/*
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 = 32;
-const int MAX_SPLITPOINTS_PER_THREAD = 8;
+struct Thread;
-class Thread;
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
+
+/// Spinlock class wraps low level atomic operations to provide spin lock functionality
+
+class Spinlock {
+
+ std::atomic_flag lock;
+
+public:
+ Spinlock() { std::atomic_flag_clear(&lock); }
+ void acquire() { while (lock.test_and_set(std::memory_order_acquire)) {} }
+ void release() { lock.clear(std::memory_order_release); }
+};
+
+
+/// 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
- Lock lock;
- 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 {
- Thread(const Thread&); // Only declared to disable the default ones
- Thread& operator=(const Thread&); // that are not suitable in this case.
-
- typedef void (Thread::* Fn) ();
-
-public:
- Thread(Fn fn);
- ~Thread();
-
- void wake_up();
+ Thread();
+ virtual void idle_loop();
bool cutoff_occurred() const;
- bool is_available_to(const Thread& master) const;
- void idle_loop(SplitPoint* sp_master);
- void idle_loop() { idle_loop(NULL); } // Hack to allow storing in start_fn
- void main_loop();
- void timer_loop();
- void wait_for_stop_or_ponderhit();
+ bool available_to(const Thread* master) 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];
- MaterialTable materialTable;
- PawnTable pawnTable;
- int idx;
+ Pawns::Table pawnsTable;
+ Material::Table materialTable;
+ Endgames endgames;
+ Position* activePosition;
+ size_t idx;
int maxPly;
- Lock sleepLock;
- WaitCondition sleepCond;
- NativeHandle handle;
- Fn start_fn;
- SplitPoint* volatile curSplitPoint;
- volatile int splitPointsCnt;
- volatile bool is_searching;
- volatile bool do_sleep;
- volatile bool do_exit;
+ SplitPoint* volatile activeSplitPoint;
+ volatile size_t splitPointsSize;
+ volatile bool searching;
+};
+
+
+/// 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();
+ volatile bool thinking = true; // Avoid a race with start_thinking()
+};
+
+struct TimerThread : public ThreadBase {
+
+ static const int Resolution = 5; // Millisec between two check_time() calls
+
+ virtual void idle_loop();
+
+ bool run = false;
};
-/// ThreadsManager 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 ThreadsManager {
- /* As long as the single ThreadsManager object is defined as a global we don't
- need to explicitly initialize to zero its data members because variables with
- static storage duration are automatically set to zero before enter main()
- */
-public:
- void init(); // No c'tor becuase Threads is static and we need engine initialized
- ~ThreadsManager();
+struct ThreadPool : public std::vector<Thread*> {
- Thread& operator[](int id) { return *threads[id]; }
- bool use_sleeping_threads() const { return useSleepingThreads; }
- int min_split_depth() const { return minimumSplitDepth; }
- int size() const { return (int)threads.size(); }
- Thread* main_thread() { return threads[0]; }
+ 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.
- void wake_up() const;
- void sleep() const;
+ MainThread* main() { return static_cast<MainThread*>(at(0)); }
void read_uci_options();
- bool available_slave_exists(const Thread& master) const;
- void set_timer(int msec);
- void wait_for_search_finished();
- void start_searching(const Position& pos, const Search::LimitsType& limits,
- const std::vector<Move>& searchMoves);
-
- 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;
-
- std::vector<Thread*> threads;
- Thread* timer;
- Lock splitLock;
- WaitCondition sleepCond;
+ Thread* available_slave(const Thread* master) const;
+ void wait_for_think_finished();
+ void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
+
Depth minimumSplitDepth;
- int maxThreadsPerSplitPoint;
- bool useSleepingThreads;
+ Spinlock spinlock;
+ std::condition_variable sleepCondition;
+ TimerThread* timer;
};
-extern ThreadsManager Threads;
+extern ThreadPool Threads;
-#endif // !defined(THREAD_H_INCLUDED)
+#endif // #ifndef THREAD_H_INCLUDED
projects / stockfish / blobdiff