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
24 #include <condition_variable>
37 const int MAX_THREADS = 128;
38 const int MAX_SPLITPOINTS_PER_THREAD = 8;
40 /// SplitPoint struct stores information shared by the threads searching in
41 /// parallel below the same split point. It is populated at splitting time.
45 // Const data after split point has been setup
54 // Const pointers to shared data
55 MovePicker* movePicker;
56 SplitPoint* parentSplitPoint;
58 // Shared variable data
60 std::bitset<MAX_THREADS> slavesMask;
61 volatile bool allSlavesSearching;
62 volatile uint64_t nodes;
64 volatile Value bestValue;
65 volatile Move bestMove;
66 volatile int moveCount;
71 /// ThreadBase struct is the base of the hierarchy from where we derive all the
72 /// specialized thread classes.
76 virtual ~ThreadBase() = default;
77 virtual void idle_loop() = 0;
79 void wait_for(volatile const bool& b);
81 std::thread nativeThread;
83 std::condition_variable sleepCondition;
84 volatile bool exit = false;
88 /// Thread struct keeps together all the thread related stuff like locks, state
89 /// and especially split points. We also use per-thread pawn and material hash
90 /// tables so that once we get a pointer to an entry its life time is unlimited
91 /// and we don't have to care about someone changing the entry under our feet.
93 struct Thread : public ThreadBase {
96 virtual void idle_loop();
97 bool cutoff_occurred() const;
98 bool available_to(const Thread* master) const;
100 void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
101 Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
103 SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
104 Pawns::Table pawnsTable;
105 Material::Table materialTable;
107 Position* activePosition;
110 SplitPoint* volatile activeSplitPoint;
111 volatile int splitPointsSize;
112 volatile bool searching;
116 /// MainThread and TimerThread are derived classes used to characterize the two
117 /// special threads: the main one and the recurring timer.
119 struct MainThread : public Thread {
120 virtual void idle_loop();
121 volatile bool thinking = true; // Avoid a race with start_thinking()
124 struct TimerThread : public ThreadBase {
126 static const int Resolution = 5; // Millisec between two check_time() calls
128 virtual void idle_loop();
134 /// ThreadPool struct handles all the threads related stuff like init, starting,
135 /// parking and, most importantly, launching a slave thread at a split point.
136 /// All the access to shared thread data is done through this class.
138 struct ThreadPool : public std::vector<Thread*> {
140 void init(); // No c'tor and d'tor, threads rely on globals that should be
141 void exit(); // initialized and are valid during the whole thread lifetime.
143 MainThread* main() { return static_cast<MainThread*>(at(0)); }
144 void read_uci_options();
145 Thread* available_slave(const Thread* master) const;
146 void wait_for_think_finished();
147 void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
149 Depth minimumSplitDepth;
151 std::condition_variable sleepCondition;
155 extern ThreadPool Threads;
157 #endif // #ifndef THREAD_H_INCLUDED