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
6 Stockfish 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.
11 Stockfish 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.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 #ifndef THREAD_H_INCLUDED
21 #define THREAD_H_INCLUDED
25 #include <condition_variable>
35 #include "thread_win32.h"
39 const size_t MAX_THREADS = 128;
42 /// ThreadBase struct is the base of the hierarchy from where we derive all the
43 /// specialized thread classes.
45 struct ThreadBase : public std::thread {
47 ThreadBase() { exit = false; }
48 virtual ~ThreadBase() = default;
49 virtual void idle_loop() = 0;
51 void wait(std::atomic<bool>& b);
52 void wait_while(std::atomic<bool>& b);
55 ConditionVariable sleepCondition;
56 std::atomic<bool> exit;
60 /// Thread struct keeps together all the thread related stuff like locks, state,
61 /// history and countermoves tables. We also use per-thread pawn and material hash
62 /// tables so that once we get a pointer to an entry its life time is unlimited
63 /// and we don't have to care about someone changing the entry under our feet.
65 struct Thread : public ThreadBase {
68 virtual void idle_loop();
69 void search(bool isMainThread = false);
71 Pawns::Table pawnsTable;
72 Material::Table materialTable;
76 std::atomic<bool> searching;
79 Search::RootMoveVector rootMoves;
81 Search::Stack stack[MAX_PLY+4];
83 MovesStats counterMoves;
87 /// MainThread and TimerThread are derived classes used to characterize the two
88 /// special threads: the main one and the recurring timer.
90 struct MainThread : public Thread {
91 MainThread() { thinking = true; } // Avoid a race with start_thinking()
92 virtual void idle_loop();
95 std::atomic<bool> thinking;
98 struct TimerThread : public ThreadBase {
100 static const int Resolution = 5; // Millisec between two check_time() calls
102 virtual void idle_loop();
108 /// ThreadPool struct handles all the threads related stuff like init, starting,
109 /// parking and, most importantly, launching a thread.
110 /// All the access to shared thread data is done through this class.
112 struct ThreadPool : public std::vector<Thread*> {
114 void init(); // No constructor and destructor, threads rely on globals that should
115 void exit(); // be initialized and valid during the whole thread lifetime.
117 MainThread* main() { return static_cast<MainThread*>(at(0)); }
118 void read_uci_options();
119 void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
120 int64_t nodes_searched();
124 extern ThreadPool Threads;
126 #endif // #ifndef THREAD_H_INCLUDED