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 ThreadBase() : exit(false) {}
77 virtual ~ThreadBase() {}
78 virtual void idle_loop() = 0;
80 void wait_for(volatile const bool& b);
82 std::thread nativeThread;
84 std::condition_variable sleepCondition;
89 /// Thread struct keeps together all the thread related stuff like locks, state
90 /// and especially split points. We also use per-thread pawn and material hash
91 /// tables so that once we get a pointer to an entry its life time is unlimited
92 /// and we don't have to care about someone changing the entry under our feet.
94 struct Thread : public ThreadBase {
97 virtual void idle_loop();
98 bool cutoff_occurred() const;
99 bool available_to(const Thread* master) const;
101 void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
102 Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
104 SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
105 Pawns::Table pawnsTable;
106 Material::Table materialTable;
108 Position* activePosition;
111 SplitPoint* volatile activeSplitPoint;
112 volatile int splitPointsSize;
113 volatile bool searching;
117 /// MainThread and TimerThread are derived classes used to characterize the two
118 /// special threads: the main one and the recurring timer.
120 struct MainThread : public Thread {
121 MainThread() : thinking(true) {} // Avoid a race with start_thinking()
122 virtual void idle_loop();
123 volatile bool thinking;
126 struct TimerThread : public ThreadBase {
128 static const int Resolution = 5; // Millisec between two check_time() calls
130 TimerThread() : run(false) {}
131 virtual void idle_loop();
137 /// ThreadPool struct handles all the threads related stuff like init, starting,
138 /// parking and, most importantly, launching a slave thread at a split point.
139 /// All the access to shared thread data is done through this class.
141 struct ThreadPool : public std::vector<Thread*> {
143 void init(); // No c'tor and d'tor, threads rely on globals that should be
144 void exit(); // initialized and are valid during the whole thread lifetime.
146 MainThread* main() { return static_cast<MainThread*>(at(0)); }
147 void read_uci_options();
148 Thread* available_slave(const Thread* master) const;
149 void wait_for_think_finished();
150 void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
152 Depth minimumSplitDepth;
154 std::condition_variable sleepCondition;
158 extern ThreadPool Threads;
160 #endif // #ifndef THREAD_H_INCLUDED