 return is_running_;
 173         }
 174
 175         bool is_current() const
 176         {
 177                 return boost::this_thread::get_id() == thread_.get_id();
 178         }
 179
 180 private:
 181
 182         std::wstring print() const
 183         {
 184                 return L"executor[" + name_ + L"]";
 185         }
 186
 187         template<typename Func>
 188         auto internal_begin_invoke(
 189                 Func&& func,
 190                 task_priority priority = task_priority::normal_priority) -> std::future<decltype(func())> // noexcept
 191         {
 192                 typedef typename std::remove_reference<Func>::type      function_type;
 193                 typedef decltype(func())                                                        result_type;
 194                 typedef std::packaged_task<result_type()>                       task_type;
 195
 196                 std::shared_ptr<task_type> task;
 197
 198                 // Use pointers since the boost thread library doesn't fully support move semantics.
 199
 200                 auto raw_func2 = new function_type(std::forward<Func>(func));
 201                 try
 202                 {
 203                         task.reset(new task_type([raw_func2]() -> result_type
 204                         {
 205                                 std::unique_ptr<function_type> func2(raw_func2);
 206                                 return (*func2)();
 207                         }));
 208                 }
 209                 catch(...)
 210                 {
 211                         delete raw_func2;
 212                         throw;
 213                 }
 214
 215                 auto future = task->get_future().share();
 216                 auto function = [task]
 217                 {
 218                         try
 219                         {
 220                                 (*task)();
 221                         }
 222                         catch(std::future_error&){}
 223                 };
 224
 225                 if (!execution_queue_.try_push(priority, function))
 226                 {
 227                         CASPAR_LOG(debug) << print() << L" Overflow. Blocking caller.";
 228                         execution_queue_.push(priority, function);
 229                 }
 230
 231                 return std::async(std::launch::deferred, [=]() mutable -> result_type
 232                 {
 233                         if (!is_ready(future) && is_current()) // Avoids potential deadlock.
 234                         {
 235                                 function();
 236                         }
 237
 238                         return future.get();
 239                 });
 240         }
 241
 242         void run() // noexcept
 243         {
 244                 ensure_gpf_handler_installed_for_thread(u8(name_).c_str());
 245                 while(is_running_)
 246                 {
 247                         try
 248                         {
 249                                 std::function<void ()> func;
 250                                 execution_queue_.pop(func);
 251                                 func();
 252                         }
 253                         catch(...)
 254                         {
 255                                 CASPAR_LOG_CURRENT_EXCEPTION();
 256                         }
 257                 }
 258         }
 259 };
 260
 261 }