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;
42 /// SplitPoint struct stores information shared by the threads searching in
43 /// parallel below the same split point. It is populated at splitting time.
47 // Const data after split point has been setup
56 // Const pointers to shared data
57 MovePicker* movePicker;
58 SplitPoint* parentSplitPoint;
60 // Shared variable data
62 std::bitset<MAX_THREADS> slavesMask;
63 volatile bool allSlavesSearching;
64 volatile uint64_t nodes;
66 volatile Value bestValue;
67 volatile Move bestMove;
68 volatile int moveCount;
73 /// ThreadBase struct is the base of the hierarchy from where we derive all the
74 /// specialized thread classes.
78 ThreadBase() : exit(false) {}
79 virtual ~ThreadBase() {}
80 virtual void idle_loop() = 0;
82 void wait_for(volatile const bool& b);
84 std::thread nativeThread;
86 std::condition_variable sleepCondition;
91 /// Thread struct keeps together all the thread related stuff like locks, state
92 /// and especially split points. We also use per-thread pawn and material hash
93 /// tables so that once we get a pointer to an entry its life time is unlimited
94 /// and we don't have to care about someone changing the entry under our feet.
96 struct Thread : public ThreadBase {
99 virtual void idle_loop();
100 bool cutoff_occurred() const;
101 bool available_to(const Thread* master) const;
103 void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
104 Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
106 SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
107 Pawns::Table pawnsTable;
108 Material::Table materialTable;
110 Position* activePosition;
113 SplitPoint* volatile activeSplitPoint;
114 volatile int splitPointsSize;
115 volatile bool searching;
119 /// MainThread and TimerThread are derived classes used to characterize the two
120 /// special threads: the main one and the recurring timer.
122 struct MainThread : public Thread {
123 MainThread() : thinking(true) {} // Avoid a race with start_thinking()
124 virtual void idle_loop();
125 volatile bool thinking;
128 struct TimerThread : public ThreadBase {
130 static const int Resolution = 5; // Millisec between two check_time() calls
132 TimerThread() : run(false) {}
133 virtual void idle_loop();
139 /// ThreadPool struct handles all the threads related stuff like init, starting,
140 /// parking and, most importantly, launching a slave thread at a split point.
141 /// All the access to shared thread data is done through this class.
143 struct ThreadPool : public std::vector<Thread*> {
145 void init(); // No c'tor and d'tor, threads rely on globals that should be
146 void exit(); // initialized and are valid during the whole thread lifetime.
148 MainThread* main() { return static_cast<MainThread*>(at(0)); }
149 void read_uci_options();
150 Thread* available_slave(const Thread* master) const;
151 void wait_for_think_finished();
152 void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
154 Depth minimumSplitDepth;
156 std::condition_variable sleepCondition;
160 extern ThreadPool Threads;
162 #endif // #ifndef THREAD_H_INCLUDED