2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2013 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
31 const int MAX_THREADS = 64; // Because SplitPoint::slavesMask is a uint64_t
32 const int MAX_SPLITPOINTS_PER_THREAD = 8;
35 Mutex() { lock_init(l); }
36 ~Mutex() { lock_destroy(l); }
38 void lock() { lock_grab(l); }
39 void unlock() { lock_release(l); }
42 friend struct ConditionVariable;
47 struct ConditionVariable {
48 ConditionVariable() { cond_init(c); }
49 ~ConditionVariable() { cond_destroy(c); }
51 void wait(Mutex& m) { cond_wait(c, m.l); }
52 void wait_for(Mutex& m, int ms) { timed_wait(c, m.l, ms); }
53 void notify_one() { cond_signal(c); }
63 // Const data after split point has been setup
65 const Search::Stack* ss;
73 // Const pointers to shared data
74 MovePicker* movePicker;
75 SplitPoint* parentSplitPoint;
79 volatile uint64_t slavesMask;
80 volatile int64_t nodes;
82 volatile Value bestValue;
83 volatile Move bestMove;
84 volatile int moveCount;
89 /// ThreadBase struct is the base of the hierarchy from where we derive all the
90 /// specialized thread classes.
94 ThreadBase() : exit(false) {}
95 virtual ~ThreadBase() {}
96 virtual void idle_loop() = 0;
98 void wait_for(volatile const bool& b);
101 ConditionVariable sleepCondition;
107 /// Thread struct keeps together all the thread related stuff like locks, state
108 /// and especially split points. We also use per-thread pawn and material hash
109 /// tables so that once we get a pointer to an entry its life time is unlimited
110 /// and we don't have to care about someone changing the entry under our feet.
112 struct Thread : public ThreadBase {
115 virtual void idle_loop();
116 bool cutoff_occurred() const;
117 bool available_to(const Thread* master) const;
120 void split(Position& pos, const Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
121 Depth depth, Move threatMove, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
123 SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
124 Material::Table materialTable;
126 Pawns::Table pawnsTable;
127 Position* activePosition;
130 SplitPoint* volatile activeSplitPoint;
131 volatile int splitPointsSize;
132 volatile bool searching;
136 /// MainThread and TimerThread are derived classes used to characterize the two
137 /// special threads: the main one and the recurring timer.
139 struct MainThread : public Thread {
140 MainThread() : thinking(true) {} // Avoid a race with start_thinking()
141 virtual void idle_loop();
142 volatile bool thinking;
145 struct TimerThread : public ThreadBase {
146 TimerThread() : run(false) {}
147 virtual void idle_loop();
149 static const int Resolution = 5; // msec between two check_time() calls
153 /// ThreadPool struct handles all the threads related stuff like init, starting,
154 /// parking and, most importantly, launching a slave thread at a split point.
155 /// All the access to shared thread data is done through this class.
157 struct ThreadPool : public std::vector<Thread*> {
159 void init(); // No c'tor and d'tor, threads rely on globals that should
160 void exit(); // be initialized and are valid during the whole thread lifetime.
162 MainThread* main() { return static_cast<MainThread*>((*this)[0]); }
163 void read_uci_options();
164 Thread* available_slave(const Thread* master) const;
165 void wait_for_think_finished();
166 void start_thinking(const Position&, const Search::LimitsType&,
167 const std::vector<Move>&, Search::StateStackPtr&);
170 Depth minimumSplitDepth;
171 size_t maxThreadsPerSplitPoint;
173 ConditionVariable sleepCondition;
177 extern ThreadPool Threads;
179 #endif // #ifndef THREAD_H_INCLUDED