/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#if !defined(THREAD_H_INCLUDED)
+#ifndef THREAD_H_INCLUDED
#define THREAD_H_INCLUDED
+#include <atomic>
+#include <bitset>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
#include <vector>
#include "material.h"
#include "position.h"
#include "search.h"
-const int MAX_THREADS = 64; // Because SplitPoint::slavesMask is a uint64_t
-const int MAX_SPLITPOINTS_PER_THREAD = 8;
+struct Thread;
-struct Mutex {
- Mutex() { lock_init(l); }
- ~Mutex() { lock_destroy(l); }
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
- void lock() { lock_grab(l); }
- void unlock() { lock_release(l); }
-private:
- friend struct ConditionVariable;
+/// Spinlock class wraps low level atomic operations to provide a spin lock
- Lock l;
-};
-
-struct ConditionVariable {
- ConditionVariable() { cond_init(c); }
- ~ConditionVariable() { cond_destroy(c); }
+class Spinlock {
- void wait(Mutex& m) { cond_wait(c, m.l); }
- void wait_for(Mutex& m, int ms) { timed_wait(c, m.l, ms); }
- void notify_one() { cond_signal(c); }
+ std::atomic_int lock;
-private:
- WaitCondition c;
+public:
+ Spinlock() { lock = 1; } // Init here to workaround a bug with MSVC 2013
+ void acquire() {
+ while (lock.fetch_sub(1, std::memory_order_acquire) != 1)
+ while (lock.load(std::memory_order_relaxed) <= 0) {}
+ }
+ void release() { lock.store(1, std::memory_order_release); }
};
-class Thread;
+
+/// SplitPoint struct stores information shared by the threads searching in
+/// parallel below the same split point. It is populated at splitting time.
struct SplitPoint {
// Const data after split point has been setup
const Position* pos;
- const Search::Stack* ss;
+ Search::Stack* ss;
+ Thread* master;
Depth depth;
Value beta;
int nodeType;
- Thread* master;
- Move threatMove;
+ bool cutNode;
// Const pointers to shared data
- MovePicker* mp;
- SplitPoint* parent;
-
- // Shared data
- Mutex mutex;
- Position* activePositions[MAX_THREADS];
- volatile uint64_t slavesMask;
- volatile int64_t nodes;
+ MovePicker* movePicker;
+ SplitPoint* parentSplitPoint;
+
+ // Shared variable data
+ Spinlock spinlock;
+ std::bitset<MAX_THREADS> slavesMask;
+ volatile bool allSlavesSearching;
+ volatile uint64_t nodes;
volatile Value alpha;
volatile Value bestValue;
volatile Move bestMove;
};
+/// ThreadBase struct is the base of the hierarchy from where we derive all the
+/// specialized thread classes.
+
+struct ThreadBase {
+
+ virtual ~ThreadBase() = default;
+ virtual void idle_loop() = 0;
+ void notify_one();
+ void wait_for(volatile const bool& b);
+
+ std::thread nativeThread;
+ std::mutex mutex;
+ std::condition_variable sleepCondition;
+ volatile bool exit = false;
+};
+
+
/// Thread struct keeps together all the thread related stuff like locks, state
/// and especially split points. We also use per-thread pawn and material hash
/// tables so that once we get a pointer to an entry its life time is unlimited
/// and we don't have to care about someone changing the entry under our feet.
-class Thread {
+struct Thread : public ThreadBase {
-public:
Thread();
- virtual ~Thread();
-
virtual void idle_loop();
- void notify_one();
bool cutoff_occurred() const;
- bool is_available_to(Thread* master) const;
- void wait_for(volatile const bool& b);
+ bool can_join(const SplitPoint* sp) const;
+
+ void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
+ Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
+ Pawns::Table pawnsTable;
Material::Table materialTable;
Endgames endgames;
- Pawns::Table pawnsTable;
+ Position* activePosition;
size_t idx;
int maxPly;
- Mutex mutex;
- ConditionVariable sleepCondition;
- NativeHandle handle;
- SplitPoint* volatile curSplitPoint;
- volatile int splitPointsCnt;
- volatile bool is_searching;
- volatile bool do_exit;
+ SplitPoint* volatile activeSplitPoint;
+ volatile size_t splitPointsSize;
+ volatile bool searching;
};
-struct TimerThread : public Thread {
- TimerThread() : msec(0) {}
+
+/// MainThread and TimerThread are derived classes used to characterize the two
+/// special threads: the main one and the recurring timer.
+
+struct MainThread : public Thread {
virtual void idle_loop();
- int msec;
+ volatile bool thinking = true; // Avoid a race with start_thinking()
};
-struct MainThread : public Thread {
- MainThread() : is_finished(false) {} // Avoid a race with start_searching()
+struct TimerThread : public ThreadBase {
+
+ static const int Resolution = 5; // Millisec between two check_time() calls
+
virtual void idle_loop();
- volatile bool is_finished;
+
+ bool run = false;
};
-/// ThreadPool class handles all the threads related stuff like init, starting,
-/// parking and, the most important, launching a slave thread at a split point.
+/// ThreadPool struct handles all the threads related stuff like init, starting,
+/// parking and, most importantly, launching a slave thread at a split point.
/// All the access to shared thread data is done through this class.
-class ThreadPool {
-
-public:
- void init(); // No c'tor and d'tor, threads rely on globals that should
- void exit(); // be initialized and valid during the whole thread lifetime.
+struct ThreadPool : public std::vector<Thread*> {
- Thread& operator[](size_t id) { return *threads[id]; }
- int min_split_depth() const { return minimumSplitDepth; }
- size_t size() const { return threads.size(); }
- MainThread* main_thread() { return static_cast<MainThread*>(threads[0]); }
- TimerThread* timer_thread() { return timer; }
+ void init(); // No c'tor and d'tor, threads rely on globals that should be
+ void exit(); // initialized and are valid during the whole thread lifetime.
+ MainThread* main() { return static_cast<MainThread*>(at(0)); }
void read_uci_options();
- bool available_slave_exists(Thread* master) const;
- void wait_for_search_finished();
- void start_searching(const Position&, const Search::LimitsType&,
- const std::vector<Move>&, Search::StateStackPtr&);
-
- template <bool Fake>
- Value split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value bestValue, Move* bestMove,
- Depth depth, Move threatMove, int moveCount, MovePicker& mp, int nodeType);
-private:
- friend class Thread;
- friend struct MainThread;
- friend void check_time();
-
- std::vector<Thread*> threads;
- TimerThread* timer;
- Mutex mutex;
- ConditionVariable sleepCondition;
+ Thread* available_slave(const SplitPoint* sp) const;
+ void wait_for_think_finished();
+ void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
+
Depth minimumSplitDepth;
- int maxThreadsPerSplitPoint;
-public:
- bool sleepWhileIdle;
+ Spinlock spinlock;
+ std::condition_variable sleepCondition;
+ TimerThread* timer;
};
extern ThreadPool Threads;
-#endif // !defined(THREAD_H_INCLUDED)
+#endif // #ifndef THREAD_H_INCLUDED
projects / stockfish / blobdiff