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  1. /*
  2.   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  3.   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
  4.   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
  5.   Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
  6.  
  7.   Stockfish is free software: you can redistribute it and/or modify
  8.   it under the terms of the GNU General Public License as published by
  9.   the Free Software Foundation, either version 3 of the License, or
  10.   (at your option) any later version.
  11.  
  12.   Stockfish is distributed in the hope that it will be useful,
  13.   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.   GNU General Public License for more details.
  16.  
  17.   You should have received a copy of the GNU General Public License
  18.   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19. */
  20.  
  21. #ifndef THREAD_H_INCLUDED
  22. #define THREAD_H_INCLUDED
  23.  
  24. #include <atomic>
  25. #include <condition_variable>
  26. #include <mutex>
  27. #include <thread>
  28. #include <vector>
  29.  
  30. #include "material.h"
  31. #include "movepick.h"
  32. #include "pawns.h"
  33. #include "position.h"
  34. #include "search.h"
  35. #include "thread_win32.h"
  36.  
  37.  
  38. /// Thread class keeps together all the thread-related stuff. We use
  39. /// per-thread pawn and material hash tables so that once we get a
  40. /// pointer to an entry its life time is unlimited and we don't have
  41. /// to care about someone changing the entry under our feet.
  42.  
  43. class Thread {
  44.  
  45.   Mutex mutex;
  46.   ConditionVariable cv;
  47.   size_t idx;
  48.   bool exit = false, searching = true; // Set before starting std::thread
  49.   std::thread stdThread;
  50.  
  51. public:
  52.   explicit Thread(size_t);
  53.   virtual ~Thread();
  54.   virtual void search();
  55.   void clear();
  56.   void idle_loop();
  57.   void start_searching();
  58.   void wait_for_search_finished();
  59.  
  60.   Pawns::Table pawnsTable;
  61.   Material::Table materialTable;
  62.   Endgames endgames;
  63.   size_t pvIdx, pvLast;
  64.   int selDepth, nmpMinPly;
  65.   Color nmpColor;
  66.   std::atomic<uint64_t> nodes, tbHits;
  67.  
  68.   Position rootPos;
  69.   Search::RootMoves rootMoves;
  70.   Depth rootDepth, completedDepth;
  71.   CounterMoveHistory counterMoves;
  72.   ButterflyHistory mainHistory;
  73.   CapturePieceToHistory captureHistory;
  74.   ContinuationHistory continuationHistory;
  75.   Score contempt;
  76. };
  77.  
  78.  
  79. /// MainThread is a derived class specific for main thread
  80.  
  81. struct MainThread : public Thread {
  82.  
  83.   using Thread::Thread;
  84.  
  85.   void search() override;
  86.   void check_time();
  87.  
  88.   double bestMoveChanges, previousTimeReduction;
  89.   Value previousScore;
  90.   int callsCnt;
  91. };
  92.  
  93.  
  94. /// ThreadPool struct handles all the threads-related stuff like init, starting,
  95. /// parking and, most importantly, launching a thread. All the access to threads
  96. /// is done through this class.
  97.  
  98. struct ThreadPool : public std::vector<Thread*> {
  99.  
  100.   void start_thinking(Position&, StateListPtr&, const Search::LimitsType&, bool = false);
  101.   void clear();
  102.   void set(size_t);
  103.  
  104.   MainThread* main()        const { return static_cast<MainThread*>(front()); }
  105.   uint64_t nodes_searched() const { return accumulate(&Thread::nodes); }
  106.   uint64_t tb_hits()        const { return accumulate(&Thread::tbHits); }
  107.  
  108.   std::atomic_bool stop, ponder, stopOnPonderhit;
  109.  
  110. private:
  111.   StateListPtr setupStates;
  112.  
  113.   uint64_t accumulate(std::atomic<uint64_t> Thread::* member) const {
  114.  
  115.     uint64_t sum = 0;
  116.     for (Thread* th : *this)
  117.         sum += (th->*member).load(std::memory_order_relaxed);
  118.     return sum;
  119.   }
  120. };
  121.  
  122. extern ThreadPool Threads;
  123.  
  124. #endif // #ifndef THREAD_H_INCLUDED
  125.