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 size_t MAX_THREADS = 128;
38 const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
39 const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
41 /// SplitPoint struct stores information shared by the threads searching in
42 /// parallel below the same split point. It is populated at splitting time.
46 // Const data after split point has been setup
55 // Const pointers to shared data
56 MovePicker* movePicker;
57 SplitPoint* parentSplitPoint;
59 // Shared variable data
61 std::bitset<MAX_THREADS> slavesMask;
62 volatile bool allSlavesSearching;
63 volatile uint64_t nodes;
65 volatile Value bestValue;
66 volatile Move bestMove;
67 volatile int moveCount;
72 /// ThreadBase struct is the base of the hierarchy from where we derive all the
73 /// specialized thread classes.
77 virtual ~ThreadBase() = default;
78 virtual void idle_loop() = 0;
80 void wait_for(volatile const bool& b);
82 std::thread nativeThread;
84 std::condition_variable sleepCondition;
85 volatile bool exit = false;
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 size_t 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 virtual void idle_loop();
122 volatile bool thinking = true; // Avoid a race with start_thinking()
125 struct TimerThread : public ThreadBase {
127 static const int Resolution = 5; // Millisec between two check_time() calls
129 virtual void idle_loop();
135 /// ThreadPool struct handles all the threads related stuff like init, starting,
136 /// parking and, most importantly, launching a slave thread at a split point.
137 /// All the access to shared thread data is done through this class.
139 struct ThreadPool : public std::vector<Thread*> {
141 void init(); // No c'tor and d'tor, threads rely on globals that should be
142 void exit(); // initialized and are valid during the whole thread lifetime.
144 MainThread* main() { return static_cast<MainThread*>(at(0)); }
145 void read_uci_options();
146 Thread* available_slave(const Thread* master) const;
147 void wait_for_think_finished();
148 void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
150 Depth minimumSplitDepth;
152 std::condition_variable sleepCondition;
156 extern ThreadPool Threads;
158 #endif // #ifndef THREAD_H_INCLUDED